title: Cephalosporinase activity in Bacteroides fragilis.
abstract: Cephalosporinase activity was demonstrated in all of 10 strains of Bacteroides fragilis investigated. Low rates of hydrolysis of cephalosporins (0.25 to 3.5 mumol of cephaloridine per h per 10(9) cells) were found, but no activity against penicillin substrates was detected. In two strains the cephalosporinase activity was increased 40-and 80-fold by growing cells in the presence of penicillin. No permeability barrier for these antibiotics was demonstrated. In most cases the substrate profile showed decreasing activity in the following order: cephaloridine > cephalothin > cephaloglycin > cephalexin. The cephalosporinase from these organisms differed from that found in facultative and aerobic gram-negative bacilli in that it was inhibited by both cloxacillin and p-chloromercuribenzoate. Among nine strains of Bacteroides fragilis subspecies fragilis, correlation was found between in vitro resistance to cephaloridine and amount of beta-lactamase activity in sonically disrupted cells.
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D001439:Bacteroides / Q000201:enzymology*; D002509:Cephaloridine / Q000494:pharmacology; D002511:Cephalosporins; D006868:Hydrolysis; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D010405:Penicillinase / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D000581:Amidohydrolases; D010405:Penicillinase; D002509:Cephaloridine; D010400:Penicillin G