Fluorescence immunochromatographic assay based on CdSe/ZnS quantum dots for the detection of OXA-48.

The production of carbapenemase is the primary mechanism of bacterial resistance to carbapenem antibiotics. This resistance seriously compromises the efficacy of carbapenem antibiotics in treating infections and poses a significant challenge to clinical anti-infective therapy. Oxacillinase-48 (OXA-48) is a class D carbapenemase, whose genes are usually located on transferable elements and can spread between different strains and genera. Therefore, from the perspective of infection control, effective monitoring and prevention of OXA-48 are imperative. In this study, CdSe/ZnS quantum dots (QDs) were coupled with an anti-OXA-48 monoclonal antibody (mAb) as a fluorescent signal probe to establish a quantum dot-based fluorescent immunochromatographic strip. The test strip contains a Test line (T-line) coated with an anti-OXA-48 monoclonal antibody and a Control line (C-line) coated with Staphylococcus protein A (SPA). Based on a double-antibody sandwich detection mode, it can complete highly sensitive detection of OXA-48 within 10 min. The visual detection limit of this test strip for OXA-48 recombinant protein was 3.13 ng/mL, and there was no cross-reaction with other common carbapenemases (IMP-1, NDM-1, KPC-2, VIM-2, OXA-23). It can be positioned as a rapid and reliable OXA-48 detection tool, providing a novel method for the rapid identification of OXA-48-producing resistant bacterial strains in clinical practice.