Detection of carbapenemase production in Enterobacterales by mCIM and eCIM: a tertiary care hospital study

Carbapenem-resistant Enterobacterales (CRE) pose a major healthcare challenge due to high resistance rates and limited treatment options. This study characterized carbapenemase production among CRE isolates using phenotypic methods-Modified Carbapenem Inactivation Method (mCIM) and EDTA-Carbapenem Inactivation Method (eCIM)-as genotypic methods have limitations like restricted gene targets and mutations.

This six-month study was conducted at Sher-i-Kashmir Institute of Medical Sciences (SKIMS). Samples including swabs, respiratory specimens, pus, body fluids, and blood were cultured on Blood Agar and MacConkey Agar (HiMedia, India). Enterobacterales were identified using conventional methods and screened for carbapenem resistance. CRE isolates underwent mCIM and eCIM testing per CLSI guidelines.

Among 471 Enterobacterales isolates tested, 160 (33.9%) were carbapenem-resistant. Of these, 97 (60.6%) were mCIM positive, indicating carbapenemase production. eCIM further identified 83 (85.5%) as metallo-beta-lactamase (MBL) producers and 14 (14.4%) as serine carbapenemase producers. CRE prevalence was higher in ICU settings and among males. Isolates showed high cephalosporin resistance, with multi-drug resistance (MDR) common in both MBL and serine carbapenemase producers.

The prevalence of CRE was found to be 33.9%. The findings underscore the critical need for continuous surveillance and stringent infection control measures to manage the spread of CRE in healthcare settings.