Comparative Evaluation of Real-Time PCR, Immunochromatographic Assay, and Modified Carbapenem Inactivation Method for Carbapenemase Detection in Enterobacterales Isolates

Carbapenem-resistant Enterobacterales represent a major global public health concern, and the rapid and reliable detection of carbapenemase production is of critical importance. In this study, real-time PCR was used as the reference method for carbapenemase detection, and the performance of immunochromatographic and phenotypic methods was comparatively evaluated. A total of 96 carbapenem-resistant Enterobacterales isolates were included, and all were identified as carbapenemase producers by the reference method. Diagnostic performance was assessed using positive percent agreement (PPA) and overall percent agreement (OPA); negative percent agreement and negative predictive value could not be calculated due to the absence of negative isolates. The immunochromatographic test showed complete agreement with real-time PCR in detecting carbapenemase production (PPA and OPA: 100%). At the gene level, sensitivity and specificity were 100% for OXA-48 and NDM, while sensitivity for KPC was 91.7%. In the modified carbapenem inactivation method (mCIM), PPA and OPA values were 97.9% due to false-negative results observed in two isolates producing OXA-48 and NDM by the reference method, and its performance was slightly lower than that of the immunochromatographic method. These findings indicate that the immunochromatographic method is a rapid, reliable, and practical option for carbapenemase detection, particularly in OXA-48-endemic intensive care settings where rapid identification is critical for timely infection control and appropriate antimicrobial therapy.