Complete genome sequencing of Acinetobacter baumannii str. K50 disclosed the large conjugative plasmid pK50a encoding the carbapenemase OXA-23 and the extended-spectrum {beta}-lactamase GES-11 [PublishAheadOfPrint]

Multidrug-resistant (MDR) Acinetobacter baumannii strains appeared as serious emerging nosocomial pathogens in clinical environments and especially in intensive care units (ICUs). A. baumannii strain K50 recovered from a hospitalized patient in Kuwait exhibited resistance to carbapenems, and additionally to ciprofloxacin, chloramphenicol, sulfonamides, amikacin and gentamicin. Genome sequencing revealed that the strain possesses two plasmids, pK50a (79.6 kb) and pK50b (9.5 kb) and a 3.75 Mb chromosome. A. baumannii K50 exhibits an Average Nucleotide Identity (ANI) value of 99.98% to the previously reported Iraqi clinical isolate AA-014, even though that the latter strain lacked plasmid pK50a. Strain K50 belongs to the Sequence Type ST158 (Pasteur scheme) and ST499 according to the Oxford scheme. Plasmid pK50a is a member of the Aci6 (RG6) group of Acinetobacter plasmids, and encodes a conjugative transfer module and two antibiotic resistance gene regions comprising the transposon Tn2008. The transposon carries the carbapenemase gene bla_OXA-23 and a class 1 integron harboring the resistance genes bla_GES-11, aacA4, dfrA7, qacE1 and sul1 conferring resistance to all β-lactams and reduced susceptibility to carbapenems, resistance to aminoglycosides, trimethoprim, quaternary ammonium compounds and sulfamethoxazole, respectively. The class 1 integron is flanked by MITEs (Miniature Inverted repeat Transposable Element) delimiting the element at its insertion site.

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