A hospital-based epidemiological study of the genes coding for carbapenemase production among carbapenem resistant Acinetobacter isolates in India.

Worldwide, Acinetobacter species is a multidrug-resistant (MDR) nosocomial pathogen capable of acquiring or upregulating resistant determinants thereby effecting drug efficacy. Resistance to Carbapenems causes high morbidity and mortality. The study aims to know prevalence of carbapenemase producing genes in Acinetobacter spp., and understand the local epidemiology of carbapenem-resistant Acinetobacter spp. in a tertiary care hospital in India. Carbapenem-resistant Acinetobacter isolates from clinical samples were analysed to identify the resistance mechanism to carbapenem drugs viz. ertapenem, meropenem and doripenem. The Multiple antibiotic resistance (MAR) index with reference to Carbapenems was calculated. Quantitative PCR was performed to investigate prevalence of antimicrobial resistance encoding bla genes (NDM, VIM, KPC, OXA-23, OXA-48, OXA-58, OXA-51). The frequency and prevalence of the different genes in various health care area of the hospital was identified. Seventeen (41.46 %) Acinetobacter isolates were multidrug-resistant (MDR) isolates and nine (21.95 %) were extensively drug-resistant (XDR) to carbapenem drugs. Twenty-two (53.65 %) isolates were from the intensive care unit. Majority of the Acinetobacter isolates with Multiple Antibiotic Resistance (MAR) indices greater than 0.2 were isolated from patients admitted to the intensive care unit. The frequencies of distribution of antimicrobial resistance genes for blaNDM and blaOXA-23 like were 84.62 % respectively; blaOXA-51 like was 76.92 %; blaVIM 73.08 % and blaOXA-48 like was 61.54 %. Many antibiotic-resistant genes were found co-existent in multiple isolates. No pan drug resistant strain was detected. The major carbapenemase genetic determinants circulating especially in the hospital intensive care unit during the period of the study were blaNDM, blaOXA-23 like, blaOXA-51 like and blaVIM.