Comparison of the novel Oxa-48 and Kpc K-SeT assay, and blue-carba test for the detection of carbapenemase-producing enterobacteriaceae using PCR as a reference method

Background: Rapid, simple, and accurate laboratory detection of carbapenemases is very important for proper antibiotic therapy and infection control. Methods: In this study, carbapenem-nonsusceptible Enterobacteriaceae (CRE) isolates were used to evaluate the performance of a new lateral flow immunochromatographic (IC) assay, the OXA-48 and KPC K-SeT assay, and modified Blue-Carba test (BCT) for the rapid detection of OXA-48 carbapenemase in comparison with polymerase chain reaction (PCR) amplification. These CREs of various enterobacterial species were isolated from various clinical samples including OXA-48 (47), NDM-1 (6), KPC-1 (1), IMP-1 (1), VIIYl-2,-4 (2), IMP-2 (1), OXA-51 (1), and OXA-23 (1) producers. Results: The OXA-48 K-SeT test detected all OXA-48 carbapenemase producers with 100% sensitivity and specificity. The BCT detected carbapenemase producers with 93% sensitivity and 100% specificity. Conclusions: Both IC assays and BCT tests have good performance and are easy to perform, rapid, simple to interpret, and highly sensitive. We suggest that BCT can be used initially as an accurate, inexpensive, and rapid phenotypic confirmation test to identify Class A, B, and D carbapenemases in the routine diagnostic microbiology laboratory, thus allowing the detection of carbapenemase activity directly from bacterial cultures.