Rapid molecular detection of extended-spectrum beta-lactamase gene variants with a novel ligation-mediated real-time PCR

Extended-spectrum beta-lactamases (ESBLs) are emerging worldwide, making rapid and adequate ESBL detection crucial for infection control measures as well as for the choice of correct antimicrobial therapy. The aim of this study was to compare the performance of a novel rapid ligation-mediated real-time PCR (LM-PCR) with a combination disc test (CDT). In total, 172 prospective putative ESBL-positive Enterobacteriaceae isolates from clinical specimens based on VITEK2 results were included in this study and tested with the phenotypic CDT and the LM-PCR. Positive ESBL results were obtained in 100 and 95 isolates using CDT and LM-PCR, respectively. The sensitivity, specificity, negative predictive value and positive predictive value of the LM-PCR were 99.0, 92.2, 98.6 and 94.0%, respectively, compared with the CDT. The LM-PCR technique provides an important reduction in turnaround time (similar to 4.5 h versus overnight incubation using CDT) for ESBL confirmation. As a consequence, all ESBL results are available within the same day, making this assay an important tool for rapid and accurate ESBL detection.