Characterization of the first clinical isolate of vancomycin-resistant Enterococcus faecalis, AH803, in Taiwan

We previously isolated a vancomycin-resistant strain of Enterococcus faecal is, designated AH803, from the sputum of a patient with pneumonia and bacte remia in Taiwan. AH803 was resistant to vancomycin (minimal inhibitory conc entration. MIC = 512 mu g/mL) but susceptible to teicoplanin (MIC = 8 mu g/ mL), and harbored the vanA gene but not the vanB gene. In this study, we fu rther characterized E. faecalis AH803 and the plasmid it was found to conta in. DNA from AH803 was analyzed for the presence of vanA and vanB resistanc e genes by polymerase chain reaction. The vancomycin resistant phenotype wa s transferable from AH803 to E. faecalis JH2-2, at a frequency of 4.8 x 10( -2). AH803 was also resistant to gentamicin and chloramphenicol, and these antibiotic resistance phenotypes cotransferred with vancomycin resistance. The genes responsible for resistance to all three antibiotics were located on a 42-kb conjugative plasmid (pBL101). This plasmid had the same restrict ion enzyme digestion patterns as Tn 1546, found in pIP816 of E. faecalis BM 4147. Epidemiologic studies of glycopeptide resistance should perhaps combi ne phenotypic and genotypic methods, rather than using phenotypic methods a lone.