Detection of Carbapenemase Producing Enterobacteriaceae using the Modified Carbapenem Inactivation Method

Abstract

Background: Carbapenem resistant Enterobacteriaceae (CRE) have been reported worldwide. Resistance to carbapenems in Enterobacteriaceae is caused mainly by carbapenemase production or by porin loss combined with the expression of beta (β)lactamases like extended-spectrum β-lactamases (ESBL) or ampicillin class C (AmpC). Objectives are to determine the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) among 202 clinical isolates of Enterobacteriaceae by the phenotypic test the modified carbapenem inactivation method (mCIM). Methodology: Initial screening for carbapenemase-producing isolates among the 202 Enterobacteriaceae isolates was done by minimum inhibitory concentration (MIC) determination for ertapenem by broth microdilution method. Confirmation of carbapenemase production among ertapenem-resistant isolates was done by the phenotypic test mCIM. Results:The prevalence of CRE by broth microdilution method was 36.1% and the prevalence of CPE among resistant isolates was 80.8% by mCIM. Conclusion:The mCIM is inexpensive, easy to perform, requires no specific reagents or media. It could be performed to detect CPE in Enterobacteriaceae that are nonsusceptible to one or more carbapenems.