Which sequence describes the pathogenesis of diarrhea-causing Salmonella?

Which sequence describes the pathogenesis of diarrhea-causing Salmonella?

• A. Adhere to epithelium via fimbriae > invade and replicate intracellularly > secrete toxins (inc Cl2 secretion, dec Na absorption) > neutrophil recruitment and inflammation (cytotoxins = cell death) > malabsorptive and secretory D+ with blood
• B. Ingested Salmonella invades the lymphatics without epithelial adhesion
• C. Salmonella replicates first in the bloodstream and then colonizes the gut
• D. Salmonella causes diarrhea solely by reducing intestinal motility

Answer: (A)

Salmonella gastroenteritis arises from an enteroinvasive sequence: the bacteria first attach to the intestinal mucosa with fimbriae and other adhesins, then actively invade epithelial cells (often via M cells over Peyer's patches) and replicate intracellularly. This invasion triggers a robust inflammatory response, with neutrophil recruitment and release of inflammatory mediators. The resulting mucosal damage and inflammation promote increased chloride secretion and impaired sodium absorption, producing a secretory and inflammatory diarrhea. Blood can appear in the stool due to mucosal injury. The other scenarios don’t fit this pattern: Salmonella typically requires epithelial adhesion and invasion to drive the inflammatory diarrhea, rather than spreading primarily through lymphatics without epithelial interaction, having the primary replication in the bloodstream, or causing diarrhea solely by reducing intestinal motility.

Salmonella gastroenteritis arises from an enteroinvasive sequence: the bacteria first attach to the intestinal mucosa with fimbriae and other adhesins, then actively invade epithelial cells (often via M cells over Peyer's patches) and replicate intracellularly. This invasion triggers a robust inflammatory response, with neutrophil recruitment and release of inflammatory mediators. The resulting mucosal damage and inflammation promote increased chloride secretion and impaired sodium absorption, producing a secretory and inflammatory diarrhea. Blood can appear in the stool due to mucosal injury. The other scenarios don’t fit this pattern: Salmonella typically requires epithelial adhesion and invasion to drive the inflammatory diarrhea, rather than spreading primarily through lymphatics without epithelial interaction, having the primary replication in the bloodstream, or causing diarrhea solely by reducing intestinal motility.