Which bacterium uses submucosal invasion as a mechanism of disease in the GI tract?

Which bacterium uses submucosal invasion as a mechanism of disease in the GI tract?

• A. Campylobacter jejuni
• B. Shigella flexneri
• C. Escherichia coli
• D. Listeria monocytogenes

Answer: (C)

Invasive disease in the GI tract can occur when a bacterium breaches the mucosal barrier and invades the submucosa, triggering a strong inflammatory response and, often, dysentery. Enteroinvasive Escherichia coli has a Shigella‑like invasion pattern, where the organism penetrates colonic mucosa and extends into the submucosa, leading to inflammatory, bloody diarrhea. This makes Escherichia coli the best fit among the options, because its invasive pathotype (EIEC) directly uses submucosal invasion to cause disease. Campylobacter jejuni mainly disrupts the mucosa with inflammation but is not classically defined by a submucosal invasion mechanism. Shigella is the classic invader of the mucosa and submucosa as well, but the choice here represents E. coli in the invasive form. Listeria monocytogenes invades cells and spreads cell to cell, rather than characteristic submucosal invasion of the gut wall.

Invasive disease in the GI tract can occur when a bacterium breaches the mucosal barrier and invades the submucosa, triggering a strong inflammatory response and, often, dysentery. Enteroinvasive Escherichia coli has a Shigella‑like invasion pattern, where the organism penetrates colonic mucosa and extends into the submucosa, leading to inflammatory, bloody diarrhea. This makes Escherichia coli the best fit among the options, because its invasive pathotype (EIEC) directly uses submucosal invasion to cause disease.

Campylobacter jejuni mainly disrupts the mucosa with inflammation but is not classically defined by a submucosal invasion mechanism. Shigella is the classic invader of the mucosa and submucosa as well, but the choice here represents E. coli in the invasive form. Listeria monocytogenes invades cells and spreads cell to cell, rather than characteristic submucosal invasion of the gut wall.