USE OF POLYMERASE CHAIN-REACTION FINGERPRINTING TO COMPARE CLINICAL ISOLATES OF BACTEROIDES-FRAGILIS AND BACTEROIDES-THETAIOTAOMICRON FROM GERMANY AND THE UNITED-STATES

Accurate identification of Bacteroides species is often problematic. T herefore, we used a polymerase chain reaction (PCR) fingerprinting tec hnique with either a single nonspecific primer derived from tDNA inter genic spacer or a single primer that anneals to mini-and microsatellit e DNA sequences to compare 34 clinical isolates of B. fragilis and 21 clinical isolates of B. thetaiotaomicron from Southern California with 32 clinical isolates of B. fragilis and 10 isolates of B. thetaiotaom icron from Germany. All German B. fragilis isolates (32 of 32) formed one PCR fingerprint group that matched the PCR profile of the B. fragi lis reference strain ATCC (American Type Culture Collection) 25285, re presentative of DNA homology group I, In contrast, the isolates from S outhern California formed two PCR fingerprint groups, Although most of these strains (29 of 34) also matched B. fragilis ATCC 25285, some st rains (4 of 34) matched the DNA homology group II reference strain VPI (Virginia Polytechnic Institute) 2393, One of the 34 strains showed a unique profile, German B. thetaiotaomicron strains (10 of 10) formed one PCR fingerprint group, matching the reference strain B. thetaiotao micron ATCC 29742, whereas the B. thetaiotaomicron isolates from South ern California showed heterogenous profiles.