Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii blood culture isolates from three hospitals in Turkey

Abstract

We aimed to investigate the clonal relationships, common sequence types, and carbapenemase genes in 177 non-repetitive blood culture isolates of Acinetobacter baumannii collected from patients in three university hospitals in 2016. The molecular epidemiological characteristics of the isolates were examined with pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) (Pasteur scheme-cpn60, fusA, gltA, pyrG, recA, rplB, rpoB). Multiplex PCR was used for investigating the carbapenemase genes; including bla_OXA-23-like, bla_OXA-24-like, bla_OXA-48-like, bla_OXA-58-like, bla_IMP, bla_VIM, and bla_NDM. PFGE genotyping yielded 92 pulsotypes with a clustering ratio of 69.7%. According to a ≥85% similarity coefficient, 159 (90.9%) isolates were found to be clonally related. The bla_OXA-23-like and bla_OXA-58-like genes were identified in 100% and 28.2% of the isolates, respectively. The bla_NDM gene was identified in two isolates. The MLST analysis included 54 isolates with different pulsotypes and identified 29 sequence types (STs). Most of the isolates (n=36) belonged to the international clone II (CC2); one isolate belonged to CC1, and one isolate belonged to CC164. Sixteen new STs (ST1235-ST1250) were found. Identifying both global ST2 and also a high number of new STs revealed high-level genetic diversity in A. baumannii isolates in the study population.