High-level resistance to ceftazidime conferred by a novel enzyme, CTX-M-32, derived from CTX-M-1 through a single Asp240-Gly substitution.
نویسندگان
چکیده
A clinical strain of Escherichia coli isolated from pleural liquid with high levels of resistance to cefotaxime, ceftazidime, and aztreonam harbors a novel CTX-M gene (bla(CTX-M-32)) whose amino acid sequence differs from that of CTX-M-1 by a single Asp240-Gly substitution. Moreover, by site-directed mutagenesis we demonstrated that this replacement is a key event in ceftazidime hydrolysis
منابع مشابه
Effect of D240G substitution in a novel ESBL CTX-M-27.
Escherichia coli clinical strain Gre-1 collected in 2000 from a French hospital harboured a novel CTX-M-encoding gene, designated blaCTX-M-27. CTX-M-27 differed from CTX-M-14 only by the substitution D240G and was the third CTX-M enzyme harbouring this mutation after CTX-M-15 and CTX-M-16. The Gly-240-harbouring enzyme CTX-M-27 conferred to E. coli higher MICs of ceftazidime (MIC, 8 versus 1 mg...
متن کاملAtomic resolution structures of CTX-M beta-lactamases: extended spectrum activities from increased mobility and decreased stability.
Extended spectrum beta-lactamases (ESBLs) confer bacterial resistance to third-generation cephalosporins, such as cefotaxime and ceftazidime, increasing hospital mortality rates. Whereas these antibiotics are almost impervious to classic beta-lactamases, such as TEM-1, ESBLs have one to four orders greater activity against them. The origins of this activity have been widely studied for the TEM ...
متن کاملNovel chimeric beta-lactamase CTX-M-64, a hybrid of CTX-M-15-like and CTX-M-14 beta-lactamases, found in a Shigella sonnei strain resistant to various oxyimino-cephalosporins, including ceftazidime.
The plasmid-mediated novel beta-lactamase CTX-M-64 was first identified in Shigella sonnei strain UIH-1, which exhibited resistance to cefotaxime (MIC, 1,024 microg/ml) and ceftazidime (MIC, 32 microg/ml). The amino acid sequence of CTX-M-64 showed a chimeric structure of a CTX-M-15-like beta-lactamase (N- and C-terminal moieties) and a CTX-M-14-like beta-lactamase (central portion, amino acids...
متن کاملHigh Prevalence of CTXM-15 Type Extended-Spectrum Beta-Lactamase Among Clinical Isolates of Klebsiella Pneumoniae
Background: Production of β–lactamases by enterobacteriacea, especially Klebsiella pneumoniae, is one of the emerging health problems in the world. The purpose of this study was to assess the frequency of blaCTX-M15 gene in K. pneumoniae isolates and determine the molecular diversity of CTXM producing isolates. Methods: In...
متن کاملA novel ceftazidime-hydrolysing extended-spectrum beta-lactamase, CTX-M-54, with a single amino acid substitution at position 167 in the omega loop.
OBJECTIVES To characterize a novel ceftazidime-hydrolysing CTX-M mutant, designated CTX-M-54, produced by Klebsiella pneumoniae clinical isolate BDK0419 and to investigate its genetic environment. METHODS Antimicrobial susceptibilities were determined by disc diffusion and agar dilution methods, and the double-disc synergy test was carried out. Detection of genes encoding class A beta-lactama...
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ورودعنوان ژورنال:
- Antimicrobial agents and chemotherapy
دوره 48 6 شماره
صفحات -
تاریخ انتشار 2004