Genetic and Biochemical Characterization of a Novel Metallo-beta-Lactamase, TMB-1, from an Achromobacter xylosoxidans Strain Isolated in Tripoli, Libya
ABSTRACT An Achromobacter xylosoxidans strain from the Tripoli central hospital produced a unique metallo-β-lactamase, designated TMB-1, which is related to DIM-1 (62%) and GIM-1 (51%). bla(TMB-1) was embedded in a class 1 integron and located on the chromosome. The TMB-1 β-lactamase has lower k(cat) values than both DIM-1 and GIM-1 with cephalosporins and carbapenems. The K(m) values were more similar to those of GIM-1 than those of DIM-1, with the overall k(cat)/K(m) values being lower than those for GIM-1 and DIM-1.
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ABSTRACT: Achromobacter xylosoxidans is an opportunistic pathogen known to be resistant to a wide range of antibiotics; however, the knowledge about the drug resistance mechanisms is limited. We used high-throughput sequencing approach to sequence the genomes of the A. xylosoxidans type strain ATCC 27061 and a clinical isolate A. xylosoxidans X02736, and then used different bioinformatic tools to analyze the drug resistance genes in these bacteria. We obtained the complete genome sequence for A. xylosoxidans ATCC 27061 and the draft sequence for X02736. We predicted a total of 50 drug resistance-associated genes in the type strain, including 5 β-lactamases and 17 efflux pump systems; these genes are also conserved among other A. xylosoxidans genomes. In the clinical isolate, except the conserved resistance genes, we also identified several acquired resistance genes carried by a new transposon embedded in a novel integrative and conjugative element. Our study provides new insights into the intrinsic and acquired drug resistance mechanisms in A. xylosoxidans, which will be helpful for better understanding the physiology of A. xylosoxidans and the evolution of antibiotic resistance in this bacterium. Copyright © 2014, American Society for Microbiology. All Rights Reserved.Antimicrobial Agents and Chemotherapy 12/2014; DOI:10.1128/AAC.04260-14 · 4.45 Impact Factor
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ABSTRACT: The aim of the present study was to investigate the molecular mechanism of carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii clinical isolates recovered from Libyan hospitals between April 2013 and April 2014. In total, 49 strains (24 P. aeruginosa and 25 A. baumannii) were isolated, including 21 P. aeruginosa and 22 A. baumannii isolates (87.75%) resistant to imipenem (minimum inhibitory concentrations ≥16 μg/ml). The blaVIM-2 gene was detected in 19 P. aeruginosa isolates. All imipenem-resistant P. aeruginosa isolates showed the presence of OprD mutations. Acquired OXA-carbapenemase-encoding genes were present in all A. baumannii isolates: blaOXA-23 (n=19) and blaOXA-24 (n=3). Finally, a total of 13 and 17 different sequence types were assigned to the 21 P. aeruginosa and the 22 A. baumannii carbapenem-resistant isolates, respectively. This study is the first report describing imipenem-resistant P. aeruginosa and A. baumannii isolated from patients in Libya. We report the first case of co-occurrence of blaVIM-2 with oprD porin loss in identical isolates of P. aeruginosa in Libya and demonstrate that these oprD mutations can be used as a tool to study the clonality in P. aeruginosa isolates. We also report the first identification of multidrug-resistant A. baumannii isolates harboring blaOXA-23-like, blaOXA-24-like, and blaOXA-48-like genes in Libya.Microbial Drug Resistance 01/2015; DOI:10.1089/mdr.2014.0235 · 2.52 Impact Factor
Emerging infectious diseases 09/2014; 20(9):1574-6. DOI:10.3201/eid2009.140117 · 7.33 Impact Factor