Comparative study of 3 carbapenem-hydrolysis methods for the confirmation of carbapenemase production in Enterobacteriaceae

The goals of the study were to examine the analytic and performance parameters of 2 commercial rapid carbapenem-hydrolysis assays, the β-CARBA test (Bio-Rad) and the Rapid CARB Blue Kit (ROSCO) in comparison with an in-house CARBA NP assay for the detection of Carbapenemase-Producing Enterobacteriaceae (CPE). Their performance was evaluated following growth on 2 chromogenic CPE screening media. The sensitivity was highest (91%) in the β-CARBA test when used from the mSuperCARBA™ plates and was lowest when the same test was used from the chromID™ CARBA plates (75%). The specificity was highest in the NP CARBA test in both media (96%), followed by the β CARBA/mSuperCARBA™ combination (92%). The specificity of the Rapid CARB Blue Kit was as low as 36% when used with the chromID™ CARBA plates. The β-CARBA test was simple to use and had the shortest turn-around time and hand-on time.