- Clinical science
Food poisoning, or foodborne illness, occurs following the ingestion of food or water contaminated with bacteria, bacterial toxins, viruses, parasites, or chemical substances. According to the Centers for Disease Control and Prevention (CDC), an estimated 1 in every 6 people in the US is annually affected with a foodborne illness. Risk factors include the cross-contamination of food, as well as improper handling and storage. In addition, immunocompromised individuals are at an increased risk of infection. Common pathogens attributed to food poisoning include , , , , Staphylococcus aureus, and . Incubation periods depend on the cause, and range from a few hours to days. The clinical presentation associated with food poisoning varies, but typical symptoms include diarrhea, nausea, vomiting, and abdominal cramping. Various laboratory tests (e.g., stool analysis, blood tests) help confirm the suspected diagnosis. Young children and the elderly are at greater risk for developing complications related to food poisoning and must be closely monitored. For most patients, supportive care, including fluid replenishment, is sufficient.
Pathogen: Staphylococcus aureus
- Gram-positive bacterium
- Some pathogenic, virulent strains produce enterotoxins that cause the symptoms
- Transmission: ingestion of the toxins in contaminated food
- Typically involves a short latency period; resolution of symptoms after 24–48 hours
- Bacteria proliferate in inadequately refrigerated food; (canned meats, mayonnaise/potato salad, custards).
- Incubation period:1–4 hours
- Clinical findings: nausea, vomiting, abdominal discomfort, diarrhea
- Antibiotics are unnecessary
- Pathogen: Bacillus cereus, a heat-stable, spore-forming bacterium that produces two different enterotoxins
- Transmission: : The bacterium grows in heated food that cools down too slowly or is improperly refrigerated. Reheated rice is a common source of infection.
- Incubation period and clinical findings
- Treatment: Supportive
"Food poisoning from reheated rice? Be serious!" (B. cereus).
- Transmission: ingestion of contaminated, inadequately refrigerated fish (e.g., fish cakes)
- Clinical findings
- Treatment: Symptoms usually resolve within 48 h. Antihistamines may be administered in severe cases.
Foodborne diseases may be classified according to the predominating symptoms. An overview is provided in this section. For details regarding the bacterial pathogens see the learning card “Bacterial gastroenteritis”.
Commonly due to delayed gastric emptying caused by changes to gastric motility.
(Enterotoxins cause the symptoms)
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|Bacillus cereus|| || || |
(Vomiting more common in children)
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Typical pathomechanism of watery diarrhea: pathogen or toxin enters gastrointestinal tract → binds epithelial cells, sometimes damaging microvilli → ↑ secretion or ↓ absorption of hydrophilic molecules or electrolytes (e.g., NaCl) → ↑ intestinal water due to osmosis → diarrhea.
Enterotoxin or bacterial invasion shifts water and electrolyte excretion/absorption in proximal small intestine → watery diarrhea
- Clinical features
- WBC negative
- No blood
|Staphylococcus aureus|| |
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|Listeria monocytogenes|| || |
|Vibrio cholerae|| |
|Cryptosporidium|| || |
|Cyclospora (Cryptosporidium cyclospora cayetanensis)|| || |
|Intestinal tapeworms|| || || |
Pathogens penetrate the mucosa and invade the reticuloendothelial system of the distal small intestine → enteric fever
|Salmonella typhi or paratyphi|| |
Bacteria or cytotoxins damage the colonic mucosa → blood in stool and fever
- WBC positive (fecal polymorphonuclear leukocytes)
- Blood present
|Salmonella (100s of strains, including S. enteritidis and S. typhimurium)|| || || |
|Campylobacter jejuni|| || || |
|Shigella dysenteriae||Fecal-oral|| |
|Yersinia enterocolitica|| || |
|Vibrio (usually parahaemolyticus)|| || || |
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|Clostridium difficile|| |
Additional non-gastrointestinal symptoms
|Pathogens||Predominating symptoms||Foods/Transmission||Incubation period||Treatment|
|Clostridium botulinum|| |
|Histamine fish poisoning|| || || || |
|Brucellosis (Brucella spp.)|| || || |
|Hepatitis A (Hepatitis A virus)|| || || || |
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|Salmonella typhi and paratyphi|| || |
|Ciguatera toxin|| || || || |
Common vectors for fecal-oral transmission in intestinal diseases are the 5 F's: fingers, feces, food, fluids, flies.
- Food hygiene
- Wash hands and surfaces frequently
- Wash fruits and vegetables with safe drinking water
- Avoid cross-contamination by keeping raw meat products, eggs and seafood separated from other kinds of food
- Use a food thermometer while cooking
- Maintain a refrigerator temperature < 4°C (40°F)
- When traveling (especially to developing countries): only consume fully cooked or dry (e.g., bread, crackers) foods, pasteurized dairy products, and fruits and vegetables you can peel or have properly washed yourself
- Water hygiene
- Do not consume untreated water or ice
- Options if water treatment is unknown:
- Consume sealed bottled beverages
- Boil water for at least one minute before consuming
- Use an appropriate filter
There is a simple rule to avoid foodborne illness while traveling: Boil it, cook it, peel it, or forget it!