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
Anti-Bacterial Agents/pharmacology
Cell-Free System
Drug Resistance, Microbial
Enterobacter/drug effects,enzymology,genetics
Enterobacteriaceae/enzymology
Isoelectric Focusing
Microbial Sensitivity Tests
Mutation
beta-Lactamases/genetics,metabolism
beta-Lactams/pharmacology
Chemicals
Anti-Bacterial Agents
beta-Lactams
beta-Lactamases
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Lampe M F
Allan B J
Minshew B H
Sherris J C
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