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Faculty: Dr. Alvin Fox

Enterobacteriaceae I (Gram negative rods) Lecture 42. Faculty: Dr. Alvin Fox. Key Words. Opportunistic diseases Shigella Diarrhea - Bacillary dysentery Dysentery - Shiga toxin Urinary tract infections Salmonella enteritidis Pili Salmonellosis

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Faculty: Dr. Alvin Fox

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  1. EnterobacteriaceaeI (Gram negative rods) Lecture 42 Faculty: Dr. Alvin Fox

  2. Key Words Opportunistic diseases Shigella Diarrhea - Bacillary dysentery Dysentery - Shiga toxin Urinary tract infections Salmonella enteritidis PiliSalmonellosis Lactose positive/negative Salmonella cholerae-suis EnterohemorrhagicE. coli Salmonella typhi - Vero toxin (Shiga-like, Shiga) - Typhoid - Hemolysin - Vi EnterotoxigenicE. coli Yersiniaentercolitica - Heat stable toxin Vibriocholerae - Heat labile toxin Choleragen (cholera toxin) EnteropathogenicE. coli Campylobacter jejuni EnteroaggregativeE. coliHelicobacter pylori EnteroinvasiveE. coli

  3. Opportunistic diseases -Enterobacteriaceae • septicemia, • pneumonia, • meningitis • urinary tract infections CitrobacterEnterobacter Escherichia Hafnia Morganella Providencia Serratia

  4. Enterobacteriaceae • gastrointestinal diseases • Escherichia coli • Salmonella • Shigella • Yersinia entercolitica

  5. Reiter's syndrome • Histocompatibility antigen (HLA) B27 • Enterobacteriaceae • Salmonella • Shigella • Yersinia • Non-Enterobacteriaceae • Campylobacter • Chlamydia

  6. Enterobacteriaceae • community acquired • otherwise healthy people • Klebsiella pneumoniae • respiratory diseases • prominent capsule • urinary tract infection • fecal contamination • E. coli • Proteus • urease (degrades urea) • alkaline urine

  7. E. coli fimbriae Type 1 mannose P • galactose • glycolipids • glycoproteins

  8. Enterobacteriaceae • gram negative facultative anaerobic rods • – oxidase negative (no cytochromeoxidase)

  9. Feces • E. coli • lactose positive • not usually identified • lactose positive sp. common, healthy intestine • Shigella, Salmonella,Yersinia • lactose negative • identified

  10. Enterobacteriaceae • other sites • identified biochemically

  11. Serotypes • reference laboratory • antigens • O (lipopolysaccharide) • H (flagellar) • K (capsular)

  12. Diarrhea (watery feces) and Dysentery (blood in stools)

  13. Caption:E. coli Escherichia coli

  14. Escherichia coli • E. coli and Shigella • genetically very similar • separated for historical reasons • overlap in pathogenesis

  15. Transmission electron micrograph Enterohemorrhagic E. coli • Usually O157:H7 Flagella

  16. Transmission – meat products or sewage-contaminated vegetables • Hemorrhagic • Bloody dysentery • copious diarrhea • few leukocytes • afebrile • hemolytic-uremic syndrome • hemolytic anemia • thrombocytopenia (low platelets) • kidney failure

  17. Enterohemorrhagic E. coli • Vero toxin • “shiga-like toxin” • shiga toxin • Hemolysins

  18. Enterotoxigenic E. coli • diarrhea like cholera • milder • travellers diarrhea

  19. Enterotoxigenic E. coli • Heat labile toxin • like choleragen • Adenyl cyclase activated • cyclic AMP • secretion water/ions • Heat stable toxin • Guanylate cyclase activated • cyclic GMP • uptake water/ions

  20. Enteropathogenic E. coli • destruction of surface microvilli • fever • diarrhea • vomiting • nausea • non-bloody stools (not generally seen as dysentery) Gut lumen

  21. Enteroaggregative • Brick-like aggregates on cell surfaces • Mucus biofilm inhibits fluid absorption • Diarrhea

  22. Enteroinvasive E. coli (EIEC ) • Dysentery • - resembles shigellosis Gut lumen

  23. Treatment -gastrointestinal disease • fluid replacement • antibiotics • not used usually unless systemic • e.g. hemolytic-uremia syndrome

  24. Shigella Modified from Fig, Dennis Kunkel

  25. Shigella • S. flexneri, S. boydii, S. sonnei, S. dysenteriae • bacillary dysentery • shigellosis • bloody feces • intestinal pain • pus

  26. Shigellosis • within 2-3 days • epithelial cell damage Gut lumen

  27. Shiga toxin • enterotoxic • cytotoxic • inhibits protein synthesis • lysing 28S rRNA

  28. Shigellosis • man only "reservoir" • mostly young children • fecal to oral contact • children to adults • transmitted by adult food handlers • unwashed hands

  29. Treating shigellosis • manage dehydration • patients respond to antibiotics • disease duration diminished

  30. Salmonella

  31. Salmonella • 2000 antigenic "types” • genetically single species • S. enterica • disease category • S. enteritidis • many serotypes • S. cholerae-suis • S. typhi

  32. Salmonellosis • S. enteritidis • the common salmonella infection • poultry, eggs • no human reservoir • Gastroenteritis • nausea • vomiting • non-bloody stool • self-limiting (2 - 5 days)

  33. Salmonellosis Gut lumen uncomplicated cases (the vast majority) antibiotic therapy not useful

  34. S. cholerae-suis • much less common • septicemia • antibiotic therapy essential

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