A single step carbapenem inactivation method for the detection of carbapenemases in carbapenem resistant escherichia coli and klebsiella pneumoniae.

The carbapenem resistance is gradually increasing particularly among Enterobacteriales isolated from patients admitted to the ICUs. Therefore a simple, convenient and accurate method for early detection of resistant isolates is essential to curtail rapid dissemination among the patients. The present study aimed to perform the newer single step carbapenem inactivation method (ssCIM) for the detection of carbapenemase production in carbepenem resistant Escherichia coli and Klebsiella pneumoniae and compared with modified CIM (mCIM) and polymerase chain reaction. The ssCIM test was performed according to Jing et al. The mCIM was performed according to CLSI- 2021 guidelines. A total of 160 carbapenem resistant E.coli and K.pneumoniae were tested for carbapenemase production by ssCIM and mCIM. The MIC of imipenem ranges between 4 mg/L and16 mg/L. Out of 160 CREK 86 were E.coli and 74 were K.pneumoniae. Among E.coli 84/86 (97%) and 69/74(93%) K.pneumoniae isolates tested positive for carbapenemase production by mCIM and ssCIM. In total 153/160(95.6%) CREK isolates were positive by phenotypic tests. A total of 152/160 (95%)isolates were positive for the presence of carpenemase genes. The results of ssCIM are in concordance with mCIM including one false positive result. The overall sensitivity and specificity of ssCIM with PCR was 100% and 87.5% respectively. The ssCIM is a less laborious, more convenient, and reliable method for detection of carbapenamase production among carbapenem resistant bacteria.