GI: Food Poisoning

Question 1

• “Food poisoning from reheated rice“
• < 6 hours incubation
• Emetic syndrome (1-5 hrs)
• > 10 hours incubation
• Diarrheal syndrome (15 - 20 hrs)
• Gram + rods
• Form spores
• Motile

Answer 1

Bacillus cerus (B. cerus)

• Heat-stable enterotoxin –> vomiting, nausea
• Increase [cAMP] –> decreased NaCl reabsorption –> diarrhea

Question 2

• “Improperly canned foods” (bulging cans)
• Gram + bacteria
• Bacilli
• Spore forming - obligate anaerobe (loves cans)

Answer 2

Clostridium botulinum

• Adult –> Food poisoning (12 - 36 hrs)
  
  • Toxin blocks acetylcholine release at Cranial nerves –> Diplopia, Dysarthria, Dysphagia
• Infant –> Floppy baby syndrome
  
  • Spores often in Honey –> absorbed over days –> blocks acetylcholine release –> Constipation, Flaccid paralysis –> good prognosis and supportive therapy

Question 3

• “Reheated meat dishes”
• > 10 hours incubation
• Enterotoxin released w/ reheating –> inhibits Glucose transport –> damages Epithelium
• Diarrhea, Gastric Pain, Nausea (NO Fever, NO Vomiting)
• Cellulitis
• Gas gangrene (Myonecrosis w/ Crepitus)
• Gram +
• Bacilli
• Spore-forming - Non-motile
• Obligate anaerobe

Answer 3

Clostridium perfringens

Question 4

• “Undercooked meat”
• Enteritis (Watery diarrhea or dysentery
• Hemolytic Uremic Syndrome (HUS)
• LT: AB₅ toxin –> Watery diarrhea
• ST: Guanylate cyclase –> increases cGMP –> Watery diarrhea
• SLT: inactivates 60S ribosome unit –> blocks protein synthesis –> cell death
• Gram - rod
• Ferments lactose

Answer 4

E. coli 0157:H7

Question 5

• “Poultry, meat, and eggs”
• Chickens / Turtles
• Gastroenteritis
• Gram - bacilli
• Lactose non-fermenter
• Oxidase -
• Produces H₂S motile
• Constipation + Fever alternating w/ history of travel to endemic areas
• Invasive –> Watery diarrhea –> Bloody diarrhea

Answer 5

Salmonella enteritidis

Question 6

• “Meats, mayonnaise, custard, preformed toxin”
• < 6 hrs
• Gram +
• Cocci
• Catalase + and Coagulase +
• Bacteria release toxin in foods –> heat-stable Enterotoxin SE-A –> Gastroenteritis –> 8 - 24 hrs self limiting
• Vomiting, Diarrhea, Abdominal pain

Answer 6

Staphylococcus aureus

Question 7

• “Contaminated seafood”
• Most often in Japan
• “Rice-water” diarrhea
• Dehydration
• AB₅ toxin –> Ribosylates Gs –> keeping Adenylate cyclase active –> increasing [cAMP] –> crypt cells secrete more Cl-, villous cells absorbe Na+ –> Osmotic loss of water in Lumen –> watery diarrhea and dehydration –> can lead to hypovalemic shock / death

Answer 7

V. parahaemolyticus and V. vulnificus