Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Clostridium botulinum

CZ: klostridie
EN: botulinal toxin

Occurrence:
Meat and Meat Products
Fish and Fish Products
Fruits and Vegetables
Delicatessen
Honey


Category:
Bacteria


Foodborne Disease:
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botulism - food poisoning - paralysis of muscles, inhibited  respiration and death, lassitude, weakness and vertigo, difficulty in breathing, weakness of muscles, abdominal distention, and constipation then botulism


Description:
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Clostridium botulinum is an anaerobic, Gram-positive spore-forming rod that produces a potent neurotoxin. The spores are heat-resistant and can survive in foods that are incorrectly or minimally processed. Seven types (A, B, C, D, E, F and G) of botulism are recognized, based on the antigenic specificity of the toxin produced by each strain. Animals most commonly affected are wild fowl and poultry, cattle, horses and some species of fish.  

Clostridium botulinum and its spores are widely distributed in nature. Sausages, meat products, canned vegetables and seafood products have been the most frequent vehicles for human botulism.

Food-borne botulism is a severe type of food poisoning caused by the ingestion of foods containing the potent neurotoxin formed during growth of the organism. The toxin is heat labile and can be destroyed if heated at 80°C for 10 minutes or longer. The incidence of the disease is low, but the disease is of considerable concern because of its high mortality rate if not treated immediately and properly.

Onset of symptoms in food-borne botulism is usually 18 to 36 hours after ingestion of the food containing the toxin, although cases have varied from 4 hours to 8 days. Early signs of intoxication consist of marked lassitude, weakness and vertigo, usually followed by double vision and progressive difficulty in speaking and swallowing.

Difficulty in breathing, weakness of other muscles, abdominal distention, and constipation may also be common symptoms. Botulinum toxin causes flaccid paralysis by blocking motor nerve terminals at the myoneural junction. The flaccid paralysis progresses symmetrically downward, usually starting with the eyes and face, to the throat, chest and extremities. When the diaphragm and chest muscles become fully involved, respiration is inhibited and death from asphyxia results.

The most direct and effective way to confirm the clinical diagnosis of botulism in the laboratory is to demonstrate the presence of toxin in the serum or faeces of the patient or in the food, which the patient consumed. Culturing of specimens takes 5-7 days.

Botulinal toxin has been demonstrated in a considerable variety of foods, such as canned corn, peppers, green beans, soups, beets, asparagus, mushrooms, ripe olives, spinach, tuna fish, chicken and chicken livers and liver pate, and luncheon meats, ham, sausage, stuffed eggplant, lobster, and smoked and salted fish.

Clostridium botulinum produces a neurotoxin that is one of the most poisonous substances known to man. Food-borne botulism occurs when food becomes contaminated with spores from the environment, which are not destroyed by initial cooking or processing. If the food provides a suitable environment for growth the spores will germinate, leading to toxin production.

The toxin is heat sensitive and so a further heat treatment of the food would prevent illness. Botulism can be prevented by using food preservation methods that are designed to inhibit the growth of C. botulinum. For example, low acid (pH > 4.4) canned foods are heat treated to 121°C for 3 min (known as the "botulism cook") or equivalent.


Pictures:

Clostridium botulinum
Source: A magnified view of botulinum bacteria
Clostridium botulinum
Source: A magnified view of botulinum bacteria - detail
Clostridium botulinum
Source: A magnified view of botulinum bacteria - scan microscopy
Clostridium botulinum
Source: Life cycle of Clostridium
Clostridium botulinum
Source: microscopic examination of clostridium colonies (colored)
Clostridium botulinum
Source: scan examination of Clostridium colonies

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