title: Mutational enzymatic resistance of Enterobacter species to beta-lactam antibiotics.
abstract: Mutants with enhanced beta-lactam resistance were selected from strains of Enterobacter cloacae and E. aerogenes by using three antibiotics. High-level beta-lactamase-producing mutants had similar degrees of increased resistance, enzyme substrate profiles, and isoelectric (pI) values irrespective of the selective agent. Reverse mutants from a resistant E. cloacae mutant regained the susceptibility pattern originally exhibited by the wild type, or were of enhanced susceptibility, and no longer expressed increased beta-lactamase production. beta-Lactamases of the mutants were similar in pI values to the wild-type enzyme. The increased resistance of the mutants therefore appeared to be accounted for by increased beta-lactamase production.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002474:Cell-Free System; D004352:Drug Resistance, Microbial; D004754:Enterobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004755:Enterobacteriaceae / Q000201:enzymology*; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D009154:Mutation; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases