Current methods and emerging strategies for the detection of foodborne bacterial protein toxins

Foodborne bacterial pathogens are a major source of disease and mortality worldwide and have a significant impact on the global economy. Many of these pathogens produce lethal toxins that may persist in various food matrices even in the absence of viable microorganisms, making direct toxin detection essential for food safety surveillance. This review focuses on five major foodborne bacterial exotoxins selected based on acute clinical severity, structural and mechanistic diversity across toxin classes, a large volume of published data on detection platforms relative to other foodborne protein toxins, and the existence of persistent unresolved detection challenges. These major toxins include botulinum neurotoxins (BnT), Shiga toxins (Stx), cholera toxin (CT), listeriolysin O (LLO), and staphylococcal enterotoxins (SEs). The mechanism of action of each toxin is integrated with a critical evaluation of its detection strategies across three target categories: nucleic acid, protein, functional activity-based methods. Different commercial detection platforms, alongside emerging research-driven methodologies, have been critically evaluated, with emphasis on analytical sensitivity, specificity, functional relevance, processing time, and matrix compatibility. It is proposed that immunoassays and nucleic acid-based tests dominate routine monitoring, while advanced biosensors and activity-based approaches offer enhanced sensitivity and mechanistic specificity. However, critical challenges persist such as in matrix interference, which systematically degrades platform performance in real food samples, the disconnect between gene detection and biologically active toxin confirmation undermines risk assessment for heat-stable toxins. The absence of regulatory validation pathways prevents adoption of emerging platforms. Future directions include CRISPR-based diagnostics, smartphone-integrated portable biosensors, AI-driven signal interpretation, and standardized validation frameworks enabling translation of laboratory innovations to field-deployable food safety tools.