title: Impact of the ampD gene and its product on beta-lactamase production in Enterobacter cloacae.
abstract: In an investigation of the influence of the ampD gene on beta-lactamase production and induction in Enterobacter cloacae, the ampR-ampC gene region cloned into a plasmid and the ampD gene cloned into another vector were transferred to a strain of Escherichia coli. The genetically manipulated E. coli strains served as a model for study of the inducibility of beta-lactamases in E. cloacae. In addition, beta-lactamase induction in E. cloacae bearing the previously mentioned plasmids was studied. After induction of the beta-lactamase with cefoxitin, the specific hydrolytic activity, the viable cell count, and the degradation of cefoxitin were determined. beta-Lactamase expression decreased with an increasing amount of the ampD gene product. The cefoxitin concentration decreased in proportion to the amount of enzyme, but the induction of beta-lactamase seemed not to be an important factor influencing the viable cell count of E. cloacae as long as cefoxitin concentrations exceeded the MIC. Despite different beta-lactamase concentrations, the decrease in the viable cell count was nearly identical in all experiments.
authors.affiliation: Institut für Medizinische Mikrobiologie und Immunologie, Universität Bonn, Federal Republic of Germany.
authors.forename: K
authors.initials: K
authors.lastname: Peter
authors.forename: G
authors.initials: G
authors.lastname: Korfmann
authors.forename: B
authors.initials: B
authors.lastname: Wiedemann
mesh_terms: D002440:Cefoxitin / Q000494:pharmacology; D003001:Cloning, Molecular; D015169:Colony Count, Microbial; D004754:Enterobacter / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004755:Enterobacteriaceae / Q000235:genetics*; D004790:Enzyme Induction; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D005822:Genetic Vectors; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D002440:Cefoxitin; D001618:beta-Lactamases