title: Citrobacter diversus ULA27 produces two forms of a chromosomal beta-lactamase.
abstract: A multi-resistant clinical isolate of Citrobacter diversus, particularly resistant to penicillins and cephalosporins, has been studied. The strain produced constitutively high levels of beta-lactamase which efficiently hydrolysed cephaloridine but not ampicillin. The apparent Km value for cephaloridine (125 +/- 25 microM) was within the range usually observed for beta-lactamases in similar bacteria. The strain possessed two forms of the enzyme as indicated by isoelectric focusing patterns, HPLC analysis and two pH optima. SDS-PAGE analysis indicated a single protein responsible for both forms. The strain possessed a single plasmid, as revealed by agarose gel electrophoresis, but beta-lactamase production was not plasmid encoded. The available data indicate the beta-lactamase(s) of C. diversus ULA27 to be chromosomally encoded.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D002954:Citrobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005815:Genetic Code; D007525:Isoelectric Focusing; D008970:Molecular Weight; D001618:beta-Lactamases / Q000032:analysis*; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases