2. Clostridium spp.
Characteristics
•Gram-positive .
•obligate anaerobes
•capable of producing endospores
which protect them in harmful
environment .
• Individual cells are rod shaped.
•The spores are usually wider than
the rods, and are located terminally
or sub terminally.
•Most clostridia are motile by
peritrichous flagella while others
have a capsule like Clostridium
perfringens
3. •The clostridia consist of many species that include common free-living
bacteria as well as important pathogens.
•Many decompose proteins or form toxins, and some do both. Their
natural habitat is the soil, marine sediments, sewage, or the
intestinal tract of animals and humans, where they live as
saprophytes.
* They cause disease primarily through the production of numerous
exotoxins.
There are four main species responsible for disease in humans:.
C. tetani: tetanus
C. botulinum: botulism
C. perfringens: gas gangrene; food poisoning
C. difficile: pseudomembranous colitis
Most Common Clostridium Species
4. The shape an position of spores varies in different species
and is useful the identification of Clostridia
*Central in Cl. bifermentans
*Sub terminal in Cl. perfringens
*Oval and terminal in Cl. tertium
*Spherical and terminal giving
drum stick appearance in Cl. tetani
Shapes Of Clostridia
6. C. botulinum
Physiology and Structure
C botulinum, which causes the disease botulism, is worldwide in
distribution; it is found in soil and occasionally in animal feces.
Motile , Have peritrichate flagella Arrangement .
Types of C botulinum are distinguished by the antigenic type of
toxin they produce.
Spores of the organism are oval , Sub-terminal and highly resistant
to heat, withstanding 100°C for several hours. Heat resistance is
diminished at acid pH or high salt concentration.
.
7. Toxins
During the growth of C botulinum and during autolysis of the
bacteria, toxin is liberated into environment.
Seven antigenic varieties of toxin (A-G) are known. Type A, B, E, and
F are the cause of human disease(Botulinum toxin).
Types A and B, have been associated with a variety of foods and
type E with fish products.
C botulinum toxins are among the most toxic substances known: The
lethal dose for a human is probably about 1–2 µg/kg.
The toxins are destroyed by heating for
20 minutes at 100°C.
C. botulinum
8. C. botulinum
Pathogenicity
Botulinum toxin is absorbed from the gut carried via the
blood, binds to receptors of presynaptic membranes of
motor neurons of peripheral nervous system and cranial nerves
where it blocks release of acetylcholine.
It is a protease that cleaves the proteins involved in acetylcholine
release. Along with tetanus toxin, it is among the most toxic
substances known.
9. Transmission
Transmitted by three ways:
1- Food or water toxin contamination
2- wound infected with C. botulinum
3- Ingestion of C. botulinum.
Most common contaminated foods are: canned or vacuum-packed
without adequate sterilization, spores survive and germinate in
the anaerobic environment. Toxin is produced within the canned
food and ingested preformed.
C. botulinum
10. The highest-risk foods are:
(1) vegetables such as green beans, peppers, and mushrooms.
(2) smoked fish.
The toxin is relatively heat-labile; it is inactivated by boiling for
several minutes.
Thus, disease can be prevented by sufficient cooking.
C. botulinum
11. C. botulinum
Clinical Diseases
•Foodborne botulism
Incubation period: 18-24 hrs.
Symptoms: double vision,
inability to swallow, speech difficulty,
bulbar paralysis, constipation, and abdominal pain. Bilateral
descending weakness of peripheral muscle. Death occurs
from respiratory paralysis or cardiac arrest. No fever.
Mortality is high.
Patients who recover do not develop antitoxin.
12. C. botulinum
Clinical Diseases
•Infant botulism
Occurs in the first month of life, when the infant ingest the
spores germinate within the intestinal tract and produce toxin
as they multiply, the neurotoxin then gets absorbed into the
bloodstream.
Ingestion of honey containing the organism is implicated in
transmission of infant botulism.
Affected infants develop weakness or paralysis and may need
respiratory support but usually recover.
13. • Wound botulism
in which spores contaminate a
wound, germinate, and produce
toxin at the site
Symptoms similar to those of
food borne botulism with longer
incubation time. Less GI
symptoms.
C. botulinum
14.
15. C. botulinum
Laboratory Diagnosis
Culture of C. botulinum in patient feces and implicated food, but
usually not cultured.
Detection of toxin and not organism is required for definitive
diagnosis. Toxin can be demonstrated in serum, gastric secretions
or stool from the patient and in leftover food.
swabs or other specimens obtained from patients should be
transported using anaerobe containers. Suspect foods should be left in
their original containers. Mice injected intraperitoneally with such
specimens from these patients die rapidly.
This mouse bioassay is the test of choice for the confirmation of
botulism.
Other methods used to detect toxin include ELISAs and PCR.
16. C. botulinum
The Clostridium botulinum isolation (CBI) Agar medium,
a selective medium for thecultivation of C. botulinum in the
laboratory can easily be prepared by adding :
Antibiotics - Cycloserine,
Sulfamethoxazole & Trimethoprim to the
Egg yolk agar medium.
Clostridium botulinum is an obligate anaerobic bacterium i.e. can
only
grow in the absence of oxygen (Strict anaerobe).
Optimum temperature – The optimum temperature for the growth
of Clostridium botulinum is 35°C. Some strains of C. botulinum can
grow
at very low temperatures (1-5°C).
. Optimum pH - 4.6 - 8.9
17. C. botulinum
Cultural
characteristics
Sheep Blood Agar
Medium
Nutrient Agar
Medium (NAM)
Egg Yolk Agar
Medium
Shape Large , Irregularly
Circular
Large , Irregularly
Circular
Large , Irregularly
Circular
Size 2-3 mm 2-3 mm 2-3 mm
Elevation Slightly raised Raised Slightly raised
Surface Smooth Smooth Smooth
Color Grey Whitish Grey Greyish White
Structure Translucent
_ Opaque
Translucent Opaque
Hemolysis B - Hemolysis --------- --------
19. Treatment
Stomach lavage and high enemas.
Trivalent (A, B, E) antitoxin administered intravenously
promptly, along with respiratory support.
Adequate ventilation by mechanical respirator.
Although most infant with botulism recover with supportive
care alone, treatment with human – derived botulinum
immune globulin (BIG)is recommended.
C. botulinum
20. Prevention and Control
Because spores of C botulinum are widely distributed in soil, they
often contaminate vegetables, fruits, and other materials. When such
foods are canned or otherwise preserved, they either must be
sufficiently heated to ensure destruction of spores or must be boiled
for 20 minutes before consumption.
Toxic foods may be spoiled and rancid, and cans may “swell,” or the
appearance may be innocuous. The risk from home-canned foods can
be reduced if the food is boiled for more than 20 minutes before
consumption.
C. botulinum
21. References
• Tiwari, Aman; Nagalli, Shivaraj (2021), "Clostridium Botulinum", StatPearls, Treasure
Island (FL): StatPearls Publishing, PMID 31971722, retrieved 2021-09-23.
• ^ Jump up to: a b c Peck MW (2009). Biology and Genomic Analysis of Clostridium
botulinum. Advances in Microbial Physiology. Advances in Microbial Physiology. Vol.
55. pp. 183–265, 320. doi:10.1016/s0065-2911(09)05503-9. ISBN 9780123747907.
PMID 19573697.
• ^ Jump up to: a b Lindström M, Korkeala H (April 2006). "Laboratory diagnostics of
botulism". Clinical Microbiology Reviews. 19 (2): 298–314. doi:10.1128/cmr.19.2.298-
314.2006. PMC 1471988. PMID 16614251.
