detail presentation on clostridium specie

1. Clostridium botulinum
Dr.T.V.Rao MD

2. Clostridium botulinum
• Clostridium botulinum is a Gram-positive, rod-
shaped 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. Characters of C.botulinum
• A gram-positive, anaerobic
bacilli.
• Spore forming.
• Toxin forming.
• Heat sensitive.
• Prefers low acid environment.
• Cause Botulism disease.

4. Botulism- Microbiology
• Toxin produced by the
bacterium Clostridium
botulinum
• Anaerobic, gram positive, rod-
shaped bacteria
• 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
C. botulinum

5. Microbiology
C. Botulinum
– Gram-positive obligate
anaerobic bacillus
– Spore-forming
– Produces botulinum
toxin
– Heat sensitive as
bacillus
– Prefers low acid
environment
Inglesby, T. The Washington Post
Wednesday, December 9, 1998; Page H01

6. Toxins
• 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 g .

7. Neurotoxin types
• Neurotoxin types production is the unifying feature of the
species C. botulinum. Seven types of toxins have been
identified and allocated a letter (A-G). Most strains produce
one type of neurotoxin but strains producing multiple toxins
have been described. The toxin type has been designated Bf
as the type B toxin was found in excess to the type F. Similarly,
strains producing Ab and Af toxins have been reported. There
is evidence that the neurotoxin genes have been the subject
of horizontal gene transfer, possibly from a viral source. This
theory is supported by the presence of integration sites
flanking the toxin in some strains of C. botulinum. However,
these integrations sites are degraded indicating that the C.
botulinum acquired the toxin genes quite far into the
evolutionary past. ( Wikipedia )

8. Toxins
• 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 found in nature

9. Toxins
• Absorbed in GIT, blood, peripheral
neuromuscular synapse.
• Presynaptic block Acetylcholine release
(by proteolysis of SNARE proteins in neuron
which is important in Ach release) muscle
paralysis.
• SNARE proteins are synaptobrevin, SNAP-25
and syntaxin.

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.

13. 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.

14. Pathogenesis
• Toxin must enter body
– Direct toxin absorption from mucosal surface
• Gut – foodborne
• Lungs – inhalational
– Via toxin produced by infection with C.botulinum
• Skin breaks – wound botulism after trauma, IV drugs
• Gut – intestinal botulism
• Would not be seen in BT event, as toxin would be used
• Does not penetrate intact skin

15. Pathogenesis
• Estimated lethal
human dose
• crystalline type
A toxin
• 0.09-0.15 g
given iv or im
• 0.70-0.90 g
inhalationally
• 70 g given po

16. Symptoms
• Appear in 18-24 hrs.
• include :
Blurry vision, Double vision.
Dry mouth.
Trouble swallowing.
Trouble breathing.
Muscle weakness.
Fever is not a symptom of botulism

17. Clinical Features
• Classic Triad
–Symmetric, descending flaccid paralysis
with prominent bulbar palsies
–Afebrile
–Clear sensorium
• Bulbar palsies summarized as "4 Ds"
–Diplopia, dysarthria, dysphonia, dysphagia

18. Botulism symptoms: Characteristic Triad
• Symmetric, descending (cranial nerves first, then upper
extremities, then respiratory muscles, and lower
extremities) flaccid paralysis with prominent bulbar
palsies, particularly:
– Diplopia – double vision
– Dysarthria – difficulty in speech articulation
– Dysphonia – difficulty in voice production
– Dysphagia – difficulty in swallowing
• Patient is afebrile (although fever may be present in
wound botulism)
• Patient’s sensibilities intact; cognitive functions
unaffected

19. 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
A. Patient at rest. Note bilateral mild
ptosis, dilated pupils, disconjugate gaze,
and symmetric facial muscles.
B, Patient was requested to perform his
maximum smile. Note absent smile
creases, ptosis, minimally asymmetric
smile.

21. Diagnostic laboratory test
• Toxins found in serum, leftover
food.
• Mice injected with toxin die rapidly.
• In infants, found in stool.
Brain scan, spinal fluid examination,
nerve conduction test.

22. 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

23. Treatment
• Trivalent (A,B,E)
antitoxin must
administrated
intravenously
(recovery takes
several weeks)
• Mechanical
respirator is
administrated if
necessary.

24. 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%)

25. Prevention
• Natural disease
–Boil home-canned foods 10 minutes
–Follow USDA instructions on home-
canning
–Restrict honey from < 1 year old
–Seek medical care for wounds
–Avoid injectable street drugs

26. • Programme Created by Dr.T.V.Rao MD
for Medical and Health Care
Professionals in the Developing World
• Email
• doctortvrao@gmail.com
Dr.T.V.Rao MD 26