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1. Vázquez-Juárez  RC, Barrera-Saldaña  HA, Hernández-Saavedra  NY, Gómez-Chiarri  M, Ascencio  F,     ( 2003 )

Molecular cloning, sequencing and characterization of omp48, the gene encoding for an antigenic outer membrane protein from Aeromonas veronii.

Journal of applied microbiology 94 (5)
PMID : 12694457  :  
Abstract >>
To clone, sequence and characterize the gene encoding the Omp48, a major outer membrane protein from Aeromonas veronii. A genomic library of Aer. veronii was constructed and screened to detect omp48 gene sequences, but no positive clones were identified, even under low stringency conditions. The cloned gene probably was toxic to the host Escherichia coli strain, so the cloning of omp48 was achieved by inverse PCR. The nucleotide sequence of omp48 consisted of an open reading frame of 1278 base pairs. The predicted primary protein is composed of 426 amino acids, with a 25-amino-acid signal peptide and common Ala-X-Ala cleavage site. The mature protein is composed of 401 amino acids with a molecular mass of 44,256 Da. The omp48 gene from Aer. veronii was cloned, sequenced and characterized in detail. BLAST analysis of Omp48 protein showed sequence similarity (over 50%) to the LamB porin family from other pathogenic Gram-negative bacteria. Bacterial diseases are a major economic problem for the fish farming industry. Outer membrane proteins are potentially important vaccine components. The characterization of omp48 gene will allow further investigation of the potential of Omp48 as recombinant or DNA vaccine component to prevent Aer. veronii and related species infections in reared fish.
KeywordMeSH Terms
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. Rangrez  AY, Dayananda  KM, Atanur  S, Joshi  R, Patole  MS, Shouche  YS,     ( 2006 )

Detection of conjugation related type four secretion machinery in Aeromonas culicicola.

PloS one 1 (N/A)
PMID : 17205119  :   DOI  :   10.1371/journal.pone.0000115     PMC  :   PMC1762418    
Abstract >>
Aeromonas sp. can now be considered relatively common enteropathogens due to the increase of diseases in humans. Aeromonas culicicola is a gram negative rod-shaped bacterium isolated for the first time from the mosquito mid-gut, but subsequently detected in other insects and waters also. Our previous study discovered that A. culicicola harbors three plasmids, which we designated as pAc3249A, pAc3249B and pAc3249C. We investigated and report here the existence and genetic organization of a Conjugal Type IV Secretion System (TFSS) in pAc3249A. The complete operon is 11,061 bp in length and has G+C content of 47.20% code for 12 ORFs. The gene order and orientation were similar to those found in other bacteria with some differences. We have designated this system as AcTra for Aeromonas culicicola transfer system. BLAST results of ORFs and phylogenetic analysis showed significant similarity towards the respective proteins of the IncI2 plasmid R721 of E. coli. Other bioinformatics studies have been performed to predict conserved motifs/domains, signal peptides, transmembrane helices, etc. of the ORFs. BLAST results of ORFs and phylogenetic analysis showed significant similarity towards the respective proteins of the IncI2 plasmid R721 of E. coli.
KeywordMeSH Terms
Conjugation, Genetic
5. Han  HJ, Kondo  H, Vivekanandhan  G, Hirono  I, Aoki  T,     ( 2006 )

Cloning of ATP-dependent protease ClpXP genes in Aeromonas veronii.

Journal of fish diseases 29 (11)
PMID : 17169116  :   DOI  :   10.1111/j.1365-2761.2006.00753.x    
Abstract >>
N/A
KeywordMeSH Terms
Carps
6. Tarr  CL, Patel  JS, Puhr  ND, Sowers  EG, Bopp  CA, Strockbine  NA,     ( 2007 )

Identification of Vibrio isolates by a multiplex PCR assay and rpoB sequence determination.

Journal of clinical microbiology 45 (1)
PMID : 17093013  :   DOI  :   10.1128/JCM.01544-06     PMC  :   PMC1828960    
Abstract >>
Vibrio, a diverse genus of aquatic bacteria, currently includes 72 species, 12 of which occur in human clinical samples. Of these 12, three species--Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus-account for the majority of Vibrio infections in humans. Rapid and accurate identification of Vibrio species has been problematic because phenotypic characteristics are variable within species and biochemical identification requires 2 or more days to complete. To facilitate the identification of human-pathogenic species, we developed a multiplex PCR that uses species-specific primers to amplify gene regions in four species (V. cholerae, V. parahaemolyticus, V. vulnificus, and V. mimicus). The assay was tested on a sample of 309 Vibrio isolates representing 26 named species (including 12 human pathogens) that had been characterized by biochemical methods. A total of 190 isolates that had been identified as one of the four target species all yielded results consistent with the previous classification. The assay identified an additional four V. parahaemolyticus isolates among the other 119 isolates. Sequence analysis based on rpoB was used to validate the multiplex results for these four isolates, and all clustered with other V. parahaemolyticus sequences. The rpoB sequences for 12 of 15 previously unidentified isolates clustered with other Vibrio species in a phylogenetic analysis, and three isolates appeared to represent unnamed Vibrio species. The PCR assay provides a simple, rapid, and reliable tool for identification of the major Vibrio pathogens in clinical samples, and rpoB sequencing provides an additional identification tool for other species in the genus Vibrio.
KeywordMeSH Terms
Sequence Analysis, DNA
7. 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
8. Vázquez-Juárez  RC, Gómez-Chiarri  M, Barrera-Saldaña  H, Hernández  N, Ascencio  F,     ( 2005 )

The major Aeromonas veronii outer membrane protein: gene cloning and sequence analysis.

Current microbiology 51 (6)
PMID : 16252131  :   DOI  :   10.1007/s00284-005-0054-6    
Abstract >>
The gene encoding the major outer membrane protein (OMP) from Aeromonas veronii, Omp38, was cloned and characterized. Sequence analysis revealed an open reading frame of 1,047 nucleotides coding for a primary protein of 349 amino acids with a 20-amino-acid signal peptide at the N-terminal and the consensus sequence Ala-X-Ala (Ala-Asn-Ala) as the signal peptidase I recognition site. The mature protein is composed of 329 amino acids with a calculated molecular mass of 36,327 Da. The degree of identity of the deduced Omp38 amino acid sequence to porins from enteric bacteria (OmpF, PhoE, and OmpC) was only 30%. Nevertheless, Omp38 possesses typical features of Gram-negative porins, including acidic pI, high glycine and low proline content, no cysteine residues, and a carboxy-terminal Phe. On the basis of PhoE-OmpF three-dimensional structure and the Kyte-Doolittle hydrophobicity analysis, it seems likely that Omp38 secondary structure consists of 16 antiparallel beta-strands and 8 loops. Phylogenetic analyses among Omp38 and related porins from Gram-negative bacteria originate well-defined clusters that agree with the taxonomy of the corresponding organisms.
KeywordMeSH Terms
9. Miñana-Galbis  D, Farfán  M, Fusté  MC, Lorén  JG,     ( 2004 )

Aeromonas molluscorum sp. nov., isolated from bivalve molluscs.

International journal of systematic and evolutionary microbiology 54 (Pt 6)
PMID : 15545437  :   DOI  :   10.1099/ijs.0.63202-0    
Abstract >>
Five Aeromonas strains (848T(T), 93M, 431E, 849T and 869N), which were isolated from bivalve molluscs and were recognized previously by numerical taxonomy as members of an unknown Aeromonas taxon, were subjected to a polyphasic taxonomic study. DNA-DNA hybridization experiments showed that DNA of strain 848T(T) was <70 % similar (27-45 %) to that of the type/reference strains of the current Aeromonas hybridization groups (HGs), but 93 % similar to that of strain 93M. The DNA G+C content of the five strains ranged from 59.0 to 59.4 mol%. 16S rRNA gene sequence analysis confirmed that the strains belonged to the genus Aeromonas and showed high similarity to Aeromonas encheleia. Amplified fragment length polymorphism fingerprinting clustered the novel strains in a homogeneous group with low genotypic relatedness to other Aeromonas species. Useful phenotypic features for differentiating the five isolates from other Aeromonas species include their negative reactions in tests for indole production, lysine decarboxylase, gas from glucose and starch hydrolysis. From the results of this study, the name Aeromonas molluscorum sp. nov. is proposed for these strains, with the type strain 848T(T) (=CECT 5864(T)=LMG 22214(T)).
KeywordMeSH Terms
10. Chacón  MR, Soler  L, Groisman  EA, Guarro  J, Figueras  MJ,     ( 2004 )

Type III secretion system genes in clinical Aeromonas isolates.

Journal of clinical microbiology 42 (3)
PMID : 15004096  :   DOI  :   10.1128/jcm.42.3.1285-1287.2004     PMC  :   PMC356863    
Abstract >>
We have identified the genes ascF and ascG, which encode components of a putative type III secretion system (TTSS) in AEROMONAS: We investigated the distribution of these and other TTSS genes in 84 clinical isolates and found hybridizing sequences in 50% of the strains, with a higher prevalence in Aeromonas hydrophila and Aeromonas veronii than in Aeromonas caviae.
KeywordMeSH Terms
Aeromonas
11. 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
12. 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
13. 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
14. Kumar  H, Rangrez  AY, Dayananda  KM, Atre  AN, Patole  MS, Shouche  YS,     ( 2011 )

Lactobacillus plantarum (VR1) isolated from an ayurvedic medicine (Kutajarista) ameliorates in vitro cellular damage caused by Aeromonas veronii.

BMC microbiology 11 (N/A)
PMID : 21707995  :   DOI  :   10.1186/1471-2180-11-152     PMC  :   PMC3145568    
Abstract >>
Lactobacillus plantarum is considered as a safe and effective probiotic microorganism. Among various sources of isolation, traditionally fermented foods are considered to be rich in Lactobacillus spp., which can be exploited for their probiotic attribute. Antibacterial property of L. plantarum has been demonstrated against various enteric pathogens in both in vitro and in vivo systems. This study was aimed at characterizing L. plantarum isolated from Kutajarista, an ayurvedic fermented biomedicine, and assessing its antagonistic property against a common enteropathogen Aeromonas veronii. We report the isolation of L. plantarum (VR1) from Kutajarista, and efficacy of its cell free supernatant (CFS) in amelioration of cytotoxicity caused by Aeromonas veronii. On the part of probiotic attributes, VR1 was tolerant to pH 2, 0.3% bile salts and simulated gastric juice. Additionally, VR1 also exhibited adhesive property to human intestinal HT-29 cell line. Furthermore, CFS of VR1 was antibacterial to enteric pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Aeromonas veronii and clinical isolates of P. aeruginosa and E. coli. Detailed study regarding the effect of VR1 CFS on A. veronii cytotoxicity showed a significant decrease in vacuole formation and detrimental cellular changes in Vero cells. On the other hand, A. veronii CFS caused disruption of tight junction proteins ZO-1 and actin in MDCK cell line, which was prevented by pre-incubation with CFS of VR1. This is the first study to report isolation of L. plantarum (VR1) from Kutajarista and characterisation for its probiotic attributes. Our study demonstrates the antagonistic property of VR1 to A. veronii and effect of VR1 CFS in reduction of cellular damage caused by A. veronii in both Vero and MDCK cell lines.
KeywordMeSH Terms
Antibiosis
15. Ndi  OL, Barton  MD,     ( 2011 )

Incidence of class 1 integron and other antibiotic resistance determinants in Aeromonas spp. from rainbow trout farms in Australia.

Journal of fish diseases 34 (8)
PMID : 21762170  :   DOI  :   10.1111/j.1365-2761.2011.01272.x    
Abstract >>
There is limited information on antibiotic resistance determinants present in bacteria of aquaculture origin in Australia. The presence of integron and other resistance determinants was investigated in 90 Aeromonas isolates derived from nine freshwater trout farms in Victoria (Australia). Polymerase chain reaction was carried out for the detection of integrase genes Int1, Int2 and Int3, gene cassette array, integron-associated aadA, sul1 and qac1 genes, streptomycin resistance genes strA-strB, �]-lactamase resistance genes bla(TEM) and bla(SHV) , and tetracycline resistance genes tetA-E and tetM. Clonal analysis was performed by pulsed-field gel electrophoresis (PFGE). Class 1 integrons were detected in 28/90 (31%) and class 2 and class 3 in none of the strains, aadA gene in 19/27 (70%) streptomycin-resistant strains, sul1 in 13/15 (86.7%) sulphonamide-resistant strains and qac1 gene in 8/28 (28.6%) integron-bearing strains. Five strains from two different farms carried gene cassettes of 1000 bp each containing the aadA2 gene and PFGE analysis revealed genetic relatedness. tetC was detected in all and tetA in 9/18 (50%) tetracycline-resistant strains. The strA-strB, bla(TEM) or bla(SHV) genes were not detected in any of the strains. Aeromonas spp. carrying integrons and other resistance genes are present in farm-raised fish and sediments even though no antibiotics were licensed for use in Australian aquaculture at the time of the study.
KeywordMeSH Terms
beta-Lactam Resistance
Genes, Bacterial
Integrons
Tetracycline Resistance
16. Maltz  M, Graf  J,     ( 2011 )

The type II secretion system is essential for erythrocyte lysis and gut colonization by the leech digestive tract symbiont Aeromonas veronii.

Applied and environmental microbiology 77 (2)
PMID : 21097598  :   DOI  :   10.1128/AEM.01621-10     PMC  :   PMC3020562    
Abstract >>
Hemolysin and the type II secretion system (T2SS) have been shown to be important for virulence in many pathogens, but very few studies have shown their importance in beneficial microbes. Here, we investigated the importance of the type II secretion pathway in the beneficial digestive-tract association of Aeromonas veronii and the medicinal leech Hirudo verbana and revealed a critical role for the hemolysis of erythrocytes. A mutant with a miniTn5 insertion in exeM, which is involved in forming the inner membrane platform in the T2SS, was isolated by screening mutants for loss of hemolysis on blood agar plates. A hemolysis assay was used to quantify the mutant's deficiency in lysing sheep erythrocytes and revealed a 99.9% decrease compared to the parent strain. The importance of the T2SS in the colonization of the symbiotic host was assessed. Colonization assays revealed that the T2SS is critical for initial colonization of the leech gut. The defect was tied to the loss of hemolysin production by performing a colonization assay with blood containing lysed erythrocytes. This restored the colonization defect in the mutant. Complementation of the mutant using the promoter region and exeMN revealed that the T2SS is responsible for secreting hemolysin into the extracellular space and that both the T2SS and hemolysin export by the T2SS are critical for initial establishment of A. veronii in the leech gut.
KeywordMeSH Terms
Hemolysis
Symbiosis
17. 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
18. 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
19. 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
20. Lamy  B, Laurent  F, Kodjo  A,     ( 2010 )

Validation of a partial rpoB gene sequence as a tool for phylogenetic identification of aeromonads isolated from environmental sources.

Canadian journal of microbiology 56 (3)
PMID : 20453908  :   DOI  :   10.1139/w10-006    
Abstract >>
A collection of 50 aeromonads isolated from environmental sources were studied, together with all known Aeromonas nomenspecies, by phenotypic, amplified 16S rDNA restriction analysis (16S rDNA RFLP) and by partial sequence alignment of both 16S rDNA and rpoB genes. Although most of the type strain showed a unique phenotypic pattern, a database constructed on type strain phenotype allowed the identification of only 24% of the isolates. Analysis of 16S rDNA RFLP and the rpoB sequence were almost concordant in identifying environmental isolates at the species level, except for strains belonging to Aeromonas caviae spp., which were not differentiated from Aeromonas aquariorum, nor Aeromonas hydrophila susbsp. dhakensis by 16S rDNA RFLP. In addition, rpoB gene analysis clustered separately a group of isolates found in snails within the A. hydrophila species. In contrast to 16S rDNA RFLP and rpoB, the partial 16S rDNA sequence analysis was weak in resolving species identity. Part of these results, phenotypic and phylogenetic data, showed that Aeromonas molluscorum and Aeromonas sharmana are distant from all other Aeromonas species and that the type species of A. hydrophila subsp. anaerogenes is similar to A. caviae and should be considered synonymous.
KeywordMeSH Terms
Environmental Microbiology
Phylogeny
21. 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
22. 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
23. 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
24. 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
25. Han  HJ, Taki  T, Kondo  H, Hirono  I, Aoki  T,     ( 2008 )

Pathogenic potential of a collagenase gene from Aeromonas veronii.

Canadian journal of microbiology 54 (1)
PMID : 18388966  :   DOI  :   10.1139/w07-109    
Abstract >>
The role of collagenase as a mechanism of bacterial pathogenicity in some pathogenic bacteria has been reported. The information on the role of collagenase in Aeromonas spp. pathogenesis is scant. In the present study, a mutant Aeromonas veronii RY001 that is deficient in the putative collagenase gene acg was constructed and compared with the wild-type strain for virulence factors. Bacterial cells and cell-free extracellular products of the mutant had significantly less collagenolytic activity, but there were not significant differences in caseinolytic, gelatinolytic, and elastolytic activities. Adhesion and invasion abilities of the mutant strain on epithelioma papillosum of carp cells was only 56% of that of the wild-type strain, and the cytotoxicity of the mutant strain to epithelioma papillosum of carp cells was only 42% of that of the wild-type strain. The LD50 values of the wild-type strain were determined as 1.6 x 10(6) and 3.5 x 10(5) cfu in goldfish and mice, respectively, whereas the mutant RY001 strain showed slightly higher values (i.e., 2.8 x 10(6) and 1.4 x 10(6) cfu in goldfish and mice, respectively). These results indicated the involvement of the collagenase gene in the pathogenesis of A. veronii.
KeywordMeSH Terms
Genes, Bacterial
26. Laufer  AS, Siddall  ME, Graf  J,     ( 2008 )

Characterization of the digestive-tract microbiota of Hirudo orientalis, a european medicinal leech.

Applied and environmental microbiology 74 (19)
PMID : 18689513  :   DOI  :   10.1128/AEM.00795-08     PMC  :   PMC2565982    
Abstract >>
FDA-approved, postoperative use of leeches can lead to bacterial infections. In this study, we used culture-dependent and culture-independent approaches to characterize the digestive-tract microbiota of Hirudo orientalis. Surprisingly, two Aeromonas species, A. veronii and A. jandaei, were cultured. Uncultured Rikenella-like bacteria were most similar to isolates from Hirudo verbana.
KeywordMeSH Terms
27. 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
28. 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
29. Bossi-Küpfer  M, Genini  A, Peduzzi  R, Demarta  A,     ( 2007 )

Tracheobronchitis caused by Aeromonas veronii biovar sobria after near-drowning.

Journal of medical microbiology 56 (Pt 11)
PMID : 17965361  :   DOI  :   10.1099/jmm.0.47202-0    
Abstract >>
A 19-year-old man developed an acute tracheobronchitis shortly after having been rescued from a near-drowning in a river where previous investigations had demonstrated the presence of 500 c.f.u. ml(-1) of Aeromonas sp. in the water. An isolate of Aeromonas veronii biovar sobria was identified as the causative agent of the tracheobronchitis. The causality was supported by the massive growth of A. veronii in bronchial secretion, the presence of a type III secretion system in the bacterial isolate, and the strong haemolytic activity of the strain on blood agar.
KeywordMeSH Terms
30. Silver  AC, Rabinowitz  NM, Küffer  S, Graf  J,     ( 2007 )

Identification of Aeromonas veronii genes required for colonization of the medicinal leech, Hirudo verbana.

Journal of bacteriology 189 (19)
PMID : 17616592  :   DOI  :   10.1128/JB.00685-07     PMC  :   PMC2045196    
Abstract >>
Most digestive tracts contain a complex consortium of beneficial microorganisms, making it challenging to tease apart the molecular interactions between symbiont and host. The digestive tract of Hirudo verbana, the medicinal leech, is an ideal model system because it harbors a simple microbial community in the crop, comprising the genetically amenable Aeromonas veronii and a Rikenella-like bacterium. Signature-tagged mutagenesis (STM) was used to identify genes required for digestive tract colonization. Of 3,850 transposon (Tn) mutants screened, 46 were identified as colonization mutants. Previously we determined that the complement system of the ingested blood remained active inside the crop and prevented serum-sensitive mutants from colonizing. The identification of 26 serum-sensitive mutants indicated a successful screen. The remaining 20 serum-resistant mutants are described in this study and revealed new insights into symbiont-host interactions. An in vivo competition assay compared the colonization levels of the mutants to that of a wild-type competitor. Attenuated colonization mutants were grouped into five classes: surface modification, regulatory, nutritional, host interaction, and unknown function. One STM mutant, JG736, with a Tn insertion in lpp, encoding Braun's lipoprotein, was characterized in detail. This mutant had a >25,000-fold colonization defect relative to colonization by the wild-type strain at 72 h and, in vitro, an increased sensitivity to sodium dodecyl sulfate, suggesting the presence of an additional antimicrobial property in the crop. The classes of genes identified in this study are consistent with findings from previous STM studies involving pathogenic bacteria, suggesting parallel molecular requirements for beneficial and pathogenic host colonization.
KeywordMeSH Terms
31. Sha  J, Wang  SF, Suarez  G, Sierra  JC, Fadl  AA, Erova  TE, Foltz  SM, Khajanchi  BK, Silver  A, Graf  J, Schein  CH, Chopra  AK,     ( 2007 )

Further characterization of a type III secretion system (T3SS) and of a new effector protein from a clinical isolate of Aeromonas hydrophila--part I.

Microbial pathogenesis 43 (4)
PMID : 17644303  :   DOI  :   10.1016/j.micpath.2007.05.002    
Abstract >>
A type III secretion system (T3SS)-associated cytotoxin, AexT, with ADP-ribosyltransferase activity and homology to Pseudomonas aeruginosa bifuncational toxins ExoT/S, was recently identified from a fish pathogen Aeromonas salmonicida. In this study, we reported the molecular characterization of an aexT-like toxin gene (designated as aexU) from a diarrheal isolate SSU of A. hydrophila. The aexU gene was 1539bp in length and encoded a protein of 512 amino acid (aa) residues. The NH(2)-terminus of AexU (aa residues 1-231) exhibited a 67% homology with the NH(2)-terminus of AexT from A. salmonicida. Importantly, its COOH-terminus (aa residues 232-512) had no homology with any known functional proteins in the database; however, the full-length AexU retained ADP-ribosyltransferase activity. The expression and subsequent secretion of AexU was T3SS dependent, as inactivation of the ascV gene that codes for an inner-membrane component of the T3SS channel from the wild-type (WT) bacterium, blocked translocation of AexU in HT-29 human colonic epithelial cells. We provided evidence that inactivation of acrV and axsE genes (homologs of lcrV and exsE in Yersinia species and P. aeruginosa, respectively) from A. hydrophila SSU, altered expression and/or secretion of AexU. We deleted an aexU gene from the WT, as well as from the DeltaaopB mutant, of A. hydrophila, generating a single knockout (DeltaaexU) and a double knockout mutant, DeltaaopB/DeltaaexU. Increased phagocytosis was observed in RAW264.7 murine macrophages infected with the DeltaaopB/DeltaaexU mutant, as compared to macrophages when infected with the parental DeltaaopB strain. Further, mice infected with the DeltaaexU mutant had a 60% survival rate, compared to animals infected with the WT or the DeltaaexU-complemented strain that caused 90-100% of the animals to die at a 2-3 LD(50s) dose. Immunization of mice with the recombinant AexU protected them from subsequent lethal challenge dose by the WT bacterium. Finally, we detected specific anti-AexU antibodies in the sera of mice that survived challenge by the WT bacterium, which may indicate that AexU plays an important role in the pathogenesis of Aeromonas infections.
KeywordMeSH Terms
32. 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  :   PMC  :   PMC4948828     DOI  :   10.1371/journal.pone.0159418    
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
33. 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
34. Jan  AT, Azam  M, Choi  I, Ali  A, Haq  QM,     ( N/A )

Analysis for the presence of determinants involved in the transport of mercury across bacterial membrane from polluted water bodies of India.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] 47 (1)
PMID : 26887227  :   DOI  :   10.1016/j.bjm.2015.11.023     PMC  :   PMC4827696    
Abstract >>
Mercury, which is ubiquitous and recalcitrant to biodegradation processes, threatens human health by escaping to the environment via various natural and anthropogenic activities. Non-biodegradability of mercury pollutants has necessitated the development and implementation of economic alternatives with promising potential to remove metals from the environment. Enhancement of microbial based remediation strategies through genetic engineering approaches provides one such alternative with a promising future. In this study, bacterial isolates inhabiting polluted sites were screened for tolerance to varying concentrations of mercuric chloride. Following identification, several Pseudomonas and Klebsiella species were found to exhibit the highest tolerance to both organic and inorganic mercury. Screened bacterial isolates were examined for their genetic make-up in terms of the presence of genes (merP and merT) involved in the transport of mercury across the membrane either alone or in combination to deal with the toxic mercury. Gene sequence analysis revealed that the merP gene showed 86-99% homology, while the merT gene showed >98% homology with previously reported sequences. By exploring the genes involved in imparting metal resistance to bacteria, this study will serve to highlight the credentials that are particularly advantageous for their practical application to remediation of mercury from the environment.
KeywordMeSH Terms
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
Bioremediation
Mercury
Mercury transport
Resistance determinants
35. Hughes  HY, Conlan  SP, Lau  AF, Dekker  JP, Michelin  AV, Youn  JH, Henderson  DK, Frank  KM, Segre  JA, Palmore  TN,     ( 2016 )

Detection and Whole-Genome Sequencing of Carbapenemase-Producing Aeromonas hydrophila Isolates from Routine Perirectal Surveillance Culture.

Journal of clinical microbiology 54 (4)
PMID : 26888898  :   DOI  :   10.1128/JCM.03229-15     PMC  :   PMC4809936    
Abstract >>
Perirectal surveillance cultures and a stool culture grew Aeromonas species from three patients over a 6-week period and were without epidemiological links. Detection of the blaKPC-2 gene in one isolate prompted inclusion of non-Enterobacteriaceae in our surveillance culture workup. Whole-genome sequencing confirmed that the isolates were unrelated and provided data for Aeromonas reference genomes.
KeywordMeSH Terms
Genome, Bacterial
Sequence Analysis, DNA
36. 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
37. Tacão  M, Correia  A, Henriques  IS,     ( 2015 )

Low Prevalence of Carbapenem-Resistant Bacteria in River Water: Resistance Is Mostly Related to Intrinsic Mechanisms.

Microbial drug resistance (Larchmont, N.Y.) 21 (5)
PMID : 26430939  :   DOI  :   10.1089/mdr.2015.0072    
Abstract >>
Carbapenems are last-resort antibiotics to handle serious infections caused by multiresistant bacteria. The incidence of resistance to these antibiotics has been increasing and new resistance mechanisms have emerged. The dissemination of carbapenem resistance in the environment has been overlooked. The main goal of this research was to assess the prevalence and diversity of carbapenem-resistant bacteria in riverine ecosystems. The presence of frequently reported carbapenemase-encoding genes was inspected. The proportion of imipenem-resistant bacteria was on average 2.24 CFU/ml. Imipenem-resistant strains (n=110) were identified as Pseudomonas spp., Stenotrophomonas maltophilia, Aeromonas spp., Chromobacterium haemolyticum, Shewanella xiamenensis, and members of Enterobacteriaceae. Carbapenem-resistant bacteria were highly resistant to other beta-lactams such as quinolones, aminoglycosides, chloramphenicol, tetracyclines, and sulfamethoxazole/trimethoprim. Carbapenem resistance was mostly associated with intrinsically resistant bacteria. As intrinsic resistance mechanisms, we have identified the blaCphA gene in 77.3% of Aeromonas spp., blaL1 in all S. maltophilia, and blaOXA-48-like in all S. xiamenensis. As acquired resistance mechanisms, we have detected the blaVIM-2 gene in six Pseudomonas spp. (5.45%). Integrons with gene cassettes encoding resistance to aminoglycosides (aacA and aacC genes), trimethoprim (dfrB1b), and carbapenems (blaVIM-2) were found in Pseudomonas spp. Results suggest that carbapenem resistance dissemination in riverine ecosystems is still at an early stage. Nevertheless, monitoring these aquatic compartments for the presence of resistance genes and its host organisms is essential to outline strategies to minimize resistance dissemination.
KeywordMeSH Terms
Water Microbiology
38. Maltz  M, LeVarge  BL, Graf  J,     ( 2015 )

Identification of iron and heme utilization genes in Aeromonas and their role in the colonization of the leech digestive tract.

Frontiers in microbiology 6 (N/A)
PMID : 26284048  :   DOI  :   10.3389/fmicb.2015.00763     PMC  :   PMC4516982    
Abstract >>
It is known that many pathogens produce high-affinity iron uptake systems like siderophores and/or proteins for utilizing iron bound to heme-containing molecules, which facilitate iron-acquisition inside a host. In mutualistic digestive-tract associations, iron uptake systems have not been as well studied. We investigated the importance of two iron utilization systems within the beneficial digestive-tract association Aeromonas veronii and the medicinal leech, Hirudo verbana. Siderophores were detected in A. veronii using chrome azurol S. Using a mini Tn5, a transposon insertion in viuB generated a mutant unable to utilize iron using siderophores. The A. veronii genome was then searched for genes potentially involved in iron utilization bound to heme-containing molecules. A putative outer membrane heme receptor (hgpB) was identified with a transcriptional activator, termed hgpR, downstream. The hgpB gene was interrupted with an antibiotic resistance cassette in both the parent strain and the viuB mutant, yielding an hgpB mutant and a mutant with both iron uptake systems inactivated. In vitro assays indicated that hgpB is involved in utilizing iron bound to heme and that both iron utilization systems are important for A. veronii to grow in blood. In vivo colonization assays revealed that the ability to acquire iron from heme-containing molecules is critical for A. veronii to colonize the leech gut. Since iron and specifically heme utilization is important in this mutualistic relationship and has a potential role in virulence factor of other organisms, genomes from different Aeromonas strains (both clinical and environmental) were queried with iron utilization genes of A. veronii. This analysis revealed that in contrast to the siderophore utilization genes heme utilization genes are widely distributed among aeromonads. The importance of heme utilization in the colonization of the leech further confirms that symbiotic and pathogenic relationships possess similar mechanisms for interacting with animal hosts.
KeywordMeSH Terms
Aeromonads
heme
iron
siderophore
symbiosis
virulence factor
Aeromonads
heme
iron
siderophore
symbiosis
virulence factor
39. 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
40. Bottoni  C, Marcoccia  F, Compagnoni  C, Colapietro  M, Sabatini  A, Celenza  G, Segatore  B, Maturo  MG, Amicosante  G, Perilli  M,     ( 2015 )

Identification of New Natural CphA Metallo-�]-Lactamases CphA4 and CphA5 in Aeromonas veronii and Aeromonas hydrophila Isolates from Municipal Sewage in Central Italy.

Antimicrobial agents and chemotherapy 59 (8)
PMID : 25987617  :   DOI  :   10.1128/AAC.00628-15     PMC  :   PMC4505251    
Abstract >>
Two new natural CphA metallo-�]-lactamases, the CphA4 and CphA5 enzymes, were identified in water samples from municipal sewage in central Italy. Compared to CphA, the CphA4 and CphA5 enzymes showed numerous point mutations. These enzymes have a narrow spectrum of substrates focused on carbapenems only. CphA5 showed kcat values about 40-, 12-, and 97-fold higher than those observed for CphA4 versus imipenem, ertapenem, and biapenem, respectively.
KeywordMeSH Terms
41. 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
42. 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
43. 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
44. 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
45. 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
46.     ( 1997 )

Aeromonas spp. possess at least two distinct type IV pilus families.

Microbial pathogenesis 23 (4)
PMID : 9344785  :   DOI  :   10.1006/mpat.1997.0152    
Abstract >>
Type IV pili have been purified from strains of most of the Aeromonas species associated with gastroenteritis (A. veronii biovar sobria, A. hydrophila, A. trota and A. caviae). They appear to be a related family (molecular mass of pilin 19 to 23 kDa) with a tendency to bundle-formation. Hence, we have designated them 'bundle-forming pili' (Bfp). A type IV pilus biogenesis gene cluster (tapABCD) recently cloned from a strain of A. hydrophila, however, encoded a 17 kDa pilin which differed significantly in its N-terminal amino acid sequence from the Bfp pilins. This paper describes the cloning of part (tapA and approximately 20% of tapB) of a homologous pilin gene cluster from a Bfp-positive strain of A. veronii biovar sobria, and presents evidence that the entire pilin gene cluster (tapABCD) is present in this strain. The predicted N-terminal amino acid sequence of the pilin encoded by the A. veronii biovar sobria tapA differed markedly from the corresponding sequence of its Bfp pilin, and those of the Bfp purified from other Aeromonas strains and species. Probing with tapA and tapD genes showed that these Bfp-positive Aeromonas strains also possessed the Tap gene cluster. TapA proteins of A. veronii biovar sobria and A. hydrophila shared 53% identity and 63% homology. We conclude that Aeromonas species are potentially able to express at least two distinct families of type IV pili (Bfp and Tap).
KeywordMeSH Terms
Genes, Bacterial
Multigene Family
47.     ( 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
48. 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
49. Foysal  MJ, Momtaz  F, Ali  MH, Siddik  MAB, Chaklader  MR, Rahman  MM, Prodhan  MSH, Cole  A,     ( 2019 )

Molecular characterization and interactome analysis of aerolysin (aer) gene from fish pathogen Aeromonas veronii: The pathogenicity inferred from sequence divergence and linked to histidine kinase (cheA).

Journal of fish diseases 42 (4)
PMID : 30734315  :   DOI  :   10.1111/jfd.12954    
Abstract >>
Aerolysin (aer) is one of the most important and abundant virulence factors in the infection of fish by Aeromonas veronii. A comprehensive study on the molecular characterization and pathogenicity of the aer gene from 34 A. veronii isolates from diseased carp and catfish was carried out and its interactome was analysed to observe the functional correlations between aer and other proteins within the A. veronii network. The PCR-based amplification of aer from the 34 isolates of A. veronii showed more aer-positive isolates from catfish with a high pathogenic potential in the in vivo challenge test than the carp fish. The analysis of aer gene sequence from challenged fish revealed significant sequence divergence according to the types and geographical distribution of the fish. The networking analysis of aer from the model A. veronii B565 revealed histidine kinase (cheA) as the most functional interacting partner. The study of the interaction between aer from the experimental A. veronii and cheA demonstrated that the A chain of cheA plays a more important role than the corresponding B chain during contact, and a linker sequence of 15 residues controlled the entire interaction process. Therefore, cheA could be an excellent drug target for controlling A. veronii infection of fish.
KeywordMeSH Terms
A. veronii
aer
PCR and sequencing
bioinformatics
cheA
A. veronii
aer
PCR and sequencing
bioinformatics
cheA
50. 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
51. 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
52. 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
53.     ( 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
54.     ( 2012 )

Changes in the gut microbiome of the sea lamprey during metamorphosis.

Applied and environmental microbiology 78 (21)
PMID : 22923392  :   DOI  :   10.1128/AEM.01640-12     PMC  :   PMC3485723    
Abstract >>
Vertebrate metamorphosis is often marked by dramatic morphological and physiological changes of the alimentary tract, along with major shifts in diet following development from larva to adult. Little is known about how these developmental changes impact the gut microbiome of the host organism. The metamorphosis of the sea lamprey (Petromyzon marinus) from a sedentary filter-feeding larva to a free-swimming sanguivorous parasite is characterized by major physiological and morphological changes to all organ systems. The transformation of the alimentary canal includes closure of the larval esophagus and the physical isolation of the pharynx from the remainder of the gut, which results in a nonfeeding period that can last up to 8 months. To determine how the gut microbiome is affected by metamorphosis, the microbial communities of feeding and nonfeeding larval and parasitic sea lamprey were surveyed using both culture-dependent and -independent methods. Our results show that the gut of the filter-feeding larva contains a greater diversity of bacteria than that of the blood-feeding parasite, with the parasite gut being dominated by Aeromonas and, to a lesser extent, Citrobacter and Shewanella. Phylogenetic analysis of the culturable Aeromonas from both the larval and parasitic gut revealed that at least five distinct species were represented. Phenotypic characterization of these isolates revealed that over half were capable of sheep red blood cell hemolysis, but all were capable of trout red blood cell hemolysis. This suggests that the enrichment of Aeromonas that accompanies metamorphosis is likely related to the sanguivorous lifestyle of the parasitic sea lamprey.
KeywordMeSH Terms
Metagenome
55.     ( 1998 )

Nucleotide and amino acid sequences of the metallo-beta-lactamase, ImiS, from Aeromonas veronii bv. sobria.

Antimicrobial agents and chemotherapy 42 (2)
PMID : 9527802  :   PMC  :   PMC105430    
Abstract >>
The Aeromonas veronii bv. sobria metallo-beta-lactamase gene, imiS, was cloned. The imiS open reading frame extends for 762 bp and encodes a protein of 254 amino acids with a secreted modified protein of 227 amino acids and a predicted pI of 8.1. To confirm the predicted sequence, purified ImiS was digested and the resulting peptides were identified, yielding an identical sequence for ImiS, with 98% identity to CphA. Both possessed the putative active-site sequence Asn-Tyr-His-Thr-Asp at positions 88 to 92, which is unique to the Aeromonas metallo-beta-lactamases.
KeywordMeSH Terms
Bacterial Proteins

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