CHARACTERIZATION OF INDOLE-NEGATIVE BACTEROIDES-FRAGILIS GROUP SPECIES WITH USE OF POLYMERASE CHAIN-REACTION FINGERPRINTING AND RESISTANCE PROFILES

Biochemical tests alone do not adequately differentiate the various Ba cteroides species, groups, and antimicrobial-resistant variants. Conse quently, we used a polymerase chain reaction (PCR) fingerprinting tech nique, with either a single nonspecific primer derived from the t-DNA intergenic spacer region (T3B) or a single primer that anneals to mini satellite and microsatellite DNA sequences (M13 core), to identify and characterize 58 clinical isolates of Bacteroides fragilis group speci es (B.fragilis, B. distasonis, and B. caccae). In addition to species- and subspecies-specific differences, 4 strains of B. fragilis, 1 of B . distasonis, and 3 of B. caccae that showed increased resistance to i mipenem, ampicillin, and ampicillin/sulbactam also produced unique PCR fingerprint profiles. Analysis by the clinical source of isolation (1 .9., blood or intraabdominal, skin, or soft-tissue infection) indicate d that no particular PCR fingerprint type was associated with greater pathogenicity or any individual clinical source. The PCR fingerprintin g technique proves to be a useful tool for species identification and taxonomic studies, as well as for epidemiological studies of Bacteroid es species.