Porcine Escherichia coli Infection Study Guide

Overview and Clinical Importance

Escherichia coli infections represent one of the most economically significant diseases in swine production worldwide. Enteric colibacillosis encompasses two major clinical syndromes: neonatal diarrhea in nursing piglets and post-weaning diarrhea (PWD) in recently weaned pigs. A distinct syndrome, edema disease (ED), occurs in the post-weaning period and is caused by Shiga toxin-producing E. coli (STEC). Understanding pathotype classification, fimbrial adhesins, and enterotoxins is essential for NAVLE success.

Etiology and Pathotype Classification

Pathogenic E. coli strains causing porcine enteric disease are classified based on their virulence factors. The two main pathotypes relevant to swine are enterotoxigenic E. coli (ETEC) and Shiga toxin-producing E. coli (STEC). ETEC strains cause secretory diarrhea through enterotoxin production, while STEC strains produce Shiga toxin 2e (Stx2e) responsible for edema disease.

E. coli Pathotype Classification in Swine

Virulence Factors

Fimbrial Adhesins

Fimbrial adhesins are essential for bacterial colonization of the small intestinal epithelium. They bind to specific receptors on enterocytes in the jejunum and ileum. Host susceptibility depends on the presence of these receptors, which is genetically determined and age-dependent.