A New Method Based on LAMP-CRISPR–Cas12a-Lateral Flow Immunochromatographic Strip for Detection

INTRODUCTION: Carbapenemase-mediated antimicrobial resistance is currently a hot spot of global concern. Carbapenem-resistant organisms are highly prevalent in hospitals associated with difficult-to-treat infections, resulting in poor clinical outcome due to limited treatment options. It is urgently needed to have a rapid, efficient, and convenient molecular assay for identifying such resistant strains. METHODS: For this end, we developed a new laboratory assay targeting Klebsiella pneumoniae carbapenemase (KPC) and New Delhi metallo-β-lactamase (NDM) based on loop-mediated isothermal amplification, CRISPR–Cas12a, and lateral flow immunochromatographic strip (CRISPR–Cas-LAMP-lateral flow strip). The method was designed to use a guide RNA (gRNA) to recognize the target DNA and guide Cas12a to cleave the target DNA, and simultaneously cleave any single-stranded DNA within the cleavage reaction system. RESULTS: The cleavage products are visible to the naked eye on the lateral flow strip. This method is highly sensitive in direct detection of bacteria in samples containing at least 3×10(5) CFU/mL without the need for bacterial culture. DISCUSSION: It provides shorter turnaround time and higher specificity than the conventional bacterial culture and susceptibility testing method. This new assay is applicable for extensive use in hospital infection control, as well as identification and treatment of resistant strains due to simple operation and inexpensive apparatuses.