CPA-Cas12a-based lateral flow strip for portable assay of Methicillin-resistant Staphylococcus aureus in clinical sample.

The rapid and accurate identification of methicillin-resistant Staphylococcus aureus at an early antibiotic therapy stage would be benefit to disease diagnosis and antibiotic selection. Herein, we integrated cross-priming amplification (CPA) and CRISPR/Cas 12a (designated as CPA-Cas 12a) systems to establish a sensitive and efficient lateral flow assay to detect methicillin-resistant Staphylococcus aureus. This assay relies on the CPA isothermal nucleic acid amplification strategy which can amplify the DNA extracted from Staphylococcus aureus and accompanying the indiscriminately trans-cleavage process of Cas 12a/CrRNA duplex after recognizing specific sequence. Taking the advantage of reporter and high turnover Cas 12a activity, a dramatic change in response was achieved to produce a significant increase in the analytical sensitivity. The signal conversion and output were realized using a lateral flow strip to achieve field-deployable detection. Furthermore, this bioassay was accommodated with a microfluidic device to realize automatically portable detection. This proposed assay completed within 30 min with the detection limit of 5 CFU mL-1, was verified by testing bacterial suspension and 202 clinical samples. Given the high sensitivity, specificity and efficiency, this colorimetric readout assay through strip could be further promoted to the clinical diagnosis, clinical medication of multidrug-resistant bacteria.