genotypic characterisation of carbapenemases in clinical isolates of acinetobacter baumannii in a tertiary care teaching hospital of kerala

Background: the multidrug-resistant and carbapenem-resistant acinetobacter baumannii strains are an increasing global concern. the primary cause of carbapenem resistance in a. baumannii is production of various beta-lactamases with versatile hydrolytic capacities. the present study investigates the prevalence of different carbapenemases among clinical isolates of carbapenem-resistant a. baumannii from a tertiary care teaching hospital in kerala, india.methods: non-duplicate isolates from sputum, endotracheal aspirate, pus, urine, and blood samples were included in the study. isolate identification and antibiotic susceptibility testing of the isolates were done using vitek 2 system. a conventional polymerase chain reaction was used to detect the carbapenemase-encoding genes in the isolates. results: a total of the 126 isolates studied, among these 105 (83.3%) isolates were from intensive care unit patients and 21(16.6%) were from non-icu inpatients. most of the isolates were obtained from respiratory specimens-78(61.9%) followed by pus-33(26.2%), urine-12(9.5%) and blood- 3(2.4%). the prevalence of carbapenemase genes were as follows:blaoxa-51(n=126, 100%) blaoxa-23 (n=98, 77.7%), blaoxa-58 (n=7, 5.6%), blandm (n=66, 52.4%), blaimp (n=26, 20.6%), and blavim (n=20, 15.9%). among the total isolates 78 (61.9%) isolates harbored metallo-beta-lactamase genes, 47(37.3%) isolates harboured a single carbapenemase gene, while 69(54.8%) isolates harbored two or more genes. conclusion: this study reveals a higher prevalence of metallo-beta lactamases and the co-occurrence of multiple carbapenemase genes in carbapenem resistant a. baumannii isolates.