Chapter 22b - Lecture Outline

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Chapter 22b - Lecture Outline

  1. 1. Microbiology: A Systems Approach, 2 nd ed. Chapter 22: The Gastrointestinal Tract and Its Defenses
  2. 2. Acute Diarrhea Caused by E.coli O157:H7 (EHEC) <ul><li>Most virulent strain of E. coli </li></ul><ul><li>Enterohemorrhagic E. coli </li></ul><ul><li>Symptoms range from mild gastroenteritis with fever to bloody diarrhea </li></ul><ul><li>About 10% of patients develop hemolytic uremic syndrome (can cause kidney damage and failure) </li></ul><ul><li>Can also cause neurological symptoms such as blindness, seizure, and stroke </li></ul>
  3. 3. Figure 22.12
  4. 4. Acute Diarrhea Caused by Other E. coli <ul><ul><li>Four other categories: </li></ul></ul><ul><ul><ul><li>Enterotoxigenic </li></ul></ul></ul><ul><ul><ul><li>Enteroinvasive </li></ul></ul></ul><ul><ul><ul><li>Enteropathogenic </li></ul></ul></ul><ul><ul><ul><li>Enteroaggregative </li></ul></ul></ul>
  5. 5. Enterotoxigenic E. coli (ETEC) <ul><li>Presentation varies depending on which type of E. coli is causing the disease </li></ul><ul><li>Traveler’s diarrhea : watery diarrhea, low-grade fever, nausea, and vomiting </li></ul>
  6. 6. Enteroinvasive E. coli (EIEC) <ul><li>Cause a disease similar to Shigella dysentery </li></ul><ul><li>Invade gut mucosa and cause widespread destruction </li></ul><ul><li>Blood and pus found in stool </li></ul><ul><li>Significant fever </li></ul>
  7. 7. Enteropathogenic E. coli (EPEC) <ul><li>Profuse, watery diarrhea </li></ul><ul><li>Fever and vomiting also common </li></ul><ul><li>Produce effacement of gut surfaces </li></ul>
  8. 8. Enteroaggregative E. coli (EAEC) <ul><ul><ul><li>Can cause chronic diarrhea in young children and in AIDS patients </li></ul></ul></ul>
  9. 9. Acute Diarrhea Caused by Campylobacter <ul><li>Most common bacterial cause of diarrhea in the U.S. </li></ul><ul><li>Frequent watery stools, fever, vomiting, headaches, and severe abdominal pain </li></ul><ul><li>Symptoms may last beyond 2 weeks </li></ul><ul><li>Symptoms may subside then recur over a period of weeks </li></ul><ul><li>In a small number of cases, can lead to a serious neuromuscular paralysis called Guillain-Barré syndrome (GBS) </li></ul>
  10. 10. Figure 22.13
  11. 11. Acute Diarrhea Caused by Yersinia Species <ul><li>Y. enterocolitica and Y. pseudotuberculosis </li></ul><ul><li>Uncommon in U.S. </li></ul><ul><li>Inflammation of the ileum and mesenteric lymph nodes gives rise to severe abdominal pain </li></ul><ul><li>Infection occasionally spreads to the bloodstream </li></ul>
  12. 12. Acute Diarrhea Caused by Clostridium difficile <ul><li>Causes pseudomembranous colitis </li></ul><ul><li>Major cause of diarrhea in hospitals </li></ul><ul><li>Able to superinfect the large intestine when drugs have disrupted the normal biota </li></ul><ul><li>Produces two enterotoxins (toxins A and B) that cause areas of necrosis in the wall of the intestine </li></ul><ul><li>Diarrhea </li></ul><ul><li>Severe cases exhibit abdominal cramps, fever, and leukocytosis </li></ul>
  13. 13. Figure 22.14
  14. 14. Acute Diarrhea Caused by Vibrio cholera <ul><li>Incubation period of a few hours to a few days </li></ul><ul><li>Symptoms begin abruptly with vomiting </li></ul><ul><li>Followed by copious watery feces called secretory diarrhea </li></ul><ul><li>Can lose up to 1 liter of fluid an hour in severe cases </li></ul>
  15. 15. Figure 22.15
  16. 16. Acute Diarrhea Caused by Cryptosporidium <ul><li>Headache, sweating, vomiting, severe abdominal cramps, and diarrhea </li></ul><ul><li>In AIDS patients may develop into chronic persistent cryptosporidial diarrhea </li></ul>
  17. 17. Figure 22.16
  18. 18. Figure 22.17
  19. 19. Acute Diarrhea Caused by Rotavirus <ul><ul><li>Effects of infection vary with age, nutritional state, general health, and living conditions of the patient </li></ul></ul>
  20. 20. Figure 22.18
  21. 21. Acute Diarrhea Caused by Other Viruses <ul><li>Many other viruses can cause gastroenteritis </li></ul><ul><li>For example adenoviruses, noroviruses, and astroviruses </li></ul><ul><li>Common in the U.S. and around the world </li></ul><ul><li>Profuse, water diarrhea of 3 to 5 days duration </li></ul>
  22. 24. Acute Diarrhea with Vomiting (Food Poisoning) <ul><li>Symptoms in the gut that are caused by a preformed toxin of some sort </li></ul><ul><li>If the symptoms are violent and the incubation period is very short, intoxication rather than infection should be considered </li></ul>
  23. 25. Food Poisoning by Staphylococus aureus Exotoxin <ul><li>Associated with food such as custards, sauces, cream pastries, processed meats, chcken salad, or ham that have been contaminated and then left unrefrigerated for a few hours </li></ul><ul><li>Toxins do not noticeably alter the food’s taste or smell </li></ul><ul><li>Heating the food after toxin production may not prevent disease </li></ul><ul><li>Symptoms: cramping, nausea, vomiting, and diarrhea </li></ul><ul><li>Rapid recovery- usually within 24 hours </li></ul>
  24. 26. Food Poisoning by Bacillus cereus Exotoxin <ul><li>Two exotoxins: one causes diarrheal-type disease, the other cause an emetic disease </li></ul><ul><li>The type of disease that takes place is influenced by the type of food that is contaminated </li></ul><ul><li>Emetic form frequently linked to fried rice, especially when cooked and kept warm for long periods of time </li></ul><ul><li>Diarrheal form associated with cook mats or vegetables that are held at a warm temperature for long periods of time </li></ul>
  25. 27. Food Poisoning by Clostridum perfringens Exotoxin <ul><li>Animal flesh and vegetables such as beans that have not been cooked thoroughly enough to destroy endospores </li></ul><ul><li>Acute abdominal pain, diarrhea, and nausea in 8 to 16 hours </li></ul><ul><li>Rapid recovery </li></ul>

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