Is This the Carbapenemase Test We've Been Waiting for? A Multicenter Evaluation of the Modified Carbapenem Inactivation Method

Abstract

A plethora of phenotypic methods exist for the detection of carbapenemases; however, clinical laboratories have struggled for years with accurate, objective phenotypic detection of carbapenemase activity in Enterobacteriaceae. In this issue of the Journal of Clinical Microbiology, V. M. Pierce et al. (J Clin Microbiol 55: 2321-2333, https://doi.org/10.1128/JCM.00193-17) report on a multicenter evaluation of the modified carbapenem inactivation method (mCIM). The high sensitivity, specificity, reproducibility, and ease of interpretation associated with the mCIM for Enterobacteriaceae will likely lead to its adoption by clinical laboratories.

Phenotypic and molecular identification of carbapenemase-producing Enterobacteriaceae - challenges in diagnosis and treatment

“…Several studies demonstrated high sensitivity of mCIM for CP-CRE screening (2,4,8). The mCIM is an affordable assay using familiar materials and methods and the test can be interpreted objectively (8). Our findings with mCIM and the combination disks test were in accordance with multiplex PCR results.…”

“…Also, our results revealed 2 strains of P. stuartii, 1 strain of S. marcescens and 1 isolate of K. pneumoniae harbouring gene bla NDM , which were negative for the MHT with both meropenem and ertapenem disks. Similar reports recognized the MHT unsatisfying performance in the detection of NDM-carriers, with sensitivity below 50% (2,8,14,21,22). Recent studies demonstrated that NDM is a lipoprotein anchored to the outer membrane in Gram-negative bacteria, unlike all other known carbapenemases (21).…”

“…A newer phenotypic method for detection of carbapenemase activity is the mCIM (14). Several studies demonstrated high sensitivity of mCIM for CP-CRE screening (2,4,8). The mCIM is an affordable assay using familiar materials and methods and the test can be interpreted objectively (8).…”

“…The CLSI and the European Committee on Antimicrobial Susceptibility Testing EUCAST have recommended reporting of susceptibility in accordance with the antimicrobial susceptibility test result (5,8,14). Detection of carbapenemase activity is undeniably important for epidemiological and infection control purposes and many would argue that it would be beneficial when making treatment decisions (8,20).…”

“…Recently, the World Health Organization (WHO) included CRE among pathogens with critical priority for research and development of new antibiotics (7). Therefore, highly sensitive and specific methods for CP-CRE detection in clinical laboratory settings are critical (2,4,8).…”