Distinct Genetic Diversity of Carbapenem-Resistant Acinetobacter baumannii from Colombian Hospitals

The global success of multidrug-resistant Acinetobacter baumannii has been associated with the dissemination of a high-risk clone designated clonal complex (CC) 92^B (Bartual scheme)/CC2^P (Pasteur scheme), which is the most frequent genetic lineage in European, Asian, and North American carbapenem-resistant Acinetobacter isolates. In these isolates, carbapenem resistance is mainly mediated by β-lactamases encoded by bla_OXA-23-like, bla_OXA-24-like, bla_OXA-51-like, and/or bla_OXA-58-like genes. In this study, we characterized the population genetics of 121 carbapenem-resistant A. baumannii complex isolates recovered from 14 hospitals in seven cities in Colombia (2008-2010). Multiplex PCR was used to detect bla_OXA-23-like, bla_OXA-24-like, bla_OXA-51-like, and bla_OXA-58-like genes. Molecular typing was performed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). PCR showed that 118 (97.5%) of the isolates were positive for both bla_OXA-23-like and bla_OXA-51-like genes, and three other isolates were only positive for bla_OXA-51-like. PFGE identified 18 different pulsotypes, while MLST identified 11 different sequence types (STs), seven of which had not been previously described in Acinetobacter. None of the STs found in this study was associated with CC92^B/CC2^P. The most widespread STs in our isolates belonged to ST636 and their single-locus variants ST121/ST124/ST634 (CC636^B) followed by STs belonging to CC110^B. Our observations suggest a wide distribution of diverse A. baumannii complex clones containing bla_OXA-23-like in Colombian hospitals (especially CC636^B and CC110^B) that differ from the high-risk clones commonly found in other regions of the world, indicating a distinct molecular epidemiology of carbapenem-resistant Acinetobacter spp. in Colombia.