1. Organism
    • Hundreds of serotypes
    • Typhoid bacillus
    • S. typhi=strictly human
  2. Epidemiology
    • industrialized societies and improper food handling
    • High infecting dose (10,000)
    • Poultry products
    • Raw milk + exotic pets
    • Industrial production = outbreaks
    • Chronic carries
    • Fecal-oral
  3. Pathogenesis
    • Large and small intestine
    • Adhesion causes membrane ruffling (actin cytoskeleton rearrangement)
    • Internalized via pinocytosis
    • Multiple effector proteins injected into cells
    • profound inflammatory response
    • S. Typhi: Vi Ag reduces infecting dose, proliferation inside intestinal macrophages, carried to nodes, liver, spleen; bacteria seed blood stream; LPS starts fever -> rises with infection; reinfection of the bowel via UTI
    • Immunity: humoral, CMI
  4. Manifestations
    • Gastroenteritis: 24-48 hrs post exposure, nausea, vomiting, abd cramps, diarrhea; persists 2-7 days; fever in 50%
    • Bacteremia: Frank sepsis in poor CMI; osteomyolitis involves long bones, sites of trauma
    • Enteric fever: multiorgan infection; prolonged fever, RES involvement; can persist for weeks; Most are constipated; chronic seeding of bloodstream leads to endotoxemia; biliary tree infections -> reseeding of bowels; Major complication is hemorrhage from perforations through wall of terminal ileum
  5. Diagnosis
    Blood/fecal culture
  6. Treatment
    • GI: fluid/electrolyte replacement, control of nausea/vomiting
    • Enteric fever: ampicillin
  7. Other enterobacteriaceae
    • Klebsiella: lobar pneumonia, polysaccharide capsule
    • Enterobacter: less virulent than klebsiella, mixeed infections
    • Yersinia: Plague
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