IDENTIFICATION AND CHARACTERIZATION OF MULTIPLE SPECIES OF VANCOMYCIN-RESISTANT ENTEROCOCCI, INCLUDING AN EVALUATION OF VITEK SOFTWARE VERSION-7.1

A total of 374 clinical isolates of Enterococcus spp. were characteriz ed to determine the species distribution and vancomycin resistance. Th e ability of the Vitek system (bioMerieux Inc, Hazelwood, St. Louis, M o.) to identify enterococci to the species level and to recognize vanc omycin resistance by using computer software version 7.1 was evaluated . Conventional methods were used for identification and agar dilution was used for susceptibility testing, the results of which were as foll ows (presented as number of vancomycin-resistant isolates/number of me mbers of that species identified): 219/234 E. faecium, 9/112 E. faecal is, 2/3 E. mundtii, 0/1 E. durans, 0/1 E. hirae, 0/1 E. raffinosis, an d 0/1 E. avium. Ten enterococci were in the vancomycin-intermediate ca tegory (six E. gallinarum, two E. casseliflavus, and one each of E. fa ecium and E. faecalis). The Vitek GPI card correctly identified 98% of E. faecium isolates, 99% of E. faecium and E. faecalis isolates, and only two isolates of other enterococcal species. The GPS-TA card was 9 8% sensitive and 95% specific for the detection of vancomycin resistan ce, generating a total of four very major (1.6%) and five minor errors (1.3%).