A study on carbapenemase producing Acinetobacter sp., and identification of OXA-51 gene in isolates from patients attending a tertiary care hospital

Abstract

Introduction: Acinetobacter sp., are Gram-negative non-fermenters that causes nosocomial infections. Multi drug resistance has been evolving very rapidly in Acinetobacter sp with also a dramatic increase in carbapenem resistance. Even though there are various mechanisms prevailing for such resistance, detection of Class D beta lactamases (oxacillinases) production is cumbersome. Accurate detection is done only by genotypic methods. Aims and objectives: In order to estimate the prevalence of Acinetobacter sp., its antimicrobial susceptibility pattern, the following study was conducted in a tertiary care hospital. Organisms resistant to Carbapenems were further tested for OXA-51 gene identification by polymerase chain reaction. Materials and Methods: All the study samples received during the study period were subjected to microbiological culture method and identification panel to isolate Acinetobacter sp., Antimicrobial susceptibility testing was done according to CLSI guidelines. Organisms that fit the criteria of multidrug resistant were further analysed for Carbapenem resistance by disc diffusion test and those isolates were subjected to polymerase chain reaction for identifying the presence of OXA-51 gene. Results: A total of 102 (4.8%) Acinetobacter sp., isolates were obtained from a total sample size of 2127 specimens during the study period. Over all, 60.78% of isolates were multidrug resistant (MDR) and 50.98% were imipenam (Carbapenem) resistant. All the imipenam resistant isolates were belonging to A.baumanii. A total of 52 isolates subjected to PCR showed positivity for OXA-51 gene. Conclusion: This warrants the need for genotyping for all of the Acinetobacter isolates to understand the gene variations in resistance and to know whether there is a universal presence of OXA-51 gene in all of the Acinetobacter baumannii.