Dataset Information

Genetic and biochemical characterization of the first extended-spectrum CARB-type beta-lactamase, RTG-4, from Acinetobacter baumannii.

ABSTRACT: Acinetobacter baumannii isolate KAR was uncommonly more resistant to cefepime and cefpirome than to ceftazidime and cefotaxime. Cloning and expression of the beta-lactamase gene content of this isolate into Escherichia coli TOP10 identified ss-lactamase RTG-4 (or CARB-10), which corresponds to the first reported extended-spectrum CARB-type enzyme. RTG-4 is a plasmid-encoded Ambler class A beta-lactamase whose sequence differs by 4 amino acid substitutions from the narrow-spectrum beta-lactamase RTG-3. RTG-4 hydrolyzes cefepime and cefpirome and weakly hydrolyzes ceftazidime due to the single Ser-to-Thr substitution at Ambler position 69. RTG-4 is less susceptible to inhibition by tazobactam and sulbactam than RTG-3. Expression of beta-lactamase RTG-4 in a wild-type A. baumannii reference strain showed that it conferred resistance to cefepime and cefpirome. The genetic environment of the bla(RTG-4) gene was made of a peculiar transposon located on a ca. 50-kb plasmid. ISAba9, located upstream of bla(RTG-4), may be responsible for its acquisition by recognizing a secondary right inverted repeat sequence, thus acting by a one-ended transposition process.

SUBMITTER: Potron A

PROVIDER: S-EPMC2704689 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Genetic and biochemical characterization of the first extended-spectrum CARB-type beta-lactamase, RTG-4, from Acinetobacter baumannii.

Potron Anaïs A Poirel Laurent L Croizé Jacques J Chanteperdrix Vanessa V Nordmann Patrice P

Antimicrobial agents and chemotherapy 20090420 7

Acinetobacter baumannii isolate KAR was uncommonly more resistant to cefepime and cefpirome than to ceftazidime and cefotaxime. Cloning and expression of the beta-lactamase gene content of this isolate into Escherichia coli TOP10 identified ss-lactamase RTG-4 (or CARB-10), which corresponds to the first reported extended-spectrum CARB-type enzyme. RTG-4 is a plasmid-encoded Ambler class A beta-lactamase whose sequence differs by 4 amino acid substitutions from the narrow-spectrum beta-lactamase ...[more]

PMID: 19380596

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Project description:Pathogens frequently associated with multi-drug resistant (MDR) phenotypes, including extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and Acinetobacter baumannii isolated from horses admitted to horse clinics, pose a risk for animal patients and personnel in horse clinics. To estimate current rates of colonization, a total of 341 equine patients were screened for carriage of zoonotic indicator pathogens at hospital admission. Horses showing clinical signs associated with colic (n = 233) or open wounds (n = 108) were selected for microbiological examination of nostril swabs, faecal samples and wound swabs taken from the open wound group. The results showed alarming carriage rates of Gram-negative MDR pathogens in equine patients: 10.7% (34 of 318) of validated faecal specimens were positive for ESBL-E (94%: ESBL-producing Escherichia coli), with recorded rates of 10.5% for the colic and 11% for the open wound group. 92.7% of the ESBL-producing E. coli were phenotypically resistant to three or more classes of antimicrobials. A. baumannii was rarely detected (0.9%), and all faecal samples investigated were negative for Salmonella, both directly and after two enrichment steps. Screening results for the equine nostril swabs showed detection rates for ESBL-E of 3.4% among colic patients and 0.9% in the open wound group, with an average rate of 2.6% (9/340) for both indications. For all 41 ESBL-producing E. coli isolated, a broad heterogeneity was revealed using pulsed-field gel electrophoresis (PFGE) patterns and whole genome sequencing (WGS) -analysis. However, a predominance of sequence type complex (STC)10 and STC1250 was observed, including several novel STs. The most common genes associated with ESBL-production were identified as blaCTX-M-1 (31/41; 75.6%) and blaSHV-12 (24.4%). The results of this study reveal a disturbingly large fraction of multi-drug resistant and ESBL-producing E. coli among equine patients, posing a clear threat to established hygiene management systems and work-place safety of veterinary staff in horse clinics.

Dataset Information

Genetic and biochemical characterization of the first extended-spectrum CARB-type beta-lactamase, RTG-4, from Acinetobacter baumannii.

Publications

Genetic and biochemical characterization of the first extended-spectrum CARB-type beta-lactamase, RTG-4, from Acinetobacter baumannii.

Similar Datasets

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