Molecular epidemiology of Enterococcus faecium isolates from an Italian hospital
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Outbreaks of vancomycin-resistant Enterococcus faecium (VRE) strains is an emerging problem worldwide. Even if still relatively uncommon in European hospitals, infections caused by VRE have also been increasing recently in this continent.
In this study, we characterized 50 consecutive VRE and 23 vancomycin-sensitive E. faecium (VSE) isolates collected in an Italian hospital. The presence of the esp gene and that of genes encoding resistance to glycopeptides was investigated by polymerase chain reaction (PCR). All of the isolates were typed by multi-locus sequence typing (MLST), and a selection of them also by pulsed-field gel electrophoresis (PFGE).
We found that all of the VRE and 18 (78%) of the VSE strains belonged to the single clonal complex-17 (CC17). The most represented sequence type (ST) was ST78 (34% of the isolates). When further analyzed by PFGE, ST78 isolates were subdivided into five pulsotypes, four of them closely related. The strong association between the esp gene and CC17 was confirmed. Interestingly, such an association was higher among vancomycin-resistant isolates. Most of the esp-positive isolates (34/46, 74%) encoded Esp4, a rare variant of this protein characterized by the absence of A repeats.
Our findings underscore the role of the CC17 lineage in the nosocomial spread of VRE and VSE, and its rapid local evolution, underscoring the need for programs designed to provide early detection in order to prevent its spreading among the nosocomial population.
KeywordsEnterococcus faecium VRE Esp MLST PFGE Vancomycin Hospital infection
The authors wish to thank Rob J.L. Willems and Janetta Top for the helpful discussion. This work was supported by the Veneto Region.
Conflict of interest
- 2.Werner G, Coque TM, Hammerum AM, et al. Emergence and spread of vancomycin resistance among enterococci in Europe. Euro Surveill 2008;13. pii: 19046Google Scholar
- 7.Werner G, Klare I, Fleige C, et al. Increasing rates of vancomycin resistance among Enterococcus faecium isolated from German hospitals between 2004 and 2006 are due to wide clonal dissemination of vancomycin-resistant enterococci and horizontal spread of vanA clusters. Int J Med Microbiol. 2008;298:515–27.PubMedCrossRefGoogle Scholar
- 21.Standards, NCCLS. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. Approved standard M7-A5. Wayne, PA, 2001.Google Scholar
- 25.Murchan S, Kaufmann ME, Deplano A, et al. Harmonization of pulsed-field gel electrophoresis protocols for epidemiological typing of strains of methicillin-resistant Staphylococcus aureus: a single approach developed by consensus in 10 European laboratories and its application for tracing the spread of related strains. J Clin Microbiol. 2003;41:1574–85.PubMedCrossRefGoogle Scholar