Prevalence of metallo beta lactamase in clinical isolates of pseudomonas aeruginosa in a tertiary care hospital.

ABSTRACT

Background: Increasing Carbapenem resistance in Pseudomonas aeruginosa is an emerging threat and a matter of particular concern. Aim: Our study was conducted to find out the prevalence of Metallo beta lactamase producing Pseudomonas aeruginosa and compare various phenotypic MBL detection methods. Methods: A prospective study was conducted on 86 non duplicate Pseudomonas aeruginosa strains isolated from clinical specimens for a period of 2 year from April 2011 to march 2013. Total 86 isolates of Pseudomonas aeruginosa were included in the study. All clinical samples were processed according to standard microbiological method. The MIC for Imipenem and Meropenem were determined by broth dilution method. As per CLSI any isolate having an MIC of >8μg/ml was considered resistant.42 isolates were both or either resistant to IMP and MRP. These 42 isolates were tested for MBL production by (a) IMP EDTA E test (17 MBL positive isolate detected), (b) IMP & IMP EDTA disc diffusion test (17 MBL positive isolate detected), (c) IMP & EDTA double disc synergy test (14 MBL positive isolate detected). Results: 48.84% isolates were resistant to Carbapenem and 19.76% isolates were found to be MBL producer. Colistin showed 100% susceptibility in all the MBL positive isolates. Conclusions: Among the 3 test done IMP & IMP EDTA test is easy to perform, cost effective and as sensitive as E test. Our results strongly suggest that for the MBL isolates should be detected on routine basis and the antibiotic prescribed accordingly.