Original Research Article Prevalence of Metallo-β-Lactamase Producers among Selected Isolates in A Tertiary Care Teaching Hospital

Background: The emergence of metallo-beta-lactamase ( MBL) producing isolates is a challenge to routine microbiology laboratories, since there are no standardized methods for detecting them. Aim: To study the prevalence of MBL producing Gram negative bacteria and non-fermenters and compare and evaluate the use of two phenotypic methods, double-disk synergy test ( DDST) and a combination disk diffusion test ( CDDT) method from various clinical samples. Materials & Methods: A prospective study was done to test for MBL production by DDST and CDDT from select isolates that were Carbapenem and Ceftazidime resistant by Kirby Bauer disc diffusion test. Results: Of the 108 isolates 48 (44.4%) were resistant to Imipenem or Meropenem or both and among them 14 (29.1 %) were metallo-beta- lactamase producers. Of the MBL producers, Acinetobacter species 5 ( 35.7 % ) was the most common followed by Pseudomonas aeruginosa 4 ( 28.5 %), Klebsiella pneumonia 3 ( 21.4 % ) and E. coli 2 ( 14.2 %).DDST was found to be a technically easier screening method over CDDT method of evaluation. Conclusion: Routine screening by DDST of isolates for MBL production should form an integral part of solving therapeutic failures, longer hospital stay and significant morbidity and mortality seen with thes