Botulism

Russell J. Mcculloh, M.D.

Basic Information

Definition

Botulism is an illness caused by a neurotoxin produced primarily by Clostridium botulinum. Five types of disease can occur: foodborne botulism, wound botulism, infant intestinal botulism, adult enteric botulism (similar to infant botulism), and inhalational botulism. Of note, inhalational botulism is exceedingly rare, but could occur as a result of bioterrorism.

Synonyms

Clostridium botulinum food poisoning
Botulinum toxin food poisoning
Wound botulism
Infantile botulism

ICD-10CM CODES
A05.1	Botulism food poisoning
A48.51	Infant botulism
A48.52	Wound botulism

Epidemiology & Demographics

Incidence (In U.S.)

An average of 110 cases of botulism are reported in the U.S. annually. One quarter of cases are due to food-borne botulism; nearly 70% of reported cases are infant botulism.

Physical Findings & Clinical Presentation

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Symptoms usually begin 12 to 36 hr following ingestion. Patients present with symmetric descending flaccid paralysis and prominent bulbar signs (diplopia, dysarthria, dysphonia, and dysphagia [the four “Ds”])
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Severity of illness is related to the quantity of toxin ingested.
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Significant findings:
1. 1.
  
  Acute, bilateral cranial nerve palsies, with ocular and bulbar manifestations being most frequent (diplopia, ophthalmoplegia, ptosis, dysphagia, dysarthria, fixed and dilated pupils, and dry mouth)
2. 2.
  
  Usually bilateral nerve involvement that may progress to a descending flaccid paralysis
3. 3.
  
  No sensory deficits, aside from possible blurred vision
4. 4.
  
  GI symptoms (dry mouth, nausea, vomiting, diarrhea, or cramps)
5. 5.
  
  Generally an absence of fever
6. 6.
  
  Normal heart rate to mild bradycardia with patient remaining normotensive
7. 7.
  
  Normal mental status
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Wound botulism
1. 1.
  
  Occurs primarily in injecting drug users (subcutaneous “black tar” heroin injection—“skin popping”) or with traumatic injury.
2. 2.
  
  Presentation is similar to that of foodborne disease, except for a longer incubation period (4-14 days) and absence of GI symptoms.
3. 3.
  
  Fever is uncommon and if present may be due to wound infection, which is not always apparent.

Etiology

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Cause is one of several types of neurotoxins (usually A, B, E, or F) produced by C. botulinum, an anaerobic, gram-positive bacillus. Spore production guarantees survival of the organism in extreme conditions, and they are found in the environment worldwide. Botulinum toxin blocks acetylcholine-mediated neurotransmission and is the most powerful neurotoxin known.
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Disease results from absorption of toxin into the circulation from a mucosal surface or wound. Botulinum toxin does not penetrate intact skin.
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In foodborne variety, disease is caused by ingestion of preformed toxin. Although rapidly inactivated by heat, the toxin can survive the proteolytic environment of the stomach.
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In wound botulism, toxin is elaborated by organisms that contaminate a wound.
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In infant botulism (and probably adult botulism of unknown etiology), toxin is produced by organisms in the GI tract. Antibiotic use and achlorhydria can predispose to colonization by C. botulinum and elaboration of toxin.
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Inhalational botulism has been demonstrated experimentally in primates. Rare case reports of inhalational botulism from snorting contaminated cocaine have been reported, and there is concern for the potential use of manufactured aerosolized toxin as a bioterrorism agent.

Diagnosis

Differential Diagnosis

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Myasthenia gravis, Lambert-Eaton myasthenic syndrome
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Guillain-Barré syndrome or other acute inflammatory demyelinating polyneuropathy
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Tick paralysis
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CVA
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Other: polio, heavy metal intoxication, and shellfish poisoning

Laboratory Tests

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Treatment should start before laboratory confirmation in suspected cases, as laboratory testing may take several days.
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Anaerobic cultures of serum, of food, and/or stool.
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Food, serum, and stool are sent for toxin assay.
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Public health laboratories may perform mouse bioassay testing, which confirms toxin type in 75% of cases.

Treatment

Nonpharmacologic Therapy

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Supportive care with intubation if respiratory failure occurs; may need to continue for prolonged period, as pharmacologic therapy halts disease progression only in the short term
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Debridement of the wound in wound botulism

Acute General Rx

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For non-infants: Give equine heptavalent botulinum antitoxin (HBAT), which contains antibodies for seven known botulism types (A through G), as early as possible. Once a clinical diagnosis is made, antitoxin should be administered before laboratory confirmation.
1. 1.
  
  The antitoxin (BAT, Cangene Corporation) is available from the Centers for Disease Control and Prevention (1-404-639-2206 Monday through Friday or 1-404-639-2888 evenings/weekends); it is derived from horse serum, so there is a significant incidence of serum sickness.
2. 2.
  
  Skin testing (conjunctival instillation and observation for 15 min), and possible desensitization, is recommended before treatment. Reported hypersensitivity rates range from 9% to 20%.
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Give wound botulism patients penicillin 2 million U IV q4h after antitoxin has been given. Use metronidazole 500 million U IV q8h as alternative for penicillin-allergic patients. Avoid aminoglycosides and tetracyclines, as they are ineffective and can worsen neuromuscular blockade.
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For infants: Give human botulinum immunoglobulin (BabyBIG) IV, single dose. Call 1-510-231-7600. Do not use equine antitoxin. Babies with infantile intestinal botulism may benefit from a cathartic to mechanically clear the number of C. botulinum vegetative forms and spores residing in the gastrointestinal tract. Avoid antibiotics in infant botulism because antimicrobials may lyse C. botulinum in the gut and increase toxin load.

Disposition

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Highest mortality in the first cases in an outbreak, with subsequent cases receiving rapid treatment
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Complete recovery for most individuals (may take up to 1 year)

Pearls & Considerations

Comments

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Routine cooking inactivates the toxin, but spores are resistant to environmental factors. At room temperature, spores can germinate and produce toxin. Pressure cooking can kill spores.
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Most outbreaks are associated with home-canned foods, including fruits, vegetables, and fish. Botulinum spores can be found in honey and corn syrup, and thus children under 12 months of age should not eat honey or foods with honey in them.
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Patients must be closely monitored for progression to respiratory paralysis.
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Notify public health authorities immediately to alert other health care services of possible additional cases and to initiate investigation into cause and scope of outbreak.
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Immunity to botulism does not occur after toxin exposure/infection, and repeated botulism can occur.

Ferri – Botulism