Detection of Metallo-β-lactamase producing Gram Negative Bacteria in clinical isolates in Tertiary care Hospital – A prospective study

ABSTRACT

Background: Carbapenem resistance in Gram Negative Bacilli is an emerging threat in tertiary care centers which is mediated by Metallo-β-lactamase (MBL) enzyme. As per the National committee for Clinical Laboratory Standards (NCCLS), still does not have documented standard procedure from there several screening methods to detect their enzyme. Some subcontinents of India still awaiting to see prevalence and screening methods to detect enzyme which is responsible for Carbapenem Resistance. Aim: The present study was undertaken to early detection of MBL by screening methods in Gram Negative Bacilli isolated from hospital and the prevalence MBL production in carbapenem resistant bacterial isolates. Materials and methods: 176 consecutive different Gram Negative Bacilli (GNB) isolated from hospitalized patients which were tested antimicrobial susceptibility for different antibiotics including Carbapenem drugs as Imipenem by Kirby Bauer Disc Diffusion (CLSI 2010) and screening of Metallo-β-lactamase production by method as Imipenem- EDTA combined disc synergy test (ICDST) and Imipenem-Double Disc Synergy Test (I-DDST) which determine the MBL by zone size enhancement with EDTA Impregnated Imipenem. Munesh Kumar Sharma, Dakshina Bisht, Shekhar Pal. Detection of Metallo-β-lactamase producing Gram Negative Bacteria in clinical isolates in Tertiary care Hospital - A prospective study. IAIM, 2019; 6(4) 107-111. Page 108 Results: Out of 176 Gram Negative Bacilli, 20.45% (n=36) of isolates were resistance to Imipenem by disc diffusion method and 94.44% (n=34) by DDST EDTA impregnated Imipenem and 88.89% (n=32) showed enhancement of zone size ≥7 mm with EDTA impregnated Imipenem CDST. Imipenem susceptible bacteria strains did not show any enhancement with EDTA impregnated antibiotic disc. Conclusion: Critically ill patient’s therapy is cause of concern for MBL mediated imipenem resistance gram Negative Bacilli. Two methods used for supplementary support in treatment of patients. In both methods of detection DDST is more effective.