Chapter 25: Microbial Diseases of the Digestive System <ul><li>Anatomy and physiology </li></ul><ul><li>Normal flora </li>...
Anatomy and physiology
Normal Flora <ul><li>Mouth </li></ul><ul><ul><li>A variety of species exist (aerobic and anaerobic) </li></ul></ul><ul><ul...
Upper digestive infections  <ul><li>Bacterial </li></ul><ul><ul><li>Dental Caries (tooth decay) </li></ul></ul><ul><ul><li...
Tooth decay (dental caries) <ul><li>Streptococcus mutans </li></ul><ul><li>Formation of extracellular glucans from dietary...
Periodontal disease <ul><li>Inflammatory response to plaque bacteria </li></ul><ul><li>Inflammation affects gums </li></ul...
Trench Mouth <ul><li>Synergistic infection – spirochetes and anaerobic bacteria </li></ul><ul><li>Acute necrotizing ulcera...
Summary of teeth and gum infections
<ul><li>Paramyxovirus family </li></ul><ul><li>Enters through respiratory tract  </li></ul><ul><li>Infect different body t...
Features of mumps
Lower digestive infections  <ul><li>Bacterial </li></ul><ul><ul><li>Heliobacter Peptic Ulcer Disease </li></ul></ul><ul><u...
Heliobacter Peptic Ulcer Disease <ul><li>Helicobacter pylori   </li></ul><ul><li>Gastric ulcer </li></ul>Figure 11.11
Features of Helicobacter gastritis
Shigellosis Figure 25.8 <ul><li>Shigella  spp. producing Shiga toxin  </li></ul><ul><li>Shiga toxin causes inflammation an...
Features of shigellosis
Salmonellosis Figure 25.9 <ul><li>S. enterica  Typhimurium </li></ul><ul><li>Mortality (<1%) due to septic shock caused by...
Features of salmonellosis
Cholera <ul><li>Vibrio cholerae  serotypes that produce cholera toxin </li></ul><ul><li>Toxin causes host cells to secrete...
Features of cholera
Gastroenteritis <ul><li>Escherichia coli  Gastroenteritis </li></ul><ul><li>Campylobacter  Gastroenteritis </li></ul><ul><...
Escherichia coli  Gastroenteritis <ul><li>Occurs as traveler's diarrhea and epidemic diarrhea in nurseries </li></ul><ul><...
Escherichia coli  gastroenteritis
Campylobacter  Gastroenteritis <ul><li>Campylobacter jejuni </li></ul><ul><li>Usually transmitted in cow's milk </li></ul>...
Campylobacter  Gastroenteritis
Other Gastroenteritis <ul><li>Yersinia  Gastroenteritis </li></ul><ul><ul><li>Y. enterocolitica  and  Y. pseudotuberculosi...
Rotavirus <ul><li>3 million cases annually  </li></ul><ul><li>1-2 day incubation, 1 week illness </li></ul><ul><li>Reoviru...
Giardiasis  <ul><li>Giardia lamblia </li></ul><ul><li>Drinking water contamination by feces </li></ul><ul><li>Traveler’s d...
Features of giardiasis
Cryptosporidiosis <ul><li>Cryptosporidium parvum   </li></ul><ul><li>Transmitted by oocysts in contaminated water  </li></...
Features of crytosporidiosis
Amoebic Dysentery <ul><li>Entamoeba histolytica   </li></ul><ul><li>Chronic – spread to the liver and other organs </li></...
Features of  Amoebic Dysentery
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Chapter 25: Microbial Diseases of the Digestive System

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Chapter 25: Microbial Diseases of the Digestive System

  1. 1. Chapter 25: Microbial Diseases of the Digestive System <ul><li>Anatomy and physiology </li></ul><ul><li>Normal flora </li></ul><ul><li>Upper digestive infections </li></ul><ul><ul><li>Bacterial </li></ul></ul><ul><ul><li>Viral </li></ul></ul><ul><li>Lower digestive infections </li></ul><ul><ul><li>Bacterial </li></ul></ul><ul><ul><li>Viral </li></ul></ul><ul><ul><li>Protozoan </li></ul></ul>
  2. 2. Anatomy and physiology
  3. 3. Normal Flora <ul><li>Mouth </li></ul><ul><ul><li>A variety of species exist (aerobic and anaerobic) </li></ul></ul><ul><ul><li>Bind to specific host cell receptors </li></ul></ul><ul><li>Intestines </li></ul><ul><ul><li>Microorganisms make up 1/3 of the weight of feces </li></ul></ul><ul><ul><li>Biochemical activities: </li></ul></ul><ul><ul><ul><li>Synthesis of vitamins </li></ul></ul></ul><ul><ul><ul><li>Degrade indigestible substances </li></ul></ul></ul><ul><ul><ul><li>Competitively inhibit pathogens </li></ul></ul></ul>
  4. 4. Upper digestive infections <ul><li>Bacterial </li></ul><ul><ul><li>Dental Caries (tooth decay) </li></ul></ul><ul><ul><li>Periodontal disease </li></ul></ul><ul><ul><li>Trench Mouth (Vincent’s disease) </li></ul></ul><ul><li>Viral </li></ul><ul><ul><li>Mumps </li></ul></ul>
  5. 5. Tooth decay (dental caries) <ul><li>Streptococcus mutans </li></ul><ul><li>Formation of extracellular glucans from dietary sucrose </li></ul><ul><li>Cariogenic dental plaque - acidity </li></ul><ul><li>Control – fluoride and restricting dietary sucrose </li></ul>Figure 25..3 b
  6. 6. Periodontal disease <ul><li>Inflammatory response to plaque bacteria </li></ul><ul><li>Inflammation affects gums </li></ul><ul><li>Dental calculus </li></ul><ul><li>Gingivitis – Porphyromonas gingivalis </li></ul><ul><li>Responsible for tooth loss in older people </li></ul>
  7. 7. Trench Mouth <ul><li>Synergistic infection – spirochetes and anaerobic bacteria </li></ul><ul><li>Acute necrotizing ulcerative gingivitis </li></ul><ul><li>Occurs at any age group (poor mouth care) </li></ul>
  8. 8. Summary of teeth and gum infections
  9. 9. <ul><li>Paramyxovirus family </li></ul><ul><li>Enters through respiratory tract </li></ul><ul><li>Infect different body tissues: </li></ul><ul><ul><li>Parotid glands </li></ul></ul><ul><ul><li>Meninges </li></ul></ul><ul><ul><li>Testicles </li></ul></ul><ul><li>Prevented with MMR vaccine </li></ul>Mumps
  10. 10. Features of mumps
  11. 11. Lower digestive infections <ul><li>Bacterial </li></ul><ul><ul><li>Heliobacter Peptic Ulcer Disease </li></ul></ul><ul><ul><li>Shigellosis </li></ul></ul><ul><ul><li>Salmonellosis </li></ul></ul><ul><ul><li>Cholera </li></ul></ul><ul><ul><li>Gastroenteritis </li></ul></ul><ul><li>Viral </li></ul><ul><ul><li>Rotavirus </li></ul></ul><ul><li>Protozoan </li></ul><ul><ul><li>Giardiasis </li></ul></ul><ul><ul><li>Cryptosporidiosis </li></ul></ul><ul><ul><li>Amoebic Dysentery </li></ul></ul>
  12. 12. Heliobacter Peptic Ulcer Disease <ul><li>Helicobacter pylori </li></ul><ul><li>Gastric ulcer </li></ul>Figure 11.11
  13. 13. Features of Helicobacter gastritis
  14. 14. Shigellosis Figure 25.8 <ul><li>Shigella spp. producing Shiga toxin </li></ul><ul><li>Shiga toxin causes inflammation and bleeding </li></ul>
  15. 15. Features of shigellosis
  16. 16. Salmonellosis Figure 25.9 <ul><li>S. enterica Typhimurium </li></ul><ul><li>Mortality (<1%) due to septic shock caused by endotoxin </li></ul><ul><li>Typhoid fever </li></ul><ul><li>Vaccine available </li></ul>
  17. 17. Features of salmonellosis
  18. 18. Cholera <ul><li>Vibrio cholerae serotypes that produce cholera toxin </li></ul><ul><li>Toxin causes host cells to secrete Cl–, HCO–, and water </li></ul>Figure 25.12
  19. 19. Features of cholera
  20. 20. Gastroenteritis <ul><li>Escherichia coli Gastroenteritis </li></ul><ul><li>Campylobacter Gastroenteritis </li></ul><ul><li>Yersinia Gastroenteritis </li></ul><ul><li>Clostridium perfringens Gastroenteritis </li></ul><ul><li>Bacillus cereus Gastroenteritis </li></ul>
  21. 21. Escherichia coli Gastroenteritis <ul><li>Occurs as traveler's diarrhea and epidemic diarrhea in nurseries </li></ul><ul><li>Four groups of pathogenic E. coli </li></ul><ul><ul><li>Enterotoxigenic </li></ul></ul><ul><ul><li>Enteroinvasive </li></ul></ul><ul><ul><li>Enteropathogenic </li></ul></ul><ul><ul><li>Enterohemorrhagic </li></ul></ul><ul><li>50% of feedlot cattle may have enterohemorrhagic strains in their intestines </li></ul><ul><ul><li>E. coli O157:H7 produce Shiga toxin </li></ul></ul><ul><ul><ul><li>O = cell wall antigen </li></ul></ul></ul><ul><ul><ul><li>H = flagellar antigen </li></ul></ul></ul>
  22. 22. Escherichia coli gastroenteritis
  23. 23. Campylobacter Gastroenteritis <ul><li>Campylobacter jejuni </li></ul><ul><li>Usually transmitted in cow's milk </li></ul><ul><li>Most common cause of diarrhea </li></ul><ul><li>Guillain – Barré syndrome </li></ul><ul><li>Low infectious dose </li></ul>
  24. 24. Campylobacter Gastroenteritis
  25. 25. Other Gastroenteritis <ul><li>Yersinia Gastroenteritis </li></ul><ul><ul><li>Y. enterocolitica and Y. pseudotuberculosis </li></ul></ul><ul><ul><li>Can reproduce at 4°C </li></ul></ul><ul><ul><li>Usually transmitted in meat and milk </li></ul></ul><ul><li>Clostridium perfringens Gastroenteritis </li></ul><ul><ul><li>Grow in intestinal tract producing exotoxin </li></ul></ul><ul><li>Bacillus cereus Gastroenteritis </li></ul><ul><ul><li>Ingestion of bacterial exotoxin produces mild symptoms </li></ul></ul>
  26. 26. Rotavirus <ul><li>3 million cases annually </li></ul><ul><li>1-2 day incubation, 1 week illness </li></ul><ul><li>Reovirus family </li></ul><ul><li>Main diarrheal illness of infants and children </li></ul><ul><li>Associated with traveler’s diarrhea </li></ul>
  27. 27. Giardiasis <ul><li>Giardia lamblia </li></ul><ul><li>Drinking water contamination by feces </li></ul><ul><li>Traveler’s diarrhea </li></ul><ul><li>Two forms </li></ul><ul><ul><li>Vegetative trophozoite </li></ul></ul><ul><ul><li>Resting form (cyst) </li></ul></ul><ul><ul><ul><li>survive chlorinated water </li></ul></ul></ul><ul><li>Diagnosed by microscopic examination of stool for ova and trophozoite </li></ul>
  28. 28. Features of giardiasis
  29. 29. Cryptosporidiosis <ul><li>Cryptosporidium parvum </li></ul><ul><li>Transmitted by oocysts in contaminated water </li></ul><ul><ul><li>difficult to remove by filtration </li></ul></ul><ul><li>Wide host range – human, domestic animals </li></ul><ul><li>Diagnosed by acid-fast staining of stool or presence of antibodies by FA or ELISA </li></ul><ul><li>Treated with oral rehydration </li></ul>
  30. 30. Features of crytosporidiosis
  31. 31. Amoebic Dysentery <ul><li>Entamoeba histolytica </li></ul><ul><li>Chronic – spread to the liver and other organs </li></ul><ul><li>Two forms </li></ul><ul><ul><li>Ameba: feeds on RBCs and GI tract tissues </li></ul></ul><ul><ul><li>Cyst (quadrinucleate cyst is infectious) </li></ul></ul><ul><li>Diagnosis by observing trophozoites in feces </li></ul><ul><li>Treated with metronidazole </li></ul>
  32. 32. Features of Amoebic Dysentery
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