Molecular epidemiology of extensively-drug resistant Acinetobacter baumannii sequence type 2 co-harboring bla (NDM) and bla (OXA) from clinical origin.

Background
The therapeutic management of carbapenem-resistant Acinetobacter baumannii (CR-AB) represents a serious challenge to the public health sector because these pathogens are resistant to a wide range of antibiotics, resulting in limited treatment options. The present study was planned to investigate the clonal spread of CR-AB in a clinical setting.

Methodology
A total of 174 A. baumannii clinical isolates were collected from a tertiary care hospitals in Lahore, Pakistan. The isolates were confirmed by VITEK 2 compact system and molecular identification of recA and blaOXA-51. Antimicrobial profile and the screening of carbapenem-resistant genes were carried out using VITEK 2 system and PCR, respectively. The molecular typing of the isolates was performed according to the Pasteur scheme.

Results
Of the 174 A. baumannii isolates collected, the majority were isolated from sputum samples (46.5%) and in the intensive care unit (ICU, 75%). Among these, 113/174 (64.9%) were identified as CR-AB, and 49.5% and 24.7% harbored blaOXA-23 and blaNDM-1, respectively. A total of 11 (9.7%) isolates co-harbored blaOXA-51, blaNDM-1, and blaOXA-23. Interestingly, 46.9% of the CR-AB belonged to sequence type 2 (ST2; CC1), whereas 15.9% belonged to ST1 (CC1). All of the CR-AB isolates showed extensive resistance to clinically relevant antibiotics, except colistin.

Conclusion
The study concluded CR-AB ST2 clone harboring blaOXA-23 and blaNDM-1 are widely distributed in Pakistan’s clinical settings, which could result in increased mortality. Strict compliance with the National Action Plan on Antimicrobial Resistance is necessary to reduce the impacts of these strains.