| 1. |
Møretrø T,
Hermansen L,
Holck AL,
Sidhu MS,
Rudi K,
Langsrud S,
( 2003 ) Biofilm formation and the presence of the intercellular adhesion locus ica among staphylococci from food and food processing environments. PMID : 12957956 : DOI : 10.1128/aem.69.9.5648-5655.2003 PMC : PMC194930 Abstract >>
In clinical staphylococci, the presence of the ica genes and biofilm formation are considered important for virulence. Biofilm formation may also be of importance for survival and virulence in food-related staphylococci. In the present work, staphylococci from the food industry were found to differ greatly in their abilities to form biofilms on polystyrene. A total of 7 and 21 of 144 food-related strains were found to be strong and weak biofilm formers, respectively. Glucose and sodium chloride stimulated biofilm formation. The biofilm-forming strains belonged to nine different coagulase-negative species of Staphylococcus. The icaA gene of the intercellular adhesion locus was detected by Southern blotting and hybridization in 38 of 67 food-related strains tested. The presence of icaA was positively correlated with strong biofilm formation. The icaA gene was partly sequenced for 22 food-related strains from nine different species of Staphylococcus, and their icaA genes were found to have DNA similarities to previously sequenced icaA genes of 69 to 100%. Northern blot analysis indicated that the expression of the ica genes was higher in strong biofilm formers than that seen with strains not forming biofilms. Biofilm formation on polystyrene was positively correlated with biofilm formation on stainless steel and with resistance to quaternary ammonium compounds, a group of disinfectants.
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2. |
Steiner P,
Sauer U,
( 2003 ) Overexpression of the ATP-dependent helicase RecG improves resistance to weak organic acids in Escherichia coli. PMID : 12898065 : DOI : 10.1007/s00253-003-1405-5 Abstract >>
Increased resistance to several weak organic acids was conferred on Escherichia coli by overexpression of the ATP-dependent helicase RecG and, to a lesser extent, by overexpressing the helicase RuvAB. This property of helicases was identified by reproducible selection of recG-bearing clones from genomic libraries of the acetate-resistant species Acetobacter aceti and Staphylococcus capitis. We show that overexpression of RecG from both species, but also from E. coli, increased the maximum biomass concentration attained by E. coli cultures that were grown in the presence of various weak organic acids and uncouplers. Furthermore, overexpression of RecG from A. aceti significantly improved the maximum growth rates of E. coli under weak organic acid challenge. Based on the known role of RecG in DNA replication/repair, our data provide a first indication that weak organic acids negatively affect DNA replication and/or repair, and that these negative effects may be counteracted by helicase activity.
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3. |
Morikawa K,
Inose Y,
Okamura H,
Maruyama A,
Hayashi H,
Takeyasu K,
Ohta T,
( 2003 ) A new staphylococcal sigma factor in the conserved gene cassette: functional significance and implication for the evolutionary processes. PMID : 12875655 : Abstract >>
Staphylococcus aureus is a major human pathogen and causes a serious hospital infection due to the acquired multidrug resistance. Unlike the well-studied bacteria such as Escherichia coli and Bacillus subtilis, which have seven and 18 sigma factors, respectively, only two sigma factors have been known for S. aureus. We searched for possible sigma factor genes by examining the S. aureus genome with a special attention to the gene arrangement around the sigma factor genes of a close relative, B. subtilis. A new sigma factor gene was identified in Staphylococcus. The gene constituted a conserved gene cluster with other genes including translation- and transcription-related genes. Phylogenetic analysis and comparison of the gene sequences among species indicated that the staphylococcal sigma factor originated from a common ancestor of B. subtilis SigH. An over-expression of this sigma factor in S. aureus resulted in a drastic induction of the expression of the com operons that encode proteins required for the natural genetic competence. We demonstrated that the newly identified staphylococcal sigma factor participated in a regulatory network of transcription that controlled the genetic competence genes. In our phylogenetic tree, the factor was classified as a single group with a common function.
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4. |
Poyart C,
Quesne G,
Boumaila C,
Trieu-Cuot P,
( 2001 ) Rapid and accurate species-level identification of coagulase-negative staphylococci by using the sodA gene as a target. PMID : 11724835 : DOI : 10.1128/JCM.39.12.4296-4301.2001 PMC : PMC88539 Abstract >>
Simple PCR and sequencing assays that utilize a single pair of degenerate primers were used to characterize a 429-bp-long DNA fragment internal (sodA(int)) to the sodA gene encoding the manganese-dependent superoxide dismutase in 40 coagulase-negative staphylococcal (CNS) type strains. The topology of the phylogenetic tree obtained was in general agreement with that which was inferred from an analysis of their 16S rRNA or hsp60 gene sequences. Sequence analysis revealed that the staphylococcal sodA genes exhibit a higher divergence than does the corresponding 16S ribosomal DNA. These results confirm that the sodA gene constitutes a highly discriminative target sequence for differentiating closely related bacterial species. Clinical isolates that could not be identified at the species level by phenotypical tests were identified by use of this database. These results demonstrate the usefulness of this method for rapid and accurate species identification of CNS isolates, although it does not allow discrimination of subspecies. The sodA sequence polymorphisms observed with staphylococcal species offer good opportunities for the development of assays based on DNA chip technologies.
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5. |
Martineau F,
Picard FJ,
Ke D,
Paradis S,
Roy PH,
Ouellette M,
Bergeron MG,
( 2001 ) Development of a PCR assay for identification of staphylococci at genus and species levels. PMID : 11427566 : DOI : 10.1128/JCM.39.7.2541-2547.2001 PMC : PMC88182 Abstract >>
We have developed a PCR-based assay which allows the detection of staphylococci at the genus level by targeting the tuf gene, which encodes the elongation factor Tu. Degenerate PCR primers derived from consensus regions of several tuf genes were used to amplify a target region of 884 bp from 11 representative staphylococcal species. Subsequently, the entire nucleotide sequence of these amplicons was determined. The analysis of a multiple alignment of these sequences revealed regions conserved among staphylococci but distinct from those of other gram-positive bacteria genetically related to staphylococci. PCR primers complementary to these regions could amplify specifically and efficiently a DNA fragment of 370 bp for all of 27 different staphylococcal species tested. There was no amplification with genomic DNA prepared from 53 nonstaphylococcal species tested to verify the specificity of the assay (20 gram positive and 33 gram negative). Furthermore, this assay amplified efficiently all 27 American Type Culture Collection (ATCC) staphylococcal reference strains as well as 307 clinical isolates of staphylococci from the Qu?bec City region. Analysis of the multiple sequence alignment for the 884-bp fragment for the 11 staphylococcal species as well as comparison of the sequences for the 370-bp amplicon from five unrelated ATCC and clinical strains for each of the species S. aureus, S. epidermidis, S. haemolyticus, S. hominis, and S. saprophyticus demonstrated sufficient interspecies polymorphism to generate genus- and species-specific capture probes. This sequence information allowed the development of Staphylococcus-specific and species-specific (targeting S. aureus, S. epidermidis, S. haemolyticus, S. hominis, or S. saprophyticus) capture probes hybridizing to the 370-bp amplicon. In conclusion, this PCR assay is suitable for detection of staphylococci at both genus and species levels.
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6. |
Linde HJ,
Schmidt M,
Fuchs E,
Reischl U,
Niller HH,
Lehn N,
( 2001 ) In vitro activities of six quinolones and mechanisms of resistance in Staphylococcus aureus and coagulase-negative staphylococci. PMID : 11302827 : DOI : 10.1128/AAC.45.5.1553-1557.2001 PMC : PMC90505 Abstract >>
Of 94 clinical isolates of Staphylococcus aureus (n = 51) and coagulase-negative staphylococci (CNS) (n = 43), mutations in the quinolone resistance-determining region of topoisomerases GrlA, GrlB, GyrA, and GyrB together with MICs of six quinolones were analyzed. Amino acid substitutions at identical residues (GrlA residues 80 and 84; GyrA residues 84 and 88) were found in S. aureus and CNS. Active efflux, as suggested by blocking by reserpine, contributed substantially to the resistance phenotype in some strains. Among ciprofloxacin, clinafloxacin, levofloxacin, nalidixic acid, trovafloxacin, and sparfloxacin, a 0.5-microg/ml concentration of sparfloxacin discriminated best between strains with two or three mutations and those with no mutations.
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7. |
Fitzgibbon JE,
Nahvi MD,
John JF,
( 1999 ) Topoisomerase sequences of coagulase-negative staphylococcal isolates resistant to ciprofloxacin or trovafloxacin. PMID : 10390214 : PMC : PMC89335 Abstract >>
Coagulase-negative staphylococcal isolates (n = 188) were screened for susceptibility to oxacillin, ciprofloxacin, and trovafloxacin, a new fluoroquinolone. At an oxacillin concentration of >/=4 microg/ml, 43% were methicillin resistant; of these, 70% were ciprofloxacin resistant (MIC, >/=4 microg/ml). Of the methicillin-resistant, ciprofloxacin-resistant isolates, 46% were susceptible to /=8 microg/ml) and increased trovafloxacin MICs (0.25 to 2 microg/ml) could be conferred by the combined presence of single mutations in each gyrA and grlA gene. Trovafloxacin MICs of >/=8 microg/ml also occurred, but these required an additional mutation in grlA.
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8. |
Layer F,
Ghebremedhin B,
König W,
König B,
( 2007 ) Differentiation of Staphylococcus spp. by terminal-restriction fragment length polymorphism analysis of glyceraldehyde-3-phosphate dehydrogenase-encoding gene. PMID : 17681623 : DOI : 10.1016/j.mimet.2007.06.015 Abstract >>
Classical phenotypic and biochemical testing do not lead to correct identification of the distinct Staphylococcus species. Therefore, the aim of our study was to develop a method for the reliable and accurate determination of distinct Staphylococcus species. In the present study, the 931-934-bp partial sequences of the glyceraldehyde-3-phosphate dehydrogenase-encoding (gap) gene of 28 validly described Staphylococcus species were amplified and sequenced. By using the respective sequence information we performed a terminal-restriction fragment length polymorphism (T-RFLP) analysis. For T-RFLP the partial gap gene was amplified with double-fluorescently labelled primers and digested with the restriction enzymes DdeI, BspHI and TaqI. Distinctive T-RFLP patterns were rendered by the use of capillary electrophoresis with laser-induced fluorescence detection. This molecular method allowed us to identify all 28 Staphylococcus species with high specificity. This was validated by analysis of 34 Staphylococcus epidermidis and 28 Staphylococcus haemolyticus isolates. These results demonstrate the feasibility and applicability of the T-RFLP method based on the partial gap gene sequences for rapid and accurate species identification.
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9. |
Schnellmann C,
Gerber V,
Rossano A,
Jaquier V,
Panchaud Y,
Doherr MG,
Thomann A,
Straub R,
Perreten V,
( 2006 ) Presence of new mecA and mph(C) variants conferring antibiotic resistance in Staphylococcus spp. isolated from the skin of horses before and after clinic admission. PMID : 17005735 : DOI : 10.1128/JCM.00868-06 PMC : PMC1698435 Abstract >>
Because of the frequency of multiple antibiotic resistance, Staphylococcus species often represent a challenge in incisional infections of horses undergoing colic surgery. To investigate the evolution of antibiotic resistance patterns before and after preventative peri- and postoperative penicillin treatment, staphylococci were isolated from skin and wound samples at different times during hospitalization. Most staphylococci were normal skin commensals and belonged to the common coagulase-negative group. In some cases they turned out to be opportunistic pathogens present in wound infections. MICs were determined for 12 antibiotics, and antibiotic resistance genes were detected by microarray. At hospital admission, horses harbored staphylococci that were susceptible to antibiotics or resistant to one group of drugs, mainly due to the presence of new variants of the methicillin and macrolide resistance genes mecA and mph(C), respectively. After 3 days, the percentage of Staphylococcus isolates displaying antibiotic resistance, as well as the number of resistance genes per isolate, increased moderately in hospitalized horses without surgery or penicillin treatment but dramatically in hospitalized horses after colic surgery as well as penicillin treatment. Staphylococcus species displaying multiple resistance were found to harbor mainly genes conferring resistance to beta-lactams (mecA and blaZ), aminoglycosides [str and aac(6')-Ie-aph(2')-Ia], and trimethoprim [dfr(A) and dfr(D)]. Additional genes conferring resistance to macrolides [mph(C), erm(C), and erm(B)], tetracycline [tet(K) and tet(M)], chloramphenicol [cat(pC221) and cat(pC223)], and streptothricin (sat4) appeared in several strains. Hospitalization and preventive penicillin use were shown to act as selection agents for multidrug-resistant commensal staphylococcal flora.
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10. |
Layer F,
Ghebremedhin B,
Moder KA,
König W,
König B,
( 2006 ) Comparative study using various methods for identification of Staphylococcus species in clinical specimens. PMID : 16891498 : DOI : 10.1128/JCM.00226-06 PMC : PMC1594629 Abstract >>
Coagulase-negative staphylococci (CNS) play a predominant role in nosocomial infections. Rapid, reliable identification of these organisms is essential for accurate diagnosis and prompt effective treatment of these infections. Quite recently, the VITEK 2 g-positive (gram-positive [GP]) identification card (bioM?rieux) has been redesigned for greater accuracy in the identification of gram-positive cocci. We compared the BD Phoenix (Becton Dickinson) and VITEK 2 (bioM?rieux) automated microbiology systems, using their respective update version cards, and the API ID32 STAPH test. The glyceraldehyde-3-phosphate dehydrogenase (gap) gene-based T-RFLP (terminal restriction fragment length polymorphism) method was used for verifying the results. In total, 86 clinical isolates of CNS and 27 reference strains were analyzed. The results show that for identification of CNS, the automated identification methods using the newest VITEK 2 and BD Phoenix identification cards are comparable. However, API ID32 STAPH revealed more correct results compared to both automated microbiology systems. Despite the increased performance of the phenotypic automated identification systems compared to the former versions, molecular methods, e.g., the gap-based T-RFLP method, still show superior accuracy in identifying Staphylococcus species other than Staphylococcus aureus.
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11. |
Fujiwara T,
Aoki S,
Komatsuzawa H,
Nishida T,
Ohara M,
Suginaka H,
Sugai M,
( 2005 ) Mutation analysis of the histidine residues in the glycylglycine endopeptidase ALE-1. PMID : 15629919 : DOI : 10.1128/JB.187.2.480-487.2005 PMC : PMC543547 Abstract >>
A novel staphylolytic enzyme, ALE-1, is a glycylglycine endopeptidase produced by Staphylococcus capitis EPK1. ALE-1 possesses seven histidines. Chemical modification studies using diethylpyrocarbonate and iodoacetic acid suggested that a histidine or tyrosine residue(s) in the molecule is important for the organism's staphylolytic activity. All of the histidine residues, one tyrosine, and one aspartic acid residue in the N-terminally truncated ALE-1 (DeltaN-term ALE-1) were systematically altered by site-directed mutagenesis, and the enzyme activities and metal contents of the variants were measured. Our studies indicated that His-150, His-200, His-231, His-233, and Asp-154 are essential for the enzyme activity of DeltaN-term ALE-1. Except for His-150 and Asp-154, all of these amino acids were located within the 38-amino-acid region conserved among 11 proteins, including 5 staphylolytic endopeptidases. Inductively coupled plasma-mass spectrometric analysis of DeltaN-term ALE-1 revealed that it contains one atom of zinc per molecule. Measurement of the zinc content of the mutant DeltaN-term ALE-1 suggested that His-150 and -233 are important for zinc binding; their loss in these variant enzymes coincided with the loss of staphylolytic activity. These results strongly suggest that ALE-1 is a novel member of zinc metalloproteases.
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12. |
Liu Y,
Ames B,
Gorovits E,
Prater BD,
Syribeys P,
Vernachio JH,
Patti JM,
( 2004 ) SdrX, a serine-aspartate repeat protein expressed by Staphylococcus capitis with collagen VI binding activity. PMID : 15501749 : DOI : 10.1128/IAI.72.11.6237-6244.2004 PMC : PMC523036 Abstract >>
Staphylococcus capitis (S. capitis) has been implicated in a large proportion of coagulase-negative staphylococcal infections in very-low-birth-weight infants. To identify potential therapeutic targets, the S. capitis genome was probed for the presence of genes encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMM). By using Southern blot analysis, an S. capitis gene, designated sdrX, that contained sequence motifs consistent with the Sdr family of MSCRAMM proteins was identified. By using monospecific antisera in Western blot and flow cytometry, SdrX was demonstrated to be expressed on the surface of S. capitis. Human collagen type VI was found to bind both the recombinant A domain of SdrX and viable S. capitis expressing SdrX. SdrX is the first collagen-binding Sdr protein described and is the first MSCRAMM protein identified in S. capitis.
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13. |
Capurro A,
Artursson K,
Waller KP,
Bengtsson B,
Ericsson-Unnerstad H,
Aspán A,
( 2009 ) Comparison of a commercialized phenotyping system, antimicrobial susceptibility testing, and tuf gene sequence-based genotyping for species-level identification of coagulase-negative staphylococci isolated from cases of bovine mastitis. PMID : 18930604 : DOI : 10.1016/j.vetmic.2008.08.028 Abstract >>
In order to evaluate the usefulness of some phenotypic and genotypic methods for species identification of coagulase-negative staphylococci (CNS), isolates were obtained from bovine cases of clinical and sub-clinical mastitis from different geographical areas in Sweden. By using the Staph-Zym test, antimicrobial susceptibility testing, and sequencing of part of the CNS tuf gene and, when needed, part of the 16S rRNA gene we characterized 82 clinical isolates and 24 reference strains of 18 different species of staphylococci. The genotypic methods identified nine different species of CNS among the 82 milk isolates. A comparison with results obtained by tuf gene sequencing showed that Staph-Zym correctly identified CNS reference strains to species level more often than bovine milk CNS isolates (83% and 61%, respectively). In addition, tests supplementary to the Staph-Zym were frequently needed in both groups of isolates (50% of reference strains and 33% of milk isolates) to obtain an identification of the strain. It is notable that Staph-Zym judged two isolates as CNS, although they belonged to other species, could not give a species name in 11% of the bovine CNS isolates, and gave 28% of the isolates an incorrect species name. The present study indicates that the studied phenotypic methods are unreliable for identification of CNS from bovine intra-mammary infections.
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14. |
de las Rivas B,
Rodríguez H,
Carrascosa AV,
Muñoz R,
( 2008 ) Molecular cloning and functional characterization of a histidine decarboxylase from Staphylococcus capitis. PMID : 17887985 : DOI : 10.1111/j.1365-2672.2007.03549.x Abstract >>
Histamine intoxication is probably the best known toxicological problem of food-borne disease. A histamine-producing Staphylococcus capitis strain has been isolated from a cured meat product. The aim of this study was to gain deeper insights into the genetic determinants for histamine production in Staph. capitis. The nucleotide sequence of a 6446-bp chromosomal DNA fragment containing the hdcA gene encoding histidine decarboxylase (HDC) has been determined in Staph. capitis IFIJ12. This DNA fragment contains five complete and two partial open reading frames. Putative functions have been assigned to gene products by sequence comparison with proteins included in the databases. The hdcA gene has been expressed in Escherichia coli resulting in HDC activity. The presence of a functional promoter (Phdc) located upstream of hdcA has been demonstrated. Insertion of the histamine biosynthetic locus in Staph. capitis seems to be associated with a noticeable genome reorganization. Among the staphylococcal species analysed in this study only Staph. capitis strains produce histamine. The hdcA gene cloned from Staph. capitis encodes a functional HDC that produce histamine from the amino acid histidine. The identification of the DNA region involved in histamine production in Staph. capitis will allow further work in order to avoid histamine production in foods.
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15. |
Ehrnstorfer IA,
Geertsma ER,
Pardon E,
Steyaert J,
Dutzler R,
( 2014 ) Crystal structure of a SLC11 (NRAMP) transporter reveals the basis for transition-metal ion transport. PMID : 25326704 : DOI : 10.1038/nsmb.2904 Abstract >>
Members of the SLC11 (NRAMP) family transport iron and other transition-metal ions across cellular membranes. These membrane proteins are present in all kingdoms of life with a high degree of sequence conservation. To gain insight into the determinants of ion selectivity, we have determined the crystal structure of Staphylococcus capitis DMT (ScaDMT), a close prokaryotic homolog of the family. ScaDMT shows a familiar architecture that was previously identified in the amino acid permease LeuT. The protein adopts an inward-facing conformation with a substrate-binding site located in the center of the transporter. This site is composed of conserved residues, which coordinate Mn2+, Fe2+ and Cd2+ but not Ca2+. Mutations of interacting residues affect ion binding and transport in both ScaDMT and human DMT1. Our study thus reveals a conserved mechanism for transition-metal ion selectivity within the SLC11 family.
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16. |
Martins Simões P,
Rasigade JP,
Lemriss H,
Butin M,
Ginevra C,
Lemriss S,
Goering RV,
Ibrahimi A,
Picaud JC,
El Kabbaj S,
Vandenesch F,
Laurent F,
( 2013 ) Characterization of a novel composite staphylococcal cassette chromosome mec (SCCmec-SCCcad/ars/cop) in the neonatal sepsis-associated Staphylococcus capitis pulsotype NRCS-A. PMID : 24060879 : DOI : 10.1128/AAC.01576-13 PMC : PMC3837888 Abstract >>
Multiresistant Staphylococcus capitis pulsotype NRCS-A has been reported to be a major pathogen causing nosocomial bacteremia in preterm infants. We report that the NRCS-A strain CR01 harbors a novel 60.9-kb composite staphylococcal cassette chromosome mec (SCCmec) element, composed of an SCCmec with strong homologies to Staphylococcus aureus ST398 SCCmec and of an SCCcad/ars/cop harboring resistance genes for cadmium, arsenic, and copper. Whole-genome-based comparisons of published S. capitis strains suggest that strain CR01 acquired the two elements independently.
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17. |
( 1997 ) Purification and molecular characterization of glycylglycine endopeptidase produced by Staphylococcus capitis EPK1. PMID : 9023202 : DOI : 10.1128/jb.179.4.1193-1202.1997 PMC : PMC178816 Abstract >>
A novel staphylolytic enzyme, ALE-1, acting on Staphylococcus aureus, was purified from a Staphylococcus capitis EPK1 culture supernatant. The optimal pH range for staphylolytic activity was 7 to 9. ALE-1 contains one Zn2+ atom per molecule. Analysis of peptidoglycan fragments released by ALE-1 indicated that the enzyme is a glycylglycine endopeptidase. The effects of various modulators were determined, and we found that o-phenanthroline, iodoacetic acid, diethylpyrocarbonate, and Cu2+ reduced the staphylolytic activity of ALE-1. beta-Casein, elastin, and pentaglycine were poor substrates for ALE-1. Molecular cloning data revealed that ALE-1 is composed of 362 amino acid residues and is synthesized as a precursor protein which is cleaved after Ala at position 35, thus producing a mature ALE-1 of 35.6 kDa. The primary structure of mature ALE-1 is very similar to the proenzyme form of lysostaphin. It has the modular design of an N-terminal domain of tandem repeats of a 13-amino-acid sequence fused to the active site containing C-terminal domain. Unlike lysostaphin, ALE-1 does not undergo processing of the N-terminal repeat domain in broth culture. ale-1 is encoded on the plasmid. Protein homology search suggested that ALE-1 and lysostaphin are members of the novel Zn2+ protease family with a homologous 38-amino-acid-long motif, Tyr-X-His-X(11)-Val-X(12/20)-Gly-X(5-6)-His.
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18. |
( 2013 ) Differences between two clinical Staphylococcus capitis subspecies as revealed by biofilm, antibiotic resistance, and pulsed-field gel electrophoresis profiling. PMID : 23052315 : DOI : 10.1128/JCM.05124-11 PMC : PMC3536240 Abstract >>
Coagulase-negative staphylococci have been identified as major causes of late-onset neonatal bacteremia in neonatal intensive care units. Sixty isolates of Staphylococcus capitis obtained from blood cultures of neonates between 2000 and 2005 were examined in this study. Biochemical analysis confirmed that 52 of these isolates belonged to the subsp. urealyticus, and the remaining 8 belonged to the subsp. capitis. Isolates of the predominant subsp. urealyticus clones were characterized by their resistance to penicillin, erythromycin, and oxacillin and their biofilm formation ability, whereas subsp. capitis isolates were generally antibiotic susceptible and biofilm negative. Pulsed-field gel electrophoresis (PFGE) after SacII digestion separated the 60 isolates into five major clusters. Sequence analysis showed that, in S. capitis, the ica operon plus the negative regulator icaR was 4,160 bp in length. PCRs demonstrated the presence of the ica operon in all isolates. Further analysis of five isolates (two biofilm-positive subsp. urealyticus, one biofilm-negative subsp. urealyticus, and two biofilm-negative subsp. capitis) revealed that the ica operons were identical in all of the biofilm-positive subsp. urealyticus strains; however, the biofilm-negative isolates showed variations. The distinctive phenotypic and genotypic characteristics revealed by this study may affect the epidemiology of the two subspecies of S. capitis in the clinical setting. These results may provide a better understanding of the contribution of these two species to bloodstream infections in neonates.
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19. |
( 2013 ) Emergence of cfr-harbouring coagulase-negative staphylococci among patients receiving linezolid therapy in two hospitals in China. PMID : 23449871 : DOI : 10.1099/jmm.0.051003-0 Abstract >>
This study reports on the emergence of cfr-harbouring coagulase-negative staphylococci (CoNS) among patients who received linezolid therapy in two hospitals in Hangzhou, China. The mechanisms of resistance and transmission were analysed for these resistant isolates. Eight Staphylococcus capitis isolates, one Staphylococcus epidermidis isolate and one Staphylococcus hominis isolate, obtained from patients who had received linezolid therapy in two hospitals in Hangzhou, China, were confirmed as linezolid resistant, with MICs ranging from 8 to >256 mg l(-1). The linezolid usage data of the ten patients before isolation of the linezolid-resistant CoNS were collected. PFGE analysis showed that the eight S. capitis isolates from the two hospitals belonged to the same clone. Nine of the linezolid-resistant CoNS isolates carried the cfr gene, which was located on plasmids of a similar size. A 5.3 kb fragment containing the cfr gene, revealing 99 % identity to the sequence of the cfr-harbouring plasmid pSS-01 reported previously, was determined by PCR mapping for all cfr-positive isolates, and the cfr gene was flanked by two copies of IS256-like elements. Thus, these results document the emergence of linezolid-resistant CoNS isolates carrying the cfr gene in Hangzhou, China. Effective nosocomial infection control strategies and the judicious use of antibiotics will be required to prevent further spread of this resistance mechanism.
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20. |
( 1997 ) epr, which encodes glycylglycine endopeptidase resistance, is homologous to femAB and affects serine content of peptidoglycan cross bridges in Staphylococcus capitis and Staphylococcus aureus. PMID : 9209049 : DOI : 10.1128/jb.179.13.4311-4318.1997 PMC : PMC179255 Abstract >>
Staphylococcus capitis EPK1 produces a glycylglycine endopeptidase, ALE-1 (M. Sugai, T. Fujiwara, T. Akiyama, M. Ohara, H. Komatsuzawa, S. Inoue, and H. Suginaka, J. Bacteriol. 179:1193-1202, 1997), which hydrolyzes interpeptide pentaglycine chains of cell wall peptidoglycan of S. aureus. Characterizations of the enzyme activity and cloning of ale-1 revealed that ALE-1 is very similar to prolysostaphin produced by S. simulans bv. staphylolyticus. Strain EPK1 is resistant to lysis by ALE-1 and by lysostaphin. A gene that renders the cells resistant to glycylglycine endopeptidase (epr) was found 322 bp upstream of and in the opposite orientation to ale-1. The deduced amino acid sequence of epr showed similarities to FemA and FemB, which have been characterized as factors essential for methicillin resistance of S. aureus. Inactivation of either femA or femB causes decreased resistance to methicillin, increased resistance to lysostaphin, and decreased glycine content in the interpeptide chains of peptidoglycan. Therefore, femAB is suggested to be involved in the addition of glycine to pentapeptide peptidoglycan precursor. S. aureus with epr on a multicopy plasmid had phenotypes similar to those of femAB mutants except that it did not alter resistance level to methicillin. These results suggest that epr and femAB belong to the protein family involved in adding amino acids to the pentapeptide peptidoglycan precursor and that epr is involved in the addition of serine to the pentapeptide.
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