Genotypic characterization of hospital Enterococcus faecalis strains using multiple-locus variable-number tandem-repeat analysis.
ABSTRACT The level of genetic diversity and relationships between the specific genotypes and the distribution of virulence determinants among Enterococcus faecalis strains isolated from patients hospitalized in different wards of two hospitals were investigated.
Fifty-six clinical strains of E. faecalis, isolated from patients hospitalized in the period of 1999-2004 in several wards in Wrocław (Poland), were analysed by multiple-locus variable-number tandem-repeat analysis (MLVA). Analysis of seven genomic loci identified 40 novel genotypes among the analysed E. faecalis strains, with two major genomic groups, designated I and II, distinguished at a cut-off of 35%. With a similarity cut-off of 85.7%, the genotypes could be combined into 12 clusters (C1-C12), containing at least two isolates. The remaining 18 MLVA types were represented by a single isolate.
Based on the data obtained by MLVA, it was found that (i) many E. faecalis isolates recovered from patients from the wards whose location allowed the potential transmission of micro-organisms, belonged to closely related MLVA types and (ii) possible relationships between specific E. faecalis genotype and the virulence factors lipase, haemolysin and esp gene can exist.
Our study confirms that MLVA is a suitable method for the epidemiological study of E. faecalis and for the first time shows possible relationships between specific genotypes and such virulence determinants, i.e. lipase, haemolysin and esp gene.
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ABSTRACT: The present study describes the first molecular characterization of environmental and clinical isolates of vancomycin-resistant enterococci (VRE) in Wales. Over a 3-month period (May-July 2000), 134 isolates of VRE (89 Enterococcus faecium and 45 Enterococcus faecalis) were isolated from the patient environment of the University Hospital of Wales (UHW) in Cardiff, Wales, UK. In addition, over the same time-period, 24 clinical isolates of VRE (20 isolates of E. faecium and four isolates of E. faecalis) were obtained from 14 patients. All study isolates were subjected to PFGE typing and their van genotypes were determined by using multiplex PCR. The vanA PCR product (231 bp) was evident in 146 (92 %) of 158 VRE isolates; the remaining 12 isolates (8 %) were positive for the vanB gene. All isolates of E. faecalis were found to be vanA-positive. In total, 16 PFGE banding profiles (pulsotypes) were observed for environmental isolates of E. faecium, whilst eight pulsotypes were found for isolates of E. faecalis. Some of these pulsotypes were isolated from multiple sites, whereas others were more restricted in their distribution. Eleven pulsotypes were evident for clinical isolates and eight of these (representing 11 isolates) were also encountered in environmental isolates. Eleven clinical isolates of E. faecium (55 %) shared an identical pulsotype that was not detected in environmental isolates. These results demonstrate a heterogeneous environmental population of VRE and an association of certain strains with clinical isolates. Predominance of a single pulsotype (not detected in the environment) amongst clinical isolates suggests non-environmental transmission between patients.Journal of Medical Microbiology 10/2003; 52(Pt 9):821-7. · 2.30 Impact Factor
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ABSTRACT: The occurrence of several virulence traits (cytolysin, adhesins and hydrolytic enzymes) was investigated in a collection of 164 enterococci, including food and clinical isolates (from human and veterinary origin), as well as type and reference strains from 20 enterococcal species. Up to fifteen different cyl genotypes were found, as well as silent cyl genes. The occurrence of the cyl operon and haemolytic potential seems to be widespread in the genus. A significant association of this virulent trait with clinical isolates was found (p < 0.05). High levels of incidence were also observed for genes encoding surface adhesins (esp, efaA(fs), efaA(fm)), agg and gelE, irrespectively of species allocation and origin of strains. Although gelE behaves as silent in the majority of the strains, gelatinase activity predominates in clinical isolates, whereas lipase and DNase were mainly detected in food isolates pointing to their minor role as virulence determinants. No hyaluronidase activity was detected for all strains. Numerical hierarchic data analysis grouped the strains in three main clusters, two of them including a total of 50 strains with low number of virulence determinants (from 2 to 7) and the other with 114 strains with a high virulence potential (up to 12 determinants). No statistical association was found between virulence clusters and species allocation (p > 0.10), strongly suggesting that virulence determinants are a common trait in the genus Enterococcus. Clinical strains seem to be significantly associated with high virulence potential, whereas food, commensal and environmental strains harbour fewer virulence determinants (p < 0.01). A high level of relative diversity in virulence patterns was observed (Shannon's index varies from 0.95 to 1.0 among clusters), reinforcing the strain-specific nature of the association of virulence factors. Although a low risk seems to be associated with the use of enterococci in long-established artisanal cheeses, screening of virulence traits and their cross-synergies must be performed, particularly for commercial starters, probiotic strains and products to be used by high risk population groups.Systematic and Applied Microbiology 03/2003; 26(1):13-22. · 3.29 Impact Factor
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ABSTRACT: In order to assess whether multiple-locus-variable number tandem repeat analysis (MLVA) could replace pulsed-field gel electrophoresis (PFGE) for genotyping vancomycin-resistant isolates of Enterococcus faecium (VREF), this study compared the typeability, discriminatory power, concordance and costs of these methods for VREF isolates obtained from patients, environmental samples and the hands of healthcare workers (HCWs) in a medical intensive care unit (ICU) where VREF was endemic. Over a 58-day period, 393 VREF isolates (373 vanA, one vanA/B, 19 vanB) were cultured from patient rectal swabs (n = 76), the environment (n = 270) and the hands of HCWs (n = 47). PFGE was able to divide 358 (91.1%) isolates into 19 PFGE types (>six bands different) and 24 subtypes (one to three bands different). MLVA was able to type 391 (99.5%) isolates into 11 genotypes. The discriminatory power of PFGE subtypes was 83%, as compared to 68% for MLVA. Concordance between the two methods, based on matched or mismatched MLVA types and PFGE types or subtypes, was 67.5% and 82.8%, respectively. Using PFGE, 13 isolates could be genotyped in 3 days; MLVA genotyped 94 isolates in 2 days. For both methods, the estimated costs were Euro 7 ($10)/isolate. PFGE and MLVA produced highly concordant results when assigning genotypes to nosocomial VREF isolates. MLVA was faster, but PFGE subtyping was more discriminatory.Clinical Microbiology and Infection 04/2008; 14(4):363-9. · 4.58 Impact Factor