Harvey's Garden

Food poisoning

2 min read

General Principles

  • Preformed Toxin: Rapid onset (1–6 hrs). Bacteria produce toxin in food before ingestion.
    • Sx: Nausea/Vomiting > Diarrhea.
    • Ex: S. aureus, B. cereus.
  • Enterotoxin Production: Delayed onset (8–16 hrs). Organisms ingested, multiply, and produce toxin in vivo.
    • Sx: Watery diarrhea, cramps.
    • Ex: C. perfringens, ETEC, Vibrio cholerae.
  • Invasive: Delayed onset (>16 hrs). Organisms invade intestinal mucosa.
    • Sx: Bloody diarrhea (Dysentery), fever, leukocytes in stool.
    • Ex: Salmonella, Shigella, Campylobacter, EIEC, Yersinia.

High-Yield Organism Associations (Buzzwords)

  • Staphylococcus aureus
    • Source: Meats, mayonnaise, custard, potato salad left at room temp.
    • Mechanism: Heat-stable enterotoxin.
    • Features: Short incubation (<6 hrs), prominent vomiting.
  • Bacillus cereus
    • Source: Reheated rice (e.g., Chinese buffets).
    • Mechanism: Emetic toxin (cereulide) is heat-stable.
    • Features: “Fried Rice Syndrome”; vomiting predominant.
  • Clostridium perfringens
    • Source: Reheated meat dishes, gravy.
    • Features: Watery diarrhea, slow onset (8–16 hrs), resolves in 24 hrs.
  • Clostridium botulinum
    • Source: Improperly canned foods (adults), honey (infants).
    • Features: Descending paralysis, diplopia, dysarthria, dysphagia (“Floppy baby”).
  • E. coli O157:H7 (EHEC)
    • Source: Undercooked ground beef (hamburgers).
    • Mechanism: Shiga-like toxin; inactivates 60S ribosome.
    • Complication: Hemolytic Uremic Syndrome (HUS) (Triad: Anemia, Thrombocytopenia, Acute Renal Failure).
    • Note: Does not ferment sorbitol.
  • Salmonella enteritidis
    • Source: Poultry, eggs, reptile pets (turtles).
    • Features: Bloody diarrhea, fever.
  • Campylobacter jejuni
    • Source: Undercooked poultry, unpasteurized milk.
    • Morphology: Comma/S-shaped rods; grows at 42°C (“Campfire”).
    • Complication: Guillain-Barré syndrome (molecular mimicry).
  • Vibrio parahaemolyticus / vulnificus
    • Source: Contaminated seafood/shellfish (oysters).
    • Features: Watery diarrhea (parahaemolyticus); Cellulitis/Sepsis in liver disease pts (vulnificus).
  • Listeria monocytogenes
    • Source: Deli meats, soft cheeses (brie/feta), unpasteurized milk.
    • Risk: Pregnant women (amnionitis, spontaneous abortion), immunocompromised, elderly (meningitis).
    • Tx: Ampicillin.
  • Yersinia enterocolitica
    • Source: Pet feces (puppies), contaminated milk/pork.
    • Features: Pseudoappendicitis (mesenteric adenitis/terminal ileitis).

Non-Bacterial Agents

  • Norovirus: #1 cause of gastroenteritis in adults; outbreaks in cruise ships, schools, nursing homes. Vomiting + Diarrhea.
  • Rotavirus: #1 cause of severe diarrhea in infants/children (unvaccinated). Daycare outbreaks.
  • Giardia lamblia: Hikers drinking stream water; foul-smelling fatty stools (steatorrhea). Tx: Metronidazole.
  • Scombroid: Spoiled dark-meat fish (tuna, mahi-mahi); Histidine → Histamine. Mimics anaphylaxis (burning mouth, flushing). Tx: Antihistamines.
  • Ciguatera: Reef fish (barracuda, snapper); ciguatoxin opens Na+ channels. Perioral numbness, reversal of hot/cold sensations.

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