Food Poisoning, Bacterial



  • Food poisoning or foodborne illness is caused by the consumption of food or water that is contaminated with bacterial, parasitic, or viral pathogens. Other causes can result from ingestion of molds, toxin, contaminants, and/or allergens.
  • Symptoms are most commonly gastrointestinal in nature and are typically self-limited. Some cases can lead to severe dehydration and critical illness.


  • The cause is unclear in up to 80% of cases. Most foodborne illnesses are secondary to viral causes, with Norovirus being the most common. Other viral causes include hepatitis A, rotavirus, and adenovirus.
  • Campylobacter and nontyphoidal Salmonella are the most common causes of bacterial foodborne illness in the United States. Other less common pathogens include Shiga toxin-producing Escherichia coli (STEC), Shigella, Cyclospora, Yersinia, Listeria, and Vibrio.
  • Salmonella (nontyphoidal) infections are most commonly associated with hospitalizations and deaths (1).

Roughly 1 in 6 Americans (48 million) and 1 in 10 across the world become ill from foodborne illness each year; approximately 128,000 hospitalizations and 3,000 deaths per year (2)

Etiology and Pathophysiology

  • Staphylococcus aureus (3)
    • Timing of symptom onset: 1 to 6 hours. Symptoms: sudden onset of severe nausea and vomiting; abdominal cramps and fever. Sources: unrefrigerated or improperly refrigerated meats and potato, mayonnaise and egg salads
  • Bacillus cereus (3)
    • Timing of symptom onset: 10 to 16 hours. Symptoms: sudden onset of severe nausea; vomiting and watery diarrhea, nausea and cramps. Sources: soil, improperly cooked rice/fried rice and red meats
  • Clostridium perfringens (3)
    • Timing of symptom onset: 8 to 16 hours. Symptoms: watery diarrhea, nausea, cramps. Sources: dry/precooked or undercooked meats, poultry, home-canned goods
  • Clostridium botulinum (3)
    • Timing of symptom onset: 12 to 72 hours. Symptoms: vomiting, diarrhea, slurred speech, diplopia, dysphagia, and descending muscle weakness/flaccid paralysis. Source: commercially canned or improperly home-canned foods
  • Enterohemorrhagic E. coli (e.g., 0157:H7) (3)
    • Timing of symptom onset: 1 to 8 days. Symptoms: severe diarrhea that often becomes bloody, abdominal pain, vomiting. Sources: undercooked ground beef, juice, unpasteurized milk, raw produce, and contaminated water
  • Enterotoxigenic E. coli (“traveler’s diarrhea”) (3)
    • Timing of symptom onset: 1 to 3 days. Symptoms: watery diarrhea, abdominal cramps, tenesmus, fecal urgency, and vomiting. Sources: food or water contaminated by human feces
  • Salmonella, nontyphoidal (3)
    • Timing of symptom onset: 6 to 48 hours. Symptoms: small volume, mucopurulent/bloody diarrhea; fever; cramps; vomiting. Food sources: contaminated eggs, poultry; unpasteurized milk or juice, cheese; contaminated raw fruit and vegetables; and contaminated peanut butter
  • Campylobacter jejuni (3)
    • Timing of symptom onset: 2 to 5 days. Symptoms: diarrhea (bloody), cramps, vomiting, fever. Food sources: raw and undercooked poultry, unpasteurized milk, and contaminated meats
  • Shigella (3)
    • Timing of symptom onset: 4 to 7 days. Symptoms: abdominal cramps, fever, mucopurulent, and bloody diarrhea. Food sources: contaminated water, raw produce, uncooked foods, foods handled by infected food workers
  • Vibrio parahaemolyticus (3)
    • Timing of symptom onset: 4 to 96 hours. Symptoms: nausea, vomiting, diarrhea, abdominal pain. Food source: undercooked or raw seafood, especially shellfish
  • Vibrio vulnificus (3)
    • Timing of symptom onset: 1 to 7 days. Symptoms: vomiting, diarrhea, abdominal pain, bacteremia, wound infections; can be fatal in patients with liver disease or those who are immunocompromised. Food source: undercooked or raw seafood, particularly oysters
  • Yersinia enterocolitica
    • Timing of symptom onset: 4 to 7 days. Symptoms: abdominal pain, fever, diarrhea (possibly bloody), vomiting. Food sources: undercooked beef and pork, unpasteurized milk, tofu, contaminated water
  • Listeria monocytogenes (3)
    • Timing of symptom onset: 4 to 48 hours. Symptoms: nausea, vomiting, fever, watery diarrhea; pregnant women may have a flu-like illness leading to premature delivery or stillbirth; immunocompromised patients may develop meningitis and bacteremia. Food sources: unpasteurized/contaminated milk, soft cheese, and processed deli meats

Risk Factors

  • Recent travel to developing countries
  • Food handlers, daycare attendees, nursing home residents, recently hospitalized patients, or patients recently exposed to antibiotics; altered immunity due to underlying disease or use of certain medications, including antacids, H2 blockers, and proton pump inhibitors
  • Cross-contamination and subsequent ingestion of improperly prepared and stored foods
  • Pregnancy; children aged <5 years and adults aged >65 years; immunocompromised patients

General Prevention

  • When preparing food:
    • Wash hands, cutting boards, and preparation surfaces. Wash fresh produce thoroughly before consuming.
    • Keep raw meat, poultry, fish, and their juices away from other food (e.g., salad). Wear gloves when handling raw meat (4). Thoroughly cook the meat. Refrigerate leftovers within 2 to 3 hours in clean, shallow, covered containers. If the temperature is >90°F, refrigerate within 1 hour.
  • When traveling to underdeveloped countries:
    • Eat only freshly prepared food. Avoid beverages and foods prepared with nonpotable water. Bottled, carbonated, and boiled beverages are safe to drink. Chemoprophylaxis for traveler’s diarrhea is recommended for high-risk travelers (e.g., immunocompromised).

Commonly Associated Conditions

  • Botulism—symmetric neurologic deficits and changes in mental status due to ingestion of toxin types A, B, and E produced by C. botulinum. Outbreaks typically involve home-canned foods such as fruits, vegetables and meats.
  • Neonatal meningitis—immunocompromised hosts, particularly neonates (<29 days old), can contract meningitis from systemic L. monocytogenes infection.
  • Hemolytic uremic syndrome (HUS)—microangiopathic hemolytic anemia, renal impairment, and thrombocytopenia caused by both Shigella and STEC.
  • Guillain-Barré syndrome—ascending paralysis strongly associated with C. jejuni infection
  • Reactive arthritis—can occur after severe infections with Salmonella, Shigella, Yersinia, or Campylobacter species

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