Starch-KI test strip and solution colorimetry for dual-mode point-of-care testing (POCT) of live Staphylococcus aureus based on the activity of lysed catalase.

Staphylococcus aureus (S. aureus), a ubiquitous foodborne pathogenic bacterium, is prevalent in a wide array of food products and frequently implicated in food poisoning incidents, necessitating effective means for its real-time monitoring and rapid detection. In response to this need, this study introduces an innovative dual-mode point-of-care testing (POCT) approach for detecting live S. aureus, leveraging the catalase (CAT)-induced H2O2-mediated reaction. This method integrates a starch-KI paper test with solution colorimetry, offering a dual-modal detection system. The use of commercial starch-KI test strips stands out for its simplicity, cost-effectiveness, rapidness, and enhanced stability and repeatability in large-scale applications, as it requires no modifications or treatments. Furthermore, combining with the solution colorimetry, the dual signal outputs enable mutual correction, significantly boosting detection accuracy and minimizing both false positives and negatives. The starch-KI test strips provide swift visual results, allowing for immediate identification, while the enzyme cascade-based solution colorimetry offers quantitative analysis with impressive lower limits of detection (72 CFU mL-1 for solution colorimetry). These low detection thresholds demonstrate the system's high sensitivity and precision. This dual-modal platform enables real-time monitoring and early intervention in food systems, preventing food poisoning. Its practicality, low cost, and user-friendliness make it an appealing diagnostic tool for both industrial food processors and public health authorities, particularly in regions with limited resources. By addressing the critical need for accurate, rapid, and cost-effective S. aureus detection, this dual-modal platform could significantly contribute to enhancing food safety globally.