Pathogenesis of escherichia Gastroenteritis, continued Enteroinvasive(EIEC Invade and destroy colonic epithelium Fever and cramps with blood and leukocytes in stool Uncommon often food-borne Enteropathogenic (EPEC; childhood diarrhea) Organism adheres to enterocyte plasma membrane and causes destruction of microvilli producing watery diarrhea Adhesiveness mediated by plasmid-encoded pili BIOL 533 17 Lecture
BIOL 533 17 Lecture 12 Pathogenesis of Escherichia • Gastroenteritis, continued – Enteroinvasive (EIEC) • Invade and destroy colonic epithelium – Fever and cramps with blood and leukocytes in stool – Uncommon; often food-borne – Enteropathogenic (EPEC; childhood diarrhea) • Organism adheres to enterocyte plasma membrane and causes destruction of microvilli producing watery diarrhea – Adhesiveness mediated by plasmid-encoded pili
Pathogenesis of escherichia Gastroenteritis, continued Enteropathogenic(continued) Infants< 1 year affected Enterohemorrhagic(EHEC; hemorrhagic colitis) Produces cytotoxin(verotoxin) Severe abdominal pain, bloody diarrhea, little or no fever Warm months of year; affects children 5 years BIOL 533 18 Lecture
BIOL 533 18 Lecture 12 Pathogenesis of Escherichia • Gastroenteritis, continued – Enteropathogenic (continued) • Infants< 1 year affected – Enterohemorrhagic (EHEC; hemorrhagic colitis) • Produces cytotoxin (verotoxin) • Severe abdominal pain, bloody diarrhea, little or no fever • Warm months of year; affects children < 5 years
Pathogenesis of escherichia Gastroenteritis, continued Enteroaggregative(EaggEC; watery diarrhea) ● Infants<6 months AIDS patients BIOL 533 Lecture
BIOL 533 19 Lecture 12 Pathogenesis of Escherichia • Gastroenteritis, continued – Enteroaggregative (EaggEC; watery diarrhea) • Infants < 6 months • AIDS patients
Pathogenesis of Different Toxins Cholera and etec Colonize mucosal surface by toxin coregulated pilus(cholera; TcpA) or colonization factor Ag Cfa, E col Ctx or Lt binds to receptor and taken up by vesicles, transported from basolateral membrane to ac complex BIOL 533 20 Lecture
BIOL 533 20 Lecture 12 Pathogenesis of Different Toxins • Cholera and ETEC – Colonize mucosal surface by toxin coregulated pilus (cholera; TcpA) or colonization factor Ag (Cfa; E. coli) – Ctx or LT binds to receptor and taken up by vesicles; transported from basolateral membrane to AC complex
Pathogenesis of Different Toxins Cholera and etEC (continued) ADP-ribosylation yields CAMP(cholera-like) ETEC (heat stable, St) binds to membrane-bound guanylate cyclase complex that produces CGMP Both CAMP and cgMP reduce Nat absorption in vilas cells Increase CI secretion in crypt cells; yields watery diarrhea BIOL 533 Lecture
BIOL 533 21 Lecture 12 Pathogenesis of Different Toxins • Cholera and ETEC (continued) – ADP-ribosylation yields cAMP (cholera-like) • ETEC (heat stable; ST) binds to membrane-bound guanylate cyclase complex that produces cGMP – Both cAMP and c-GMP reduce Na+ absorption in vilus cells • Increase CI— secretion in crypt cells; yields watery diarrhea