Evaluation of MASTDISCS combi Carba plus for the identification of metallo‐β‐lactamases, KPC and OXA‐48 carbapenemase genes in Enterobacteriaceae clinical isolates

The increasing frequency of class A KPC enzymes, class B metallo‐β‐lactamases (MBLs) and class D OXA‐48 enzymes in Enterobacteriaceae makes their early identification urgent. A simple commercial MASTDISCS combi Carba plus disc system (MAST‐Carba plus) was designed for the identification of MBLs, KPC and OXA‐48 carbapenemase genes in Enterobacteriaceae. To validate the MAST‐Carba plus, a total of 77 isolates of carbapenemase‐producing Enterobacteriaceae (CPE) and 84 isolates of noncarbapenemase‐producing Enterobacteriaceae (non‐CPE) were selected for differentiation of the genes of Enterobacteriaceae by MAST‐Carba plus. Meanwhile, the carbapenemase genes such as blaKPC, blaIMP, blaVIM, blaNDM‐₁ and blaOXA‐₄₈ were detected by PCR (polymerase chain reaction). Thus, when considered on the basis of PCR results, the sensitivity of MAST‐Carba plus detection of KPC strains is 82·3%, the specificity is 100·0%, the positive predictive value is 100·0% and the negative predictive value is 92·4%. For MBLs strains, the sensitivity is 100·0%, the specificity is 97·1%, the positive predictive value is 84·6% and the negative predictive value is 100·0%. For OXA‐48 strains, the sensitivity is 100·0%, the specificity is 99·4%, the positive predictive value is 80·0% and the negative predictive value is 100·0%. Our findings suggest that MAST‐Carba plus is a rapid and promising method for identifying the MBLs, KPC and OXA‐48 carbapenemase genes in Enterobacteriaceae, which could be exploited in basic microbiology laboratory to prevent the transmission of CPE. SIGNIFICANCE AND IMPACT OF THE STUDY: Not only detection of carbapenemases but also identification of their genes accurately and rapidly in Enterobacteriaceae is still a major challenge for clinical laboratories in order to prevent the transmission of carbapenemase‐producing Enterobacteriaceae (CPE). Therefore, this study aimed to evaluate the performance of a new rapid method (MASTDISCS combi Carba plus) for the identification of metallo‐β‐lactamases (MBLs), KPC and OXA‐48 carbapenemase genes in Enterobacteriaceae clinical isolates.