Carbapenemase producing pseudomonas aeruginosa: A cause of concern

Background: Pseudomonas aeruginosa is one of the most important cause of Healthcare associated infections. Carbapenems are often used as a last resort for treating serious infections caused by multidrug resistant Pseudomonas aeruginosa. Carbapenamases are β-lactamases which cause carbapenem hydrolysis. Aim: The present study was undertaken to detect the incidence of Carbapenemase producing Pseudomonas aeruginosa from clinical isolates. Material and Methods: 150 clinical isolates of Pseudomonas aeruginosa were studied for antibiotic susceptibility profile by Kirby Bauer disk diffusion method as per CLSI guidelines, 2016. All Pseudomonas aeruginosa strains were screened for Carbapenemase activity by Classical Hodge test. Metallobetalactamases (MBL) production was detected and confirmed by Disc potentiation (DP) test using Imipenem and Imipenem plus EDTA and by E-test. Klebsiella pneumoniae Carbapenemases (KPC) production was detected by combine disc method using Imipenem and imipenem plus Phenyl boronic acid (PBA). Both MBL and KPC producing strains were detected by Imipenem disc and disc containing Imipenem plus PBA plus EDTA. Class D carbapenemase i.e, OXA β– lactamases were not included in our study. Results: The highest sensitivity was observed to Colistin 149(99.3 %), followed by Imipenem 107(71.3%). 43(28.7%) Pseudomonas aeruginosa strains were Classical Hodge test positive, 6(4%) were positive for MBL only by DP test. 15(10 %) were positive for KPC only and 34 (22.6 %) were positive for both MBL and KPC. These 40 MBL producing strains were positive by MBL E test. Conclusion: All Pseudomonas aeruginosa strains must be screened for carbapenamase production in Cinical Microbiology laboratory.