Characterization of the Relationship Between Rumen Protozoa and Enhanced Salmonella Virulence

Findings: Salmonella is a food-borne pathogen that can cause intestinal disease that is occasionally life-threatening. Treatment of Salmonella involves antibiotics although some strains have become antibiotic resistant. One particular antibiotic resistant strain, designated as DT104, is also more adept at causing disease in cattle. The results of this study show that hypervirulence, i.e. the ability to cause a more profound disease, in DT104 is related to exposure to protozoa normally present in the first stomach (rumen) of cattle. These rumen protozoa hyperactivate disease-causing processes in DT104 and a single gene was found to underlie this phenomenon. Additionally, this research shows that rumen protozoa also promote antibiotic resistance gene exchange whereby Salmonella can acquire new antibiotic resistances. Fortunately, eliminating the rumen protozoa prevented both of these phenomena thus this elimination step may soon become a way to curb problems associated with Salmonella in cattle.