Visual and fluorescent detection of Moraxella catarrhalis by multiple cross displacement amplification-based assay

Moraxella catarrhalis (M. catarrhalis), once considered as a harmless commensal bacterium, is now recognized as a significant pathogen associated with human mucosal infection. Hence, development of rapid, accurate, and user-friendly detection method is crucial for effective control and management of M. catarrhalis infections. Here, we introduce the M. catarrhalis MCDA-FRT assay, a novel diagnostic approach based on multiple cross displacement amplification (MCDA) for the visual and fluorescent (FRT) detection of M. catarrhalis. This innovative method amplifies the target sequence through MCDA reaction and provides results through the visual observation of a fluorescent signal when exposed to blue light. The generation of the fluorescent signal is facilitated by the cleavage of the restriction endonuclease Nb.BsrDⅠ. The M. catarrhalis MCDA-FRT assay can efficiently detect M. catarrhalis at a temperature of 65 °C in 40 min. It exhibits a remarkable sensitivity of 35 fg of M. catarrhalis genomic DNA, with a specificity of 100%. Furthermore, the assay accurately identified all M. catarrhalis-infected clinical samples tested. In conclusion, the M. catarrhalis MCDA-FRT assay showcases outstanding performance in terms of simplicity, sensitivity, and specificity, which can be used as a promising diagnostic tool for the swift and reliable detection of M. catarrhalis in both field and basic medical settings.