What is the pathophysiology of bacterial colitis?

Updated: Oct 02, 2017
  • Author: David A Piccoli, MD; Chief Editor: Carmen Cuffari, MD  more...
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Answer

The most common bacterial causes of colitis in children are Escherichia coli (including both enterohemorrhagic E coli [EHEC] and enteroinvasive E coli [EIEC]) and species of Shigella, Salmonella, Campylobacter, and Yersinia.

Salmonella infections can be divided into those that cause typhoid (enteric) fever and those that do not. In more industrialized countries, infection with nontyphoid Salmonella accounts for a significant proportion of cases of food poisoning. Salmonella infections are typically spread via the fecal-oral route; outbreaks are commonly associated with contaminated eggs, dairy products, and meats. Gastric acid is usually lethal to the organism, but susceptibility to infection is increased with decreased GI motility, rapid emptying of the stomach after gastrectomy, a large quantity of ingested bacteria, malnutrition, antibiotic use, and achlorhydria. Salmonellae can penetrate the epithelial layer to the level of the lamina propria and evoke a leukocyte response. They cause diarrhea by producing several toxins and prostaglandins, which stimulate the active secretion of fluids and electrolytes.

Shigella species attach to binding sites on the surface of the intestinal mucosal cells. The organism penetrates and proliferates in the cell, which leads to cell destruction, produces mucosal ulcerations, and causes bleeding. Shigellae also elaborate the exotoxins that produce diarrhea.

E coli may produce diarrhea in several different ways, depending on their specific pathologic characteristics. Pathologic strains of E coli have been classified as follows:

  • Enteropathogenic

  • Enterotoxic

  • Enteroinvasive

  • Enteroaggregative

  • Enteroadherent

  • Enterohemorrhagic

EHEC, including O157:H7 and O26:H11, causes hemorrhagic colitis and systemic complications (eg, hemolytic uremic syndrome [HUS]). The risk of developing HUS after infection with E coli O157 is estimated to be 10-15% in children. In typical infectious colitis, the lamina propria of the large intestine is infiltrated by PMNs. EIEC, on the other hand, exhibits almost exactly the same pathogenetic mechanisms as Shigella.


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