Botulism

Background

Cluster of wound botulism in injecting drug users

Information from National Disease Surveillance Centre
Sporadic cases have been peported in IV drug users
All cases had a flaccid paralysis
Drugs contaminated with the anaerobic Clostridium botulinum

Abroad

Several people had (2023, France) botulism poisoning from eating contaminated food
In the USA, botulism is associated with skin popping "black tar" heroin

Causative organism

Symptoms of botulism are caused by a toxin produced by the gram +ve, anaerobic, spore forming Clostridium botulinum
The toxin blocks the release of acetylcholine at the neuromuscular junction → descending flaccid paralysis
Botulism is not spread from one person to another
There are three naturally occurring forms of botulism:
- Food-borne botulism, caused by ingestion of pre-formed toxin
- Wound botulism, which occurs when C. botulinium spores contaminate a wound, germinate and produce toxin in vivo
- Intestinal colonisation botulism, usually seen in infants

Clinical features

Afebrile
Descending
Flaccid Paralysis

Patients with botulism typically present with:

Difficulty speaking, seeing and/or swallowing
May have double vision, blurred vision, drooping eyelids
Slurred speech, difficulty swallowing, and muscle weakness (later, loss of tendon reflexes)
Paralysis may progress to the arms, legs, trunk and respiratory muscles
Usually no fever
No loss of sensation
No loss of awareness

There may also be autonomic signs with:

Dry mouth, fixed or dilated pupils
Cardiovascular, GI and urinary dysfunction

If onset is very rapid, there may be no symptoms before sudden respiratory paralysis occurs, which may be fatal. Recovery can take months.

Differential Dx of BOTULISM

Guillain Barré
- Usually ascending motor paralysis
Miller Fisher (Guillain Barré variant):
- May be descending, paralysis ± bulbar
Organophosphate poisoning
Myaesthenia gravis:
- Fatiguability, better at rest
Lambert Eaton syndrome:
- Proximal muscle weakness (not face)
Paralytic shellfish poisoning
Tick paralysis
Encephalitides
Enterovirus infection

Laboratory

Confirmation of the clinical diagnosis is by the demonstration of botulinum toxin in blood samples or, in the case of wound botulism, by the identification of C. botulinum in wound specimens. Specimens should be sent immediately to the reference laboratory.

Samples to be taken from acutely ill patients include:

Serum. At least 10ml. Serum samples must be collected before antitoxin is administered
Wound. Pus. As much as possible in a sterile container. If no pus - swab in anaerobic culture medium.)
Biopsy tissues. If surgical debridement is performed, biopsy tissues should be placed immediately into a sterile container
Post mortem specimens. Heart blood (10ml), if not haemolysed, should be sent for serum for serum collection. Specimens from infected wounds may also be useful
All samples must be kept refrigerated after collection
Specimens should be sent directly to the reference laboratory with the sender’s name and address clearly marked. Call the reference laboratory prior to sending the sample

Clinical management

Botulism Antitoxin

Botulism anti-toxin (if required) can be procured by contacting: Dr Seamus O’Dea, Cherry Orchard

Tel 01 620 6000 (or medical officer on call)

Specialist advice should be urgently sought from ID or Micro
Botulinum antitoxin is effective in reducing the severity of symptoms if administered early in the course of the disease
C. botulinum is sensitive to benzyl penicillin and metronidazole
In cases of wound infection, antimicrobial therapy and surgical debridement should reduce the organism load and therefore toxin production, but circulating toxin can only be neutralised by the early administration of antitoxin
Beware respiratory fatigue - regular blood gases and spirometry (intubate if ↓O₂ or ↑CO₂ or FVC < 30%)
Where there is definite clinical suspicion of botulism, treatment with antitoxin should not be delayed for microbiological testing
Discuss with neurophysiology re nerve conduction studies in (well!) cases of suspected Miller Fisher

Reporting & public health investigation

Food samples associated with suspected cases of food borne botulism must be obtained as a matter of extreme urgency in order to prevent further cases
Reference for this page is : CEM/CMO/2002/14