Bacteria of the Month

Clostridium botulinum (C. botulinum)

THE BUG
Clostridium botulinum (C. botulinum) is a gram-positive, rod shaped bacterium that produces the neurotoxin botulin, which causes muscular paralysis. It is also the main paralytic agent in botox. There are seven types of botulism toxin that are recognized and are categorized by their antigenic specificity. Four types (A, B, E, and F) cause human botulism, while two types (C and D) cause botulism in animals.

NATURAL ENVIRONMENT
C. botulinum is a bacterium that exists commonly in nature. It is an anaerobic spore-former, which produces endospores and is commonly food in soil and in aquatic sediments.

ASSOCIATED FOODS
C. botulinum can be associated with improperly prepared home-canned, low-acid foods (e.g. corn, green beans, mushrooms, spaghetti sauce, and salmon) are most likely to represent a risk for botulism. Outbreaks of botulism have also occurred in Canada’s Inuit populations when people have eaten improperly prepared raw or parboiled meats from marine mammals. Improperly stored low acid fruit juices (e.g., carrot juice). Improperly stored baked potatoes can also be a potential source. Honey may also be contaminated with C. botulinum and has been linked to cases of infantile botulism.

SYMPTOMS
Symptoms can range from nausea, vomiting, fatigue, dizziness, headache, double vision, dryness in the throat and nose to respiratory failure, paralysis and in some cases, death. In infants the symptoms can range from constipation, lethargy, poor muscle tone, weak cries, and loss of appetite. In babies it is hard to assess their symptoms since they cannot communicate that they do not feel well.

The onset of symptoms is generally from 12-36 hours after ingesting the toxin. The duration of illness may be 2 hours to 14 days, although some symptoms may linger much longer. With proper treatment the fatality rate of C. botulinum cases in Canada is as low as five to ten per cent.

Botulinum toxin is the most poisonous natural substance known to man. The lethal dose is only 1/10,000,000 mg per kg of body weight. This amount of toxin would be invisible to the naked eye. This tiny amount in the blood stream can cause death within minutes through paralysis of the muscles used in breathing. Food borne intoxication symptoms begin in the face and eyes, and progress down both sides of the body. If left untreated, muscles in the arms, legs, and torso, as well as those used in breathing become paralyzed. Death can also occur.

TREATMENT
Laboratory tests can detect the presence of botulinum toxin or a bacterial culture can be grown from a stool sample. Treatment of botulism includes administration of botulinum antitoxin and intensive respiratory care. Death occurs in 70% of untreated cases. The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care. After several weeks, the paralysis slowly improves. If diagnosed early, food borne botulism can be treated with an antitoxin which blocks the action of toxin circulating in the blood. This can prevent patients from deterioration, but full recovery may take a while. Physicians may try to remove contaminated food still in the gut by inducing vomiting or using an enema. Currently, antitoxin is not routinely given for treatment of infant botulism. The best case scenario is treatment with early detection. If you experience symptoms of botulism, seek medical attention immediately.

PREVENTION
To help prevent botulism do not consume cans that are dented, leaking or have bulging ends or jars that do not have a proper vacuum seal. If you buy a jarred product and it doesn’t pop or release its vacuum discard it. Often grocery stores sell dented cans for less but the risk is not worth the monetary savings.

When canning foods at home, be sure to process all low-acid foods (e.g. vegetables, mushrooms, seafood) in a pressure canner following the manufacturer’s instructions closely. Take precautions with home-prepared foods stored in oil (e.g., vegetables, herbs and spices). If these products are prepared using fresh ingredients, they must be refrigerated and for no longer than a week and a half. When purchasing homemade canned goods from farmers markets or roadside stands make sure that it is from a reputable source. When at home only consume products if the jar seal pops releasing a vacuum when you open it. After opening a jar or can make sure you refrigerate any of the remaining product. Date and label preserves and canned goods and follow proper canning requirements strictly. Keep all work surfaces, food, utensils, equipment, and hands clean during all stages of the canning process. When preparing your own home fermented meats ensure that you follow proper procedures, do not take shortcuts, and consult reputable resources for preparation methods. Date and label preserves and canned goods and follow proper canning requirements strictly. Keep all work surfaces, food, utensils, equipment, and hands clean during all stages of the canning process.

Do not feed honey to infants; honey should only be given to children one or older. The bacterium cannot grow or make toxins in the honey, but it may grow and make toxins in a baby’s body.

The toxin is heat labile and can be destroyed if heated at 80°C for 10 minutes or longer, so heat the contents of canned goods and foods to high temperatures to ensure they are safe to eat.

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