Food Poisoning

What is Food poisoning?

Food poisoning is the term used for any condition associated with ingestion of food or water that has been contaminated with microorganisms (bacteria, parasites or viruses), microbial toxins, poisonous plants, or chemicals. According to its cause, food poisoning can be classified into infective (capable of being transmitted to someone else) and noninfective types.

Certain bacteria, most belonging to the Salmonella group, are commonly harbored in the intestines of farm animals or poultry. Poisoning can occur if meats, poultry, or fish are not completely thawed, correctly prepared, and properly cooked. Bacteria can also be spread to food from the excretion of infected animals or people, either by flies or by unsanitary handling of food (including inadequate hand washing). Some bacteria form poisons (toxins) that are difficult to destroy even with thorough cooking. These include toxin-forming strains of Staphylococcal bacteria and botulism. Viruses commonly responsible for causing food poisoning are the Norwalk virus (a common contaminant of shellfish) and the rotavirus. Food poisoning occurs when food, which has been in contact with water contaminated by human excrement, is eaten raw or only partly cooked.

Non-infective causes of food poisoning include poisonous mushrooms and toadstools. Also fresh fruit and vegetables can cause food poisoning if they have accidentally been contaminated with high doses of insecticide. Food that is stored in an unsuitable container can cause chemical poisoning, including food stored in a container that has previously held poison or acidic fruit juice stored in a metal container made partly of zinc.

Certain exotic foods, if improperly prepared or cooked, can also cause moderate to lethal poisoning. These include the Japanese puffer fish or the tropical cassava. Some foods can cause either type (infectious or noninfectious) of food poisoning. For example, shellfish can become contaminated by viruses or bacteria, by toxins received from poisonous plankton, or by chemical pollutants in the water.

How is it diagnosed?

History: Symptoms vary according to the type of poisoning and to how heavily the food was contaminated. In general, symptoms usually include stomach pain, nausea, vomiting, and diarrhea. In severe cases, shock or collapse may occur. Symptoms of chemical poisoning usually develop within 30 minutes. Bacterial toxins may take one to twelve hours to develop, while virus or Salmonella poisoning usually takes from 12 to 48 hours.

Physical exam may be normal or reveal abdominal tenderness. Findings are usually nonspecific (could apply to any number of conditions). The individual may have signs of dehydration including orthostatic blood pressure (blood pressure that changes with body position changes), dry mucous membranes, sunken eyes, and decreased skin tension (turgor). The rectal exam may be painful due to inflammation caused by constant diarrhea.

Tests used may vary with the suspected causative agent. They usually include microscopic examination or cultures of stools, vomitus, or blood (serum). Cultures may be done on remaining suspected food, food preparation area, or the food handlers. Other tests that may be necessary to identify the causative organism include gel diffusion, radioimmunoassay (RIA), enzyme linked immunoassay (ELISA), latex agglutination, serotyping of suspected organism, gene probe for toxin, tissue culture assays, and immunoelectron microscopy.

How is Food poisoning treated?

Treatment depends on the causative agent. Most cases of food poisoning are self-limited and require only supportive care. Poisoning due to a chemical or bacterial toxin may be treated by washing out the stomach (gastric lavage). Drugs that may be used include antibiotics, pain relievers (analgesics), or medications to encourage vomiting (antiemetics) in order to clear the stomach of any remaining food contents. Severe dehydration may require intravenous replacement of fluid and electrolytes.

Medications

Information	Brand	Generic	Label	Rating
	Noroxin	Norfloxacin
	Minocin	Minocycline
Salmonella Food Poisoning Drugs
	Cipro	Ciprofloxacin
	Bactrim	Co-trimoxazole
	Principen	Ampicillin

Activity

Bed rest during acute phase. Convenient access to a bathroom or bedpan is important.

Diet

• Liquid diet using special oral glucose-electrolyte preparations, clear broth, or bouillon. Use salt and sugar in liquids to replace what was lost. Try to take small sips even if vomiting continues. This will help with volume replacement and oral rehydration.
• Progress to soft, bland diet. Return to regular diet gradually.

What might complicate it?

The infection may be complicated if the infection develops into chronic disease with fluid accumulation and lymphatic vessel blockage or rupture. Chronic lung damage may result from worm invasion of the lungs. Relapses may occur. Antifilarial drug treatment of chronic disease may lead to systemic allergic reactions to the dying worms. Dead adult worms may calcify and create abscesses in the tissues.

Predicted outcome

Complications can include hemolytic uremic syndrome, Guillain Barr' syndrome, Reiter syndrome, severe dehydration, respiratory failure, neurological problems, abscess formation, infection in the blood (sepsis), and pneumonia.

Alternatives

Conditions with similar symptoms include heavy metal poison, endocrine disorders, and congenital or acquired enzyme deficiency.

Appropriate specialists

Internist, gastroenterologist and infectious disease specialist.

Last updated 19 December 2011