Survey of Virulence Determinants among Vancomycin Resistant Enterococcus faecalis and Enterococcus faecium Isolated from Clinical Specimens of Hospitalized Patients of North west of Iran



Yaeghob Sharifi1, 2, 6, Alka Hasani1, 2, *, Reza Ghotaslou 2, Mojtaba Varshochi 1, 3, Akbar Hasani 1, 4, Mohammad Aghazadeh 2, Morteza Milani 2, 5
1 Research Center of Infectious Diseases and Tropical Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
2 Department of Clinical Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
3 Department of Infectious Diseases, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
4 Department of Clinical Biochemistry and Biotechnology, Tabriz University of Medical Sciences, Tabriz, Iran
5 Faculty of Pharmacy, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
6 Microbiology laboratory of Imam Khomeini Hospital, Orumieh University of Medical Sciences, Orumieh, Iran


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© Sharifi et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Research Center of Infectious Diseases and Tropical Medicine, and Department of Clinical Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Tel: 0098 411 3364661; Fax: 0098 411 3364661 E-mails: hasanialka@tbzmed.ac.irdr.alkahasani@gmail.com


Abstract

Recent data indicates an increasing rate of vancomycin resistance in clinical enterococcal isolates worldwide. The nosocomial enterococci are likely to harbor virulence elements that increase their ability to colonize hospitalized patients. The aim of this study was to characterize virulence determinants in vancomycin-resistant enterococci (VRE) obtained from various clinical sources.

During the years 2008 to 2010, a total of 48 VRE isolates were obtained from three University teaching hospitals in Northwest, Iran. Initially, phenotypic speciation was done and minimum inhibitory concentrations (MICs) of vancomycin were determined by agar dilution method and E-test. Then, species identification and resistance genotypes along with detection of virulence genes (asa1, esp, gelE, ace and cpd) of the isolates were performed by multiplex PCR.

Thirty eight isolates were identified as vancomycin-resistant Enterococcus faecium (VREfm) and ten as E. faecalis (VREfs). Irrespective of the species, vanA gene (89.58%) was dominant and three phenotypically vancomycin susceptible E. faecium isolates carried the vanB gene. Among virulence genes investigated, the esp was found in 27(71%) VREfm strains, but did not in any VREfs. Other virulence determinants were highly detected in VREfs strains. Our data indicate a high prevalence of E. faecium harboring vancomycin resistance with vanA genotype and the two VRE species displayed different virulence genes.

Keywords: Enterococcus faecalis, Enterococcus faecium, Vancomycin resistance, Virulence gene.