Phenotypic evaluation of different methods for the detection of Metallo-Beta-Lactamases in Pseudomonas aeruginosa

Pseudomonas aeruginosa is known to cause wide range of infections. It exhibits resistance to several antimicrobial agents and produces ß-lactamases, which are responsible for the widespread ß-lactam resistance. In the present study, 41 isolates of Pseudomonas aeruginosa were obtained from various clinical specimens like pus, urine, stool and wounds. 13/41 (32%) Pseudomonas aeruginosa isolates were found to be positive for the production of ESBL by disc diffusion method. 9/41 (22%) Pseudomonas aeruginosa isolates were found to be positive for the production of metallo-β-lactamases. All the 9 isolates were subjected for the detection of metallo-β-lactamases by different methods. Imipenem (IMP)- EDTA combined disc test detected 4(45%) compared to EDTA disc potentiation using Ceftazidime, Ceftizoxime and Cefotaxime which detected 3(33%), and Imipenem (IMP)- EDTA double disc synergy test detected 2(22%) of MBL producing P.aeruginosa and hence IMP-EDTA CDT was a better method compared to other methods used in the study to detect MBL producers.