Botulism food poisoning: It’s not just bulging cans

What is Clostridium?

Clostridium species are gram-positive anaerobic bacteria that are normally found in soil, air and seawater. One Clostridium species, C. difficile, is part of the normal gut flora in humans. Strains that cause food poisoning are usually C. botulinum and C. perfingens. Depending on the strain, 8 different neurotoxic proteins can be produced in the spores: A, B, C, D, E, F, G, and H.

Clostridia produces spores which are very resistant to heat, so if food is not heated to a high enough temperature, the spores can germinate in the food and form the neurotoxins. The neurotoxins that most often cause food borne illness are A, B and E. Foods contaminated with A and B may look or smell bad, but if contaminated with type E, the look and smell will seem normal.

What are the symptoms of Clostridiumfood poisoning?

The botulinum toxin prevents the release of the neurotransmitter acetylcholine by binding irreversibly to cholinergic nerves, resulting in a paralysis that starts in the upper part of body and works its way down.

The onset of symptoms varies depending on the toxin, but is usually around 1 day (0-7 days for type A, 0-5 days for type B, and 0-2 days for type E). Initial symptoms include nausea, vomiting, abdominal distention, and pain. Because these symptoms are nonspecific, botulism may not be suspected at first. After a lag of 12-36 hours, neurologic symptoms including diplopia (double vision), ptosis (droopy eyelids), dysarthria (weak speech muscles and slowed or slurred speech), dysphagia (difficulty swallowing), and dysphonia (hoarse voice) occur. This is followed by paralysis of the limbs. Constipation can occur due to decrease in gut motility. Respiratory muscle weakness can lead to respiratory failure. Botulism can be fatal.

Infant botulism is the most common form of botulism in the US. Initial symptoms of infant botulism include decreased muscle tone (the baby may seem “floppy”), difficulty feeding, a weak cry, lethargy, and constipation. The survival rate for infant botulism is 98%.

How do you get Clostridium food poisoning?

In adults, the ingestion of spores does not produce illness. Under anaerobic conditions and slightly acidic pH (4.6-7), the spores germinate, which results in formation of the botulinum toxin. Toxicity is due to ingestion of a preformed toxin most often found in improperly home-preserved canned meat, fish, vegetables, beans, and alcohol. One usually associates foodborne botulism with canned foods, but it is also found in other foods, including potatoes (baked or salad), beef or turkey pot pie, loaf or stuffing, and fermented salted and smoked fish. Foods such as meat, poultry, stews, and gravy that sit out for too long at room temperature can also be a source of botulism.

Infant botulism occurs following ingestion of C. botulinum or spores in food (such as honey) or by inhaling them in dust. It occurs more often in breastfed babies than in formula-fed babies. Due to the immaturity of flora in the infant digestive tract, C. botulinum can colonize and produce spores which germinate and release toxin.

What are other types of botulism caused by Clostridium?

Wound botulism is caused by Clostridium botulinum. In wounds such as punctures, lacerations, open fractures, and gunshot wounds, the spores can germinate in the anaerobic wound environment, forming the toxin which is then absorbed into the blood stream. The onset is longer (1-3 weeks) and fever is more likely, but other symptoms are similar to foodborne botulism, except for absence of nausea and vomiting.

Clostridium tetani can also contaminate wounds causing tetanus. Tetanus is different than botulism in that it causes a spastic paralysis (increased muscle tone, stiffness) while botulism causes a flaccid paralysis (weak or reduced muscle tone). There is a vaccine to prevent tetanus, but not one for botulism.

Botulism can also occur when botulinum type A in Botox and similar products are used for treatment of wrinkles, muscle spasms, eye problems, and other indications. Onset is usually within 1-2 days of injection and symptoms are similar to foodborne botulism.

The botulinum toxin is considered Category A (highest priority agents) bioterrorism agent by the CDC. There is concern that some countries have developed botulinum toxins for use as a weapon.

Is Clostridium contagious?

Botulism is not contagious, meaning you cannot spread the bacterium or spores from person to person.

What to do if you suspect botulism; How to treat a Clostridium infection

You cannot treat Clostridium food poisoning at home. If you suspect you are experiencing Clostridium food poisoning, use the webPOISONCONTROL^® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.

Clostridium food poisoning needs to be treated at a hospital. A laboratory can confirm that it is botulism by identifying the toxin in the blood, stool, or stomach contents. However, treatment needs to be commenced before the laboratory results come back. Patients usually need respiratory support including intubation and mechanical ventilation. If the person presents soon after eating the contaminated food, it may be possible to remove the bacteria and spores from the gut with lavage (bringing stomach contents up through a tube) and/or by using activated charcoal (to absorb the toxin and keep it from being absorbed into the blood stream).

Another specific treatment includes administering the botulism antitoxin, ideally within 24 hours of the onset of symptoms, so that it can bind free toxin. For infant botulism, BabyBIG (Botulism immune globulin intravenous) should be administered.