A Study on Phenotypic Characterization of Carbapenemases among Gram Negative Bacilli in a Tertiary Care Hospital

Abstract

Introduction: The emerging resistance to Carbapenems which are generally considered as life saving drugs to treat infections caused by ESBL and AmpC producing bacteria, has become a serious issue worldwide. It is therefore necessary to detect Carbapenemases to limit the spread of multidrug resistant organisms for effective Antibiotic surveillance and Infection Control in the Hospital. Aim & Objectives: To detect the presence of MBL, KPC Carbapenemase and their Co-Existence among the Carbapenem resistant clinical isolates of Gram Negative Bacilli Materials & Methods: The present study was carried out in a Tertiary care hospital; to detect Carbapenamases among Gram Negative Bacilli by Inhibitor based combined Disc tests in which Phenylboronic Acid and Dipicolinic acid are incorporated onto Meropenem discs. Results: A Total of 718 strains of Gram Negative Bacilli comprising of 516 strains of Enterobacteriaceae and 202 Non-fermenters were included in the study. Out of these 718 strains, 89 strains were resistant to carbapenems, of which 2.5% (18 /718) were KPC (Klebsiella Pneumoniae Carbapenemase –class A) producers, 8.08%(58/718) were MBL (Metallo Beta Lactamases-class B) producers .Co-existence of MBL and KPC was observed in 1.25% (9 /718) of isolates and no mechanism was detected in 4 isolates. Conclusion: Inhibitor based combined disc test is simple and cost effective phenotypic test for detecting Carbapenem resistance in the Laboratory. Antibiotic stewardship programme has to be implemented in Hospital to achieve good Infection control for better patient outcome and reduce the health care costs.