Food Poisoning: Practice Essentials, Background, Pathophysiology (2023)

Table 1.Causes of Food Poisoning.

Causative Agents

Source and

Clinical Features


Diagnosis and



Improperly stored foods with high salt or sugar content favors growth of staphylococci.

Intense vomiting and watery diarrhea start 1-4 h after ingestion and last as long as 24-48 h

Enterotoxin acts on receptors in the gut that transmit impulses to the medullary centers

Symptomatic treatment

B cereus

Contaminated fried rice (emetic)

Meatballs (diarrheal)

Emetic: Duration is 9 h, vomiting and cramps

Diarrheal: Lasts for 24 h

Mainly vomiting after 1-6 h and mainly diarrhea after 8-16 h after ingestion; lasts as long as 1 d

Emetic enterotoxin (short incubation and duration) - Poorly understood

Diarrheal enterotoxin (long incubation and duration) - Increasing intestinal secretion by activation of adenylate cyclase in intestinal epithelium

Symptomatic treatment

C perfringens

Inadequately cooked meat, poultry, or legumes

Acute onset of abdominal cramps with diarrhea starts 8-24 h after ingestion.

Vomiting is rare. It lasts less than 1 d.

Enteritis necroticans associated with C perfringens type C in improperly cooked pork (40% mortality)

Enterotoxin produced in the gut, and food causes hypersecretion in the small intestine

Culture of clostridia in food and stool

Symptomatic treatment

C botulinum

Canned foods (eg, smoked fish, mushrooms, vegetables, honey)

Descending weakness and paralysis start 1-4 d after ingestion, followed by constipation.

Mortality is high

Toxin absorbed from the gut blocks the release of acetylcholine in the neuromuscular junction

Toxin present in food, serum, and stool.

Respiratory support

Intravenous trivalent antitoxin from CDC

Listeria monocytogenes

Raw and pasteurized milk, soft cheeses, raw vegetables, shrimp

Systemic disease associated with bacteremia

Intestinal symptoms precede systemic disease

Can seed meninges, heart valves, and other organs

Highest mortality among bacterial food poisonings

Highly motile, heat-resistant, gram-positive organism

CSF or blood culture

Must treat with antibiotics if bacteremic

Enterotoxic E coli (eg, traveler's diarrhea)

Contaminated water and food (eg, salad, cheese, meat)

Acute-onset watery diarrhea starts 24-48 h after ingestion

Concomitant vomiting and abdominal cramps may be present. It lasts for 1-2 d

Enterotoxin causes hypersecretion in small and large intestine via guanylate cyclase activation

Supportive treatment

No antibiotics

Enterohemorrhagic E coli (eg, E coli O157:H7)

Improperly cooked hamburger meat and previously spinach

Most common isolate pathogen in bloody diarrhea starts 3-4 d after ingestion

Usually progresses from watery to bloody diarrhea. It lasts for 3-8 d

May be complicated by hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura

Cytotoxin results in endothelial damage and leads to platelet aggregation and microvascular fibrin thrombi

Diagnosis with stool culture

Supportive treatment

No antibiotics

Enteroinvasive E coli

Contaminated imported cheese

Usually watery diarrhea (some may present with dysentery)

Enterotoxin produces secretion

Shigalike toxin facilitates invasion

Supportive treatment

No antibiotics

Enteroaggregative E coli

Implicated in traveler's diarrhea in developing countries

Can cause bloody diarrhea

Bacteria clump on the cell surfaces

Ciprofloxacin may shorten duration and eradicate the organism

V cholera

Contaminated water and food

Large amount of nonbloody diarrhea starts 8-24 h after ingestion. It lasts for 3-5 d

Enterotoxin causes hypersecretion in small intestine

Infective dose usually is 107 -109 organisms

Positive stool culture finding

Prompt replacement of fluids and electrolytes (oral rehydration solution)

Tetracycline (or fluoroquinolones) shortens the duration of symptoms and excretion of Vibrio

V parahaemolyticus

Raw and improperly cooked seafood (ie, mollusks and crustaceans)

Explosive watery diarrhea starts 8-24 h after ingestion

It lasts for 3-5 d

Enterotoxin causes hypersecretion in small intestine

Hemolytic toxin is lethal

Infective dose is usually 107 -109 organisms

Positive stool culture

Prompt replacement of fluids and electrolytes

Sensitive to tetracycline, but unclear role for antibiotics

V vulnificus

Wound infection in salt water or consumption of raw oysters

Can be lethal in patients with liver disease (50% mortality)

Polysaccharide capsule

Growth correlates with availability of iron (especially transferrin saturation >70%)

Culture of characteristic bullous lesions or blood

Immediate antibiotics if suspected (eg, doxycycline and ceftriaxone)

C jejuni

Domestic animals, cattle, chickens

Fecal-oral transmission in humans

Foul-smelling watery diarrhea followed by bloody diarrhea

Abdominal pain and fever also may be present; it starts 1-3 d after exposure and recovery is in 5-8 d

Uncertain about endotoxin production and invasion

Culture in special media at 42°C

Erythromycin for invasive disease (fever)


Potato, egg salad, lettuce, vegetables, milk, ice cream, and water

Abrupt onset of bloody diarrhea, cramps, tenesmus, and fever starts 12-30 h after ingestion.

Usually self-limited in 3-7 d

Organisms invade epithelial cells and produce toxins

Infective dose is 102 -103 organisms

Enterotoxin-mediated diarrhea followed by invasion (dysentery/colitis)

Polymorphonuclear leukocytes (PMNs), blood, and mucus in stool

Positive stool culture

Oral rehydration is mainstay

Trimethoprim-sulfamethoxazole (TMP-SMX) or ampicillin for severe cases

No opiates


Beef, poultry, eggs, and dairy products

Abrupt onset of moderate-to-large amount of diarrhea with low-grade fever; in some cases, bloody diarrhea

Abdominal pain and vomiting also present, beginning 6-48 h after exposure and lasts 7-12 d

Invasion but no toxin production

Positive stool culture finding

Antibiotic for systemic infection


Pets; transmission in humans by fecal-oral route or contaminated milk or ice cream

Acute abdominal pain, diarrhea, and fever (enterocolitis)

Incubation period not known Polyarthritis and erythema nodosum in children

May mimic appendicitis

Gastroenteritis and mesenteric adenitis

Direct invasion and enterotoxin

Polymorphonuclear leukocytes and blood in stool

Positive stool culture finding

No evidence that antibiotics alter the course but may be used in severe infections


Untreated well or spring water

Diarrhea may be bloody

May be chronic up to 42 d in the United States

Enterotoxin, hemolysin, and cytotoxin

Positive stool culture

Fluoroquinolones or TMP/SMX for chronic diarrhea

Parasitic Food Poisoning

Source and Clinical Features


Diagnosis and Treatment

E histolytica

Contaminated food and water

90% asymptomatic

10% dysentery

Minority may develop liver abscesses

Invasion of the mucosa by the parasites

Criterion standard is colonoscopy with biopsy

Ova and parasites may be seen in the stool but has low sensitivity

Luminal amebicides (eg, paromomycin)

Tissue amebicides (eg, metronidazole)

G lamblia

Contaminated ground water

Fecal-oral transmission in humans

Mild diarrhea with nausea and abdominal cramps starts 2-3 d after ingestion; lasts for 1 wk

May become chronic


Highest concentration in the distal duodenum and proximal jejunum

Initial diagnostic test is stool enzyme-linked immunosorbent assay

Duodenal aspiration or small bowel biopsy

Cyst in the stool


Seafood/Shellfish Poisoning

Source and

Clinical Features


Diagnosis and


Paralytic shellfish poisoning

Temperate coastal areas

Source - Bivalve mollusks

Onset usually is 30-60 min

Initial symptoms include perioral and intraoral paresthesia

Other symptoms include paresthesia of the extremities, headache, ataxia, vertigo, cranial nerve palsies, and paralysis of respiratory muscles, resulting in respiratory arrest

Fish acquires toxin-producing dinoflagellates

General observation for 4-6 h

Maintain patent airway.

Administer oxygen, and assist ventilation if necessary

For recent ingestion, charcoal 50-60 g may be helpful

Neurotoxic shellfish poisoning

Coastal Florida

Source - Mollusks

Illness is milder than in paralytic shellfish poisoning

Fish acquires toxin-producing dinoflagellates



Hawaii, Florida, and Caribbean

Source - Carnivorous reef fish

Vomiting, diarrhea, and cramps start 1-6 h after ingestion and last from days to months

Diarrhea may be accompanied by a variety of neurologic symptoms including paresthesia, reversal of hot and cold sensation, vertigo, headache, and autonomic disturbances such as hypotension and bradycardia

Chronic symptoms (eg, fatigue, headache) may be aggravated by caffeine or alcohol

Fish acquires toxin-producing dinoflagellates

Toxin increases intestinal secretion by changing intracellular calcium concentration


Anecdotal reports of successful treatment of neurologic symptoms with mannitol 1 g/kg IV

Tetrodotoxin poisoning


Source - Puffer fish

Onset of symptoms usually is 30-40 min but may be as short as 10 min; it includes lethargy, paresthesia, emesis, ataxia, weakness, and dysphagia; ascending paralysis occurs in severe cases; mortality is high.

Neurotoxin is concentrated in the skin and viscera of puffer fish.



Source - Tuna, mahi-mahi, kingfish

Allergic symptoms such as skin flush, urticaria, bronchospasm, and hypotension usually start within 15-90 min

Improper preservation of large fish results in bacterial degradation of histidine to histamine

Antihistamines (diphenhydramine 25-50 mg IV)

H2 blockers (cimetidine 300 mg IV)

Severe reactions may require subcutaneous epinephrine (0.3-0.5 mL of 1:1000 solution)

Heavy Metal Poisoning





Ingestion of inorganic mercuric salts

Causes metallic taste, salivation, thirst, discoloration and edema of oral mucous membranes, abdominal pain, vomiting, bloody diarrhea, and acute renal failure

Consult a toxicologist

Remove ingested salts by emesis and lavage, and administer activated charcoal and a cathartic

Dimercaprol is useful in acute ingestion


Toxicity results from chronic repeated exposure

It is rare after single ingestion

Common symptoms include colicky abdominal pain, constipation, headache, and irritability

Diagnosis is based on lead level (>10 mcg/dL)

Other than activated charcoal and cathartic, severe toxicity should be treated with antidotes (edetate calcium disodium [EDTA] and dimercaprol).


Ingestion of pesticide and industrial chemicals

Symptoms usually appear within 1 h after ingestion but may be delayed as long as 12 h

Abdominal pain, watery diarrhea, vomiting, skeletal muscle cramps, profound dehydration, and shock may occur

Gastric lavage and activated charcoal

Dimercaprol injection 10% solution in oil (3-5 mg/kg IM q4-6h for 2 d) and oral penicillamine (100 mg/kg/d divided qid for 1 wk)


What is the pathophysiology of food poisoning? ›

Food poisoning is defined as an illness caused by the consumption of food or water contaminated with bacteria and/or their toxins, or with parasites, viruses, or chemicals. The most common pathogens are Norovirus, Escherichia coli, Salmonella, Clostridium perfringens, Campylobacter, and Staphylococcus aureus.

What causes food poisoning PDF? ›

Infectious organisms — including bacteria, viruses and parasites — or their toxins are the most common causes of food poisoning. Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.

What are the 4 types of food poisoning? ›

Types of infection
  • Campylobacter. In the UK, campylobacter bacteria are the most common cause of food poisoning. ...
  • Salmonella. Salmonella bacteria are often found in raw or undercooked meat, raw eggs, milk, and other dairy products. ...
  • Listeria. ...
  • Escherichia coli (E. ...
  • Shigella. ...
  • Viruses. ...
  • Parasites.
16 Dec 2020

What are the 3 links of food poisoning? ›

To grow, bacteria need warmth, moisture, food and time, these four elements are known as the Food Poisoning Chain, to protect food, and your customers, a link of the chain must be broken.

What is food poisoning question and answer? ›

Food poisoning (also known as food-borne illness) occurs when you eat or drink something that contains harmful germs. Q. Consuming adulterated food causes food poisoning.

Why is it called food poisoning? ›

These toxins are poisons (the reason for the name "food poisoning"), and can cause diarrhea and vomiting. Usually, doctors use "food poisoning" to describe an illness that comes on quickly after eating contaminated food.

What is the classification of food poisoning? ›

Food infections are classified as bacterial, viral, parasitic or fungal. Food poisoning is classified according to the type of toxin that causes it which may be natural, bacterial, fungal or chemical.

When can food poisoning start? ›

The time it takes food poisoning symptoms to start can vary. Illness often starts in about 1 to 3 days. But symptoms can start any time from 30 minutes to 3 weeks after eating contaminated food. The length of time depends on the type of bacteria or virus causing the illness.

What are the two main causes of food poisoning? ›

Bacteria and Viruses: Bacteria and viruses are the most common cause of food poisoning. The symptoms and severity of food poisoning vary, depending on which bacteria or virus has contaminated the food. Parasites: Parasites are organisms that derive nourishment and protection from other living organisms known as hosts.

What is the most common cause of poisoning? ›

Ethanol intoxication is the commonest type of acute poisoning and suicide by medical drug overdose is the commonest type of suicide by poisoning. Death from acute poisoning is most commonly the result of either smoke inhalation or illegal drug use.

What organs are affected by food poisoning? ›

Most of the time, food poisoning is an illness of your stomach and intestines.

What is the most serious form of food poisoning? ›

The most dangerous types of food poisoning include E. coli and botulism.

What are 5 ways to prevent food poisoning? ›

8 Tips To Help Prevent Food Poisoning
  1. Wash Your Hands Often. ...
  2. Clean Fruits And Vegetables. ...
  3. Don't Wash Raw Meat. ...
  4. Clean All Surfaces. ...
  5. Keep It Cool. ...
  6. Avoid The “Danger Zone” ...
  7. Separate, So You Don't Cross-Contaminate. ...
  8. Cook To The Right Temperature.

What are the 6 main symptoms of food poisoning? ›

While different types of pathogenic bacteria can cause different symptoms, food poisoning generally presents itself with symptoms such as nausea, vomiting, diarrhea, abdominal cramping, and fever.

What is poisoning Short answer? ›

Poisoning is injury or death due to swallowing, inhaling, touching or injecting various drugs, chemicals, venoms or gases. Many substances — such as drugs and carbon monoxide — are poisonous only in higher concentrations or dosages.

What are the names of food poisoning? ›

At least 250 different kinds of food poisoning have been documented, but the most common ones are e. coli, listeria, salmonella, and norovirus, which is commonly called "stomach flu." Other less common illnesses that can be transferred from food or food handling are botulism, campylobacter, vibrio, and shigella.

What are the 10 main reasons for food poisoning? ›

The top seven causes of food poisoning are Salmonella, Listeria, Staphylococcus, Trichinosis, E. coli, Campylobacter, Clostridium.

What medication helps food poisoning? ›

In some cases, adults can take over-the-counter medicines such as loperamide link (Imodium) and bismuth subsalicylate link (Pepto-Bismol, Kaopectate) to treat diarrhea caused by food poisoning.

What are the complications of food poisoning? ›

What are the complications of food poisoning? In some cases, food poisoning can lead to dehydration, hemolytic uremic syndrome, or other complications. However, serious complications are uncommon. In most cases, food poisoning lasts only a short time, and most people recover without developing complications.

What type of virus is food poisoning? ›

You may hear norovirus illness be called “food poisoning,” “stomach flu,” or “stomach bug.” Noroviruses are the leading cause of foodborne illness, but other germs and chemicals can also cause foodborne illness. Norovirus illness is not related to the flu, which is caused by influenza virus.

How many types of poisoning do we have? ›

In regard to poisoning, chemicals can be divided into three broad groups: agricultural and industrial chemicals, drugs and health care products, and biological poisons—i.e., plant and animal sources. These three groups, along with a fourth category, radiation, are discussed below.

What are the most common food poisoning bacteria? ›

The top five germs that cause illnesses from food eaten in the United States are:
  • Norovirus.
  • Salmonella.
  • Clostridium perfringens.
  • Campylobacter.
  • Staphylococcus aureus (Staph)
18 Mar 2020

How long does food take to digest? ›

After you eat, it takes about six to eight hours for food to pass through your stomach and small intestine. Food then enters your large intestine (colon) for further digestion, absorption of water and, finally, elimination of undigested food. It takes about 36 hours for food to move through the entire colon.

How long does it take to recover from food poisoning? ›

Most people fully recover from the most common types of food poisoning within 12 to 48 hours. Some types of food poisoning can cause serious complications. Death from food poisoning in people who are otherwise healthy is rare in the United States.

What are the most common 2 symptoms of food poisoning? ›

Foodborne illness, more commonly referred to as food poisoning, is the result of eating contaminated, spoiled, or toxic food. The most common symptoms of food poisoning include nausea, vomiting, and diarrhea.

How immediate is food poisoning? ›

Sometimes we eat something we wish we hadn't. Emergency room physician Dr. Troy Madsen says food poisoning generally takes about six hours to take effect, but most people get through it all right. Learn about the symptoms of food poisoning and things you can do to help yourself get through it.

What are the factors of poisoning? ›

The toxicity of a substance usually depends on the following factors:
  • Form and innate chemical activity.
  • Dosage , especially dose -time relationship.
  • Exposure route.
  • Species.
  • Life stage, such as infant, young adult, or elderly adult.
  • Gender.
  • Ability to be absorbed.
  • Metabolism.
6 Jul 2022

What are the major types of poisoning? ›

Common poisons include:
  • Alcohol.
  • Berries and Seeds.
  • Carbon Monoxide.
  • Food Poisoning.
  • Hazardous Chemicals.
  • Herbal Supplements.
  • Household Products.
  • Inhalants.

Where is food poisoning most commonly found? ›

Raw foods of animal origin are the most likely to be contaminated, specifically raw or undercooked meat and poultry, raw or lightly cooked eggs, unpasteurized (raw) milk, and raw shellfish. Fruits and vegetables also may get contaminated.

How do you control food poisoning outbreaks? ›

What are outbreak control measures?
  1. Cleaning and disinfecting food facilities.
  2. Temporarily closing a restaurant or processing plant.
  3. Recalling food items.
  4. Telling the public how to make the food safe (such as cooking to a certain temperature) or to avoid it completely.

What is the pathophysiology of gastroenteritis? ›

Pathophysiology: Bacteria attach to the wall of the small bowel and enterotoxins are released, drawing fluid and electrolytes from the mucosa into the lumen, causing profuse watery diarrhea.

What is gastroenteritis and it pathophysiology? ›

Pathophysiology. Gastroenteritis is defined as vomiting or diarrhea due to inflammation of the small or large bowel, often due to infection. The changes in the small bowel are typically noninflammatory, while the ones in the large bowel are inflammatory.

How does the body react to food poisoning? ›

Bloody diarrhea. High fever (temperature over 102°F, measured in your mouth) Frequent vomiting that prevents keeping liquids down (which can lead to dehydration) Signs of dehydration, including little or no urination, a very dry mouth and throat, or feeling dizzy when standing up.

What is the pathophysiology of diarrhea? ›

Diarrhoea is the result of a disruption in the delicate balance between the absorptive and secretory processes within the bowel. In general, diarrhoea can be considered to be either osmotic or secretory.

What is the pathophysiology of infectious diarrhea? ›

After ingestion, organisms colonize the intestine and either invade the ileal and colonic mucosa or secrete a noxious cytotoxin intraluminally. Both these pathways induce an acute inflammatory reaction of the mucosa. The products of this reaction induce intestinal secretion and diarrhea.

What is the pathophysiology of vomiting? ›

Pathophysiology of nausea and vomiting. Vomiting is caused by noxious stimulation of the vomiting center directly or indirectly via 1 or more of 4 additional sites: the gastrointestinal (GI) tract, the vestibular system, the chemoreceptor trigger zone, and higher centers in the cortex and thalamus.

What is the difference between gastroenteritis and food poisoning? ›

Most people develop viral gastroenteritis symptoms within 24 to 72 hours of exposure to a virus, while food poisoning symptoms can appear anytime within a few hours to weeks following exposure to a foodborne or waterborne pathogen.

How long can food poisoning last? ›

Symptoms of food poisoning can appear anywhere between four hours and one week after ingesting a contaminated food item, and can persist for as short a time as 24 hours or as long as a week.

What are the two types of gastroenteritis? ›

The main types are rotavirus and norovirus. Rotavirus is the world's most common cause of diarrhea in infants and young children. Norovirus is the most common cause of serious gastroenteritis and also foodborne disease outbreaks in the U.S. Although not as common, bacteria such as E.

What happens to the body after poisoning? ›

Poisoning can cause short-term effects, like a skin rash or brief illness. In serious cases, it can cause brain damage, a coma, or death.

Where do food poisoning bacteria live? ›

Clostridium perfringens

perfringens) is a type of bacteria often found in soil, sewage, and the intestines of humans and animals. It usually is transferred by someone handling food to the food itself, where it multiplies and produces its toxin.

What is the biggest source of food poisoning? ›

Raw foods of animal origin are the most likely to be contaminated, specifically raw or undercooked meat and poultry, raw or lightly cooked eggs, unpasteurized (raw) milk, and raw shellfish. Fruits and vegetables also may get contaminated.


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