Antibiotic susceptibility of black-pigmented Bacteroides isolates from the human oral cavity.

The minimal inhibitory concentrations of penicillin and six other antibiotics were determined for 66 oral black-pigmented Bacteroides isolates by using the National Committee for Clinical Laboratory Standards proposed standard agar dilution technique. These results plus iodometric determination of beta-lactamase activity showed that oral isolates of black-pigmented Bacteroides are remaining relatively susceptible to commonly used antibiotics.