Evaluation of rapid phenotypic tests (CARBANP and BLUE-CARBA) for carbapenemase production among Enterobacteriaceae

Abstract

Carbapenems are considered the last resort for the treatment of multidrug-resistant Enterobacteriaceae. The massive use of these agents, in addition to the horizontal transfer of resistance determinants, are responsible for the emergence and spread of carbapenemases. The rapid detection of these enzymes will allow early infection control measures, reducing the risk of therapeutic failure and avoiding the spread of the carbapenemases. The development of rapid tests for carbapenemase detection is mandatory. The aim of this study was to evaluate the performance of the rapid tests CARBA NP and BLUE-CARBA against carbapenemase-producing and non-carbapenemase-producing Enterobacteriaceae. A total of 90 isolates – 45 carbapenemase-producing- and 45 -non-producing-Enterobacteriaceae – were selected for this study. We performed both CARBA NP and BLUE-CARBA as previously described. We also added phenylboronic acid (PBA) in both assays to evaluate the presence of Class A carbapenemases. The sensitivity/specificity were 64.44%/97.78% and 91.11%/86.67% for CARBA NP and BLUE-CARBA, respectively. The modified assays with PBA did not provide any reliable results. Our results indicated that the BLUE-CARBA proved to be the best methodology (higher sensitivity) to be used as a screening test for carbapenemase detection.