RESUMEN
A total of 83 clinical isolates of the Bacteroides fragilis group collected from two Brazilian hospitals during 1993 and 1994, were tested for susceptibility to six antimicrobial agents by using an agar dilution method. The species most frequently isolated was B. fragilis (63.8%), followed by B. thetaiotaomicron (15.6%), B. vulgatus (9.6%) and B. distasonis (7.2%). The various species of the B. fragilis group had different patterns of resistance; B. fragilis was the most susceptible species in both medical centers. All isolates were susceptible to metronidazole and chloramphenicol. The following resistance rates were observed: 89.1% (Penicillin G); 77.1% (tetracycline); 18% (clindamycin) and 7.2% (cefoxitin). These results reflect the value of identification of clinical important isolates and the periodic determination of B. fragilis group susceptibility patterns at each medical institution.