Evaluation Of Phenotypic Methods For Detection Of Carbapenem Resistance In Isolates Of Pseudomonas Aeruginosa In A Tertiary Care Hospital

Abstract

Objective: To assess the effectiveness of Modified Hodge test (MHT) and Modified carbapenemase inactivation method (mCIM) for detection of carbapenemase enzyme produced by Pseudomonas aeruginosa strains that code for resistance towards carbapenem. Study Design and Setting: This observational cross sectional study was carried out from January 18 to January 19 in microbiology department of PNS SHIFA Karachi. Methodology: 140 isolates of Pseudomonas aeruginosa were cultured from pus samples of hospitalized patients from different wards like ENT, Surgery, Burn Unit, Plastic Surgery, ICU, Medicine, Pediatrics and family ward. These isolates were tested carbapenem resistance by two phenotypic methods namely MHT and mCIM test. This data was analyzed by using SPSS Version 23.0. Results: In our research study mCIM method showed 100% sensitivity, 99.1% specificity, positive predictive value 96.1% and negative predictive value 100% as compare to Modified Hodge Test which gave 77% sensitivity, 99.1% specificity, 95.2% PPV and 100% NPV. Conclusion: mCIM test is simple, accurate and more reliable method for detection of carbapenemase production as compared with MHT. It is recommended, cabapenemase producing isolates should be tested as a routine practice by all clinical labs laboratory.

Evaluation of the Relative Frequency of Carbapenemase Genes by Phenotypic and Genotypic Methods in Pseudomonas aeruginosa Isolates from Patients with Open Heart Surgery in Iran

“…mCIM (modified carbapenem inactivation method) test: In addition to the above-mentioned phenotypic methods, the mCIM phenotypic test was performed to evaluate the production of carbapenemase enzymes in P. aeruginosa isolates that were resistant to imipenem and meropenem based on the three methods of disk diffusion, Phoenix (broth microdilution method), and E-test. This test was performed according to the instructions described by Bakhat et al (2019) [20] . A growth inhibition zone diameter of 6-15 mm is considered as positive, 15-19 mm as intermediate, and >19 mm as negative (i.e., no carbapenemase is detected).…”