Botulism, Emergency Medicine

Basics

Description

Rare in US, causing <200 cases/yr; however, has significant bioterrorism potential.
Caused by a polypeptide, heat-labile exotoxin produced by Clostridium botulinum:
- Most potent poison known
Toxin blocks neuromuscular transmission in cholinergic nerve fibers.
Symptoms occur by inhibition of acetylcholine release from presynaptic nerve membranes:
- Damage is permanent.
- Recovery is by formation of new synapses through sprouting from the axon.
Onset: 12-72 hr after exposure; may be up to 1 wk after exposure:
- Death can occur 24 hr after onset of symptoms.
Slow recovery; symptoms often persist for months
Mortality:
- Untreated: 60-70%
- With supportive care: 3-10%
3 major types: Food-borne botulism, wound botulism, and infantile botulism (see "Pediatric Considerations"). Absorbed through mucosal surfaces or nonintact skin
Food-borne botulism:
- Occurs by ingestion of preformed toxin; from improperly canned food, improper refrigeration
- Conditions required for exposure:
  - Food product contaminated with C. botulinum bacilli or spores
  - Proper conditions for germination of spores exist.
  - Time and conditions permit production of toxin before eating.
  - Food not heated sufficiently to destroy botulism toxin
  - Toxin-containing food ingested by susceptible host
Wound botulism:
- Clinical evidence of botulism after trauma with a resultant infected wound and no history suggestive of food-borne illness
- Botulinum isolated in about 50%
- Wounds usually contaminated with soil
- Majority of US cases from IV drug use
Other types:
- Adult intestinal toxemia botulism:
  - Seen in adults with functional or structural GI abnormalities, are immunocompromised or with prolonged antibiotic use
  - Predisposes to Clostridial colonization
  - May have sporadic or recurrent botulism with no known source and even after immunoglobulin treatment
- Iatrogenic botulism:
  - Doses found in cosmetic applications are insufficient to cause systemic symptoms.
  - No known recent cases from medical use.
  - Symptoms would be expected to be classic.
- Inhalation botulism:
  - Aerosolization of toxin may have bioterrorism applications. Last reported naturally occurring case in 1962 from the disposal of animal remains.

Infantile botulism occurs from the ingestion of C. botulinum spores, which germinate in the gut and produce the toxin.
Accounts for 50-76% of botulism cases
90% occur in children <6 mo:
- Associated with patient or family exposure to soil, dust, or agricultural industry.
- May also be associated with weaning from breast milk, which may alter intestinal flora and increase susceptibility to Clostridia infection.
Usually presents with change in stool pattern or constipation, progressing over several days to symptoms of bulbar weakness, then descending flaccid paralysis.
Slower onset is attributed to the toxin being produced locally as opposed to being ingested in 1 dose.
C. botulinum spores found in honey:
- Honey not recommended for children <1 yr.

Etiology

C. botulinum is a large spore-forming, usually gram-positive, strictly anaerobic bacilli ubiquitous in nature.
Each strain produces antigenically distinct toxins, designated types A to G:
- Types A, B, E, and rarely F are responsible for most human cases.

Diagnosis

Signs and Symptoms

History

Ingestions/food history for previous 4-5 days:
- Exposures traditionally from home-processed fruit or vegetable products
- In prison populations ingestion of "pruno" (alcohol product created by prisoners using leftover food products)
Immune status (AIDS, cancer, chronic illness)
IV drug use

Physical Exam

Food-borne botulism (classic botulism):
- Bulbar weakness is invariably the initial presentation: Diplopia, dysphagia, dysarthria, and dysphonia
- Subsequent symmetric, descending weakness or paralysis of the extremities (hallmark of the disease)
- No sensory deficit
- May have progressively diminishing deep tendon reflexes
- Patient remains awake/alert; mentation unaffected.
- Ventilatory insufficiency from weakness of respiratory muscles
- Autonomic dysfunction (sympathetic and parasympathetic):
  - Dry mouth
  - Blurred vision
  - Orthostatic hypotension
  - Constipation
  - Urinary retention
- Nausea and vomiting with food-borne botulism only
- Afebrile
Wound botulism:
- Finding similar to food-borne botulism
- May be febrile as a result of soft-tissue infection
Infantile botulism:
- Constipation
- Weakness
- Poor suck
- Weak cry
- Lethargy
- Hypotonia
- Flaccid facial expression
- Respiratory difficulty
Inhalation botulism:
- Similar to food-borne botulism with absence of GI symptoms

Essential Workup

Diagnosis is entirely clinical.
Workup focuses on differentiation from other conditions causing general paralysis.
If diagnosis is suspected, immediately notify state health department or CDC (770-488-7100 for adults or 1-510-231-7600 for infant cases).

Diagnosis Tests & Interpretation

Lab

CBC
Electrolytes, BUN/creatinine, and glucose:
- Check for hypokalemia.
Arterial blood gas (ABG):
- For signs of respiratory insufficiency
Confirmatory testing via mouse assay performed by select state and federal labs, using samples from:
- Blood
- Feces
- Gastric contents
- Suspected food and containers
- Takes between 6-96 hr for results
Anaerobic blood cultures:
- May detect bacterium
Nasal swab for ELISA test:
- For inhalation botulism, as less reliably detected in sera and stool than other forms
- Sample needs to be collected within 24 hr of exposure

Imaging
CT/MRI of brain:

Normal

Diagnostic Procedures/Surgery

CSF testing:
- Normal
- Helps differentiate from Guillain-Barr © syndrome (which as markedly elevated CSF protein)
Electrophysiologic studies:
- Normal nerve conduction with diminished evoked muscle action potential
Edrophonium testing may be positive, but not to the degree seen in myasthenia gravis.

Differential Diagnosis

Myasthenia gravis (less acute)
Lambert-Eaton myasthenic syndrome (less acute)
Polio (fever and asymmetric)
Guillain-Barr © (simultaneous sensory findings and elevated spinal fluid protein)
Tick paralysis
Magnesium intoxication
Hypokalemic periodic paralysis
Diphtheritic neuropathy
Rare basilar stroke syndromes with bulbar palsy

Often misdiagnosed as dehydration, sepsis, or Reye syndrome
Other diagnoses include inborn errors of metabolism, Guillain-Barr © syndrome, and spinal muscle atrophy.

Treatment

Death is invariably from progressive ventilatory failure:

Intubate as soon as respiratory insufficiency noted, clinically and/or in conjunction with ABG.
May require several weeks of ventilatory support

Pre-Hospital

Transcutaneous pacing for unstable type II 2nd- or 3rd-degree block
Atropine:
- Avoid with type II 2nd-degree block because it may precipitate complete heart block
- Contraindicated in 3rd-degree heart block with a widened QRS complex
Attempts should be made at preventing increases in vagal tone.

Initial Stabilization/Therapy

Early intubation and ventilatory support is the key to survival.
Respiratory difficulties occur rapidly.

Ed Treatment/Procedures

Bivalent AB antitoxin:
- IV administration as soon as the diagnosis is made and initial samples are collected, without waiting for lab confirmation
- Before use assess hypersensitivity with skin test using horse serum or antitoxin
- Using recommended dose <1% will have hypersensitivity reaction
With wound botulism perform wound d ©bridement even if it appears to be healing.
Antibiotics for specific infectious complications
Standard precautions only; no evidence of person-to-person transmission
If environmental exposure, wash clothing and skin with soap and water

Medication

ABE antitoxin formulations no longer used because of declines in titer to type E toxin
1st-line treatment:
- Baby BIG human-derived antitoxin to types A and B licensed by USFDA for treatment of infant botulism and distributed by CA Dept. of Public Health (510-231-7600). www.infantbotulism.org/
- Heptavalent antitoxin (H-Bat) available from CDC as an investigational use drug protocol and emergency therapeutic use. Not for infant botulism.

Baby BIG halves average hospital stay from 6-3 wk:
- Adult equine antitoxin should not be used on pediatric patients
Antibiotics:
- Ineffective in eradicating organism from the intestine
- Release of toxin in the gut through bacterial cell lysis may worsen neurologic symptoms.

Second Line
Pentavalent toxoid for lab workers

Follow-Up

Disposition

Admission Criteria
Admit patients with suspected botulism poisoning to monitored bed:

ICU admission for any respiratory deficiency

Discharge Criteria
Clinical course of botulism poisoning is unpredictable; it can become rapidly progressive and fatal:

Discharge patients only after a prolonged period of progressive recovery from symptoms.

Follow-Up Recommendations

Physical medicine and rehabilitation:
- Residual weakness can last for up to 1 yr
Mental health:
- Patients and their families often experience stress and depression with the prolonged recovery.

Pearls and Pitfalls

Botulism is a public health emergency; early consultation with state and federal health departments is required.
Suspect botulism if there are more than 2 cases; other conditions in the differential do not produce outbreaks.
Antitoxin does not reverse paralysis but only halts its progression. Therefore, administer antitoxin once diagnosis is suspected. Do not wait until signs of respiratory compromise are present.
Initial signs of respiratory distress may not be clinically apparent secondary to paralysis.
Bulbar palsy at presentation may be mistaken for altered mental status.

Additional Reading

CDC. Botulism. Emergency Preparedness and Response. Accessed on 11/02/09 from http://emergency.cdc.gov/agent/botulism.
Dembek ZF, Smith LA, Rusnak JM. Botulism: Cause, effects, diagnosis, clinical and laboratory identification, and treatment modalities. Disaster Med Public Health Prep. 2007;1:122-134.
Domingo RM, Haller JS, Gruenthal M. Infant botulism: Two recent cases and literature review. J Child Neurol. 2008;23:1336-1346.
Ho RY. Chapter 170. Botulinum antitoxin. In: Olson KR, ed. Poisoning & Drug Overdose. 6th ed. New York, NY: McGraw-Hill; 2012. http://www.accessmedicine.com/content.aspx?aID=55987003. Accessed January 10, 2013.
Gouveia C, Mookherjee S, Russell MS. Wound botulism presenting as deep space neck infection. Laryngoscope. 2012;122:2688-2689.
Thurston D. Botulism from drinking prison-made illicit alcohol. MMWR Morb Mortal Wkly Rep. 2012;61:782-784.
Khakshoor H, Moghaddam AA, Vejdani AH, et al. Diplopia as the primary presentation of foodborne botulism. Oman J Opthalmol. 2012;5:109-111.

Codes

ICD9

005.1 Botulism food poisoning
040.41 Infant botulism
040.42 Wound botulism

ICD10

A05.1 Botulism food poisoning
A48.51 Infant botulism
A48.52 Wound botulism

SNOMED

398565003 Infection due to clostridium botulinum (disorder)
398530003 Wound botulism (disorder)
414488002 Infantile botulism
409563004 Intestinal botulism

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