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  1. 1. Chapter 25: Disease of the digestive system <ul><li>The digestive system consists of the mouth, salivary glands, pharynx, esophagus, stomach, small and large intestines, liver, gall bladder, and pancreas </li></ul><ul><li>Part of this tract is a tube running through the body from the mouth to anus is colonized by many different normal microbiota </li></ul>
  2. 2. Disease of the digestive system <ul><li>3. Diseases of digestive system are mainly of 2 types: infection an intoxications </li></ul><ul><li>a. infection occurs when a pathogen enters the GI tract and multiplies </li></ul><ul><li>b. intoxication is caused by ingestion of preformed toxins </li></ul><ul><li>4. Gastroenteritis = an infection of the stomach or intestinal mucosa caused by ingestion of food or water with pathogens </li></ul>
  3. 3. Bacterial Diseases of the Lower GI Tract <ul><li>Staphylococcal food poisoning – 2 nd most reported of foodborne disease, Salmonella related illnesses are #1 </li></ul><ul><li>1. Staphylococcus aureus causes a food intoxication by ingesting an enterotoxin of S. aureus in contaminated food </li></ul><ul><li>a. enterotoxin = exotoxin that caused gastroenteritis (Staphylococcus, Vibrio, Escherichia) </li></ul><ul><li>b. gram positive coccus </li></ul>
  4. 4. Staphylococcus food poisoning <ul><li>2. Vegetative cells have a high resistance to heat – can tolerate 30 minutes at 60 C (140 F) </li></ul><ul><li>a. the toxin is also heat stable and can tolerate 30 minutes of boiling </li></ul><ul><li>3. Found on hands and is easily transferred to food ( Staph aureus is a normal microbiota of nasal passages and is found in skin wounds) </li></ul><ul><li>a. food prepared in advance and not refrigerated is a potential source of Staphylococcal food poisoning </li></ul>
  5. 5. Staphylococcus food poisoning <ul><li>4. High risk foods are custards, cream pies, ham, poultry products and there is no obvious signs of spoilage – no unusual tastes, odor or appearance </li></ul><ul><li>5. Incubation period is 1-6 hours after ingestion, recovery in 24 hours </li></ul><ul><li>6. Sxs = abdominal cramps, severe nausea, vomiting, HA, fever, prostration, diarrhea </li></ul><ul><li>(toxin causes release of water) </li></ul>
  6. 6. Salmonellosis <ul><li>1. Many species of Salmonella cause foodborne infection, Gram neg rods </li></ul><ul><li>2. The intensity of Salmonella food poisoning depends on the number of bacteria ingested in contaminated products such as poultry </li></ul><ul><li>3. The bacteria replicate in the intestinal mucosa and in macrophages </li></ul><ul><li>4. Incubation period from the time of infection is </li></ul><ul><li>1-3 days before onset of sxs </li></ul>
  7. 7. Salmonellosis <ul><li>5. Sxs = nausea, severe abdominal cramping, watery diarrhea, fever and possibly vomiting after 6 - 48 hours </li></ul><ul><li>a. sxs may last more than a week </li></ul><ul><li>6. Dx = isolate pathogen from px stool or leftover food </li></ul><ul><li>7. Tx = antibiotics are not useful, if dehydrated fluid replacement </li></ul>
  8. 8. Salmonellosis <ul><li>8. Salmonella infect poultry and poultry products such as eggs </li></ul><ul><li>a. they infect the ovary of hens and pass into the egg before the shell forms </li></ul><ul><li>b. infect egg products – custard pies, cream cakes, egg nog, ice cream, mayonnaise </li></ul><ul><li>9. Not a lethal bioweapon but in 1984 in Oregon, members of a religious cult sprayed the bacteria on the salad bars of some restaurants, 750 people became ill but none died </li></ul>
  9. 9. Cholera – one of the most serious GI diseases <ul><li>Vibrio cholerae – curved, gram neg, flagellated rod – 1 st isolated by Robert Koch in 1883 </li></ul><ul><ul><li>Grows in the small intestine where an enterotoxin of Vibrio cholera interferes with water and electrolyte re-absorption </li></ul></ul><ul><ul><li>1) the enterotoxin is an exotoxin = cholera toxin </li></ul></ul><ul><ul><li>b. Result is watery stools called “rice water stools” </li></ul></ul>
  10. 10. Cholera <ul><li>b. 1) can lose 3 – 5 gallons of fluids/day </li></ul><ul><li> 2) sudden loss of fluids and electrolytes can cause shock, collapse, and death </li></ul><ul><li> 3) blood becomes viscous and organs can’t function </li></ul><ul><li> 4) violent vomiting also occurs </li></ul><ul><li>c. dx is based on sxs and culturing the pathogen from feces </li></ul>
  11. 11. Cholera <ul><li>d. transmitted through contaminated food or water </li></ul><ul><li>e. tx = intravenous replacement of fluids and electrolytes </li></ul><ul><li>1) untreated there is a 50% mortality rate </li></ul><ul><li>2. Non cholera vibrios </li></ul><ul><li>a. Vibrio parahaemolyticus likes brackish water and have been associated with outbreaks of gastroenteritis associated with seafood ingestion </li></ul>
  12. 12. Cholera <ul><li>2. b. Vibrio vulnificus – found in estuaries </li></ul><ul><li>1) ingestion of raw or undercooked seafood causes septicemia </li></ul><ul><li>2) people with compromised immune systems are at higher risks </li></ul><ul><li>3) causes dangerous infections of minor skin lesions with rapidly spreading tissue destruction that may require limb amputation </li></ul>
  13. 13. Campylobacter gastroenteritis <ul><li>Campylobacter jejuni – gram neg, spirally curved rod that is becoming a leading cause of food borne illness in the US </li></ul><ul><ul><li>a. Invades and damages the mucosal surfaces of the small intestine and colon </li></ul></ul><ul><li>Sxs = bloody or watery diarrhea, abdominal pain, cramps, fever – recovery in 1 week </li></ul><ul><li>Complication – 1 in 1000 cases is Guillain-Barre syndrome = a neurological disease that causes temporary paralysis </li></ul>
  14. 14. Shigellosis = Bacillary dysentery <ul><li>Bacterial infections – Salmonellosis and shigellosis have loner incubation periods </li></ul><ul><li>(12 hrs to 2 weeks) than intoxications </li></ul><ul><li>Shigellosis – severe diarrhea caused by facultative anaerobic gram neg rods </li></ul><ul><li>4 species of pathogenic Shigella </li></ul><ul><li>a. most common in US = Shigella sonnei – causes mild diarrhea </li></ul><ul><li>b. Shigella dysenteriae – severe dysentery and prostration </li></ul><ul><li>1) can cause 20 bowel movements a day with abdominal cramps and fever </li></ul>
  15. 15. Diseases of the digestive tract <ul><li>Shigellosis </li></ul><ul><li>2. Food contaminated with Shigella dysenteriae gives rise to dysentery through the production of an enterotoxin (Shiga toxin) </li></ul><ul><li>3. Sx = abdominal pain, fever, watery stool with mucus and blood, dehydration </li></ul><ul><li>4. Dx = recovery of microbe from rectal swab </li></ul><ul><li>5. Tx = antibiotics and oral re- hydration </li></ul>
  16. 16. Escherichia coli gastroenteritis – produce toxins <ul><li>Normally harmless but certain strains are pathogenic O157: H7 </li></ul><ul><li>Traveler’s diarrhea –sxs appear within 2 weeks of travel to a tropical location and last up to 10 days </li></ul><ul><li>a. Enterotoxigenic E. coli – not invasive, produce enterotoxin in the small intestine that causes watery diarrhea that resembles a mild case of cholera </li></ul>
  17. 17. Escherichia coli gastroenteritis <ul><li>2. Traveler’s diarrhea </li></ul><ul><li>b. Enteroinvasive E. coli – invades the intestinal wall resulting in inflammation, fever, and Shigella like dysentery </li></ul><ul><li>3. E. coli O157:H7 </li></ul><ul><li>a. confined to the large intestine – bloody diarrhea = hemorrhagic colitis </li></ul><ul><li>b. involves kidneys – kidney failure = hemolytic uremic syndrome (HUS) </li></ul><ul><li>1) seizures, coma, colon perforation, liver disorders are associated with it </li></ul>
  18. 18. Escherichia coli gastroenteritis <ul><li>3. E. coli O157:H7 </li></ul><ul><li>c. this bacteria is in the intestines of cattle and do not produce disease </li></ul><ul><li>1) contamination takes place during slaughter of the animal and brings E. coli to the beef product such as hamburger meat </li></ul><ul><li>2) excretion to the soil brings E. coli to plants such as spinach and fruits - cantaloupe </li></ul>
  19. 19. Viral Diseases of the Digestive Tract <ul><li>Mumps – caused by RNA virus </li></ul><ul><li>Sign = swelling of salivary lands esp. parotid glands </li></ul><ul><li>a. obstruction of the ducts leading from the parotid glands retards the flow of saliva and causes swelling – the skin over the glands – taut, shiny </li></ul>
  20. 20. Mumps <ul><li>2. Sx/signs = painful swelling of the parotid glands, fever, chills, HA, malaise, pain when swallowing </li></ul><ul><li>3. In adult males may infect testicles (orchitis) and cause sterility </li></ul><ul><li>4. Transmitted via the saliva and respiratory secretions </li></ul><ul><li>a. portal of entry = respiratory tract </li></ul><ul><li>b. spreads to the salivary glands from the blood </li></ul><ul><li>5. MMR vaccine – attenuated live vaccine </li></ul>