title: A new TEM-derived extended-spectrum beta-lactamase (TEM-91) with an R164C substitution at the omega-loop confers ceftazidime resistance.
abstract: A new plasmid-mediated TEM-derived extended-spectrum beta-lactamase, TEM-91, was identified in a ceftazidime-resistant (MIC, >128 microg per ml) Escherichia coli strain isolated in 1996 in Japan. TEM-91 has three amino acid substitutions, R164C, M184T, and E240K, compared with TEM-1 penicillinase. The isoelectric point (pI), K(m), and k(cat) of TEM-91 for ceftazidime were 5.7, 179 microM, and 29.0 s(-1), respectively. The K(i) of clavulanic acid for ceftazidime hydrolysis was 30.3 nM.
authors.affiliation: Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kurokawa
authors.forename: Naohiro
authors.initials: N
authors.lastname: Shibata
authors.forename: Yohei
authors.initials: Y
authors.lastname: Doi
authors.forename: Keigo
authors.initials: K
authors.lastname: Shibayama
authors.forename: Kazunari
authors.initials: K
authors.lastname: Kamachi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yagi
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Arakawa
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology*; D018550:Cephalosporin Resistance / Q000235:genetics*; D002511:Cephalosporins / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology / Q000652:urine; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D017354:Point Mutation / Q000235:genetics; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D065093:beta-Lactamase Inhibitors; D002442:Ceftazidime; D001618:beta-Lactamases; C477889:TEM-91 beta-lactamase, E coli