Dissemination of blaOXA-23-harbouring carbapenem-resistant Acinetobacter baumannii clones in Pakistan

Abstract

Objectives: The rise of carbapenem resistance in Acinetobacter baumannii represents a challenge for the therapeutic management of infections. The present study aimed to investigate the sequence types (STs) and carbapenem resistance in A. baumannii strains collected from various clinical specimens from patients admitted to five tertiary-care hospitals in Pakistan.

Methods: A total of 156 A. baumannii clinical strains were analysed for antimicrobial susceptibility, followed by genetic screening for carbapenem resistance determinants. All of the strains were typed by multilocus sequence typing (MLST) according to the Pasteur scheme.

Results: Of the 156 A. baumannii isolates, 139 (89.1%) were carbapenem-resistant, of which 136 carried bla_OXA-23-like genes. Interestingly, the most commonly identified ST was ST589 (n = 52), classified as clonal complex 1 (CC1). ST2 was the second most common (n = 38), corresponding to CC2/92 (Pasteur/Oxford scheme), which was distributed in all five hospitals.

Conclusion: Diverse clones of carbapenem-resistant A. baumannii, including previously reported STs as well as new STs, carrying bla_OXA-23 are distributed in Pakistan. This is the first study to describe the molecular epidemiology of widely disseminated A. baumannii isolates in Pakistan. The findings will help to improve our knowledge of the predominant STs and will be valuable for a deeper understanding of resistance mechanisms among various STs.

Keywords: Acinetobacter; Carbapenem-resistant; MLST; Sequence type; bla(OXA-23).