title: Unusual tazobactam-sensitive AmpC beta-lactamase from two Escherichia coli isolates.
abstract: Two Escherichia coli isolates were studied. MIC patterns and hydrolysis assays suggested that they hyperproduced AmpC beta-lactamase, but synergy between ceftazidime and tazobactam was greater than between ceftazidime and Ro 48-1256, whereas the converse pattern is typical of AmpC hyperproducers. Studies with purified beta-lactamase from one of the isolates confirmed that tazobactam was a 100-fold stronger inhibitor than for the classical E. coli AmpC enzyme. Moreover, in contrast to typical AmpC types, the new enzyme had greater affinity for cephaloridine than for benzylpenicillin.
authors.affiliation: Department of Medical Microbiology, St Bartholomew's, London, UK.
authors.forename: G S
authors.initials: GS
authors.lastname: Babini
authors.forename: F
authors.initials: F
authors.lastname: Danel
authors.forename: S D
authors.initials: SD
authors.lastname: Munro
authors.forename: P A
authors.initials: PA
authors.lastname: Micklesen
authors.forename: D M
authors.initials: DM
authors.lastname: Livermore
mesh_terms: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000078142:Tazobactam; D001618:beta-Lactamases / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D010397:Penicillanic Acid; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; D000078142:Tazobactam