Carbapenem-resistant Enterobacterales (CRE) possessing various carbapenemases, particularly the OXA-48 group, are now rapidly spreading and becoming a major public health concern worldwide. Phenotypic detection of OXA-48-like carbapenemases is still suboptimal due to their weak carbapenemase activity, whereas highly sensitive and specific polymerase chain reaction (PCR)-based methods take at least 3-4 h. We, therefore, developed a recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip assay for the rapid detection of blaOXA-48-like in Enterobacterales. A total of 131 clinical isolates including 61 blaOXA-48-like-carrying Enterobacterales isolates and 70 Gram-negative bacilli isolates containing other bla genes were subjected to the RPA method performed under isothermal conditions at 37 °C within 10 min and visually inspected by LF strip within 5 min. The RPA-LF assay provided 100% sensitivity (95% confidence interval, 92.6-100%) and 100% specificity (93.5-100%) for detecting blaOXA-48-like genes from bacterial colonies. Its detection limit was 100 times less than that of the PCR method. This assay is rapid, easy to perform, and provides excellent performance without any special equipment. It may be applied for directly identifying the blaOXA-48-like genes in Enterobacterales obtained from blood culture. Rapid identification of carbapenemase types is essential for selecting appropriate antimicrobial options, particularly the β-lactams combined with novel β-lactamase inhibitors.
Keywords: Gram-negative bacilli; carbapenem resistance; isothermal amplification.