Characterization of an Enterococcus gallinarum carrying dual vanA and vanB cassette

The ability of vancomycin resistance determinants to be horizontally transferred within enterococci species is a concern. Identification and characterization of vancomycin resistant enterococci (VRE) in a clinical isolate has a significant impact on infection control practices. In this study, we describe a clinical isolate of E. gallinarum exhibiting high level resistance to vancomycin and teicoplanin. Genetic characterization of this isolate showed the presence of vanA and vanB genes in addition to naturally carrying vanC gene. vanA was identified on pA6981, a 35,608-bp circular plasmid with significant homology to plasmid pS177. vanB operon was integrated into the bacterial chromosome and showed high level of homology to previously reported Tn 1549 and Tn 5382. To the best of our knowledge, this is the first report of E. gallinarum carrying both vanA and vanB operons, indicating the importance of identifying vancomycin resistance mechanism in non- E. faecium and - E. faecalis enterococcal species.