Phenotypic and Molecular Detection of BlaNDM Gene Among Drug-Resistant Klebsiella Isolates.

Background: In the past few centuries, a widespread increase in antimicrobial resistance has been observed among Klebsiella species. The antibiotic- resistant strains of the genus Klebsiella are becoming a serious threat in clinical settings due to their involvement in severe invasive and non-invasive infections. The emergence of resistance among these strains is associated with their strong enzymatic activity against several broad-spectrum antibiotics. These enzymes include beta-lactamases, extended-spectrum beta-lactamases (ESBL), AmpC beta-lactamases, and carbapenemases. These resistance enzymes are capable of hydrolyzing various broad-spectrum drugs like extended-spectrum cephalosporin and carbapenems.

Objective: The present study was conducted to determine the emerging resistance among Klebsiella strains by identifying the production of carbapenemase enzyme phenotypically and the frequency of the NDM resistance gene by a polymerase chain reaction.

Methods: In this study, 236 Gram-negative isolates from different clinical laboratories were identified. Out of which, 125 isolates were found as Klebsiella species by using standard microbiological techniques. Minimum inhibitory concentrations (MIC) were determined using eight representative antibiotics by the Macro broth dilution method. Phenotypic detection of carbapenemase producing Klebsiella species was performed by Modified Hodge Test. Phenotypic findings were then checked and compared with genotypic results obtained by using the Polymerase chain reaction (PCR) for the detection of resistance genes responsible for the production of carbapenemase.

Results: In this study, carbapenemase production was found only in 6 (5%) Klebsiella isolates by using the phenotypic method; however, 3 isolates out of 125 were screened positive for the gene NDM-1.

Conclusion: Since we are considering carbapenems as the last therapeutic option for treating infections, mainly caused by Gram-negative isolates, the prevailing resistance against this drug is widely disseminating. It is better to evaluate the antibiotic susceptibility, phenotypic screening as well genotypic screening (where possible) for implementing strict antibiotic control policies in health care settings, hospitals, laboratories, etc.