Two Structurally Distinct VanA Resistance Elements at Different Locations in a Glycopeptide-Resistant Strain of Enterococcus faecalis.

Glycopeptide-resistant enterococci (GRE) can carry more than one VanA element (3, 5), but we are unaware of previous evidence for separate transfer of such elements. Enterococcus faecalis JS3B was examined as one of 46 GRE isolated from fecal screens of a hematology patient at Addenbrooke’s Hospital, Cambridge, United Kingdom (7). Overlapping PCR (1) showed that this strain contained a group H element (11). VanA resistance appeared to be associated with a 35-MDa plasmid, but Palepou et al. (6) suggested that group H elements reside on the chromosome. Strain JS3B was therefore investigated for carriage of multiple VanA elements. Transfer of vancomycin resistance was performed by crossstreak conjugation (10). The recipient strains were E. faecalis JH2-2 and E. faecium GE-1, which are resistant to fusidic acid and rifampin and lack pheromone response genes prgA and prgB (see below). After incubation at 37°C for 72 h, the transconjugants were selected on brain heart infusion agar