Label-free, real-time and multiplex detection of Mycobacterium tuberculosis based on silicon photonic microring sensors and asymmetric isothermal amplification technique (SPMS-AIA)

Abstract Rapid diagnosis of Mycobacterium tuberculosis complex (MTBC) is crucial for the control and treatment of tuberculosis. Currently available diagnostic tools are unable to meet clinical needs, especially in resource limited settings, as they suffer from being time-consuming, costly, insensitive, or dependant on sophisticated instruments and well trained personnel. An optical diagnostic platform (SPMS-AIA) consisting of the silicon photonic microring sensor and the asymmetric isothermal amplification technique was developed to detect MTBC in a rapid (one hour), isothermal, label-free and real-time manner. The performance of the SPMS-AIA platform was assessed by detecting two MTBC specific biomarkers, IS 6110 and IS 1081 . Detection limits were as low as 3.2 copies for IS 6110 and 12 copies for IS1081 respectively when tested with Mycobacterium tuberculosis H37Rv genomic DNA. An evaluation for detection of IS 6110 in clinical sputa showed that the SPMS-AIA platform performed as well as the established market leader GeneXpert MTB/RIF platform. Of 26 MTBC culture-positive and smear-positive specimens, 23 were found positive by the SPMS-AIA platform (89% sensitivity). Of 47 MTBC culture-positive and smear-negative specimens, 34 were positive by the SPMS-AIA platform (72% sensitivity): this is similar to the sensitivity of 70% by the GeneXpert MTB/RIF platform. The versatility of the SPMS-AIA platform was demonstrated by multiplex detection of IS 6110 and IS 1081 in 10 clinical specimens. The SPMS-AIA platform shows great potential for development into a point-of-care (POC) diagnostic tool for use in resource limited settings.