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1. Fosse  T, Giraud-Morin  C, Madinier  I, Labia  R,     ( 2003 )

Sequence analysis and biochemical characterisation of chromosomal CAV-1 (Aeromonas caviae), the parental cephalosporinase of plasmid-mediated AmpC 'FOX' cluster.

FEMS microbiology letters 222 (1)
PMID : 12757951  :   DOI  :   10.1016/S0378-1097(03)00253-2    
Abstract >>
Aeromonas caviae CIP 74.32 was resistant to amoxicillin, ticarcillin and cephalothin, and susceptible to cefoxitin, cefotaxime, ceftazidime, aztreonam and imipenem. This strain produced a cephalosporinase (pI 7.2) and an oxacillinase (pI 8.5). The cephalosporinase gene cav-1 was cloned and sequenced. Unlike A. caviae donor, Escherichia coli pNCE50 transformant producing CAV-1 beta-lactamase was resistant to cefoxitin. The deduced protein sequence CAV-1 contained 382 amino acids, and shared >96% homology with FOX-1 to FOX-5 cephalosporinase. CAV-1 presented only two amino acid substitutions (Thr270Ser and Arg271Ala) with FOX-1. CAV-1 is the chromosomal putative ancestor of the FOX family, a cluster of class C/group 1 plasmidic cephalosporinases spreading in Klebsiella and E. coli clinical isolates via conjugative plasmids.
KeywordMeSH Terms
Bacterial Proteins
beta-Lactam Resistance
2. Pidiyar  VJ, Jangid  K, Dayananda  KM, Kaznowski  A, Gonzalez  JM, Patole  MS, Shouche  YS,     ( 2003 )

Phylogenetic affiliation of Aeromonas culicicola MTCC 3249(T) based on gyrB gene sequence and PCR-amplicon sequence analysis of cytolytic enterotoxin gene.

Systematic and applied microbiology 26 (2)
PMID : 12866846  :   DOI  :   10.1078/072320203322346047    
Abstract >>
We determined the gyrB gene sequences of all 17 hybridizations groups of Aeromonas. Phylogenetic trees showing the evolutionary relatedness of gyrB and 16S rRNA genes in the type strains of Aeromonas were compared. Using this approach, we determined the phylogenetic position of Aeromonas culicicola MTCC 3249(T), isolated from midgut of Culex quinquefasciatus. In the gyrB based-analysis A. culicicola MTCC 3249(T) grouped with A. veronii whereas, it grouped with A. jandaei in the 16S rRNA based tree. The number of nucleotide differences in 16S rRNA sequences was less than found with the gyrB sequence data. Most of the observed nucleotide differences in the gyrB gene were synonymous. The Cophenetic Correlation Coefficient (CCC) for gyrB sequences was 0.87 indicating this gene to be a better molecular chronometer compared to 16S rRNA for delineation of Aeromonas species. This strain was found to be positive for the cytolytic enterotoxin gene. PCR-Amplicon Sequence Analysis (PCR-ASA) of this gene showed that the isolate is affiliated to type I and is potentially pathogenic. These PCR-ASA results agreed in part with the gyrB sequence results.
KeywordMeSH Terms
Genes, Bacterial
3. Yáñez  MA, Catalán  V, Apráiz  D, Figueras  MJ, Martínez-Murcia  AJ,     ( 2003 )

Phylogenetic analysis of members of the genus Aeromonas based on gyrB gene sequences.

International journal of systematic and evolutionary microbiology 53 (Pt 3)
PMID : 12807216  :   DOI  :   10.1099/ijs.0.02443-0    
Abstract >>
The phylogenetic relationships of all known species of the genus Aeromonas were investigated by using the sequence of gyrB, a gene that encodes the B-subunit of DNA gyrase. Nucleotide sequences of gyrB were determined from 53 Aeromonas strains, including some new isolates, which were also characterized by analysis of the 16S rDNA variable regions. The results support the recognition of the family Aeromonadaceae, as distinct from Plesiomonas shigelloides and other enteric bacteria. This phylogenetic marker revealed strain groupings that are consistent with the taxonomic organization of all Aeromonas species described to date. In particular, gyrB results agreed with 16S rDNA analysis; moreover, the former showed a higher capacity to differentiate between species. The present analysis was useful for the elucidation of reported discrepancies between different DNA-DNA hybridization sets. Additionally, due to the sequence diversity found at the intraspecies level, gyrB is proposed as a useful target for simultaneous identification of species and strains. In conclusion, the gyrB gene has proved to be an excellent molecular chronometer for phylogenetic studies of the genus Aeromonas.
KeywordMeSH Terms
Phylogeny
Sequence Analysis, DNA
4. Hisano  T, Tsuge  T, Fukui  T, Iwata  T, Miki  K, Doi  Y,     ( 2003 )

Crystal structure of the (R)-specific enoyl-CoA hydratase from Aeromonas caviae involved in polyhydroxyalkanoate biosynthesis.

The Journal of biological chemistry 278 (1)
PMID : 12409309  :   DOI  :   10.1074/jbc.M205484200    
Abstract >>
The (R)-specific enoyl coenzyme A hydratase ((R)-hydratase) from Aeromonas caviae catalyzes the addition of a water molecule to trans-2-enoyl coenzyme A (CoA), with a chain-length of 4-6 carbons, to produce the corresponding (R)-3-hydroxyacyl-CoA. It forms a dimer of identical subunits with a molecular weight of about 14,000 and is involved in polyhydroxyalkanoate (PHA) biosynthesis. The crystal structure of the enzyme has been determined at 1.5-A resolution. The structure of the monomer consists of a five-stranded antiparallel beta-sheet and a central alpha-helix, folded into a so-called "hot dog" fold, with an overhanging segment. This overhang contains the conserved residues including the hydratase 2 motif residues. In dimeric form, two beta-sheets are associated to form an extended 10-stranded beta-sheet, and the overhangs obscure the putative active sites at the subunit interface. The active site is located deep within the substrate-binding tunnel, where Asp(31) and His(36) form a catalytic dyad. These residues are catalytically important as confirmed by site-directed mutagenesis and are possibly responsible for the activation of a water molecule and the protonation of a substrate molecule, respectively. Residues such as Leu(65) and Val(130) are situated at the bottom of the substrate-binding tunnel, defining the preference of the enzyme for the chain length of the substrate. These results provide target residues for protein engineering, which will enhance the significance of this enzyme in the production of novel PHA polymers. In addition, this study provides the first structural information of the (R)-hydratase family and may facilitate further functional studies for members of the family.
KeywordMeSH Terms
Protein Structure, Secondary
Protein Structure, Tertiary
5. Shen  GX, Shi  JP,     ( 1999 )

Cloning and Nucleotide Sequencing of Prolyl Endopeptidase Gene from Aeromonas punctata subsp. punctata.

Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 31 (5)
PMID : 12114972  :  
Abstract >>
Prolyl endopeptidase activity was found in Aeromonas punctata subsp. Punctata. The genomic DNA was partially digested with EcoRI and the recovered 8-16 kb DNA fragments were inserted into the EcoRI site of plasmid pUC19, and were transformated into Escherichia coli DH5alpha. The resulted clones were screened by using Benzyloxycarbonyl-Gly-Pro-beta-naphthylamide, the specific substrate of prolyl endopeptidase and a positive clone was obtained. The 12 kb insertion fragment of recombinant plasmid was digested with HincII and subcloned. The PEP gene was found in the 3.5 kb HincII/EcoRI fragment. Nucleotide sequence of the gene was completely sequenced by Auto Sequencer. The complete gene consisted of 2 073 bp corresponding to 690 amino acid residues with a calculated molecular weight of 76 467 Da. The amino acid sequence was 92.3% 53.2% 33.5% 33.2% and 20.5% homologous to those of Aeromonas hydrophila, Flavobacterium meningosepticum, porcine brain, human lymphocytes and Pyrococcus furiosus respectively. From a survey of sequence homology with other members of the prolyl endopeptidase family, the amino acid residues involved in the catalytic triad were deduced to be Ser(538) Asp(622) and His(657).
KeywordMeSH Terms
6. Goñi-Urriza  M, Arpin  C, Capdepuy  M, Dubois  V, Caumette  P, Quentin  C,     ( 2002 )

Type II topoisomerase quinolone resistance-determining regions of Aeromonas caviae, A. hydrophila, and A. sobria complexes and mutations associated with quinolone resistance.

Antimicrobial agents and chemotherapy 46 (2)
PMID : 11796341  :   DOI  :   10.1128/aac.46.2.350-359.2002     PMC  :   PMC127024    
Abstract >>
Most Aeromonas strains isolated from two European rivers were previously found to be resistant to nalidixic acid. In order to elucidate the mechanism of this resistance, 20 strains of Aeromonas caviae (n = 10), A. hydrophila (n = 5), and A. sobria (n = 5) complexes, including 3 reference strains and 17 environmental isolates, were investigated. Fragments of the gyrA, gyrB, parC, and parE genes encompassing the quinolone resistance-determining regions (QRDRs) were amplified by PCR and sequenced. Results obtained for the six sensitive strains showed that the GyrA, GyrB, ParC, and ParE QRDR fragments of Aeromonas spp. were highly conserved (> or =96.1% identity), despite some genetic polymorphism; they were most closely related to those of Vibrio spp., Pseudomonas spp., and members of the family Enterobacteriaceae (72.4 to 97.1% homology). All 14 environmental resistant strains carried a point mutation in the GyrA QRDR at codon 83, leading to the substitution Ser-83-->Ile (10 strains) or Ser-83-->Arg. In addition, seven strains harbored a mutation in the ParC QRDR either at position 80 (five strains), generating a Ser-80-->Ile (three strains) or Ser-80-->Arg change, or at position 84, yielding a Glu-84-->Lys modification. No amino acid alterations were discovered in the GyrB and ParE QRDRs. Double gyrA-parC missense mutations were associated with higher levels of quinolone resistance compared with the levels associated with single gyrA mutations. The most resistant strains probably had an additional mechanism(s) of resistance, such as decreased accumulation of the drugs. Our data suggest that, in mesophilic Aeromonas spp., as in other gram-negative bacteria, gyrase and topoisomerase IV are the primary and secondary targets for quinolones, respectively.
KeywordMeSH Terms
7. Kirov  SM, Tassell  BC, Semmler  AB, O'Donovan  LA, Rabaan  AA, Shaw  JG,     ( 2002 )

Lateral flagella and swarming motility in Aeromonas species.

Journal of bacteriology 184 (2)
PMID : 11751834  :   DOI  :   10.1128/jb.184.2.547-555.2002     PMC  :   PMC139559    
Abstract >>
Swarming motility, a flagellum-dependent behavior that allows bacteria to move over solid surfaces, has been implicated in biofilm formation and bacterial virulence. In this study, light and electron microscopic analyses and genetic and functional investigations have shown that at least 50% of Aeromonas isolates from the species most commonly associated with diarrheal illness produce lateral flagella which mediate swarming motility. Aeromonas lateral flagella were optimally produced when bacteria were grown on solid medium for approximately 8 h. Transmission and thin-section electron microscopy confirmed that these flagella do not possess a sheath structure. Southern analysis of Aeromonas reference strains and strains of mesophilic species (n = 84, varied sources and geographic regions) with a probe designed to detect lateral flagellin genes (lafA1 and lafA2) showed there was no marked species association of laf distribution. Approximately 50% of these strains hybridized strongly with the probe, in good agreement with the expression studies. We established a reproducible swarming assay (0.5% Eiken agar in Difco broth, 30 degrees C) for Aeromonas spp. The laf-positive strains exhibited vigorous swarming motility, whereas laf-negative strains grew but showed no movement from the inoculation site. Light and scanning electron microscopic investigations revealed that lateral flagella formed bacterium-bacterium linkages on the agar surface. Strains of an Aeromonas caviae isolate in which lateral flagellum expression was abrogated by specific mutations in flagellar genes did not swarm, proving conclusively that lateral flagella are required for the surface movement. Whether lateral flagella and swarming motility contribute to Aeromonas intestinal colonization and virulence remains to be determined.
KeywordMeSH Terms
8. Rabaan  AA, Gryllos  I, Tomás  JM, Shaw  JG,     ( 2001 )

Motility and the polar flagellum are required for Aeromonas caviae adherence to HEp-2 cells.

Infection and immunity 69 (7)
PMID : 11401962  :   DOI  :   10.1128/IAI.69.7.4257-4267.2001     PMC  :   PMC98495    
Abstract >>
Aeromonas caviae is increasingly being recognized as a cause of gastroenteritis, especially among the young. The adherence of aeromonads to human epithelial cells in vitro has been correlated with enteropathogenicity, but the mechanism is far from well understood. Initial investigations demonstrated that adherence of A. caviae to HEp-2 cells was significantly reduced by either pretreating bacterial cells with an antipolar flagellin antibody or by pretreating HEp-2 cells with partially purified flagella. To precisely define the role of the polar flagellum in aeromonad adherence, we isolated the A. caviae polar flagellin locus and identified five polar flagellar genes, in the order flaA, flaB, flaG, flaH, and flaJ. Each gene was inactivated using a kanamycin resistance cartridge that ensures the transcription of downstream genes, and the resulting mutants were tested for motility, flagellin expression, and adherence to HEp-2 cells. N-terminal amino acid sequencing, mutant analysis, and Western blotting demonstrated that A. caviae has a complex flagellum filament composed of two flagellin subunits encoded by flaA and flaB. The predicted molecular mass of both flagellins was approximately 31,700 Da; however, their molecular mass estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was approximately 35,500 Da. This aberrant migration was thought to be due to their glycosylation, since the proteins were reactive in glycosyl group detection assays. Single mutations in either flaA or flaB did not result in loss of flagella but did result in decreased motility and adherence by approximately 50%. Mutation of flaH, flaJ, or both flagellin genes resulted in the complete loss of motility, flagellin expression, and adherence. However, mutation of flaG did not affect motility but did significantly reduce the level of adherence. Centrifugation of the flagellate mutants (flaA, flaB, and flaG) onto the cell monolayers did not increase adherence, whereas centrifugation of the aflagellate mutants (flaH, flaJ, and flaA flaB) increased adherence slightly. We conclude that maximum adherence of A. caviae to human epithelial cells in vitro requires motility and optimal flagellar function.
KeywordMeSH Terms
9. Suzuki  T, Kitagawa  E, Sakakibara  F, Ibata  K, Usui  K, Kawai  K,     ( 2001 )

Cloning, expression, and characterization of a family 52 beta-xylosidase gene (xysB) of a multiple-xylanase-producing bacterium, Aeromonas caviae ME-1.

Bioscience, biotechnology, and biochemistry 65 (3)
PMID : 11330658  :   DOI  :   10.1271/bbb.65.487    
Abstract >>
A lambda phage genomic library of Aeromonas caviae ME-1, a multiple-xylanase-producing bacterium, was screened for xylan degradation activities. We isolated one clone, B65, which had weak xylanase activity, by the DNS method, but gave no visible bands on zymogram assay using SDS-xylan-PAGE. Based on TLC analyses of enzymatic products and some glycosidase assays using p-nitrophenyl substrates, we established that pB65 encodes a beta-xylosidase gene. In the nucleotide sequence analysis, we found a 2190-bp open reading frame (ORF) named xysB. XysB protein is similar to some beta-xylosidases, which are categorized in the glycosyl hydrolase family 52. Another ORF (xyg), that showed similarity to the family 67 alpha-glucuronidase, was also found downstream of the xysB gene. The xysB ORF and its promoter region were cloned into the pT7-Blue vector and the transformant cells had beta-xylosidase activity. The relative molecular mass were estimated to be 75 kDa by SDS-PAGE and 159 kDa by gel filtration. These data showed that XysB has a dimeric structure of 80,697 Da subunits. This enzyme showed optimal activity at 50 degrees C and pH 6.0. It was stable below 40 degrees C and pH 5-8. The Km and Vmax were calculated to be 0.34 mM and 33 nmol x min(-1) x microg(-1), respectively. This enzyme also showed transglycosylation activity against X3 and produced X4 and X5.
KeywordMeSH Terms
10. Gryllos  I, Shaw  JG, Gavín  R, Merino  S, Tomás  JM,     ( 2001 )

Role of flm locus in mesophilic Aeromonas species adherence.

Infection and immunity 69 (1)
PMID : 11119490  :   DOI  :   10.1128/IAI.69.1.65-74.2001     PMC  :   PMC97856    
Abstract >>
The adherence mechanism of Aeromonas caviae Sch3N to HEp-2 cells was initially investigated through four mini-Tn5 mutants that showed a 10-fold decrease in adherence. These mutants lost motility, flagella, and their lipopolysaccharide (LPS) O antigen (O-Ag). Three genes, flmB-neuA-flmD, were found to be interrupted by the transposon insertions; additionally, two other genes, one lying upstream (flmA) and one downstream (neuB), were found to be clustered in the same operon. While the flmA and flmB genes were present in all mesophilic Aeromonas spp. (A. hydrophila, A. caviae, A. veronii bv. veronii, and A. veronii bv. sobria) tested, this was not the case for the neuA-flmD-neuB genes. Construction and characterization of flmB insertion mutants in five other mesophilic Aeromonas strains revealed the loss of motility, flagella, and adherence but did not alter the LPS composition of these strains. Taking the above findings into consideration, we conclude (i) that flagella and possibly the LPS O-Ag are involved in the adherence of the mesophilic Aeromonas to human epithelial cells; (ii) flmA and flmB are genes widely distributed in the mesophilic Aeromonas and are involved in flagella assembly, and thus adherence; and (iii) in A. caviae Sch3N the flmA and flmB genes are found in a putative operon together with neuA, flmD, and neuB and are involved in LPS O-Ag biosynthesis and probably have a role in flagellum assembly.
KeywordMeSH Terms
Bacterial Adhesion
Chromosome Mapping
Genes, Bacterial
11. Toma  C, Kawakami  K,     ( 2000 )

Cloning, sequencing and expression of the gene encoding the extracellular metalloprotease of Aeromonas caviae.

Microbiology and immunology 44 (5)
PMID : 10888351  :   DOI  :   10.1111/j.1348-0421.2000.tb02504.x    
Abstract >>
A gene (apk) encoding the extracellular protease of Aeromonas caviae Ae6 has been cloned and sequenced. For cloning the gene, the DNA genomic library was screened using skim milk LB agar. One clone harboring plasmid pKK3 was selected for sequencing. Nucleotide sequencing of the 3.5 kb region of pKK3 revealed a single open reading frame (ORF) of 1,785 bp encoding 595 amino acids. The deduced polypeptide contained a putative 16-amino acid signal peptide followed by a large propeptide. The N-terminal amino acid sequence of purified recombinant protein (APK) was consistent with the DNA sequence. This result suggested a mature protein of 412 amino acids with a molecular mass of 44 kDa. However, the molecular mass of purified recombinant APK revealed 34 kDa by SDS-PAGE, suggesting that further processing at the C-terminal region took place. The 2 motifs of zinc binding sites deduced are highly conserved in the APK as well as in other zinc metalloproteases including Vibrio proteolyticus neutral protease, Emp V from Vibrio vulnificus, HA/P from Vibrio cholerae, and Pseudomonas aeruginosa elastase. Proteolytic activity was inhibited by EDTA, Zincov, 1,10-phenanthroline and tetraethylenepentamine while unaffected by the other inhibitors tested. The protease showed maximum activity at pH 7.0 and was inactivated by heating at 80 C for 15 min. These results together suggest that APK belongs to the thermolysin family of metalloendopeptidases.
KeywordMeSH Terms
12. Ibata  K, Usui  K,     ( 1999 )

XynX, a possible exo-xylanase of Aeromonas caviae ME-1 that produces exclusively xylobiose and xylotetraose from xylan.

Bioscience, biotechnology, and biochemistry 63 (8)
PMID : 10500996  :   DOI  :   10.1271/bbb.63.1346    
Abstract >>
A gene, xynX, encoding a novel xylanase, was cloned from Aeromonas caviae ME-1. This gene encoded an enzyme that was constituted of 334 amino acid residues (38,580 Da) and was similar in sequence to Family 10 (Family F) beta-1,4 endo-xylanases. XynX produced only xylobiose and xylotetraose from birch wood xylan, and xylotriose, xylopentaose, and higher oligosaccharides were not detected in the TLC analysis. We designated it as X2/X4-forming xylanase. This enzyme does not have transglycosylation activity. These data suggested that this enzyme is a possible exo-xylanase. According to homology modeling, the enzyme has a ring-shaped (alpha/beta)8 barrel (TIM barrel) structure, typical of Family 10 endo-xylanases, with the extraordinary feature of a longer bottom-loop structure.
KeywordMeSH Terms
Genes, Bacterial
13. Yoshida  M, Zhang  Z, Nakajima  Y,     ( 1999 )

Molecular cloning and expression in Escherichia coli of the extracellular endoprotease of Aeromonas caviae T-64, a pro-aminopeptidase processing enzyme(1).

Biochimica et biophysica acta 1433 (1��2��)
PMID : 10446382  :   DOI  :   10.1016/s0167-4838(99)00158-2    
Abstract >>
PA protease (pro-aminopeptidase processing protease) activates the pro-aminopeptidases from Aeromonas caviae T-64 and Vibrio proteolytica by removal of their pro-regions. Cloning and sequencing of the PA protease gene revealed that PA protease was translated as a preproprotein consisting of four domains: a signal peptide; an N-terminal propeptide; a mature region; and a C-terminal propeptide. The deduced amino acid sequence of the PA protease precursor showed significant homology with several bacterial metalloproteases. Expression of the PA protease gene in Escherichia coli indicated that the N-terminal propeptide of the PA protease precursor is essential to obtain the active form of the protease. The N- and C-terminal propeptides of the expressed pro-PA protease were processed autocatalytically.
KeywordMeSH Terms
Bacterial Proteins
14. Al-Benwan  K, Abbott  S, Janda  JM, Huys  G, Albert  MJ,     ( 2007 )

Cystitis caused by Aeromonas caviae.

Journal of clinical microbiology 45 (7)
PMID : 17522269  :   DOI  :   10.1128/JCM.00480-07     PMC  :   PMC1932975    
Abstract >>
Aeromonas sp. organisms rarely cause urinary tract infection. We report for the first time a case of urinary tract infection caused by A. caviae in an adult patient with a history of increased frequency of urination, dysuria, hematuria, and weight loss.
KeywordMeSH Terms
15. Li  Q, Xiao  X, Wang  F,     ( 2007 )

Screening of genes involved in chitinase production in Aeromonas caviae CB101 via transposon mutagenesis.

Journal of applied microbiology 102 (3)
PMID : 17309612  :   DOI  :   10.1111/j.1365-2672.2006.03132.x    
Abstract >>
To find genes involved in chitinase production in chitinolytic bacterium Aeromonas caviae CB101. By transposome mutagenesis, a high-quality mutant library containing around 20,000 insertion mutants was constructed in A. caviae CB101. Mutants with higher, lower and delayed chitinase-producing abilities were identified and analysed further. Genomic sequences flanking the insertion sites of these mutants were amplified by thermal asymmetric interlaced-PCR, cloned and sequenced. The mutated genes involved in chitinase production and/or secretion in CB101 include (i) nagA and nagB gene homologues that are related to the metabolism of the chitin digestion product GlcNAc; (ii) ftsX and exeL gene homologues that are related to transport or secretion systems; (iii) varA and rpoH gene homologues that are related to transcriptional regulator sequences; (iv) other genes with unknown functions. Transposome mutagenesis is an efficient method to identify genes involved in the chitinase production in CB101. Chitinase production in CB101 is a complex system, and genes with various functions were identified in this study. Understanding regulation of chitinase production in CB101 would make molecular engineering of the bacterium for higher enzyme production possible.
KeywordMeSH Terms
16. Saavedra  MJ, Figueras  MJ, Martínez-Murcia  AJ,     ( 2006 )

Updated phylogeny of the genus Aeromonas.

International journal of systematic and evolutionary microbiology 56 (Pt 10)
PMID : 17012583  :   DOI  :   10.1099/ijs.0.64351-0    
Abstract >>
Recent phylogenetic studies of the genus Aeromonas based on gyrB and rpoD gene sequences have improved the phylogeny based on 16S rRNA gene sequences first published in 1992, particularly in the ability to split closely related species. These studies did not include the recently described species Aeromonas simiae and Aeromonas molluscorum and only a single strain of Aeromonas culicicola was available for analysis at that time. In the present work, these Aeromonas species and newly isolated strains of A. culicicola were examined. Sequence analysis indicates that A. simiae and A. molluscorum belong to non-described phylogenetic lines of descent within this genus, which supports the original description of both species. The most closely related species are Aeromonas schubertii and Aeromonas encheleia, respectively, which is consistent with 16S rRNA gene sequencing results. However, while the five strains of A. molluscorum showed nucleotide differences in their gyrB and rpoD gene sequences, the only two known A. simiae strains exhibited identical gene sequences, suggesting that they are isolates of the same strain. On the basis of the rpoD gene sequence phylogeny, A. culicicola strains from the original description and new isolates from drinking water and ornamental fish clustered within the species Aeromonas veronii, suggesting inconsistencies with previous results. Other strains with previously controversial taxonomy and new isolates from other studies were included in this study in order to clarify their phylogenetic affiliation at the species level.
KeywordMeSH Terms
Phylogeny
17. Sen  K,     ( 2005 )

Development of a rapid identification method for Aeromonas species by multiplex-PCR.

Canadian journal of microbiology 51 (11)
PMID : 16333335  :   DOI  :   10.1139/w05-089    
Abstract >>
Existing biochemical methods cannot distinguish among some species of Aeromonads, while genetic methods are labor intensive. In this study, primers were developed to three genes of Aeromonas: lipase, elastase, and DNA gyraseB. In addition, six previously described primer sets, five corresponding to species-specific signature regions of the 16S rRNA gene from A. veronii, A. popoffii, A. caviae, A. jandaei, and A. schubertii, respectively, and one corresponding to A. hydrophila specific lipase (hydrolipase), were chosen. The primer sets were combined in a series of multiplex-PCR (mPCR) assays against 38 previously characterized strains. Following PCR, each species was distinguished by the production of a unique combination of amplicons. When the assays were tested using 63 drinking water isolates, there was complete agreement in the species identification (ID) for 59 isolates, with ID established by biochemical assays. Sequencing the gyrB and the 16S rRNA gene from the remaining four strains established that the ID obtained by mPCR was correct for three strains. For only one strain, no consensus ID could be obtained. A rapid and reliable method for identification of different Aeromonas species is proposed that does not require restriction enzyme digestions, thus simplifying and speeding up the process.
KeywordMeSH Terms
18. Usui  K, Suzuki  T, Akisaka  T, Kawai  K,     ( 2003 )

A cytoplasmic xylanase (XynX) of Aeromonas caviae ME-1 is released from the cytoplasm to the periplasm by osmotic downshock.

Journal of bioscience and bioengineering 95 (5)
PMID : 16233445  :  
Abstract >>
Aeromonas caviae ME-1 is a multiple xylanase-producing gram-negative bacterium which was isolated from the gut contents of a wild silkworm, Samia cynthia pryeri. One of the xylanases produced by A. caviae ME-1, XynX (38 kDa, family 10 xylanase), hydrolyzes xylan to xylobiose and xylotetraose as final degradation products. Generally, xylanases are extracellular or cell surface enzymes. However, XynX is not exported to the extracellular fluid by A. caviae ME-1 and an Escherichia coli transformant harboring the xynX gene. In this study, we investigated the intracellular localization of XynX in A. caviae ME-1 and an E. coli transformant. XynX was found in the cytoplasm when the cells were grown under normal culture conditions. However, XynX was released from the cytoplasm to the periplasm during osmotic downshock. This release of XynX in the E. coli transformant was blocked in the presence of gadolinium chloride, which has been reported to be an inhibitor of bacterial mechanosensitive channels.
KeywordMeSH Terms
19. Sinha  S, Chattopadhyay  S, Bhattacharya  SK, Nair  GB, Ramamurthy  T,     ( 2004 )

An unusually high level of quinolone resistance associated with type II topoisomerase mutations in quinolone resistance-determining regions of Aeromonas caviae isolated from diarrhoeal patients.

Research in microbiology 155 (10)
PMID : 15567276  :   DOI  :   10.1016/j.resmic.2004.06.008    
Abstract >>
We examined 158 strains belonging to different Aeromonas species isolated from hospitalized acute diarrhoea cases for susceptibility to quinolones. Compared to other species, a high percentage of the A. caviae strains were resistant to ciprofloxacin and norfloxacin. Based on MIC values, 6 A. caviae strains were selected and the nucleotide sequences for the quinolone-resistant-determining regions (QRDRs) of gyrA, gyrB and parC genes were analysed. In resistant strains, double mutations (Ser(83)-->Ile and Asp(87)-->Asn) and a single mutation (Ser(80)-->Ile) were detected in the QRDR of gyrA and parC, respectively.
KeywordMeSH Terms
20. Rhodes  G, Parkhill  J, Bird  C, Ambrose  K, Jones  MC, Huys  G, Swings  J, Pickup  RW,     ( 2004 )

Complete nucleotide sequence of the conjugative tetracycline resistance plasmid pFBAOT6, a member of a group of IncU plasmids with global ubiquity.

Applied and environmental microbiology 70 (12)
PMID : 15574953  :   DOI  :   10.1128/AEM.70.12.7497-7510.2004     PMC  :   PMC535204    
Abstract >>
This study presents the first complete sequence of an IncU plasmid, pFBAOT6. This plasmid was originally isolated from a strain of Aeromonas caviae from hospital effluent (Westmorland General Hospital, Kendal, United Kingdom) in September 1997 (G. Rhodes, G. Huys, J. Swings, P. McGann, M. Hiney, P. Smith, and R. W. Pickup, Appl. Environ. Microbiol. 66:3883-3890, 2000) and belongs to a group of related plasmids with global ubiquity. pFBAOT6 is 84,748 bp long and has 94 predicted coding sequences, only 12 of which do not have a possible function that has been attributed. Putative replication, maintenance, and transfer functions have been identified and are located in a region in the first 31 kb of the plasmid. The replication region is poorly understood but exhibits some identity at the protein level with replication proteins from the gram-positive bacteria Bacillus and Clostridium. The mating pair formation system is a virB homologue, type IV secretory pathway that is similar in its structural organization to the mating pair formation systems of the related broad-host-range (BHR) environmental plasmids pIPO2, pXF51, and pSB102 from plant-associated bacteria. Partitioning and maintenance genes are homologues of genes in IncP plasmids. The DNA transfer genes and the putative oriT site also exhibit high levels of similarity with those of plasmids pIPO2, pXF51, and pSB102. The genetic load region encompasses 54 kb, comprises the resistance genes, and includes a class I integron, an IS630 relative, and other transposable elements in a 43-kb region that may be a novel Tn1721-flanked composite transposon. This region also contains 24 genes that exhibit the highest levels of identity to chromosomal genes of several plant-associated bacteria. The features of the backbone of pFBAOT6 that are shared with this newly defined group of environmental BHR plasmids suggest that pFBAOT6 may be a relative of this group, but a relative that was isolated from a clinical bacterial environment rather than a plant-associated bacterial environment.
KeywordMeSH Terms
Conjugation, Genetic
Sequence Analysis, DNA
21. Soler  L, Yáñez  MA, Chacon  MR, Aguilera-Arreola  MG, Catalán  V, Figueras  MJ, Martínez-Murcia  AJ,     ( 2004 )

Phylogenetic analysis of the genus Aeromonas based on two housekeeping genes.

International journal of systematic and evolutionary microbiology 54 (Pt 5)
PMID : 15388703  :   DOI  :   10.1099/ijs.0.03048-0    
Abstract >>
The phylogenetic relationships of all known species of the genus Aeromonas, and especially Aeromonas bestiarum and Aeromonas salmonicida, were investigated on 70 strains using the rpoD sequence, which encodes the sigma70 factor. This analysis was complemented with the sequence of gyrB, which has already proven useful for determining the phylogenetic relationships in the genus. Nucleotide sequences of rpoD and gyrB showed that both genes had similar substitution rates (< 2 %) and a similar number of variable positions (34 % for rpoD versus 32 % for gyrB). Strain groupings by analysis of rpoD, gyrB and a combination of both genes were consistent with the taxonomic organization of all Aeromonas species described to date. However, the simultaneous analysis of both clocks improved the reliability and the power to differentiate, in particular, closely related taxa. At the inter-species level, gyrB showed a better resolution for differentiating Aeromonas sp. HG11/Aeromonas encheleia and Aeromonas veronii/Aeromonas culicicola/Aeromonas allosaccharophila, while rpoD more clearly differentiated A. salmonicida from A. bestiarum. The analysis of rpoD provided initial evidence for clear phylogenetic divergence between the latter two species.
KeywordMeSH Terms
Phylogeny
22. Figueira  V, Vaz-Moreira  I, Silva  M, Manaia  CM,     ( 2011 )

Diversity and antibiotic resistance of Aeromonas spp. in drinking and waste water treatment plants.

Water research 45 (17)
PMID : 21907383  :   DOI  :   10.1016/j.watres.2011.08.021    
Abstract >>
The taxonomic diversity and antibiotic resistance phenotypes of aeromonads were examined in samples from drinking and waste water treatment plants (surface, ground and disinfected water in a drinking water treatment plant, and raw and treated waste water) and tap water. Bacteria identification and intra-species variation were determined based on the analysis of the 16S rRNA, gyrB and cpn60 gene sequences. Resistance phenotypes were determined using the disc diffusion method. Aeromonas veronii prevailed in raw surface water, Aeromonas hydrophyla in ozonated water, and Aeromonas media and Aeromonas puntacta in waste water. No aeromonads were detected in ground water, after the chlorination tank or in tap water. Resistance to ceftazidime or meropenem was detected in isolates from the drinking water treatment plant and waste water isolates were intrinsically resistant to nalidixic acid. Most of the times, quinolone resistance was associated with the gyrA mutation in serine 83. The gene qnrS, but not the genes qnrA, B, C, D or qepA, was detected in both surface and waste water isolates. The gene aac(6')-ib-cr was detected in different waste water strains isolated in the presence of ciprofloxacin. Both quinolone resistance genes were detected only in the species A. media. This is the first study tracking antimicrobial resistance in aeromonads in drinking, tap and waste water and the importance of these bacteria as vectors of resistance in aquatic environments is discussed.
KeywordMeSH Terms
Genetic Variation
Waste Disposal, Fluid
Water Microbiology
Water Purification
23. Fontes  MC, Saavedra  MJ, Martins  C, Martínez-Murcia  AJ,     ( 2011 )

Phylogenetic identification of Aeromonas from pigs slaughtered for consumption in slaughterhouses at the North of Portugal.

International journal of food microbiology 146 (2)
PMID : 21402427  :   DOI  :   10.1016/j.ijfoodmicro.2011.02.010    
Abstract >>
In the present study, 710 isolates of Aeromonas spp. have been collected from pig carcasses, diaphragm muscle, faeces, dehairing equipment and water in slaughterhouses at the North of Portugal. The isolates were obtained from a total of 154 samples. All presumptive Aeromonas isolates were subjected to ERIC-PCR analysis and those which presented a different pattern were taken and the species classified by gyrB gene sequencing. We have found the species A. hydrophila, A. salmonicida, A. bestiarum, A. caviae, A. media, A. veronii, A. allosaccharophila, A. simiae and A. aquariorum. To our knowledge, this extent of Aeromonas species diversity has not been previously described from meat or from the slaughter environment, perhaps due to the unreliability of available identification methods. A noticeable level of isolate redundancy (strains with identical gyrB sequence) from different samples collected in different dates was also obtained, indicating that only a few predominant strains of these species persist at the slaughter system. It is also important to emphasise the presence of Aeromonas species previously associated with illness in man.
KeywordMeSH Terms
24. Martinez-Murcia  AJ, Monera  A, Saavedra  MJ, Oncina  R, Lopez-Alvarez  M, Lara  E, Figueras  MJ,     ( 2011 )

Multilocus phylogenetic analysis of the genus Aeromonas.

Systematic and applied microbiology 34 (3)
PMID : 21353754  :   DOI  :   10.1016/j.syapm.2010.11.014    
Abstract >>
A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several "bona fide" strains representing all described species.
KeywordMeSH Terms
25. Farfán  M, Miñana-Galbis  D, Garreta  A, Lorén  JG, Fusté  MC,     ( 2010 )

Malate dehydrogenase: a useful phylogenetic marker for the genus Aeromonas.

Systematic and applied microbiology 33 (8)
PMID : 21095084  :   DOI  :   10.1016/j.syapm.2010.09.005    
Abstract >>
The reconstruction of correct genealogies among biological entities, the estimation of the divergence time between organisms or the study of the different events that occur along evolutionary lineages are not always based on suitable genes. For reliable results, it is necessary to look at full-length sequences of genes under stabilizing selection (neutral or purifying) and behaving as good molecular clocks. In bacteria it has been proved that the malate dehydrogenase gene (mdh) can be used to determine the inter- and intraspecies divergence, and hence this gene constitutes a potential marker for phylogeny and bacterial population genetics. We have sequenced the full-length mdh gene in 36 type and reference strains of Aeromonas. The species grouping obtained in the phylogenetic tree derived from mdh sequences was in agreement with that currently accepted for the genus Aeromonas. The maximum likelihood models applied to our sequences indicated that the mdh gene is highly conserved among the Aeromonas species and the main evolutionary force acting on it is purifying selection. Only two sites under potential diversifying selection were identified (T 108 and S 193). In order to determine if these two residues could have an influence on the MDH structure, we mapped them in a three-dimensional model constructed from the sequence of A. hydrophila using the human mitochondrial MDH as a template. The presence of purifying selection together with the linear relationship between substitutions and gene divergence makes the mdh an excellent candidate gene for a phylogeny of Aeromonas and probably for other bacterial groups.
KeywordMeSH Terms
26. Girlich  D, Poirel  L, Nordmann  P,     ( 2011 )

Diversity of clavulanic acid-inhibited extended-spectrum �]-lactamases in Aeromonas spp. from the Seine River, Paris, France.

Antimicrobial agents and chemotherapy 55 (3)
PMID : 21149627  :   DOI  :   10.1128/AAC.00921-10     PMC  :   PMC3067085    
Abstract >>
Environmental Aeromonas sp. isolates resistant to ceftazidime were recovered during an environmental survey performed with water samples from the Seine River, in Paris, France, in November 2009. Selected isolates were identified by sequencing of the 16S rRNA and rpoB genes. PCR and cloning experiments were used to identify broad-spectrum-�]-lactamase-encoding genes and their genetic context. Clavulanic acid-inhibited extended-spectrum-�]-lactamase (ESBL) genes were identified in 71% of the Aeromonas sp. isolates. A variety of ESBL genes were detected, including bla(VEB-1a), bla(SHV-12), bla(PER-1), bla(PER-6), bla(TLA-2), and bla(GES-7), suggesting an aquatic reservoir of those ESBL genes. Moreover, the repeated elements and different insertion sequences were identified in association with the bla(PER-6) and the bla(VEB-1a) genes, respectively, indicating a wide diversity of mobilization events, making Aeromonas spp. a vehicle for ESBL dissemination.
KeywordMeSH Terms
27. Xia  R, Guo  X, Zhang  Y, Xu  H,     ( 2010 )

qnrVC-like gene located in a novel complex class 1 integron harboring the ISCR1 element in an Aeromonas punctata strain from an aquatic environment in Shandong Province, China.

Antimicrobial agents and chemotherapy 54 (8)
PMID : 20516288  :   DOI  :   10.1128/AAC.01668-09     PMC  :   PMC2916331    
Abstract >>
A qnrVC-like gene, qnrVC4, was found in a novel complex class 1 integron gene cassette array following the ISCR1 element and bla(PER-1) in a multidrug-resistant strain of the aquatic bacterium Aeromonas punctata. The deduced QnrVC4 protein sequence shares 45% to 81% amino acid identity with quinolone resistance determinants QnrB6, QnrA1, QnrS1, QnrC, QnrVC1, and QnrVC3. A Ser-83 to Ile amino acid substitution in gyrase A may be mainly responsible for ciprofloxacin resistance in this strain.
KeywordMeSH Terms
28. Lorén  JG, Farfán  M, Miñana-Galbis  D, Fusté  MC,     ( 2010 )

Prediction of whole-genome DNA G+C content within the genus Aeromonas based on housekeeping gene sequences.

Systematic and applied microbiology 33 (5)
PMID : 20466501  :   DOI  :   10.1016/j.syapm.2010.03.007    
Abstract >>
Different methods are available to determine the G+C content (e.g. thermal denaturation temperature or high performance liquid chromatography, HPLC), but obtained values may differ significantly between strains, as well as between laboratories. Recently, several authors have demonstrated that the genomic DNA G+C content of prokaryotes can be reliably estimated from one or several protein coding gene nucleotide sequences. Few G+C content values have been published for the Aeromonas species described and the data, when available, are often incomplete or provide only a range of values. Our aim in this current work was twofold. First, the genomic G+C content of the type or reference strains of all species and subspecies of the genus Aeromonas was determined with a traditional experimental method in the same laboratory. Second, we wanted to see if the sequence-based method to estimate the G+C content described by Fournier et al. [7] could be applied to determine the G+C content of the different species of Aeromonas from the sequences of the genes used in taxonomy or phylogeny for this genus.
KeywordMeSH Terms
29. Li  M, Chen  C, Davies  DR, Chiu  TK,     ( 2010 )

Induced-fit mechanism for prolyl endopeptidase.

The Journal of biological chemistry 285 (28)
PMID : 20444688  :   DOI  :   10.1074/jbc.M109.092692     PMC  :   PMC2898448    
Abstract >>
Prolyl peptidases cleave proteins at proline residues and are of importance for cancer, neurological function, and type II diabetes. Prolyl endopeptidase (PEP) cleaves neuropeptides and is a drug target for neuropsychiatric diseases such as post-traumatic stress disorder, depression, and schizophrenia. Previous structural analyses showing little differences between native and substrate-bound structures have suggested a lock-and-key catalytic mechanism. We now directly demonstrate from seven structures of Aeromonus punctata PEP that the mechanism is instead induced fit: the native enzyme exists in a conformationally flexible opened state with a large interdomain opening between the beta-propeller and alpha/beta-hydrolase domains; addition of substrate to preformed native crystals induces a large scale conformational change into a closed state with induced-fit adjustments of the active site, and inhibition of this conformational change prevents substrate binding. Absolute sequence conservation among 28 orthologs of residues at the active site and critical residues at the interdomain interface indicates that this mechanism is conserved in all PEPs. This finding has immediate implications for the use of conformationally targeted drug design to improve specificity of inhibition against this family of proline-specific serine proteases.
KeywordMeSH Terms
30. Ye  Y, Xu  XH, Li  JB,     ( 2010 )

Emergence of CTX-M-3, TEM-1 and a new plasmid-mediated MOX-4 AmpC in a multiresistant Aeromonas caviae isolate from a patient with pneumonia.

Journal of medical microbiology 59 (Pt 7)
PMID : 20339022  :   DOI  :   10.1099/jmm.0.016337-0    
Abstract >>
Aeromonas species rarely cause pulmonary infection. We report, for what is believed to be the first time, a case of severe pneumonia in a cancer patient caused by Aeromonas caviae. Detailed microbiological investigation revealed that this isolate carried three beta-lactamase-encoding genes (encoding MOX-4, CTX-M-3 and TEM-1) conferring resistance to all beta-lactams but imipenem. The beta-lactamase with a pI of 9.0 was transferred by conjugation and associated with a 7.3 kb plasmid, as demonstrated by Southern blot hybridization. Analysis of the nucleotide and amino acid sequences showed a new ampC gene that was closely related to those encoding the MOX-1, MOX-2 and MOX-3 beta-lactamases. This new plasmid-mediated AmpC beta-lactamase from China was named MOX-4. This is believed to be the first report of MOX-4, CTX-M-3 and TEM-1 beta-lactamases in a multiresistant A. caviae.
KeywordMeSH Terms
31. Alperi  A, Figueras  MJ,     ( 2010 )

Human isolates of Aeromonas possess Shiga toxin genes (stx1 and stx2) highly similar to the most virulent gene variants of Escherichia coli.

Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 16 (10)
PMID : 20219084  :   DOI  :   10.1111/j.1469-0691.2010.03203.x    
Abstract >>
Strains producing Shiga toxins, encoded by stx1 and stx2 genes, can cause diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome. PCR screening of 80 clinical Aeromonas strains showed that 19 were stx1-positive and only one was positive for both stx1 and stx2. PCR bands were very faint for some strains and negative results were obtained after subculturing. The obtained sequences of Aeromonas stx1 and stx2 genes were highly similar to those of the most virulent stx gene variants of Shiga toxin-producing Escherichia coli. These results may lead to a better understanding of the potential pathogenicity and virulence mechanisms of Aeromonas.
KeywordMeSH Terms
32. Farfán  M, Miñana-Galbis  D, Fusté  MC, Lorén  JG,     ( 2009 )

Divergent evolution and purifying selection of the flaA gene sequences in Aeromonas.

Biology direct 4 (N/A)
PMID : 19622168  :   DOI  :   10.1186/1745-6150-4-23     PMC  :   PMC2724415    
Abstract >>
The bacterial flagellum is the most important organelle of motility in bacteria and plays a key role in many bacterial lifestyles, including virulence. The flagellum also provides a paradigm of how hierarchical gene regulation, intricate protein-protein interactions and controlled protein secretion can result in the assembly of a complex multi-protein structure tightly orchestrated in time and space. As if to stress its importance, plants and animals produce receptors specifically dedicated to the recognition of flagella. Aside from motility, the flagellum also moonlights as an adhesion and has been adapted by humans as a tool for peptide display. Flagellar sequence variation constitutes a marker with widespread potential uses for studies of population genetics and phylogeny of bacterial species. We sequenced the complete flagellin gene (flaA) in 18 different species and subspecies of Aeromonas. Sequences ranged in size from 870 (A. allosaccharophila) to 921 nucleotides (A. popoffii). The multiple alignment displayed 924 sites, 66 of which presented alignment gaps. The phylogenetic tree revealed the existence of two groups of species exhibiting different FlaA flagellins (FlaA1 and FlaA2). Maximum likelihood models of codon substitution were used to analyze flaA sequences. Likelihood ratio tests suggested a low variation in selective pressure among lineages, with an omega ratio of less than 1 indicating the presence of purifying selection in almost all cases. Only one site under potential diversifying selection was identified (isoleucine in position 179). However, 17 amino acid positions were inferred as sites that are likely to be under positive selection using the branch-site model. Ancestral reconstruction revealed that these 17 amino acids were among the amino acid changes detected in the ancestral sequence. The models applied to our set of sequences allowed us to determine the possible evolutionary pathway followed by the flaA gene in Aeromonas, suggesting that this gene have probably been evolving independently in the two groups of Aeromonas species since the divergence of a distant common ancestor after one or several episodes of positive selection. This article was reviewed by Alexey Kondrashov, John Logsdon and Olivier Tenaillon (nominated by Laurence D Hurst).
KeywordMeSH Terms
Evolution, Molecular
Selection, Genetic
33. Miñana-Galbis  D, Urbizu-Serrano  A, Farfán  M, Fusté  MC, Lorén  JG,     ( 2009 )

Phylogenetic analysis and identification of Aeromonas species based on sequencing of the cpn60 universal target.

International journal of systematic and evolutionary microbiology 59 (Pt 8)
PMID : 19567585  :   DOI  :   10.1099/ijs.0.005413-0    
Abstract >>
An analysis of the universal target (UT) sequence from the cpn60 gene was performed in order to evaluate its usefulness in phylogenetic and taxonomic studies and as an identification marker for the genus Aeromonas. Sequences of 555 bp, corresponding to the UT region, were obtained from a collection of 35 strains representing all of the species and subspecies of Aeromonas. From the analysis of these sequences, a range of divergence of 0-23.3% was obtained, with a mean of 11.2+/-0.9%. Comparative analyses between cpn60 and gyrB, rpoD and 16S rRNA gene sequences were carried out from the same Aeromonas strain collection. Sequences of the cpn60 UT region showed similar discriminatory power to gyrB and rpoD sequences. The phylogenetic relationships inferred from cpn60 sequence distances indicated an excellent correlation with the present affiliation of Aeromonas species with the exception of Aeromonas hydrophila subsp. dhakensis, which appeared in a separate phylogenetic line, and Aeromonas sharmana, which exhibited a very loose phylogenetic relationship to the genus Aeromonas. Sequencing of cpn60 from 33 additional Aeromonas strains also allowed us to establish intra- and interspecific threshold values. Intraspecific divergence rates were
KeywordMeSH Terms
34. Alperi  A, Figueras  MJ, Inza  I, Martínez-Murcia  AJ,     ( 2008 )

Analysis of 16S rRNA gene mutations in a subset of Aeromonas strains and their impact in species delineation.

International microbiology : the official journal of the Spanish Society for Microbiology 11 (3)
PMID : 18843597  :  
Abstract >>
Characterization of 999 Aeromonas strains using a published 16S rDNA RFLP identification method showed that 8.1% of the strains produced unexpected (hereafter called "atypical") restriction patterns, making their identification uncertain. Atypical patterns were due to the presence of nucleotide polymorphisms among the rrn operons of the 16S rRNA gene (so-called microheterogeneities). Double sequencing signals at certain positions revealed the nucleotide composition was responsible for the microheterogeneities. Although the number of microheterogeneities was relatively low (0.06-0.66%), trees inferred from the 16S rRNA gene led either to a misidentification or to an inconclusive result for the majority of these strains. Strains with atypical patterns were, however, correctly identified using the rpoD gene sequences, as belonging to Aeromonas caviae, A. veronii, and A. media. All of them, but particularly the two former species, are associated with human disease. Microheterogeneities in 16S rRNA gene sequence were significantly (P 0.01) more prevalent in clinical than in environmental strains. This work also analyzed the effects of these microheterogeneities on the taxonomic position of the investigated strains. The results suggest the need for recording microheterogeneities in the 16S rRNA gene.
KeywordMeSH Terms
Bacterial Typing Techniques
Genes, rRNA
Mutation
35. Reith  ME, Singh  RK, Curtis  B, Boyd  JM, Bouevitch  A, Kimball  J, Munholland  J, Murphy  C, Sarty  D, Williams  J, Nash  JH, Johnson  SC, Brown  LL,     ( 2008 )

The genome of Aeromonas salmonicida subsp. salmonicida A449: insights into the evolution of a fish pathogen.

BMC genomics 9 (N/A)
PMID : 18801193  :   DOI  :   10.1186/1471-2164-9-427     PMC  :   PMC2556355    
Abstract >>
Aeromonas salmonicida subsp. salmonicida is a Gram-negative bacterium that is the causative agent of furunculosis, a bacterial septicaemia of salmonid fish. While other species of Aeromonas are opportunistic pathogens or are found in commensal or symbiotic relationships with animal hosts, A. salmonicida subsp. salmonicida causes disease in healthy fish. The genome sequence of A. salmonicida was determined to provide a better understanding of the virulence factors used by this pathogen to infect fish. The nucleotide sequences of the A. salmonicida subsp. salmonicida A449 chromosome and two large plasmids are characterized. The chromosome is 4,702,402 bp and encodes 4388 genes, while the two large plasmids are 166,749 and 155,098 bp with 178 and 164 genes, respectively. Notable features are a large inversion in the chromosome and, in one of the large plasmids, the presence of a Tn21 composite transposon containing mercury resistance genes and an In2 integron encoding genes for resistance to streptomycin/spectinomycin, quaternary ammonia compounds, sulphonamides and chloramphenicol. A large number of genes encoding potential virulence factors were identified; however, many appear to be pseudogenes since they contain insertion sequences, frameshifts or in-frame stop codons. A total of 170 pseudogenes and 88 insertion sequences (of ten different types) are found in the A. salmonicida genome. Comparison with the A. hydrophila ATCC 7966T genome reveals multiple large inversions in the chromosome as well as an approximately 9% difference in gene content indicating instances of single gene or operon loss or gain.A limited number of the pseudogenes found in A. salmonicida A449 were investigated in other Aeromonas strains and species. While nearly all the pseudogenes tested are present in A. salmonicida subsp. salmonicida strains, only about 25% were found in other A. salmonicida subspecies and none were detected in other Aeromonas species. Relative to the A. hydrophila ATCC 7966T genome, the A. salmonicida subsp. salmonicida genome has acquired multiple mobile genetic elements, undergone substantial rearrangement and developed a significant number of pseudogenes. These changes appear to be a consequence of adaptation to a specific host, salmonid fish, and provide insights into the mechanisms used by the bacterium for infection and avoidance of host defence systems.
KeywordMeSH Terms
Genome, Bacterial
36. Sepe  A, Barbieri  P, Peduzzi  R, Demarta  A,     ( 2008 )

Evaluation of recA sequencing for the classification of Aeromonas strains at the genotype level.

Letters in applied microbiology 46 (4)
PMID : 18346137  :   DOI  :   10.1111/j.1472-765X.2008.02339.x    
Abstract >>
To evaluate the usefulness of partial recA sequences for the identification of Aeromonas strains at the genotype level. A partial recA sequence was obtained from 21 type or reference strains and 33 Aeromonas isolates, collected in the South of Switzerland from human, animal and aquatic environments. The 272 bp long recA fragments showed a mean interspecies divergence of 7.8% and allowed the classification of strains at genotype level. However, some discrepancies could be observed with other gene sequence based analyses in the classification of some strains. The 272 bp long recA fragment is a good molecular marker to infer taxonomy of members of the genus Aeromonas, even if the primers we chose for the amplification did not allow its direct sequencing. In the genus Aeromonas, nucleotide sequences of some protein-encoding genes have already been evaluated as molecular markers to be used in taxonomical and epidemiological researches. This study suggests the usefulness of a recA fragment as a further sequence to investigate for these purposes.
KeywordMeSH Terms
37. Cattoir  V, Poirel  L, Aubert  C, Soussy  CJ, Nordmann  P,     ( 2008 )

Unexpected occurrence of plasmid-mediated quinolone resistance determinants in environmental Aeromonas spp.

Emerging infectious diseases 14 (2)
PMID : 18258115  :   DOI  :   10.3201/eid1402.070677     PMC  :   PMC2600179    
Abstract >>
We searched for plasmid-mediated quinolone resistance determinants of the Qnr type in several water samples collected at diverse locations from the Seine River (Paris, France). The qnrS2 genes were identified from Aeromonas punctata subsp. punctata and A. media. The qnrS2 gene was located on IncU-type plasmids in both isolates, which resulted in increased MIC values of quinolones and fluoroquinolones, once they were transferred into Escherichia coli. The qnrS2 gene identified in A. punctata was part of novel genetic structure corresponding to a mobile insertion cassette element. This identification of plasmid-mediated qnr genes outside Enterobacteriaceae underlines a possible diffusion of those resistance determinants within gram-negative rods.
KeywordMeSH Terms
38. Moura  A, Henriques  I, Ribeiro  R, Correia  A,     ( 2007 )

Prevalence and characterization of integrons from bacteria isolated from a slaughterhouse wastewater treatment plant.

The Journal of antimicrobial chemotherapy 60 (6)
PMID : 17913715  :   DOI  :   10.1093/jac/dkm340    
Abstract >>
To investigate the presence and distribution of integron-carrying bacteria from a slaughterhouse wastewater treatment plant (WWTP). Enterobacteriaceae and aeromonads were isolated at different stages of the wastewater treatment process and screened for the presence of integrase genes by dot-blot hybridization. Integrase-positive strains were characterized in terms of phylogenetic affiliation, genetic content of integrons and antimicrobial resistance profiles. Plasmid location of some integrons was established by Southern-blot hybridization. Strains containing integron-carrying plasmids were selected for mating experiments. Integrase genes were present in all samples, including the final effluent. The global prevalence was determined to be 35%, higher than in other aquatic environments. Forty-two integrase-positive isolates were further characterized. Nine distinct cassette arrays were found, containing genes encoding resistance to beta-lactams (bla(OXA-30)), aminoglycosides (aadA1, aadA2, aadA13, aadB), streptothricin (sat1, sat2), trimethoprim (dfrA1, dfrA12), a putative esterase (estX) and a protein with unknown function (orfF). Gene cassette arrays aadA1, dfrAI-aadA1 and estX-sat2-aadA1 were common to aeromonads and Enterobacteriaceae. The class 2 integron containing an estX-sat2-aadA1 cassette array was detected for the first time in Aeromonas sp. Nearly 12% (5 out of 43) of intI genes were located in plasmids. intI genes from isolates MM.1.3 and MM.1.5 were successfully conjugated into Escherichia coli at frequencies of 3.79 x 10(-5) and 5.46 x 10(-5) per recipient cell, respectively. Our data support the hypothesis that WWTPs constitute a potential hot spot for horizontal gene transfer and for selection of antimicrobial resistance genes among aquatic bacteria. Moreover, water discharges represent a possible risk for dissemination of undesirable genetic traits.
KeywordMeSH Terms
Abattoirs
Gene Transfer, Horizontal
Water Microbiology
39. Chang  YC, Shih  DY, Wang  JY, Yang  SS,     ( 2007 )

Molecular characterization of class 1 integrons and antimicrobial resistance in Aeromonas strains from foodborne outbreak-suspect samples and environmental sources in Taiwan.

Diagnostic microbiology and infectious disease 59 (2)
PMID : 17908616  :   DOI  :   10.1016/j.diagmicrobio.2007.04.007    
Abstract >>
One hundred thirty-three Aeromonas spp. isolates were examined for multiple antibiotic resistance phenotypes and prevalence of class 1 integron sequences. Twenty-four (18.0%) of these isolates contained class 1 integron. Seven different class 1 integrons were found among 24strains, with a total of 10 different gene cassettes encoding for resistance to trimethoprim (dfr12 and dfr2d), aminoglycosides (aadA1 and aadA2), beta-lactam antibiotics (oxa2), chloramphenicol (catB3 and catB8), quaternary ammonium amines (qacE2), and 2 ORFs (orfD and orfF) with unknown function. Rate of antibiotic resistance was different between integron-positive and integron-negative strains. Trimethoprim and trimethoprim-sulphamethoxazole resistances were commonly associated with integron, and all of integron-positive isolates were multiple resistant to more than 3 agents. Resistance to as many as 10 antimicrobial agents were observed in integron-positive strains. Several cassette arrays of class 1 integrons identified in this study were not previously reported in Aeromonas strains. This study demonstrates the wide distribution of class 1 integron in Aeromonas spp. isolated from foodborne outbreak-suspect samples and environmental sources in Taiwan.
KeywordMeSH Terms
Disease Outbreaks
Environmental Microbiology
40. Neuwirth  C, Siebor  E, Robin  F, Bonnet  R,     ( 2007 )

First occurrence of an IMP metallo-beta-lactamase in Aeromonas caviae: IMP-19 in an isolate from France.

Antimicrobial agents and chemotherapy 51 (12)
PMID : 17938180  :   DOI  :   10.1128/AAC.01462-06     PMC  :   PMC2167964    
Abstract >>
We describe the first IMP metallo-beta-lactamase in Aeromonas caviae: IMP-19, which differed from IMP-2 by a single amino acid change (Arg to Ala at position 38). bla(IMP-19) was found within a class 1 integron located on a 35-kb plasmid. This is also the first description of an IMP producer in France.
KeywordMeSH Terms
41. Barlow  RS, Fegan  N, Gobius  KS,     ( 2008 )

A comparison of antibiotic resistance integrons in cattle from separate beef meat production systems at slaughter.

Journal of applied microbiology 104 (3)
PMID : 17927756  :   DOI  :   10.1111/j.1365-2672.2007.03572.x    
Abstract >>
To compare antibiotic resistance integrons in cattle from three separate grass-fed, grain-fed and certified organic cattle production systems at slaughter. In this study 198 samples from three separate cattle production systems were tested by PCR for the presence of class 1 and class 2 integrons. Integron-containing bacteria were readily isolated from pen faeces and hide samples regardless of production system. Lower numbers of integron-containing bacteria were isolated from the remaining sample types. Ninety-one class 1 and 34 class 2 integron-containing bacteria were isolated. Characterization of the integrons demonstrated a high degree of similarity across the three production systems with aadA1 and aadA2 routinely present. Integrons harbouring the cassette array cmlA5-bla(OXA-10)-aadA1 and the putative insertion sequence IS1066 were isolated from organic and grass-fed cattle and have not been described previously. Integrons carrying antibiotic resistance genes were common in cattle from differing production systems at slaughter and the likelihood of presence appears unrelated to the production system. Similar integron arrays are present in different cattle production systems suggesting that their presence may be independent of production practices. This is the first report of two novel integron structures present in Aeromonas.
KeywordMeSH Terms
Animal Feed
42. de Araujo  CF, Silva  DM, Carneiro  MT, Ribeiro  S, Fontana-Maurell  M, Alvarez  P, Asensi  MD, Zahner  V, Carvalho-Assef  AP,     ( 2016 )

Detection of Carbapenemase Genes in Aquatic Environments in Rio de Janeiro, Brazil.

Antimicrobial agents and chemotherapy 60 (7)
PMID : 27139469  :   DOI  :   10.1128/AAC.02753-15     PMC  :   PMC4914687    
Abstract >>
This study reveals the presence of different carbapenemase genes (blaKPC, blaNDM, blaGES, and blaOXA48-like genes) detected directly from water samples and clonal dispersion (by pulsed-field gel electrophoresis [PFGE] and multilocus sequence typing [MLST]) of KPC-2-producing Enterobacteriaceae in two important urban aquatic matrixes from Rio de Janeiro, Brazil, highlighting the role of aquatic environments as gene pools and the possibility of community spreading.
KeywordMeSH Terms
43. Wen  Y, Pu  X, Zheng  W, Hu  G,     ( 2016 )

High Prevalence of Plasmid-Mediated Quinolone Resistance and IncQ Plasmids Carrying qnrS2 Gene in Bacteria from Rivers near Hospitals and Aquaculture in China.

PloS one 11 (7)
PMID : 27427763  :   DOI  :   10.1371/journal.pone.0159418     PMC  :   PMC4948828    
Abstract >>
Effluents from hospital and aquaculture are considered important sources of quinolone resistance. However, little information is available on the impact of this effluent on nearby rivers. In this study, 188 ciprofloxacin-resistant bacterial isolates obtained from rivers near hospitals and aquaculture were screened for plasmid-mediated quinolone resistance (PMQR) genes. Species identification, antibiotic susceptibility testing, and PMQR gene transferability assessment were conducted for PMQR-positive bacteria. Representative qnrS2-encoding plasmids were subsequently sequenced using a primer-walking approach. In total, 44 isolates (23.4%) were positive for qnr genes (16 qnrB2, 3 qnrS1, and 25 qnrS2) and 32 isolates (17.0%) were positive for aac(6')-Ib-cr. Other PMQR genes were not detected. The qnrB2 and aac(6')-Ib-cr genes had a higher prevalence in aquaculture samples than in hospital samples, and were significantly associated with Enterobacteriaceae (p < 0.05). In contrast, the prevalence of qnrS2 was not site-related, but was significantly associated with Aeromonas spp. (p < 0.05). All PMQR isolates were resistant to three or more classes of antibiotics. Eleven qnrS2-harboring plasmids from Aeromonas spp., including a novel conjugative plasmid pHP18, were selected for sequencing. These plasmids were small in size (6,388-16,197 bp) and belonged to the IncQ or IncU plasmid family, with qnrS2 being part of a mobile insertion cassette. Taken together, our findings suggest that aquaculture is a possible source for aac(6')-Ib-cr and qnrB2 dissemination, and demonstrate the ubiquity of qnrS2 in aquatic environments. Finally, Aeromonas spp. served as vectors for qnrS2 with the help of IncQ-type plasmids.
KeywordMeSH Terms
Conjugation, Genetic
Water Microbiology
44. Khor  WC, Puah  SM, Tan  JA, Puthucheary  SD, Chua  KH,     ( 2015 )

Phenotypic and Genetic Diversity of Aeromonas Species Isolated from Fresh Water Lakes in Malaysia.

PloS one 10 (12)
PMID : 26710336  :   DOI  :   10.1371/journal.pone.0145933     PMC  :   PMC4692508    
Abstract >>
Gram-negative bacilli of the genus Aeromonas are primarily inhabitants of the aquatic environment. Humans acquire this organism from a wide range of food and water sources as well as during aquatic recreational activities. In the present study, the diversity and distribution of Aeromonas species from freshwater lakes in Malaysia was investigated using glycerophospholipid-cholesterol acyltransferase (GCAT) and RNA polymerase sigma-factor (rpoD) genes for speciation. A total of 122 possible Aeromonas strains were isolated and confirmed to genus level using the API20E system. The clonality of the isolates was investigated using ERIC-PCR and 20 duplicate isolates were excluded from the study. The specific GCAT-PCR identified all isolates as belonging to the genus Aeromonas, in agreement with the biochemical identification. A phylogenetic tree was constructed using the rpoD gene sequence and all 102 isolates were identified as: A. veronii 43%, A. jandaei 37%, A. hydrophila 6%, A. caviae 4%, A. salmonicida 2%, A. media 2%, A. allosaccharophila 1%, A. dhakensis 1% and Aeromonas spp. 4%. Twelve virulence genes were present in the following proportions--exu 96%, ser 93%, aer 87%, fla 83%, enolase 70%, ela 62%, act 54%, aexT 33%, lip 16%, dam 16%, alt 8% and ast 4%, and at least 2 of these genes were present in all 102 strains. The ascV, aexU and hlyA genes were not detected among the isolates. A. hydrophila was the main species containing virulence genes alt and ast either present alone or in combination. It is possible that different mechanisms may be used by each genospecies to demonstrate virulence. In summary, with the use of GCAT and rpoD genes, unambiguous identification of Aeromonas species is possible and provides valuable data on the phylogenetic diversity of the organism.
KeywordMeSH Terms
45. Mosser  T, Talagrand-Reboul  E, Colston  SM, Graf  J, Figueras  MJ, Jumas-Bilak  E, Lamy  B,     ( 2015 )

Exposure to pairs of Aeromonas strains enhances virulence in the Caenorhabditis elegans infection model.

Frontiers in microbiology 6 (N/A)
PMID : 26583012  :   DOI  :   10.3389/fmicb.2015.01218     PMC  :   PMC4631986    
Abstract >>
Aeromonad virulence remains poorly understood, and is difficult to predict from strain characteristics. In addition, infections are often polymicrobial (i.e., are mixed infections), and 5-10% of such infections include two distinct aeromonads, which has an unknown impact on virulence. In this work, we studied the virulence of aeromonads recovered from human mixed infections. We tested them individually and in association with other strains with the aim of improving our understanding of aeromonosis. Twelve strains that were recovered in pairs from six mixed infections were tested in a virulence model of the worm Caenorhabditis elegans. Nine isolates were weak worm killers (median time to death, TD50, ?7 days) when administered alone. Two pairs showed enhanced virulence, as indicated by a significantly shortened TD50 after co-infection vs. infection with a single strain. Enhanced virulence was also observed for five of the 14 additional experimental pairs, and each of these pairs included one strain from a natural synergistic pair. These experiments indicated that synergistic effects were frequent and were limited to pairs that were composed of strains belonging to different species. The genome content of virulence-associated genes failed to explain virulence synergy, although some virulence-associated genes that were present in some strains were absent from their companion strain (e.g., T3SS). The synergy observed in virulence when two Aeromonas isolates were co-infected stresses the idea that consideration should be given to the fact that infection does not depend only on single strain virulence but is instead the result of a more complex interaction between the microbes involved, the host and the environment. These results are of interest for other diseases in which mixed infections are likely and in particular for water-borne diseases (e.g., legionellosis, vibriosis), in which pathogens may display enhanced virulence in the presence of the right partner. This study contributes to the current shift in infectiology paradigms from a premise that assumes a monomicrobial origin for infection to one more in line with the current pathobiome era.
KeywordMeSH Terms
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
Aeromonas
Caenorhabditis elegans
mixed infection
polymicrobial infection
virulence determinants
46. Antonelli  A, D'Andrea  MM, Montagnani  C, Bartolesi  AM, Di Pilato  V, Fiorini  P, Torricelli  F, Galli  L, Rossolini  GM,     ( 2016 )

Newborn bacteraemia caused by an Aeromonas caviae producing the VIM-1 and SHV-12 �]-lactamases, encoded by a transferable plasmid.

The Journal of antimicrobial chemotherapy 71 (1)
PMID : 26410172  :   DOI  :   10.1093/jac/dkv304    
Abstract >>
N/A
KeywordMeSH Terms
beta-Lactam Resistance
47. Persson  S, Al-Shuweli  S, Yapici  S, Jensen  JN, Olsen  KE,     ( 2015 )

Identification of clinical aeromonas species by rpoB and gyrB sequencing and development of a multiplex PCR method for detection of Aeromonas hydrophila, A. caviae, A. veronii, and A. media.

Journal of clinical microbiology 53 (2)
PMID : 25411168  :   DOI  :   10.1128/JCM.01963-14     PMC  :   PMC4298543    
Abstract >>
Conventional identification of Aeromonas species based on biochemical methods is challenged by the heterogeneous nature of the species. Here, we present a new multiplex PCR method directed toward the gyrB and rpoB genes that identifies four Aeromonas species, A. hydrophila, A. media, A. veronii, and A. caviae, and we describe the application of this method on a Danish strain collection.
KeywordMeSH Terms
48. Lorén  JG, Farfán  M, Fusté  MC,     ( 2014 )

Molecular phylogenetics and temporal diversification in the genus Aeromonas based on the sequences of five housekeeping genes.

PloS one 9 (2)
PMID : 24586399  :   DOI  :   10.1371/journal.pone.0088805     PMC  :   PMC3930666    
Abstract >>
Several approaches have been developed to estimate both the relative and absolute rates of speciation and extinction within clades based on molecular phylogenetic reconstructions of evolutionary relationships, according to an underlying model of diversification. However, the macroevolutionary models established for eukaryotes have scarcely been used with prokaryotes. We have investigated the rate and pattern of cladogenesis in the genus Aeromonas (�^-Proteobacteria, Proteobacteria, Bacteria) using the sequences of five housekeeping genes and an uncorrelated relaxed-clock approach. To our knowledge, until now this analysis has never been applied to all the species described in a bacterial genus and thus opens up the possibility of establishing models of speciation from sequence data commonly used in phylogenetic studies of prokaryotes. Our results suggest that the genus Aeromonas began to diverge between 248 and 266 million years ago, exhibiting a constant divergence rate through the Phanerozoic, which could be described as a pure birth process.
KeywordMeSH Terms
Evolution, Molecular
Models, Genetic
Phylogeny
49. Vega-Sánchez  V, Latif-Eugenín  F, Soriano-Vargas  E, Beaz-Hidalgo  R, Figueras  MJ, Aguilera-Arreola  MG, Castro-Escarpulli  G,     ( 2014 )

Re-identification of Aeromonas isolates from rainbow trout and incidence of class 1 integron and �]-lactamase genes.

Veterinary microbiology 172 (3��4��)
PMID : 25008317  :   DOI  :   10.1016/j.vetmic.2014.06.012    
Abstract >>
Forty-eight Aeromonas isolates from rainbow trout previously identified by the 16S rDNA-RFLP technique were re-identified using 2 housekeeping genes (gyrB and rpoD). After sequencing the prevalences of the species were A. veronii (29.2%), A. bestiarum (20.8%), A. hydrophila (16.7%), A. sobria (10.4%), A. media (8.3%), A. popoffii (6.2%), A. allosaccharophila (2.1%), A. caviae (2.1%), A. salmonicida (2.1%) and one isolate (2.1%) belongs to a candidate new species "Aeromonas lusitana". Coincident identification results to the 16S rDNA-RFLP technique were only obtained for 68.8% of the isolates. PCR amplification of the enterobacterial repetitive intergenic consensus (ERIC-PCR) indicated that the 48 isolates belonged to 33 different ERIC genotypes. Several genotypes were isolated from different farms and organs in the same fish, indicating a systemic dissemination of the bacteria. The presence of genes (blaIMP, blaCphA/IMIS, blaTEM, blaSHV and intI1) that encode extended-spectrum beta-lactamases (ESBLs), metallo-beta-lactamases (MBLs) and class 1 integrons were studied by PCR. Only 39.6% (19/48) of the strains showed the presence of one or more resistance genes. The gene blaCphA/IMIS was detected in 29.2% of the isolates, followed by the intI1 (6.2%) and blaSHV (4.2%) genes. The variable region of class 1 integrons of the 3 positive isolates was sequenced revealing the presence of the gene cassette aadA1 (aminoglycoside transferase) that plays a role in streptomycin/spectinomycin resistance.
KeywordMeSH Terms
ESBLs
Integrons
Aeromonas
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Aeromonas
ESBLs
Integrons
Rainbow trout
gyrB
rpoD
Oncorhynchus mykiss
50. Martino  ME, Fasolato  L, Montemurro  F, Novelli  E, Cardazzo  B,     ( 2014 )

Aeromonas spp.: ubiquitous or specialized bugs?

Environmental microbiology 16 (4)
PMID : 23919504  :   DOI  :   10.1111/1462-2920.12215    
Abstract >>
The genus Aeromonas comprises ubiquitous bacteria that are known to play several roles in the environment. These bacteria were first described as fish pathogens, but their presence was documented in other reservoirs, such as animals and humans. Today, these bacteria are described as emerging pathogens, but their effective role in human pathogenicity is still controversial. In addition, their taxonomy is heavily debated, as species distinction is often difficult to achieve. To study the interspecies relationships and to investigate their connection with the environment, a multilocus sequence typing scheme previously developed for Aeromonas spp. was applied to 258 strains, and the genetic data were analysed by population software. Sampling was a fundamental step, including several of the main sources of Aeromonas: fish, food products and human cases of disease. The objective was to characterize the isolates and to find potential associations among them according to the following: species, sharing of virulence factors, source and adaptation to a specific habitat. The strains were characterized and demonstrated exceptionally high nucleotide variability in the Aeromonas genus. Among the sampled sources, different species distributions were found, highlighting the occurrence of adaptation processes towards specific habitats.
KeywordMeSH Terms
51. Maravi?  A, Sko?ibuši?  M, Samani?  I, Fredotovi?  Z, Cvjetan  S, Jutroni?  M, Puizina  J,     ( 2013 )

Aeromonas spp. simultaneously harbouring bla(CTX-M-15), bla(SHV-12), bla(PER-1) and bla(FOX-2), in wild-growing Mediterranean mussel (Mytilus galloprovincialis) from Adriatic Sea, Croatia.

International journal of food microbiology 166 (2)
PMID : 23973842  :   DOI  :   10.1016/j.ijfoodmicro.2013.07.010    
Abstract >>
Aeromonas species are becoming renowned as emerging pathogens by increasingly giving rise to a wide spectrum of food and waterborne infections in humans. Another worrisome feature of aeromonads is the growing frequency of antibiotic resistance as a consequence of their prominent diversity in terms of resistance determinants. This study aimed at determining the antimicrobial resistance pattern, prevalence and characterization of acquired �]-lactamases, including extended-spectrum-�]-lactamases (ESBLs) and AmpC cephalosporinases, as well as the presence of class 1 and 2 integrons, in Aeromonas isolates from wild-growing Mediterranean mussel (Mytilus galloprovincialis) of the eastern coast of Adriatic Sea, Croatia. Isolates were tested for susceptibility to 16 antibiotics and �]-lactam/�]-lactamase inhibitor combinations. Cephalosporin-resistant isolates were further screened by PCR for genes encoding AmpC (bla(FOX), bla(CMY), bla(MOX), bla(LAT), bla(BIL), bla(DHA), bla(ACC), bla(MIR), bla(ACT)), ESBLs (bla(TEM), bla(SHV), bla(CTX-M), bla(PER), bla(VEB), bla(GES/IBC), bla(OXA)) and integrases (intI1, intI2, intI3). Location of bla genes was characterized by plasmid DNA fingerprinting and Southern blot hybridization. Plasmids carrying ESBL genes were investigated for transferability by conjugation and PCR-based replicon typed. Out of 147 Aeromonas isolates recovered, 30 (20%) demonstrated multiple resistance profile, with co-resistance most frequently detected against penicillins, piperacillin/sulbactam and tetracycline. ESBL-encoding genes were detected in 21 (13 Aeromonas caviae and 8 Aeromonas hydrophila) isolates, with bla(CTX-M-15) gene identified in 19 and bla(SHV-12) in 12 isolates. Among them, 10 isolates simultaneously harboured bla(CTX-M-15) and bla(SHV-12), while 3 isolates additionally carried an AmpC �]-lactamase bla(FOX-2) gene. bla(PER-1) gene was identified in a single isolate also harbouring the bla(CTX-M-15) gene. While bla(SHV-12) was chromosomally encoded, bla(CTX-M-15) was located on conjugative IncFIB-type plasmids of ~40 kb in A. caviae isolates. IntI1 and intI2 genes were detected in 57.1% and 33.3% of ESBL-producing isolates. To the best our knowledge, this is the first report of environmental A. caviae isolates producing CTX-M-15, and isolation of SHV-12-producing A. hydrophila and A. caviae strains worldwide. This is also believed to be the first report of the FOX-2, CTX-M-15 and SHV-12 simultaneous production in aeromonads, highlighting both the potential risk for human health, and a role of these foodborne pathogens as reservoirs of resistance determinants in coastal marine environment.
KeywordMeSH Terms
Aeromonads
AmpC β-lactamase
Antibiotic resistance
ESBL
Marine environment
Mussels
Aeromonads
AmpC β-lactamase
Antibiotic resistance
ESBL
Marine environment
Mussels
Aeromonads
AmpC β-lactamase
Antibiotic resistance
ESBL
Marine environment
Mussels
Aeromonads
AmpC β-lactamase
Antibiotic resistance
ESBL
Marine environment
Mussels
52. Miñana-Galbis  D, Farfán  M, Albarral  V, Sanglas  A, Lorén  JG, Fusté  MC,     ( 2013 )

Reclassification of Aeromonas hydrophila subspecies anaerogenes.

Systematic and applied microbiology 36 (5)
PMID : 23759598  :   DOI  :   10.1016/j.syapm.2013.04.006     DOI  :   10.1016/j.syapm.2013.04.006    
Abstract >>
Technological advances together with the continuous description of new taxa have led to frequent reclassifications in bacterial taxonomy. In this study, an extensive bibliographic revision, as well as a sequence analysis of nine housekeeping genes (cpn60, dnaJ, dnaX, gyrA, gyrB, mdh, recA, rpoB and rpoD) and a phenotypic identification of Aeromonas hydrophila subspecies anaerogenes were performed. All data obtained from previous physiological, phylogenetic, and DNA-DNA hybridization studies together with those presented in this study suggested that A. hydrophila subspecies anaerogenes belonged to the species Aeromonas caviae rather than A. hydrophila. Therefore, the inclusion of A. hydrophila subsp. anaerogenes in the species A. caviae is proposed.
KeywordMeSH Terms
53. Senderovich  Y, Ken-Dror  S, Vainblat  I, Blau  D, Izhaki  I, Halpern  M,     ( 2012 )

A molecular study on the prevalence and virulence potential of Aeromonas spp. recovered from patients suffering from diarrhea in Israel.

PloS one 7 (2)
PMID : 22355306  :   DOI  :   10.1371/journal.pone.0030070     PMC  :   PMC3280246    
Abstract >>
Species of the genus Aeromonas are native inhabitants of aquatic environments and have recently been considered emerging human pathogens. Although the gastrointestinal tract is by far the most common anatomic site from which aeromonads are recovered, their role as etiologic agents of bacterial diarrhea is still disputed. Aeromonas-associated diarrhea is a phenomenon occurring worldwide; however, the exact prevalence of Aeromonas infections on a global scale is unknown. The prevalence and virulence potential of Aeromonas in patients suffering from diarrhea in Israel was studied using molecular methods. 1,033 diarrheal stools were sampled between April and September 2010 and Aeromonas species were identified in 17 (?2%) patients by sequencing the rpoD gene. Aeromonas species identity and abundance was: A. caviae (65%), A. veronii (29%) and Aeromonas taiwanensis (6%). This is the first clinical record of A. taiwanensis as a diarrheal causative since its recent discovery from a wound infection in a patient in Taiwan. Most of the patients (77%) from which Aeromonas species were isolated were negative for any other pathogens. The patients ranged from 1 to 92 years in age. Aeromonas isolates were found to possess different virulence-associated genes: ahpB (88%), pla/lip/lipH3/apl-1 (71%), act/hlyA/aerA (35%), alt (18%), ast (6%), fla (65%), lafA (41%), TTSS ascV (12%), TTSS ascF-ascG (12%), TTSS-dependent ADP-ribosylating toxins aexU (41%) and aexT (6%) in various combinations. Most of the identified strains were resistant to beta-lactam antibiotics but susceptible to third-generation cephalosporin antibiotics. Aeromonas may be a causative agent of diarrhea in patients in Israel and therefore should be included in routine bacteriological screenings.
KeywordMeSH Terms
54. Roger  F, Marchandin  H, Jumas-Bilak  E, Kodjo  A, N/A  N/A, Lamy  B,     ( 2012 )

Multilocus genetics to reconstruct aeromonad evolution.

BMC microbiology 12 (N/A)
PMID : 22545815  :   DOI  :   10.1186/1471-2180-12-62     PMC  :   PMC3487998    
Abstract >>
Aeromonas spp. are versatile bacteria that exhibit a wide variety of lifestyles. In an attempt to improve the understanding of human aeromonosis, we investigated whether clinical isolates displayed specific characteristics in terms of genetic diversity, population structure and mode of evolution among Aeromonas spp. A collection of 195 Aeromonas isolates from human, animal and environmental sources was therefore genotyped using multilocus sequence analysis (MLSA) based on the dnaK, gltA, gyrB, radA, rpoB, tsf and zipA genes. The MLSA showed a high level of genetic diversity among the population, and multilocus-based phylogenetic analysis (MLPA) revealed 3 major clades: the A. veronii, A. hydrophila and A. caviae clades, among the eleven clades detected. Lower genetic diversity was observed within the A. caviae clade as well as among clinical isolates compared to environmental isolates. Clonal complexes, each of which included a limited number of strains, mainly corresponded to host-associated subsclusters of strains, i.e., a fish-associated subset within A. salmonicida and 11 human-associated subsets, 9 of which included only disease-associated strains. The population structure was shown to be clonal, with modes of evolution that involved mutations in general and recombination events locally. Recombination was detected in 5 genes in the MLSA scheme and concerned approximately 50% of the STs. Therefore, these recombination events could explain the observed phylogenetic incongruities and low robustness. However, the MLPA globally confirmed the current systematics of the genus Aeromonas. Evolution in the genus Aeromonas has resulted in exceptionally high genetic diversity. Emerging from this diversity, subsets of strains appeared to be host adapted and/or disease specialized" while the A. caviae clade displayed an atypical tempo of evolution among aeromonads. Considering that A. salmonicida has been described as a genetically uniform pathogen that has adapted to fish through evolution from a variable ancestral population, we hypothesize that the population structure of aeromonads described herein suggested an ongoing process of adaptation to specialized niches associated with different degrees of advancement according to clades and clusters."
KeywordMeSH Terms
Environmental Microbiology
Evolution, Molecular
Genetic Variation
55. Pan  ZH, Lu  CP,     ( 2012 )

Identity and virulence properties of Aeromonas isolates from diseased fish, healthy controls and water environment in China.

Letters in applied microbiology 55 (3)
PMID : 22725694  :   DOI  :   10.1111/j.1472-765X.2012.03281.x    
Abstract >>
To investigate the species distribution in Aeromonas isolates from diseased fish, healthy controls and water environment in China; to evaluate the frequency of the aerolysin (aer), cytotonic enterotoxin (alt), cytotoxic enterotoxin (act), temperature-sensitive protease (eprCAI) and serine protease (ahp) genes in Aeromonas isolates; and to determine the potential pathogenicity of these isolates. Two hundred and two Aeromonas isolates from diseased fish (n = 42), healthy fish (n = 120) and water environment (n = 40) in China were identified to species levels based on sequencing of the housekeeping gene gyrB, while the distribution of five virulence factors, including aer, alt, act, eprCAI and ahp, was investigated by PCR. Aeromonas veronii (25/42; 60%) and Aeromonas hydrophila (14/42; 33%) were the species most commonly isolated from diseased fish, while Aer. veronii was the most common species in healthy fish (90/120; 75%) and water samples (25/40; 62�P5%). All the five virulence genes were present in 9% (19/202), among which 10 strains were from diseased fish and nine were identified as Aer. hydrophila. For the strains carrying five virulence genes, the average 50% lethal doses (LD(50s)) of strains from diseased fish were lower when compared with the strains from healthy fish and water environment. Aeromonas veronii is the most common species, but no significant difference exists in the isolates obtained from diseased fish and from healthy fish. However, Aer. hydrophila isolates were significantly more frequent from diseased fish than from healthy fish. aer+alt+act+eprCAI+ ahp+ was more frequent virulence genotype in Aeromonas isolates from diseased fish than from healthy fish and water environment, and the aer+alt+act+eprCAI+ahp+ isolates were more virulent to zebrafish comparing to the other genetic profiles. Aeromonas species in aquatic environments are various and have considerable virulence potential, and therefore, there is a need for more careful and intensive epidemiology studies.
KeywordMeSH Terms
Water Microbiology
56. Moura  A, Pereira  C, Henriques  I, Correia  A,     ( 2012 )

Novel gene cassettes and integrons in antibiotic-resistant bacteria isolated from urban wastewaters.

Research in microbiology 163 (2)
PMID : 22127350  :   DOI  :   10.1016/j.resmic.2011.10.010    
Abstract >>
In this study, the occurrence and diversity of integrons were evaluated in 697 isolates belonging to Enterobacteriaceae and Aeromonas spp. isolated from urban wastewaters. Screening of integrons was performed by dot blot hybridization and intI-positive strains were further characterized. The global prevalence of integrons was 3.73%. Three new gene cassettes were identified: a novel aadA variant (aadA17), a gene putatively involved in cell signaling (dcyA) and an open reading frame of unknown function interrupted by a novel insertion sequence (orfER.17::ISAs12). In total, thirteen different gene cassette arrays were detected, 4 representing novel integrons: intI1-dcyA-tniC, intI1-orfER.1.7::ISAs12-aadA13-qacE�G1-sul1, intI1-aacA4-catB3-bla(OxA-10)-aadA1-qacE�G1-sul1 and intI1-catB8-aadA17-qacE�G1-sul1. Approximately 80% of strains were resistant to at least 3 antibiotics of different classes. The presence of novel integron structures in treated effluents suggests that domestic wastewaters may favor the formation of novel combinations of gene cassettes. Moreover, the high prevalence of multiresistant strains highlights the urgent need to employ effective means of effluent disinfection to avoid dissemination of antibiotic-resistant bacteria.
KeywordMeSH Terms
Aeromonas
Enterobacteriaceae
57.     ( 1997 )

Cloning and analysis of the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) biosynthesis genes of Aeromonas caviae.

Journal of bacteriology 179 (15)
PMID : 9244271  :   DOI  :   10.1128/jb.179.15.4821-4830.1997     PMC  :   PMC179330    
Abstract >>
A 5.0-kbp EcoRV-EcoRI restriction fragment was cloned and analyzed from genomic DNA of Aeromonas caviae, a bacterium producing a copolyester of (R)-3-hydroxybutyrate (3HB) and (R)-3-hydroxyhexanoate (3HHx) [P(3HB-co-3HHx)] from alkanoic acids or oils. The nucleotide sequence of this region showed a 1,782-bp poly (3-hydroxyalkanoate) (PHA) synthase gene (phaC(Ac) [i.e., the phaC gene from A. caviae]) together with four open reading frames (ORF1, -3, -4, and -5) and one putative promoter region. The cloned fragments could not only complement PHA-negative mutants of Alcaligenes eutrophus and Pseudomonas putida, but also confer the ability to synthesize P(3HB-co-3HHx) from octanoate or hexanoate on the mutants' hosts. Furthermore, coexpression of ORF1 and ORF3 genes with phaC(Ac) in the A. eutrophus mutant resulted in a decrease in the polyester content of the cells. Escherichia coli expressing ORF3 showed (R)-enoyl-coenzyme A (CoA) hydratase activity, suggesting that (R)-3-hydroxyacyl-CoA monomer units are supplied via the (R)-specific hydration of enoyl-CoA in A. caviae. The transconjugant of the A. eutrophus mutant expressing only phaC(Ac) effectively accumulated P(3HB-co-3HHx) up to 96 wt% of the cellular dry weight from octanoate in one-step cultivation.
KeywordMeSH Terms
58.     ( 1996 )

Characterization of cytotoxic, hemolytic Aeromonas caviae clinical isolates and their identification by determining presence of a unique hemolysin gene.

Journal of clinical microbiology 34 (12)
PMID : 8940472  :   PMC  :   PMC229483    
Abstract >>
Aeromonas caviae has recently been recognized as an important enteropathogen and its hemolysin is purported to be one of the virulence factors, In this study, a total of 80 clinical isolates of Aeromonas spp. were investigated by PCR with synthetic oligonucleotides targeting a cloned hemolysin-encoding sequence from an A. caviae isolate of clinical origin. Of the 35 clinical A. caviae isolates tested, only 6 contained the target sequence.
KeywordMeSH Terms
Genes, Bacterial
59.     ( 1996 )

Study of the intergenic exeF-exeG region and its application as a simple preliminary test for Aeromonas spp.

FEMS microbiology letters 137 (1)
PMID : 8935655  :   DOI  :   10.1111/j.1574-6968.1996.tb08079.x    
Abstract >>
The exeF-exeG intergenic regions from different hybridization groups (HG) of Aeromonas were studied by PCR amplification using a single pair of primers. Six main classes of PCR products were identified according to size: 360 bp, 320 bp, 280 bp, 230-240 bp, 220 bp and 160 bp. Direct sequencing of the PCR products indicated that the shorter intergenic regions had probably originated from deletion of DNA segments between direct repeats. Correlation of certain PCR products with Aeromonas caviae (HG4), A. caviae (HG5), A. veronii (HG8) and A. salmonicida (HG3) was revealed. The PCR reaction was also shown to be generally specific for Aeromonas spp. Thus, the usefulness of this rapid, single colony-based PCR test for both identification and preliminary differentiation of Aeromonas spp. is demonstrated.
KeywordMeSH Terms
60. Sitrit  Y, Vorgias  CE, Chet  I, Oppenheim  AB,     ( 1995 )

Cloning and primary structure of the chiA gene from Aeromonas caviae.

Journal of bacteriology 177 (14)
PMID : 7608101  :   DOI  :   10.1128/jb.177.14.4187-4189.1995     PMC  :   PMC177160    
Abstract >>
The chiA gene from Aeromonas caviae encodes an extracellular chitinase, 865 amino acids long, that shows a high degree of similarity to chitinase A of Serratia marcescens. Expression in Escherichia coli yielded an enzymatically active protein from which a leader sequence was removed, presumably during transport of the enzyme across the cell membrane.
KeywordMeSH Terms
61. Falmagne  P, Portetelle  D, Stalon  V,     ( 1985 )

Immunological and structural relatedness of catabolic ornithine carbamoyltransferases and the anabolic enzymes of enterobacteria.

Journal of bacteriology 161 (2)
PMID : 3968036  :   PMC  :   PMC214941    
Abstract >>
Purified catabolic ornithine carbamoyltransferase of Pseudomonas putida and anabolic ornithine carbamoyltransferase (argF product) of Escherichia coli K-12 were used to prepare antisera. The two specific antisera gave heterologous cross-reactions of various intensities with bacterial catabolic ornithine carbamoyltransferases formed by Pseudomonas and representative organisms of other bacterial genera. The immunological cross-reactivity observed only between the catabolic ornithine carbamoyltransferases and the anabolic enzymes of enterobacteria suggests that these proteins share some structural similarities. Indeed, the amino acid composition of the anabolic ornithine carbamoyltransferase of E. coli K-12 (argF and argI products) closely resembles the amino acid compositions of the catabolic enzymes of Pseudomonas putida, Aeromonas formicans, Streptococcus faecalis, and Bacillus licheniformis. Comparison of the N-terminal amino acid sequence of the E. coli anabolic ornithine carbamoyltransferase with that of the A. formicans and Pseudomonas putida catabolic enzymes shows, respectively, 45 and 28% identity between the compared positions; the A. formicans sequence reveals 53% identity with the Pseudomonas putida sequence. These results favor the conclusion that anabolic ornithine carbamoyltransferases of enterobacteria and catabolic ornithine carbamoyltransferases derive from a common ancestral gene.
KeywordMeSH Terms
62. Hossain  S, Dahanayake  PS, De Silva  BCJ, Wickramanayake  MVKS, Wimalasena  SHMP, Heo  GJ,     ( 2019 )

Multidrug resistant Aeromonas spp. isolated from zebrafish (Danio rerio): antibiogram, antimicrobial resistance genes and class 1 integron gene cassettes.

Letters in applied microbiology 68 (5)
PMID : 30790321  :   DOI  :   10.1111/lam.13138    
Abstract >>
Aeromonas spp. are Gram-negative opportunistic bacteria which have been commonly associated with fish diseases. In this study, antibiogram, antimicrobial resistance genes and integrons of 43 zebrafish-borne Aeromonas spp. were studied. The isolates were identified as six Aeromonas species (A. veronii biovar veronii (n = 26), A. veronii biovar sobria (n = 3), A. hydrophila (n = 8), A. caviae (n = 3), A. enteropelogenes (n = 2) and A. dhakensis (n = 1)). Antibiogram of the isolates indicated that most of them were resistant to amoxicillin (100�P00%), nalidixic acid (100�P00%), oxytetracycline (100�P00%), ampicillin (93�P02%), tetracycline (74�P42%), rifampicin (67�P44%) and imipenem (65�P15%). Multiple antimicrobial resistance (MAR) index values ranged from 0�P19-0�P44 to 90�P70% isolates showed multidrug resistance. PCR of antimicrobial resistance genes revealed that the tetracycline resistance gene (tetA) was the most predominant (67�P44%) among the isolates. The qnrS (53�P49%), tetB (30�P23%), tetE (30�P23%), qnrB (23�P26%) and aac(6')-Ib-cr (4�P65%) genes were also detected. Class 1 integrase (IntI1) gene was found in 46�P51% of the isolates. Two types of class 1 integron gene cassette profiles (qacG-aadA6-qacG and drfA1) were identified. The results showed that zebrafish-borne aeromonads can harbour different types of antimicrobial resistance genes and class 1 integrons. SIGNIFICANCE AND IMPACT OF THE STUDY: Aeromonas spp. are important pathogens found in diverse environments. Antimicrobial resistance genes and integrons of ornamental fish-borne Aeromonas spp. are not well studied. The antibiogram, antimicrobial resistance genes and class 1 integrons of Aeromonas spp. isolated from zebrafish were characterized for the first time in Korea. The prevalence of tetracycline resistance genes, plasmid-mediated quinolone resistance genes and class 1 integron gene cassettes were observed among the isolates. The qacG-aadA6-qacG gene cassette was identified for the first time in Aeromonas spp. The results suggest that the wise use of antimicrobials is necessary for the better management of the ornamental fish.
KeywordMeSH Terms
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
Aeromonas spp.
antibiogram
antimicrobial resistance genes
class 1 integron gene cassettes
zebrafish
63. Shi  Y, Tian  Z, Leclercq  SO, Zhang  H, Yang  M, Zhang  Y,     ( 2019 )

Genetic characterization and potential molecular dissemination mechanism of tet(31) gene in Aeromonas caviae from an oxytetracycline wastewater treatment system.

Journal of environmental sciences (China) 76 (N/A)
PMID : 30528016  :   DOI  :   10.1016/j.jes.2018.05.008    
Abstract >>
Recently, the rarely reported tet(31) tetracycline resistance determinant was commonly found in Aeromonas salmonicida, Gallibacterium anatis, and Oblitimonas alkaliphila isolated from farming animals and related environment. However, its distribution in other bacteria and potential molecular dissemination mechanism in environment are still unknown. The purpose of this study was to investigate the potential mechanism underlying dissemination of tet(31) by analysing the tet(31)-carrying fragments in A. caviae strains isolated from an aerobic biofilm reactor treating oxytetracycline bearing wastewater. Twenty-three A. caviae strains were screened for the tet(31) gene by polymerase chain reaction (PCR). Three strains (two harbouring tet(31), one not) were subjected to whole genome sequencing using the PacBio RSII platform. Seventeen A. caviae strains carried the tet(31) gene and exhibited high resistance levels to oxytetracycline with minimum inhibitory concentrations (MICs) ranging from 256 to 512 mg/L. tet(31) was comprised of the transposon Tn6432 on the chromosome of A. caviae, and Tn6432 was also found in 15 additional tet(31)-positive A. caviae isolates by PCR. More important, Tn6432 was located on an integrative conjugative element (ICE)-like element, which could mediate the dissemination of the tet(31)-carrying transposon Tn6432 between bacteria. Comparative analysis demonstrated that Tn6432 homologs with the structure ISCR2-?phzF-tetR(31)-tet(31)-?glmM-sul2 were also carried by A. salmonicida, G. anatis, and O. alkaliphila, suggesting that this transposon can be transferred between species and even genera. This work provides the first report on the identification of the tet(31) gene in A. caviae, and will be helpful in exploring the dissemination mechanisms of tet(31) in water environment.
KeywordMeSH Terms
Aeromonas caviae
ICE-like element
ISCR2
Wastewater
tet(31) gene
Aeromonas caviae
ICE-like element
ISCR2
Wastewater
tet(31) gene
64. Amos  GCA, Ploumakis  S, Zhang  L, Hawkey  PM, Gaze  WH, Wellington  EMH,     ( 2018 )

The widespread dissemination of integrons throughout bacterial communities in a riverine system.

The ISME journal 12 (3)
PMID : 29374269  :   DOI  :   10.1038/s41396-017-0030-8     PMC  :   PMC5864220    
Abstract >>
Anthropogenic inputs increase levels of antimicrobial resistance (AMR) in the environment, however, it is unknown how these inputs create this observed increase, and if anthropogenic sources impact AMR in environmental bacteria. The aim of this study was to characterise the role of waste water treatment plants (WWTPs) in the dissemination of class 1 integrons (CL1s) in the riverine environment. Using sample sites from upstream and downstream of a WWTP, we demonstrate through isolation and culture-independent analysis that WWTP effluent significantly increases both CL1 abundance and antibiotic resistance in the riverine environment. Characterisation of CL1-bearing isolates revealed that CL1s were distributed across a diverse range of bacteria, with identical complex genetic resistance determinants isolated from both human-associated and common environmental bacteria across connected sites. Over half of sequenced CL1s lacked the 3'-conserved sequence ('atypical' CL1s); surprisingly, bacteria carrying atypical CL1s were on average resistant to more antibiotics than bacteria carrying 3'-CS CL1s. Quaternary ammonium compound (QAC) resistance genes were observed across 75% of sequenced CL1 gene cassette arrays. Chemical data analysis indicated high levels of boron (a detergent marker) downstream of the WWTP. Subsequent phenotypic screening of CL1-bearing isolates demonstrated that ~90% were resistant to QAC detergents, with in vitro experiments demonstrating that QACs could solely select for the transfer of clinical antibiotic resistance genes to a naive Escherichia coli recipient. In conclusion, this study highlights the significant impact of WWTPs on environmental AMR, and demonstrates the widespread carriage of clinically important resistance determinants by environmentally associated bacteria.
KeywordMeSH Terms
Gene Transfer, Horizontal
Integrons
65. Wimalasena  SHMP, De Silva  BCJ, Hossain  S, Pathirana  HNKS, Heo  GJ,     ( 2017 )

Prevalence and characterisation of quinolone resistance genes in Aeromonas spp. isolated from pet turtles in South Korea.

Journal of global antimicrobial resistance 11 (N/A)
PMID : 28743647  :   DOI  :   10.1016/j.jgar.2017.06.001    
Abstract >>
The aim of this study was to characterise Aeromonas spp. isolated from popular species of pet turtle to assess the potential risk of pet turtles as a source of target gene alterations in the quinolone resistance-determining region (QRDR) and transferable plasmid-mediated quinolone resistance (PMQR) genes. Twenty-five isolates comprising four species, namely Aeromonas enteropelogenes, Aeromonas hydrophila, Aeromonas caviae and Aeromonas veronii, were obtained from healthy pet turtles. The antimicrobial susceptibility of the isolates to nalidixic acid, ciprofloxacin and ofloxacin was examined by minimum inhibitory concentration (MIC) determination. QRDR substitutions and PMQR genes were detected using conventional PCR assays and sequencing. Although more than one-half of the isolates were resistant to nalidixic acid (14/25; 56%), most were susceptible to ciprofloxacin and ofloxacin. In QRDR substitution analysis, gyrA Ser-83��Ile substitution was predominant among A. enteropelogenes isolates, whilst two isolates of A. caviae displayed a novel Asp-95��Pro substitution. With regard to parC, Ser-80��Ile substitution was noted in all species except A. veronii. Furthermore, qnrS, qnrB and aac(6')-Ib-cr genes were detected in 68% (17/25), 8% (2/25) and 8% (2/25) of the isolates, respectively; 86% (12/14) of A. enteropelogenes isolates harboured a qnrS gene. Unexpectedly, quinolone resistance determinants were also detected in some isolates that were phenotypically susceptible to the tested quinolones. The current study reveals the mismatch phenomenon between quinolone resistance phenotype and genotype of turtle-borne aeromonads and suggests that susceptible isolates might be a potential risk source for storage and transmission of resistance genes.
KeywordMeSH Terms
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
Aeromonas spp.
PMQR genes
Pet turtle
Plasmid-mediated quinolone resistance
QRDR mutations
Quinolone resistance-determining region
66. Hoel  S, Vadstein  O, Jakobsen  AN,     ( 2017 )

Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi.

Frontiers in microbiology 8 (N/A)
PMID : 28596762  :   DOI  :   10.3389/fmicb.2017.00931     PMC  :   PMC5442234    
Abstract >>
Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens because of their widespread occurrence in food, especially seafood and vegetables. The aim of this work was to assess the species identity and phylogenetic relationship of 118 Aeromonas strains isolated from fresh retail sushi from three producers, and to characterize the isolates with respect to genetic and phenotypic virulence factors. We also evaluate the potential hazard associated with their presence in ready-to-eat seafood not subjected to heat treatment. Mesophilic Aeromonas salmonicida was most prevalent (74%), followed by A. bestiarum (9%), A. dhakensis (5%), A. caviae (5%), A. media (4%), A. hydrophila (2%), and A. piscicola (1%). All isolates were considered potentially pathogenic due to the high prevalence of genes encoding hemolysin (hlyA) (99%), aerolysin (aerA) (98%), cytotoxic enterotoxin (act) (86%), heat-labile cytotonic enterotoxin (alt) (99%), and heat-stable cytotonic enterotoxin (ast) (31%). The shiga-like toxins 1 and 2 (stx-1 and stx-2) were not detected. Moreover, there was heterogeneity in toxin gene distribution among the isolates, and the combination of act/alt/hlyA/aerA was most commonly detected (63%). �]-hemolysis was species-dependent and observed in 91% of the isolates. All A. media and A. caviae strains were non-hemolytic. For isolates belonging to this group, lack of hemolysis was possibly related to the absence of the act gene. Swimming motility, linked to adhesion and host invasion, occurred in 65% of the isolates. Partial sequencing of the gyrB gene demonstrated its suitability as a genetic marker for Aeromonas species identification and for assessment of the phylogenetic relationship between the isolates. The gyrB sequence divergence within a given species ranged from 1.3 to 2.9%. A. bestiarum, A. salmonicida, and A. piscicola were the most closely related species; their sequences differed by 2.7-3.4%. The average gyrB sequence similarity between all species was 93%, demonstrating its acceptable taxonomic resolution. The presence of multiple species of potential pathogenic Aeromonas in fresh retail sushi raises new food safety issues related to the increased consumption of ready-to-eat food composed of raw ingredients.
KeywordMeSH Terms
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
Aeromonas spp.
food safety
gyrB
ready-to-eat food
sushi
virulence factors
67.     ( 2013 )

Characterization of Aeromonas strains isolated from Indian foods using rpoD gene sequencing and whole cell protein analysis.

World journal of microbiology & biotechnology 29 (4)
PMID : 23255059  :   DOI  :   10.1007/s11274-012-1212-1    
Abstract >>
Aeromonas are responsible for causing gastroenteritis and extra-intestinal infections in humans. Twenty-two Aeromonas strains isolated from different food sources were re-identified up to species level using rpoD gene sequence analysis. Biochemical tests and 16S rRNA gene sequencing were insufficient to identify Aeromonas till species level. However, incorporation of additional biochemical tests lead to correct identification of 95.5 % strains up to species level. The 16S rRNA gene sequencing was useful to identify Aeromonas isolates at the genus level only. Sequences of the rpoD gene showed greater discriminatory power than 16S rRNA gene and provided conclusive discrimination of the strains for which the phenotypic species identification was uncertain. All these 22 strains were accurately identified up to species level by rpoD gene as A. salmonicida (6), A. veronii bv. veronii (4), A. caviae (3), A. hydrophila (2), A. veronii bv. sobria (2), A. jandaei (1), A. trota (1), A. sobria (1), A. allosaccharophila (1) and A. bivalvium (1). All these strains were also characterized using whole cell protein (WCP) analysis by gradient SDS-PAGE and showed different whole cell protein (WCP) profile [22-28 polypeptide bands (~10 to >97 kDa)], indicating high genetic diversity. The present work emphasizes the use of molecular methods such as rpoD gene sequencing along with comprehensive biochemical tests for the rapid and accurate identification of Aeromonas isolates till species level. The WCP profile can be subsequently used to characterize Aeromonas isolates below species level.
KeywordMeSH Terms
Food Microbiology
68.     ( 2012 )

Phylogenetic diversity, antibiotic resistance and virulence traits of Aeromonas spp. from untreated waters for human consumption.

International journal of food microbiology 159 (3)
PMID : 23107502  :   DOI  :   10.1016/j.ijfoodmicro.2012.09.008    
Abstract >>
It is well known that water constitutes an important contamination route for microorganisms. This is especially true for Aeromonas which are widespread in untreated and treated waters. In this study, Portuguese untreated waters not regularly monitored were screened for the presence and diversity of aeromonads. A total of 206 isolates were discriminated by RAPD-PCR and 80 distinct strains were identified by gyrB based phylogenetic analysis. The most frequently detected species were Aeromonas hydrophila, Aeromonas bestiarum and Aeromonas media. The antibiotic susceptibility profile of these strains was determined and showed a typical profile of the genus. Nonetheless, the percentage of resistant strains to tetracycline, chloramphenicol and/or trimethoprim/sulfamethoxazole was lower than that reported for clinical isolates and isolates recovered from aquacultures and other environments historically subjected to antibiotic contamination. This suggests that the existence of such pressures in those environments selects for resistant Aeromonas. A similar trend for integron presence was found. Genes coding for CphA and TEM, and tet(A), (E), (C) or (D) genes were found in 28%, 1%, and 10% of the strains, respectively. 10% of the strains contained an integron. Variable regions of seven class 1 integrons and one class 2 integron were characterised. Furthermore, strains displayed virulence related phenotypes such as extracellular lipolytic and proteolytic activities as well as aerolysin related genes (43% of strains). The ascV and aexT genes were found in 16% and 3% of strains respectively and, in some cases, concomitantly in the same specimen. This study shows that diverse Aeromonas spp. presenting distinct antibiotic resistance features and putative virulence traits are frequently present in waters for human and animal consumption in Portugal. Genes associated to antibiotic resistance and microbial virulence previously identified in organisms with human health significance were detected in these aeromonads, suggesting that these waters may act as a pivotal route for infections.
KeywordMeSH Terms
Biodiversity
Phylogeny
Water Microbiology
Water Quality
69.     ( 1998 )

Expression and characterization of (R)-specific enoyl coenzyme A hydratase involved in polyhydroxyalkanoate biosynthesis by Aeromonas caviae.

Journal of bacteriology 180 (3)
PMID : 9457873  :   PMC  :   PMC106937    
Abstract >>
Complementation analysis of a polyhydroxyalkanoate (PHA)-negative mutant of Aeromonas caviae proved that ORF3 in the pha locus (a 402-bp gene located downstream of the PHA synthase gene) participates in PHA biosynthesis on alkanoic acids, and the ORF3 gene is here referred to as phaJ(Ac). Escherichia coli BL21(DE3) carrying phaJ(Ac). under the control of the T7 promoter overexpressed enoyl coenzyme A (enoyl-CoA) hydratase, which was purified by one-step anion-exchange chromatography. The N-terminal amino acid sequence of the purified hydratase corresponded to the amino acid sequence deduced from the nucleotide sequence of phaJ(Ac) except for the initial Met residue. The enoyl-CoA hydratase encoded by phaJ(Ac) exhibited (R)-specific hydration activity toward trans-2-enoyl-CoA with four to six carbon atoms. These results have demonstrated that (R)-specific hydration of 2-enoyl-CoA catalyzed by the translated product of phaJ(Ac) is a channeling pathway for supplying (R)-3-hydroxyacyl-CoA monomer units from fatty acid beta-oxidation to poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) biosynthesis in A. caviae.
KeywordMeSH Terms

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