Dual Proximity Ligation Mediated Chain Extension and Displacement Assisted Signal Cycles for Sensitive and Accurate Methicillin-Resistant Staphylococcus Aureus (MRSA) Detection

Abstract

Infectious diseases have emerged as a significant global concern, posing a substantial burden in terms of the high morbidity and mortality, and presenting considerable challenges in clinical diagnosis and treatment. Therefore, it is highly-desired to develop new strategies for sensitive and accurate bacteria detection to address the global epidemic of antibiotic resistance. In this study, a new technique utilizing dual proximity ligation mediated chain extension and displacement strategy was developed for precise identification and highly sensitive detection of Methicillin-Resistant Staphylococcus Aureus (MRSA). The antibodies recognize both protein A and PBP2a on the surface of MRSA, leading to the initiation of proximity ligation and signal amplification process. The signal amplification procedure generated a substantial number of G-quadruplex sequences, which subsequently bind with thioflavin T (ThT) to significantly amplify its fluorescence, enabling the detection of MRSA with a low detection limit of 3.5 cfu/mL. In this method, dual proximity ligation assays were integrated to mediate the signal amplification process, thus endowing the method a greatly elevated specificity in both MRSA identification and signal amplification. Due to its non-label format, high selectivity, and sensitivity, this method can serve as a practical and versatile approach for detecting different bacteria in the early stages of infectious diseases.