title: Factors contributing to resistance to beta-lactam antibiotics in Bacteroides fragilis.
abstract: Fifteen strains of Bacteroides fragilis, five highly resistant, five moderately resistant, and five susceptible to benzylpenicillin and cephaloridine, were tested for beta-lactamase production. In the highly resistant and the moderately resistant groups of strains, a correlation between formation of beta-lactamase and minimal inhibitory concentrations was demonstrated. In the presence of the beta-lactamase inhibitors clavulanic acid and CP-45,899 at concentrations of 1 mug/ml, the susceptibility to cephaloridine increased fourfold or more in the beta-lactamase-producing strains. Crypticity measurements (beta-lactamase activity broken/intact cells) with cephaloridine as substrate could indicate a diffusion barrier in the cell wall.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D002509:Cephaloridine / Q000494:pharmacology; D002510:Cephalosporinase / Q000378:metabolism; D004352:Drug Resistance, Microbial; D013997:Time Factors; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D002510:Cephalosporinase; D002509:Cephaloridine