Profiling Clostridium botulinum

Clostridium botulinum produces a toxin so deadly that it could be used as a biological weapon.

Some history

Sausage poisoning, one of the earliest recognized forms of food poisoning, was first described in the 18th and early 19th centuries and was likely due to Clostridium botulinum. Infant botulism, a different form of illness, was described for the first time in California in 1976.

What is Clostridium botulinum, and where is its natural habitat?

Clostridium botulinum is a spore-forming bacterium that is only able to grow in the complete absence of molecular oxygen (anaerobic conditions), such as conditions found inside a hermetically sealed, processed can or jar of food. The spores are able to withstand normal cooking temperatures, but not the very high temperatures reached during the processing of most canned foods. Spores of Clostridium botulinum are found in soil and water around the world.

How is Clostridium botulinum transmitted? What is the incubation period of the infection?

Clostridium botulinum food poisoning results when an individual eats food in which the microbe has germinated, grown and produced its lethal toxin. In the case of infant botulism, the infant (one year old or less) ingests the spores that are in a food – honey is a typical vehicle – and the toxin is formed when the spores germinate and grow in the baby’s intestine. The incubation period for infant botulism is 3 to 10 days; for the more typical form of botulism, it is 12 to 72 hours.

What is botulism? How long does it take to develop?

Botulism is the syndrome produced by the action of Clostridium botulinum toxin on the body’s nervous system.

What are the symptoms of botulism?

Initial symptoms may include nausea, vomiting, difficulty in swallowing, blurred vision and muscle weakness. Early symptoms of infant botulism include lethargy, weakness, poor muscle tone, constipation, difficulty feeding and a poor gag reflex. As the action of the toxin progresses, breathing becomes more difficult.

What is the prognosis of botulism?

Botulism can be fatal in 10 to 60% of cases, usually due to respiratory failure. Infant botulism, if treated appropriately, has a survival rate nearing 100%.

What foods carry Clostridium botulinum and its toxin?

Clostridium botulinum is associated with foods where molecular oxygen is absent – typically, processed low-acid canned foods. Because the microbe cannot grow in a very acid environment or in the presence of high levels of salt or sugar, botulism is not a risk in most canned tomato products or in jams or jellies containing sugar. Cases of botulism have been traced to a variety of foods, including home-canned vegetables, improperly stored foil-wrapped baked potatoes, and garlic packed in oil. Approximately 20% of infant botulism cases are traced back to honey that contains Clostridium botulinum spores.

How can people protect themselves from botulism poisoning?

The toxin produced by Clostridium botulinum is inactivated by boiling. Home-canned vegetables should be heated to a boil and simmered for 10 minutes before being served. Leftovers – especially thick sauces and stews that probably contain little or no oxygen – also should be heated to a boil and simmered for 10 minutes before serving.

Never taste a food to see whether it is “off”; Clostridium botulinum can grow and produce its toxin without altering the appearance, taste, or odor of a food, and even a minuscule quantity of toxin is enough to make a person very ill.

Always cool leftovers promptly in the refrigerator or freezer. Do not let food stand at room temperature for extended periods of time. When thawing a frozen dish, do so in the refrigerator – not at room temperature.

Always pay attention to recall notices, and return any recalled item to the store, or discard it in a sealed bag.

For more information on Clostridium botulinum and other food-borne pathogens, visit the CDC website or read Food Safety: Old Habits, New Perspectives.