What characterizes enteroaggregative E. coli (EAEC) and what is its typical clinical pattern?

What characterizes enteroaggregative E. coli (EAEC) and what is its typical clinical pattern?

• A. Attaching and effacing lesions via a type III secretion system.
• B. Invasion of mucosa with abdominal pus.
• C. Stacked-brick adherence pattern via aggregative adherence fimbriae; causes persistent watery diarrhea.
• D. Shiga toxin production.

Answer: (C)

EAEC is defined by its distinctive adhesion to intestinal mucosa in a stacked-brick pattern, mediated by aggregative adherence fimbriae. This tight, biofilm-like attachment allows bacteria to persist on the gut lining and disrupt absorption, leading to a persistent, non-bloody (often watery) diarrhea that can be prolonged, especially in children and travelers. The key clinical pattern is prolonged or persistent watery diarrhea rather than a sudden invasive illness. This differs from other descriptions: attaching and effacing lesions caused by a type III secretion system are characteristic of enteropathogenic E. coli, which forms pedestal-like changes on enterocytes; Shiga toxin production is typical of Shiga-toxin–producing E. coli, linked to more severe disease and potential complications like HUS; invasion with mucosal pus points to invasive pathogens such as Shigella or certain Salmonella species.

EAEC is defined by its distinctive adhesion to intestinal mucosa in a stacked-brick pattern, mediated by aggregative adherence fimbriae. This tight, biofilm-like attachment allows bacteria to persist on the gut lining and disrupt absorption, leading to a persistent, non-bloody (often watery) diarrhea that can be prolonged, especially in children and travelers. The key clinical pattern is prolonged or persistent watery diarrhea rather than a sudden invasive illness.

This differs from other descriptions: attaching and effacing lesions caused by a type III secretion system are characteristic of enteropathogenic E. coli, which forms pedestal-like changes on enterocytes; Shiga toxin production is typical of Shiga-toxin–producing E. coli, linked to more severe disease and potential complications like HUS; invasion with mucosal pus points to invasive pathogens such as Shigella or certain Salmonella species.