Article

Genotypic characterization of hospital Enterococcus faecalis strains using multiple-locus variable-number tandem-repeat analysis.

Department of Food Hygiene and Consumer Health Protection, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
Letters in Applied Microbiology (Impact Factor: 1.63). 05/2009; 49(1):79-84. DOI: 10.1111/j.1472-765X.2009.02629.x
Source: PubMed

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.

1 Bookmark
 · 
76 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the antibiotic resistance pattern and the presence of genes encoding several virulence factors in 91 Enterococcus faecalis strains isolated from different human clinical sources in Sardinia were investigated. Genotypic determination of virulence genes (gelE, esp, agg, ace, cylA,B,M,L(L),L(S), efaA, fsrB) was carried out by PCR. The production of gelatinase and haemolytic activity were also determined. Antimicrobial susceptibility tests were performed by an automated microdilution test (Vitek). The strains examined in this study contained at least one and up to as many as all virulence genes investigated. Examining the distribution of these factors in the different groups of clinical strains, we found that all but one virulence determinant were detected more frequently among urinary isolates. The detection of some factors by PCR did not always correlate with its phenotypic expression. Antibiotic susceptibilities among the Enterococcus faecalis strains investigated in our study were typical for the species, with expected levels of acquired resistance. Faecal isolates had the highest percentage of resistance, especially to high level-gentamicin, ciprofloxacin and norfloxacin. In summary, a wide variety of genes encoding virulence factors have been detected among our clinical Enterococcus faecalis strains, and those isolated from UTI were characterized by a higher virulence potency compared with strains from other clinical sources. Silent virulence genes (cyl or gelE) were frequently detected, therefore both the genotypic and phenotypic assays seem necessary for a better characterization of the strains. Our results may serve as a basis for additional surveillance studies of infections caused by this microorganism.
    Journal of preventive medicine and hygiene 03/2010; 51(1):31-6.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Enterococcus faecalis plays a dual role in human ecology, predominantly existing as a commensal in the alimentary canal, but also as an opportunistic pathogen that frequently causes nosocomial infections like bacteremia. A number of virulence factors that contribute to the pathogenic potential of E. faecalis have been established. However, the process in which E. faecalis gains access to the bloodstream and establishes a persistent infection is not well understood. To enhance our understanding of how this commensal bacterium adapts during a bloodstream infection and to examine the interplay between genes we designed an in vitro experiment using genome-wide microarrays to investigate what effects the presence of and growth in blood have on the transcriptome of E. faecalis strain V583. We showed that growth in both 2xYT supplemented with 10% blood and in 100% blood had a great impact on the transcription of many genes in the V583 genome. We identified several immediate changes signifying cellular processes that might contribute to adaptation and growth in blood. These include modulation of membrane fatty acid composition, oxidative and lytic stress protection, acquisition of new available substrates, transport functions including heme/iron transporters and genes associated with virulence in E. faecalis. The results presented here reveal that cultivation of E. faecalis in blood in vitro has a profound impact on its transcriptome, which includes a number of virulence traits. Observed regulation of genes and pathways revealed new insight into physiological features and metabolic capacities which enable E. faecalis to adapt and grow in blood. A number of the regulated genes might potentially be useful candidates for development of new therapeutic approaches for treatment of E. faecalis infections.
    PLoS ONE 01/2009; 4(11):e7660. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Urinary tract infection (UTI) is the most common infection caused by enterococci, and Enterococcus faecalis accounts for the majority of enterococcal infections. Although a number of virulence related traits have been established, no comprehensive genomic or transcriptomic studies have been conducted to investigate how to distinguish pathogenic from non-pathogenic E. faecalis in their ability to cause UTI. In order to identify potential genetic traits or gene regulatory features that distinguish pathogenic from non-pathogenic E. faecalis with respect to UTI, we have performed comparative genomic analysis, and investigated growth capacity and transcriptome profiling in human urine in vitro. Six strains of different origins were cultivated and all grew readily in human urine. The three strains chosen for transcriptional analysis showed an overall similar response with respect to energy and nitrogen metabolism, stress mechanism, cell envelope modifications, and trace metal acquisition. Our results suggest that citrate and aspartate are significant for growth of E. faecalis in human urine, and manganese appear to be a limiting factor. The majority of virulence factors were either not differentially regulated or down-regulated. Notably, a significant up-regulation of genes involved in biofilm formation was observed. Strains from different origins have similar capacity to grow in human urine. The overall similar transcriptional responses between the two pathogenic and the probiotic strain suggest that the pathogenic potential of a certain E. faecalis strain may to a great extent be determined by presence of fitness and virulence factors, rather than the level of expression of such traits.
    PLoS ONE 01/2010; 5(8):e12489. · 3.53 Impact Factor

Full-text (2 Sources)

Download
0 Downloads
Available from
Dec 3, 2014