Molecular detection of blaNDM and blaOXA-48 genes in Carbapenem-Resistant Klebsiella pneumoniae isolates from a tertiary care hospital

Abstract

BackgroundThe incidence of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections is increasing globally. In India, around 65% of K. pneumoniae isolates are resistant to carbapenem antibiotics. The blaNDM is the predominant carbapenem-resistant gene in CRKP isolates. However, blaOXA-48 has also been reported to be increasing in recent days. MethodsK. pneumoniae strains isolated from the clinical specimens of patients attending a tertiary care hospital in Hyderabad from June 2021 to May 2022 were included in this study. Resistance to carbapenems and other antibiotics was screened using Kirby-Bauer’s disc diffusion method. Phenotypic tests such as the Carbapenemase Nordmann Poirel (CarbaNP) test, Modified Carbapenem Inactivation Method (mCIM), and EDTA Carbapenem Inactivation Method (eCIM) were used to detect the carbapenemase producers. The genes responsible for carbapenemase production were detected by the real-time polymerase chain reaction (RT-PCR) method. ResultsOut of 1265 K. pneumoniae strains isolated, 241 (19 %) isolates showed resistance to any one of the carbapenem antibiotics tested. Phenotypic tests such as CarbaNP, mCIM, and eCIM revealed that 94.6 %, 97.1 %, and 95.4 % of CRKP isolates were carbapenemase producers, respectively. About 66.4 % of CRKP isolates harbored blaNDM, 17.4 % harbored blaOXA-48, and 16.2 % harbored both blaNDM and OXA-48 genes. None of the isolates tested positive for blaKPC, blaVIM, and blaIMP genes. ConclusionIn this study, blaNDM is the most prevalent carbapenemase gene in CRKP isolates. Furthermore, blaOXA-48 and the co-existence of both blaNDM and blaOXA-48 genes were also found. CRKP is emerging as a serious threat among drug-resistant bacterial pathogens which would complicate the treatment of bacterial infections with available antibiotics.