Fully integrated injector system for point-of-care testing of Staphylococcus aureus

In resource-limited settings, the combination of integrated devices and isothermal amplification has become one of the most promising methods for nucleic acid detection of pathogenic bacteria. Herein, we developed an injector strategy named the Fully Integrated Injector System (FIIS) for point-of-care testing (POCT) of Staphylococcus aureus (S. aureus). The detection results can be visually presented after nucleic acids were enriched by chitosan-functionalized magnetic beads (CMBs), and underwent in-situ loop-mediated isothermal amplification (LAMP) reaction. In this work, a five-component oil − water two-phase system was innovatively constructed. Mineral oil was used to separate three aqueous phases, including the lysis phase, washing phase, and amplification/detection phase. CMBs could shuttle rapidly and nondestructively among phases through the movement of an external magnet. After the sample was sucked by the injector, DNA was released and enriched by CMBs within 3 min. It is worth noting that the FIIS integrated the whole detection steps including lysis, enrichment, washing and amplification of nucleic acid, and the detection of S. aureus could be detected visually within 1 h by simple manual operation. The sensitivity of the fully integrated FIIS for artificially spiked chicken was 103 CFU/g without cumbersome sample preparation, while the sensitivity reached 1 CFU/g after 12 h of enrichment. The detection results of real animal samples were satisfactory compared with the culture method, with a sensitivity of 95.24 % and a specificity of 100 %. Due to its simple operation, non-requirement of external equipment, and visual readouts, we anticipate that the FIIS would facilitate the detection of S. aureus and other foodborne pathogens in limited-resource settings.