Detection of carbapenemase production by blood culture carbapenem inactivation method (bcCIM) compared to modified carbapenem inactivation method (mCIM) in bloodstream infections

Abstract

Background: Early detection of bloodstream infections (BSIs) caused by carbapenemase-producing organisms can guide rapid lifesaving appropriate therapy.A new variant of the modified Carbapenem Inactivation Method (mCIM) test, named blood culture CIM (bcCIM), can directly detect carbapenemase enzymes from positive blood culture. Objective: This study aimed at comparing detection of carbapenemase activity in Gram-negative bacilli (GNB) by Carbapenem Inactivation Method on positive blood culture and isolated colonies. Methodology: bcCIM test was used to detect carbapenemase production in 38 positive blood cultures. Subculture of blood samples followed by isolation and identification of causative pathogens was done, antimicrobial susceptibility by disk diffusion test as well as performing mCIM test were applied to all isolated GNB. Results: Forty-one GNB were isolated. Klebsiella spp. was the most common isolated GNB 16 (39%). Most isolated GNB were carbapenemresistant 31(75.6%). For monomicrobial bloodstream infection, there was fair (kappa =0.327), moderate (kappa=0.429), and slight agreement (kappa=0.158) between results of mCIM and results of bcCIM as regards all GNB, Enterobacteriaceae, and Pseudomonas, respectively. Conclusion: bcCIM is a promising test for direct detection of carbapenemase activity, particularly in carbapenem-resistant Enterobacteriaceae. Further studies are needed for the standardization of this method.