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Prevalence of virulence genes among VRE genotypes and their association with clinical outcome


The dramatic upsurge in the incidence of VRE worldwide had contributed serious concerns in early and specific diagnosis, infection control measures and treatment. There exists a paucity of information regarding VRE genotypes and their virulence genes contributing to disease severity in India. This study determines the prevalence of VRE and the role of four virulence genes in their clinical outcome.


Enterococci were isolated from a total of 2500 clinical specimens and species identification was done based on conventional methods. VRE were confirmed by agar dilution (vancomycin and teicoplanin) and by the presence of vanA/vanB genes. The presence of esp, agg, gelE and cylA gene among VRE were detected by PCR.


VRE were isolated from 7.3% of clinical specimens. VR E.faecalis and VR E.faecium were primarily derived from UTI and BSI (56.7% and 43.3%) respectively. Among the VRE isolates, 80% of vanA genes were noted in E.faecium and 64% of vanB genes were observed in E.faecalis. Most of VR E.faecalis harboured 2 virulence genes (38.5%) and VR E.faecium harboured one virulence gene (62.5%). The ability to cause invasive infections increased with the number of virulence genes harboured by E.faecalis. An association was observed between the presence of virulence gene esp, cylA and agg with UTI, BSI and IAP infections respectively among the VRE isolates.


Isolation of VRE harbouring vanA and vanB gene gains significance as they are transmissible to co infecting/ resident organisms and to implement infection control measures.

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Correspondence to Ramamurthi Arularasi Aberna.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Aberna, R.A., Prabhakar, K. Prevalence of virulence genes among VRE genotypes and their association with clinical outcome. BMC Infect Dis 14 (Suppl 3), P44 (2014).

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