Mechanistic modeling of salmonellosis: Update and future directions

ABSTRACT

Microbial risk assessors often make simplifying assumptions that lead to the selection of simple concave functions with low-dose linearity, consistent with no-threshold and single-hit hypotheses, as default dose–response model forms. However, evidence is accumulating as the “microbiome revolution” progresses that challenge these assumptions that influence the estimates of the nature and magnitude of uncertainties associated with microbial risks. Scientific advances in the knowledge of the human “superorganism” (hybrid consortium of human plus microbial communities that cooperatively regulates health and disease) enable the design of definitive studies to estimate the pathogen doses overcome by the innate defenses, including the protective microbiota. The systematic investigation of the events of non-typhoid salmonellosis in humans undertaken nearly 2 decades ago was updated to incorporate recent scientific advances in the understanding of impact of the healthy superorganism that strengthens and extends the biological motivations for sublinear or convex dose–response curves in microbial risk assessment. The knowledge of colonization resistance (innate protection of the human superorganism from low doses of ingested pathogens) and microbiota-mediated clearance is advancing mechanistically for many pathosystems. However, until more detailed mechanistic data become available for salmonellosis, the consideration of a variety of empirical model forms is essential for depicting the uncertainty of the “true” dose–response model.

KEYWORDS:

• microbiome
• innate immunity
• colonization resistance

Acknowledgments

Springer approved republication of Coleman and Marks (2000) for this special collection.

Special thanks are due to the authors of companion papers in this special collection, as well as reviewers of the original manuscript (Charles Haas, Noreen Hynes, Bradley Jones, Karen Near, and James Slauch). The original work was prepared with the support of USDA, Food Safety and Inspection Service.