Molecular epidemiology of carbapenem and colistin resistant Acinetobacter baumanii

Abstract Introduction- Acinetobacter baumanii (AB) is a bacterium of concern in the hospital set up due to its ability to thrive in unfavorable conditions as well as rapid emergence of antibiotic resistance. Carbapenem resistance in this organism is disheartening which is further clouded by emergence of colistin resistance. Aim- The present prospective study aims to note the epidemiology, molecular profile, and clinical outcome of patients with colistin resistance ABinfections in a multispecialty tertiary care set up in Odisha in Eastern India. Methods- All AB strains received from March 2021 to February 2022 as identified by Vitek2, Biomerieux and confirmed by oxa-51 genes were included. Carbapenem and colistin resistance was identified as per CLSI guidelines. Known mutations for blaOXA-23-like, blaIMP, blaVIM, blaKP, lpxA, lpxC, pmrA, pmrB and plasmid mediated mcr (mcr1-5) were screened by conventional PCR techniques. The clinical outcome was noted retrospectively from case sheets. Data was entered in excel and tabulated using SPSS software. Results - In the study period, 350 AB were obtained of which 317(90.5%) were carbapenem resistant (CRAB). Among the CRAB isolates 19 (5.9%) were colistin resistant (CR). Most useful antibiotics in the study were tigecycline (65.4% in CI; 31.6% in CR) and minocycline (44.3% in CI; 36.8% in CR). There was significant difference in mortality among ABCoI and ABCoR infections.bla OXA was the predominant cerbapenem resistance genotype while pmrA was the predominant colistin resistant genotype. There were no plasmid mediated mcr genes detected in the present study.