Evaluation of two broth disk methods for antibiotic susceptibility testing of anaerobes

We evaluated the aerobic thioglycolate broth disk and the vaspar overlay broth disk methods for antibiotic susceptibility testing of 144 strains of anaerobes. For penicillin, carbenicillin, chloramphenicol, and metrionidazale, both broth disk methods yielded at least 95% agreement with results obtained by the National Committee for Clinical Laboratory Standards reference agar dilution procedure. For cefoxitin and clindamycin, the agreement was ca. 90%. Overall, the aerobic thioglycolate broth disk and vaspar overlay broth disk methods yielded agreements of 93.3 and 93%, respectively, with the National Committee for Clinical Laboratory Standards method.