Botulism and Clostridia Species Review
Clostridia species and toxins
- C. botulinum produces serotypes A through H
- C. baratti → toxin F
- C. batyricum → toxin E
- C. argentinense → toxin G
Clostridia species review
- Types
- Type A = West of Mississippi (0-7 day incubation)
- Typer B = East of Mississippi (0-5 day incubation)
- A/B process meat/vegetables – smells putrified
- E – ALASKA -> Raw fermented fish/animals (food looks and tastes NORMAL) (incubation 0-2 days)
- Most cases A, B, E or F
- All spores resistant to heat, pH >4.5, NaCl content < 3.5%, low nitrite content
- Toxin is protected from gastric pH by complexing with hemagluttinins that protect it from proteolytic environment – then dissociates in alkaline intestine (or PPI/H2RA)
- Toxin is heat labile
- BoNT most potent toxin known (LD50 1 mcg). Inhaled botulinum toxin 100 times more potent than ingested.
- Iatrogenic botulism- Synthetic pharm agents: Patients develop neutralizing antibodies from long term use
- Wound botulism – black tar heroin “skin popping”
MOA/Clinical Manifestations
- Dichain toxin binds to the peripheral cholinergic nerve terminal
- Impairs transmission at ACh dependent synapses at PNS
- Delayed onset (12-24 hours)- if rapid onset, consider (ciguatera, TTX)
- PERIPHERAL ANTICHOLINERGIC toxidrome
- NO CNS involvement (ddx Miller-fisher variant of myasthenia gravis)
- 1st sx is GI distress – occurs within a few hours, but not bad enough to seek medical attention
- Followed by neuro: horizontal diplopia, b/l symmetric descending flaccid paralysis), constipation
- 12 D’s = dry mouth, diplopia, dilated pupils, droopy eyes (ptosis), droopy face, diminished gag reflex, dysphagia, dysarthria, dysphonia, difficulty lifting head, descending paralysis, diaphragmatic paralysis.
- ALASKA has 5 D’s: dilated pupils, diplopia, dry throat, dysphagia, n/v.
- Infant Bot – ingestion of spores – germinate in GI. Also exposure to dust @ sites where soil is disrupted, farming, plant nursery or plumbing.Can cause SIADH
- Almost always A or B
- 1st sx – constipation, difficulty feeding/sucking, febile cry, diffusely decreased muscle tone
- Rare in adults but can be if: GI pH increased
Diagnosis
- Edrophonium testing (inh ACh metabolism): Positive response = myasthenia gravis/ miller-fisher variant of Guillain Barre; negative response = botulism (since it prevents the release of ACh)
- Electrophysiologic testing: in all forms of Botulism, sensory nerve potentials are normal
- Labs: anaerobic culture and mouse bioassay for BoNT. Mouse lethality test is the gold standard (serum, stool or food sample): 2 sets of mice inj with sample from patient: one control and one pretreated with antitoxin
- Negative inspiratory force (NIF) MOST reliable, rabidly obtainable for determining need for intubation: intubate if NIF < minus 30 cm H20
- DDX: Tick paralysis, hypokalemia, elapid envenomation
Treatment
- Should be initiated based on clinical suspicion and NOT wait for testing
- AC+Sorbitol (due to decreased GI motility)
- H-BAT – heptavalent botulinum antitoxin (equine) A through G
- Doesn’t reverse paralysis
- Dose: 1 vial diluted 1:10 in NS over 60 min
- Used for all adult forms of bot: wound, iatrogenic, intestinal toxemia. Can be used for infant if not responding to BIG or non A/B type
- Botulism immune globulin (BabyBIG) A+B only.
- Must use H-BAT in infants for non A/B
- Single dose, no repeat dosing
For more chapters, visit the ABAT Study Guide homepage
Botulism and Clostridia Species Review
Leave A Comment