Which pathogens are classic examples of invasive infectious diarrhea?

Which pathogens are classic examples of invasive infectious diarrhea?

• A. Campylobacter, Shigella, Salmonella, Yersinia, and enterohemorrhagic E. coli
• B. Norovirus
• C. Vibrio cholerae
• D. Rotavirus

Answer: (A)

Invasive infectious diarrhea is defined by invasion of the intestinal mucosa with a strong inflammatory response, usually presenting with fever and blood or pus in the stool. Among pathogens, the classic examples are Campylobacter, Shigella, Salmonella, Yersinia, and enterohemorrhagic E. coli because each tends to breach the mucosal lining and elicit an inflammatory colitis. Campylobacter jejuni is a curved Gram-negative organism that penetrates and inflames the intestinal mucosa, especially in the ileum and colon, leading to inflammatory, often bloody, diarrhea. Shigella is highly invasive; it crosses the intestinal barrier via M cells in the colon and causes dysentery with mucosal ulceration and neutrophilic inflammation. Salmonella species invade the intestinal mucosa as well, producing fever and inflammatory diarrhea, and they can involve Peyer’s patches in the ileum. Yersinia enterocolitica invades the terminal ileum and can cause mesenteric lymphadenitis and inflammation that mimics appendicitis, contributing to the inflammatory picture. Enterohemorrhagic E. coli also produces inflammatory colitis with bloody stool, due to attaching and effacing lesions and toxin-mediated damage, leading to hemorrhagic colitis and potential systemic complications like HUS. In contrast, noninvasive pathogens such as Norovirus and Rotavirus primarily cause watery, noninflammatory diarrhea, while Vibrio cholerae causes profuse secretory (toxin-mediated) diarrhea without invading the mucosa. That distinction is why the first group is the best answer for invasive infectious diarrhea.

Invasive infectious diarrhea is defined by invasion of the intestinal mucosa with a strong inflammatory response, usually presenting with fever and blood or pus in the stool. Among pathogens, the classic examples are Campylobacter, Shigella, Salmonella, Yersinia, and enterohemorrhagic E. coli because each tends to breach the mucosal lining and elicit an inflammatory colitis.

Campylobacter jejuni is a curved Gram-negative organism that penetrates and inflames the intestinal mucosa, especially in the ileum and colon, leading to inflammatory, often bloody, diarrhea. Shigella is highly invasive; it crosses the intestinal barrier via M cells in the colon and causes dysentery with mucosal ulceration and neutrophilic inflammation. Salmonella species invade the intestinal mucosa as well, producing fever and inflammatory diarrhea, and they can involve Peyer’s patches in the ileum. Yersinia enterocolitica invades the terminal ileum and can cause mesenteric lymphadenitis and inflammation that mimics appendicitis, contributing to the inflammatory picture. Enterohemorrhagic E. coli also produces inflammatory colitis with bloody stool, due to attaching and effacing lesions and toxin-mediated damage, leading to hemorrhagic colitis and potential systemic complications like HUS.

In contrast, noninvasive pathogens such as Norovirus and Rotavirus primarily cause watery, noninflammatory diarrhea, while Vibrio cholerae causes profuse secretory (toxin-mediated) diarrhea without invading the mucosa. That distinction is why the first group is the best answer for invasive infectious diarrhea.