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Chp25. Presentation Transcript

  • 1. Chapter 25: Disease of the digestive system
    • The digestive system consists of the mouth, salivary glands, pharynx, esophagus, stomach, small and large intestines, liver, gall bladder, and pancreas
    • Part of this tract is a tube running through the body from the mouth to anus is colonized by many different normal microbiota
  • 2. Disease of the digestive system
    • 3. Diseases of digestive system are mainly of 2 types: infection an intoxications
    • a. infection occurs when a pathogen enters the GI tract and multiplies
    • b. intoxication is caused by ingestion of preformed toxins
    • 4. Gastroenteritis = an infection of the stomach or intestinal mucosa caused by ingestion of food or water with pathogens
  • 3. Bacterial Diseases of the Lower GI Tract
    • Staphylococcal food poisoning – 2 nd most reported of foodborne disease, Salmonella related illnesses are #1
    • 1. Staphylococcus aureus causes a food intoxication by ingesting an enterotoxin of S. aureus in contaminated food
    • a. enterotoxin = exotoxin that caused gastroenteritis (Staphylococcus, Vibrio, Escherichia)
    • b. gram positive coccus
  • 4. Staphylococcus food poisoning
    • 2. Vegetative cells have a high resistance to heat – can tolerate 30 minutes at 60 C (140 F)
    • a. the toxin is also heat stable and can tolerate 30 minutes of boiling
    • 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)
    • a. food prepared in advance and not refrigerated is a potential source of Staphylococcal food poisoning
  • 5. Staphylococcus food poisoning
    • 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
    • 5. Incubation period is 1-6 hours after ingestion, recovery in 24 hours
    • 6. Sxs = abdominal cramps, severe nausea, vomiting, HA, fever, prostration, diarrhea
    • (toxin causes release of water)
  • 6. Salmonellosis
    • 1. Many species of Salmonella cause foodborne infection, Gram neg rods
    • 2. The intensity of Salmonella food poisoning depends on the number of bacteria ingested in contaminated products such as poultry
    • 3. The bacteria replicate in the intestinal mucosa and in macrophages
    • 4. Incubation period from the time of infection is
    • 1-3 days before onset of sxs
  • 7. Salmonellosis
    • 5. Sxs = nausea, severe abdominal cramping, watery diarrhea, fever and possibly vomiting after 6 - 48 hours
    • a. sxs may last more than a week
    • 6. Dx = isolate pathogen from px stool or leftover food
    • 7. Tx = antibiotics are not useful, if dehydrated fluid replacement
  • 8. Salmonellosis
    • 8. Salmonella infect poultry and poultry products such as eggs
    • a. they infect the ovary of hens and pass into the egg before the shell forms
    • b. infect egg products – custard pies, cream cakes, egg nog, ice cream, mayonnaise
    • 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
  • 9. Cholera – one of the most serious GI diseases
    • Vibrio cholerae – curved, gram neg, flagellated rod – 1 st isolated by Robert Koch in 1883
      • Grows in the small intestine where an enterotoxin of Vibrio cholera interferes with water and electrolyte re-absorption
      • 1) the enterotoxin is an exotoxin = cholera toxin
      • b. Result is watery stools called “rice water stools”
  • 10. Cholera
    • b. 1) can lose 3 – 5 gallons of fluids/day
    • 2) sudden loss of fluids and electrolytes can cause shock, collapse, and death
    • 3) blood becomes viscous and organs can’t function
    • 4) violent vomiting also occurs
    • c. dx is based on sxs and culturing the pathogen from feces
  • 11. Cholera
    • d. transmitted through contaminated food or water
    • e. tx = intravenous replacement of fluids and electrolytes
    • 1) untreated there is a 50% mortality rate
    • 2. Non cholera vibrios
    • a. Vibrio parahaemolyticus likes brackish water and have been associated with outbreaks of gastroenteritis associated with seafood ingestion
  • 12. Cholera
    • 2. b. Vibrio vulnificus – found in estuaries
    • 1) ingestion of raw or undercooked seafood causes septicemia
    • 2) people with compromised immune systems are at higher risks
    • 3) causes dangerous infections of minor skin lesions with rapidly spreading tissue destruction that may require limb amputation
  • 13. Campylobacter gastroenteritis
    • Campylobacter jejuni – gram neg, spirally curved rod that is becoming a leading cause of food borne illness in the US
      • a. Invades and damages the mucosal surfaces of the small intestine and colon
    • Sxs = bloody or watery diarrhea, abdominal pain, cramps, fever – recovery in 1 week
    • Complication – 1 in 1000 cases is Guillain-Barre syndrome = a neurological disease that causes temporary paralysis
  • 14. Shigellosis = Bacillary dysentery
    • Bacterial infections – Salmonellosis and shigellosis have loner incubation periods
    • (12 hrs to 2 weeks) than intoxications
    • Shigellosis – severe diarrhea caused by facultative anaerobic gram neg rods
    • 4 species of pathogenic Shigella
    • a. most common in US = Shigella sonnei – causes mild diarrhea
    • b. Shigella dysenteriae – severe dysentery and prostration
    • 1) can cause 20 bowel movements a day with abdominal cramps and fever
  • 15. Diseases of the digestive tract
    • Shigellosis
    • 2. Food contaminated with Shigella dysenteriae gives rise to dysentery through the production of an enterotoxin (Shiga toxin)
    • 3. Sx = abdominal pain, fever, watery stool with mucus and blood, dehydration
    • 4. Dx = recovery of microbe from rectal swab
    • 5. Tx = antibiotics and oral re- hydration
  • 16. Escherichia coli gastroenteritis – produce toxins
    • Normally harmless but certain strains are pathogenic O157: H7
    • Traveler’s diarrhea –sxs appear within 2 weeks of travel to a tropical location and last up to 10 days
    • a. Enterotoxigenic E. coli – not invasive, produce enterotoxin in the small intestine that causes watery diarrhea that resembles a mild case of cholera
  • 17. Escherichia coli gastroenteritis
    • 2. Traveler’s diarrhea
    • b. Enteroinvasive E. coli – invades the intestinal wall resulting in inflammation, fever, and Shigella like dysentery
    • 3. E. coli O157:H7
    • a. confined to the large intestine – bloody diarrhea = hemorrhagic colitis
    • b. involves kidneys – kidney failure = hemolytic uremic syndrome (HUS)
    • 1) seizures, coma, colon perforation, liver disorders are associated with it
  • 18. Escherichia coli gastroenteritis
    • 3. E. coli O157:H7
    • c. this bacteria is in the intestines of cattle and do not produce disease
    • 1) contamination takes place during slaughter of the animal and brings E. coli to the beef product such as hamburger meat
    • 2) excretion to the soil brings E. coli to plants such as spinach and fruits - cantaloupe
  • 19. Viral Diseases of the Digestive Tract
    • Mumps – caused by RNA virus
    • Sign = swelling of salivary lands esp. parotid glands
    • 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
  • 20. Mumps
    • 2. Sx/signs = painful swelling of the parotid glands, fever, chills, HA, malaise, pain when swallowing
    • 3. In adult males may infect testicles (orchitis) and cause sterility
    • 4. Transmitted via the saliva and respiratory secretions
    • a. portal of entry = respiratory tract
    • b. spreads to the salivary glands from the blood
    • 5. MMR vaccine – attenuated live vaccine