Dissemination of blaOXA-23 harboring Carbapenem-Resistant Acinetobacter baumannii clones in Pakistan

Abstract Objective The rise of carbapenem resistance among Acinetobacter baumannii represents a challenge for the therapeutic management of infections. The present study aimed to investigate the sequence types and carbapenem resistance in A. baumannii strains collected from various clinical specimens from the patients admitted to tertiary care hospitals in Pakistan. Methods A total of 156 A. baumannii clinical strains were analyzed for antimicrobial susceptibility, followed by genetic screening for the carbapenem-resistant determinants. All the A. baumannii strains were typed using multilocus sequence typing by the Pasteur scheme. Results One thirty-nine of the 156 isolates (89.1%) were carbapenem-resistant and out of these 136 carried the blaOXA-23-like genes. Interestingly the sequence type (ST) 589 was the most common sequence type that was classified as clonal complex 1 (CC1). The ST2 was the second most common sequence type that corresponds to the clonal complex 2/92 (Pasteur scheme/oxford scheme), however, it was distributed in all the hospitals. Conclusion The diverse clones of carbapenem-resistant A. baumannii including the already reported STs as well as new STs carrying OXA-23 are mainly distributed in Pakistan. This is the first study that described the molecular epidemiology of widely disseminated A. baumannii in Pakistan. The findings will help to improve the knowledge of predominant sequence types and will be valuable for the deeper understanding of resistance mechanisms among various MLST types.