Modified Carba NP Test: Simple and rapid method to differentiate KPC- and MBL-producing Klebsiella species

Abstract

Background: The aim of this study was to evaluate the modified Carba NP test to differentiate KPC (Klebsiella pneumoniae carbapenemase)- and MBL (metallo-β-lactamase)-producing Klebsiella species. Methods: A total of 508 non-duplicate clinical isolates of Klebsiella spp. were processed by modified Carba NP and combined disc tests which were further confirmed by conventional polymerase chain reaction (PCR), a gold standard method for statistical analysis. Results: Modified Carba NP test demonstrated 91.7% sensitivity, 100% specificity, 100% positive predictive value (PPV) and 99.8% negative predictive value (NPV) for KPC and 96.7%, 100%, 100%, and 99.5% for MBL detection, respectively. Conclusion: The performance of modified Carba NP test was significantly better than combined disc test, fulfilling the requirement of simple and rapid test for clinical applications.