Genotypic Characterisation of Carbapenemases in Clinical Isolates of Acinetobacter baumannii in a Tertiary Care Teaching Hospital of Kerala

Lakshmi K  Sathyanesan; Rosmi Jose; Chithra Valsan; Liji Maria Joy

doi:10.18502/jmb.v12i3.16608

Lakshmi K Sathyanesan Department of Microbiology, Jubilee Mission Medical College, Thrissur, Kerala, India.
Rosmi Jose Department of Microbiology, Jubilee Mission Medical College, Thrissur, Kerala, India.
Chithra Valsan Department of Microbiology, Jubilee Mission Medical College, Thrissur, Kerala, India.
Liji Maria Joy Department of Microbiology, Jubilee Mission Medical College, Thrissur, Kerala, India.

DOI: https://doi.org/10.18502/jmb.v12i3.16608

Keywords: Acinetobacter baumannii, Carbapenemases, India, Kerala, OXA-derived Metallo-beta-lactamases.

Abstract

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.