Evaluation of the modified broth-disk method for determining antibiotic susceptibilities of anaerobic bacteria

A total of 110 strains of anaerobic bacteria including 9 different genera was tested for antibiotic susceptibility by the modified broth-disk method of Wilkins and Thiel (1973), using prereduced media and the VPI anaerobic culture system. Results were compared with those obtained with an agar dilution technique with incubation in a GasPak jar. There was greater than 95% agreement between the two methods with ampicillin, cephalothin, chloramphenicol, and clindamycin, and 90% or greater agreement with erythromycin, penicillin, and tetracycline.