Comparative Evaluation of the Modified Carbapenem Inactivation Method for Phenotypic Detection of Guiana Extended-Spectrum β-Lactamase-Type Carbapenemases in Enterobacterales.

Objective: We comparatively evaluated the performance of 3 phenotypic tests for the detection of carbapenemase production.

Materials And Methods: Carbapenemase production was evaluated using the modified Hodge test (MHT), the modified carbapenemase inhibition method (mCIM), and the Rapidec Carba NP test (RCNP).

Results: Among the 170 isolates, 79 were CP-CRE and 91 were non-CP-CRE. The CP-CRE isolates produced GES-5 (n = 66), KPC (n = 4), NDM (n = 7), NDM and OXA-48 (n = 1), and VIM (n = 1). For KPC producers, all 3 methods showed a sensitivity of 75%. The sensitivities of MHT, mCIM, and RCNP were 14.3%, 100%, and 71.4%, respectively, for NDM producers, and 1.5%, 12.1%, and 18.2% for GES-5 producers, respectively.

Conclusion: The performance of the phenotypic tests varied depending on the type of carbapenemase. For intensive infection control, phenotypic and molecular tests are required for the detection of common and rare types of carbapenemases.