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Virulence Assessment and Molecular Pathogenesis of Salmonella Typhimurium DT 104 and Shigella


This project will compare the virulence of multi-antibiotic resistant S. Typhimurium with non-resistant strains, use animal models to generate dose response data, determine means of transfer of resistance genes, and develop rapid detection methods for MDR ST and for Shigella.

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Initial reports on multi-drug resistant S. Typhimurium (MDR ST) suggested that it was associated with a higher mortality rate than non-resistant S. Typhimurium. Using animal and tissue culture models,the virulence of MDR ST strains will be compared with non-resistant Typhimurium and other salmonellae isolates. An animal model that mimics diarrheal disease will be used to determine the dose response curve of MDR ST. Chromosome- and plasmid-mediated antibiotic resistance will be examined.Mode of transfer will be studied by examining the flanking regions of the resistance genes. A rapid PCR method will be developed to detect any MDR ST. Rapid methods for the detection of Shigella will be developed,adapted for produce and other relevant foods, and transferred to FDA field labs.

This project will supply information on MDR ST for science-based regulatory decisions. Dose response data will be collected from animal models for hazard assessment. New, rapid detection methods for MDR ST and Shigella will be designed, evaluated and transferred to FDA laboratories.

Hanes, Darcy
DHHS/FDA - Center for Food Safety & Applied Nutrition
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