title: The detection of enzyme A of Yersinia enterocolitica by a disc diffusion method.
abstract: Yersinia enterocolitica has been described as expressing two types of chromosomal beta-lactamase, the broad spectrum enzyme A and the inducible cephalosporinase enzyme B. Nevertheless, not all Y. enterocolitica strains express both enzyme A and enzyme B; Y. enterocolitica strains of the less commonly isolated biotype 2, serotype O:5 (27) lack the enzyme A. Also, no other members of the Enterobacteriaceae have been demonstrated to produce enzyme A. Detection of this enzyme could therefore be a useful laboratory tool in distinguishing common pathogenic strains of Y. enterocolitica from other Enterobacteriaceae. A simple test by disc diffusion on agar for the recognition of enzyme A expression in Y. enterocolitica was evaluated. The test was based on the resistance to ticarcillin conferred by enzyme A and the highly effective inhibition of this enzyme by clavulanic acid. A typical additional zone of inhibition between the zones of inhibition around a ticarcillin 75 micrograms disc and an amoxycillin/clavulanate 3 micrograms disc was indicative of the presence of enzyme A. By contrast, a large zone of inhibition around the ticarcillin disc without an additional zone of inhibition, reflected the absence of enzyme A.
authors.affiliation: Department of Microbiology, Prince of Wales Hospital, Sydney, Australia.
authors.forename: J N
authors.initials: JN
authors.lastname: Pham
authors.forename: S M
authors.initials: SM
authors.lastname: Bell
authors.forename: L
authors.initials: L
authors.lastname: Martin
authors.forename: E
authors.initials: E
authors.lastname: Carniel
mesh_terms: D000362:Agar; D019818:Clavulanic Acid / Q000494:pharmacology; D004058:Diffusion; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013982:Ticarcillin / Q000494:pharmacology; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D018440:beta-Lactam Resistance; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D000362:Agar; D001618:beta-Lactamases; D013982:Ticarcillin