General Principles
- Preformed Enterotoxin (Onset 1–6 hrs; rapid):
- Staphylococcus aureus: Mayonnaise, cream pastries, deli meats, potato salad.
- Bacillus cereus: Reheated fried rice.
- Enterotoxin Produced In Vivo (Onset 8–16 hrs):
- Clostridium perfringens: Reheated meat, poultry, buffet dishes.
- ETEC (Enterotoxigenic E. coli): Unwashed vegetables, water (traveler’s diarrhea).
- Invasive / Inflammatory Bacterial (Onset 16–72 hrs):
- Campylobacter jejuni: Undercooked poultry, unpasteurized milk (most common bacterial cause in US).
- Salmonella enteritidis: Poultry, eggs, reptiles/turtles.
- STEC (Shiga toxin-producing E. coli / O157:H7): Undercooked ground beef, raw leafy greens, unpasteurized juices.
- Shigella sonnei/flexneri: Daycare centers, food handled by infected workers (fecal-oral).
- Vibrio vulnificus / parahaemolyticus: Raw shellfish/oysters (high risk of severe sepsis in underlying liver disease/hemochromatosis).
- Listeria monocytogenes: Deli meats, unpasteurized milk/soft cheeses, hot dogs (high risk in pregnant, elderly, immunocompromised).
- Viral Gastroenteritis (Onset 24–48 hrs): c
- Norovirus: Cruise ships, schools, communal dining, raw shellfish (most common overall cause).
- Rotavirus: Unvaccinated infants, daycares.E
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. c
- 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.