Study on Clostridium botulinum.

1. CLOSTRIDIUM
BOTULINUM
B Y
M D . A S H FA Q A Z I Z
D E PA R T M E N T O F M I C R O B I O L O G Y
P R I M E A S I A U N I V E R S I T Y

2. INTRODUCTION
• Clostridium botulinum is a Gram-positive, rodshaped
bacterium that produces several toxins. The best known are
its neurotoxins, subdivided in types A-G, that cause the
flaccid muscular paralysis seen in botulism. They are also
the main paralytic agent in botox. C. Botulinum is an
anaerobic spore-former, which produces oval, sub terminal
endospores and is commonly found in soil.

3. MORPHOLOGICAL CHARACTERISTIC
• A gram-positive, anaerobic bacilli.
• Spore forming.
• Toxin forming.
• Heat sensitive.
• Prefers low acid environment.
• Cause Botulism disease.

4. MORPHOLOGICAL CHARACTERISTIC
• Bacteria are 0.5 to 2.0 mcm in width and 1.6 to 22.0 mcm in
length
• Create spores that can remain dormant for 30 years or more
• Spores extremely resistant to environmental stressors, such
as heat and UV light

5. MORPHOLOGICAL CHARACTERISTIC

6. VIRULENCE FACTOR
• Neurotoxin:
- Liberated during growth.
- Seven types of toxins (A-G).
- Antigenic (light and heavy chain).
- Environmental survival. (Inactivated by heat 100ºC for 20min ).
- Most potential biological warfare agents.
- Lethal dose= 1-2 micro gram.

7. VIRULENCE FACTOR
• Botulinum toxin:
- Botulinum toxin is synthesized as a single polypeptide chain ( low
potency).
- The toxin is nicked by a bacterial protease (or by gastric proteases) to
produce two chains :
a light chain (the A fragment)
a heavy chain (the B fragment) connected by a disulfide
bond.
- The A fragment of the nicked toxin, becomes the most potent toxin

8. VIRULENCE FACTOR
• Mechanism of Botulinum toxin:
– Absorbed from the gut.
– Binds to receptors of presynaptic membranes of motor neurons of the
peripheral nervous system and cranial nerves.
– Proteolysis-by the light chain of botulinum toxin of the target SNARE
proteins in the neurons inhibits the release of acetylcholine at the
synapse, resulting in lack of muscle contraction and paralysis.
– SNARE proteins are-synaptobrevin, SNAP 25, syntaxin.
– Type A and E toxin cleaves-SNAP 25.
– Type B toxin cleaves synaptobrevin.

9. VIRULENCE FACTOR
• Mechanism of Botulinum toxin:
Figure: Mechanism A Figure: Mechanism B

10. PATHOGENESIS
• Transmitted in three ways:
– Food or water toxin contamination.
– Wound infected with C. Botulinum.
– Ingestion of C. botulinum.
• Most common contaminated food:
Vacuum packed, or canned alkaline food.
E.g. fish, green beans, any home-canned food.
• Foods eaten without cooking

11. PATHOGENESIS OF INFANT BOTULISM
• Cause :infection by C. botulinum.
• Age: 5 - 20 weeks of age.
• Characterized by constipation and weak sucking.
• It cause “sudden infant death syndrome-SIDS”.
• Found in the stool.

12. SYMPTOMS
• Appear in 18-24 hrs.
• Include :
-Blurry vision, double vision. -Thrombocytopenia.
-Dry mouth.
-Trouble swallowing.
-Trouble breathing.
-Muscle weakness.
-Constipation.
-Dropping eyelid.
-Irritability.
• Fever is not a symptom of botulism.

13. SIGNS OF FOOD-BORNE AND WOUND
BOTULISM
• Ventilatory (respiratory) problems.
• Eye muscle paresis/paralysis (extra ocular, eyelid).
• Dry mucous membranes in mouth/throat.
• Dilated, fixed pupils.
• Ataxia.
• Hypotension.
• Nystagmus.
• Decreased to absent deep tendon reflexes.

14. DIAGNOSIS
• Clinical diagnosis
• Diagnostic tests help confirm
– Toxin neutralization mouse bioassay
• Serum, stool, or suspect foods
– Infant botulism
• C. botulinum organism or toxin in feces
• Testing is done in Reference laboratories under Biosafety regulations

15. TREATMENT
• Passive immunization - equine antitoxin
– Antibodies to Types A, B and E toxins.
– Binds and inactivates circulating toxin.
– Stops further damage but doesn’t reverse.
• Heptavalent antitoxin
– Investigational.
– Effective against all toxins.

16. TREATMENT
• Antitoxin action
– Food-borne botulism
• Neutralizing antibody levels exceed toxin levels
• Single dose adequate
– Large exposure (e.g. biological weapon)
• can confirm adequacy of neutralization
– recheck toxin levels after treatment
• Antitoxin adverse effects
– Serum sickness (2-9%), anaphylaxis (2%)

17. THANK YOU