Two hundred twenty-four isolates of Bacteroides sp. were recovered from recurrently inflamed tonsils, infected peritoneal fluid, abscesses, wounds, and burns of hospitalized children. Isolates were examined for beta-lactamase production by the chromogenic cephalosporin analog 87/312 methodology. Altogether, 119 isolates were beta-lactamase producers. Of these, 53 were in the B. fragilis group, ...