| Acinetobacter baumannii is a gram-negative human pathogen causing a variety of diseases including pneumonia, meningitis, septicemia, urinary tract infection, and wound infection. Carbapenem antibiotics (imipenem and meropenem) have been primarily used to treat A. baurrannit infections. However, carbapenem resistant A. baumannii has been emerged in patients worldwide and has proved a challenge to treatment the infections. Carbapenem resistant A. baumannii harbors genes encoding OXA-type carbapenemases that confer resistance to all known p-lactam antibiotics. This study is aimed to characterize the molecular details of carbarenem resistance in A. baumannii. Clinical isolates of A. baumannii were collected from Downstate Medical Center (Brooklyn, NY; 6 isolates) and Texas Medical Center (Houston, TX; 17 isolates). The isolates were characterized by i) antibiotic susceptibility, ii) genotype analysis, iii) multilocus sequence t:ping (MLST), iv) detection of carbapenemase-encoding genes and v) the genetic structure surrounding the carbapenemase-encoding gene. The isolates from Downstate Medical Center exhibited 4 different genotypes (or 4 different sequence types) and all isolates from. Texas Medical Center exhibited a single genotype (or a single sequence type). PCR-based-cloning of lambda phage genomic library clones, and DNA sequencing analysis revealed that all carbapenem resistant isolates harbored carbapenemase-encoding gene (blaOXA-51) which was preceded by an insertion sequence element (lAbal). This gene cassette (IS Abal- blaOXA-51 was located between fxsA and yncA on the chromosome of A. baumannii. •... |
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