Modified Carbapenem Inactivation Method and Ethylenediaminetetraacetic Acid (EDTA)-Carbapenem Inactivation Method for Detection of Carbapenemase-Producing Enterobacterales and Pseudomonas aeruginosa.

Introduction: The rising incidence of carbapenem resistance in Enterobacterales and is a concern. Since carbapenemase production is the primary resistance mechanism, detecting and identifying the genes responsible for it is crucial to effectively monitor its spread.

Objective: This study aims to detect positivity for the modified carbapenem inactivation method (mCIM) and ethylenediaminetetraacetic acid (EDTA)-carbapenem inactivation method (eCIM) for the detection of carbapenemase-producing Enterobacterales and .

Methods: Methods: A cross-sectional study was carried out at a tertiary care hospital, including 250 clinical isolates of Enterobacterales and . These isolates exhibited resistance to at least one of the carbapenems as determined by the VITEK AST 2 System (bioMérieux, USA). The isolates were subjected to mCIM testing, and those that tested positive were further tested using eCIM. The results were interpreted in accordance with the guidelines provided by the Clinical and Laboratory Standards Institute (CLSI) 2023.

Results: Out of the total 250 carbapenem-resistant Enterobacterales and isolates, 151 (60.4%) were 44 (17.6%) were 10 (4.0%) were , 6 (2.4%) were ., 4 (1.6%) were , 4 (1.6%) were and 31 (12.4%) were . Positivity for the mCIM was observed in 96% (240 out of 250) of the isolates. Of the mCIM-positive isolates, 234 (97.5%) also tested positive for eCIM, indicating metallo-β-Lactamase (MLB) production. A statistically significant association was found between both mCIM and eCIM positivity and the degree of resistance to carbapenem (p<0.05) Conclusion: This study shows that the inexpensive method, a combination of mCIM and eCIM assists in differentiating between serine carbapenemase producers and MLB producers, thereby guiding the selection of appropriate therapy and useful in infection control in resource-limited settings.