Clostridium is a genus of anaerobic, Gram-positive bacteria. Species of Clostridium inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative agents of botulism and tetanus.

1. CLOSTRIDIUM
Dr. Rachana Choudhary
Department of Microbiology
Shri Shankaracharya Mahavidyalaya, Junwani Bhilai (C.G.)

2. Synopsis
•Introduction
•History
•Classification
•Some common pathogenic bacteria
1. Clostridium botulinum
2. Clostridium tetani
3. Clostridium perfringens
•Conclusion
•Reference

3. INTRODUCTION
The genus Clostridium consists
•Gram positive
•Anaerobic, spore bearing
•Straight or slightly curved
rods
•Saprophytes
•Some are commensals of the
animal & human gut.
•Disease Caused
Gas gangrene,
Tetanus,
Botulism Fig:- Clostridium

4. HISTORY
•5th Century BC: Hippocrates first described the disease
•1884: Carle and Rattone discovered the etiology .
•Produced tetanus by injecting pus from a fatal human case
•1897: Nocard demonstrated the protective effect of
passively transferred antitoxin  used in WWI
•1924: Descombey developed tetanus toxoid for active
immunization  used in WWII

5. CLASSIFICATION
Position of
spore
Both proteolytic & saccharolytic Slightly proteolytic / Saccharolytic
/ Neither proteolytic nor
saccharolytic
Proteolytic Saccharolytic
Central or
sub-
terminal
Oval &
terminal
Spherical
& terminal
Cl.bifermentans
Cl.botulinum
Cl. histolyticum
Cl. sordelli
Cl. sporogenes
___
___
Cl. perfringens
Cl. septicum
Cl. chuvoei
Cl. novyi
Cl. difficile
___
Cl. fallax ( S/nPro.)
Cl. botulinum ( “=“ )
Cl. tertium
Cl. tetani
A Morphological & Biochemical Classification of Clostridia

6. SOME COMMON PATHOGENIC BACTERIA
• Cl. Perfringens
• Cl. botulinum
• Cl. tetani
They are dealt as following
 Introduction
 Morphology
 Classification
 Cultural characteristics
 Resistance
 Toxins
 Pathogenicity
 Treatment & Diagnosis
 Prevention

7. 1. Clostridium perfringens
Fig:- Cl. Perfringens
Introduction:-
• Formerly known as Cl. welchii
• Gram- positive, anaerobic, spore
forming bacteria
• Present in – decaying vegetation,
marine sediment, intestinal tract
human & vertebrates, soil.
Morphology :-
• Large rod shape, about 4-
6µm×1µm, capsulated, non
motile, filamentous, spores are
central & sub terminal.

8.  Classification:-
Based on production of
toxins.
Type-A
Type-B
Type-C
Type-D
Type-E
Cultural characteristics :-
• It is an anaerobe but can also grow under micro aerophilic condition.
• pH range - 5.5-8.0
• Temp. range - 20ºC–50ºC
• Media – Robertson’s cooked meat medium & blood agar.
• Resistance :-
• Spores destroyed - 5 min.
• Strain, Type-A & Type-C resist boiling 1-2 hour.

9. Toxins:-
•Cl. perfringens , forming at least 12 distinct toxins.
•The 4 major toxin’s – α, β, ε & iota are responsible for
pathogenicity.
 Alpha toxin – causes RBC rupture and tissue destruction.
 Enterotoxin is heat labile toxin produced in colon → food
poisoning
Pathogenicity:-
•Cl. perfringens produce following human infections – gas
gangrene, food poisoning, necrotising entritis etc.
•It produce Enterotoxin
•Incubation: 1-7 days after infection.

10. Enterotoxin
•Stomach acids initiate spore germination
•When the cell lyses, it releases mature endospores
•Spores bind to intestinal epithelial cells and induce
intestinal tissue damage
•Usually symptoms occur within 6-24 hours of ingestion
and can last ~24 hours

11.  Pathogenicity
Fig:- Action of Alpha toxin of Cl. perfringens

12. Treatment
Prevention
•Handling foods properly, especially meats
•Use of correct temperatures when cooking and cooling food
•165° F kills bacteria,Must be cooled quickly and reheated
to 165° F again
•Maintaining raw meat at very low temperatures (<40° F)
•Depends on toxicity and type of strain ingested
•For Animals: Not much can be done once spores are Ingested
•For Humans: Penicillin and other antibiotics are used for gas
gangrene and wound infections.
• Surgery is used for cases in which severe tissue damages
occur
• Keep hydrated

13. 2. Clostridium botulinum
Fig:-Clostridium botulinum
 Introduction:-
• A gram-positive, anaerobic bacilli.
• Spore forming.
• Toxin forming.
• Heat sensitive.
• Prefers low acid environment.
• Cause Botulism disease.
 Morphology :-
• Rod shape,5µm ×1µm
• Motile, noncapsulated
• Spores subterminal

14. Classification
• 8 types of Cl. botulinum on the basis of toxins.
• Type A, B, C1, C2, D, E, F, G.
Cultural characteristics
• Strict anaerobic
• Optimum temp. for growth - 35ºC
• Some may grow even 1–5ºC.
• Spores produced – Glucose gelatin media (20–25ºC).
Resistance
• Spores are heat & radiation resistant –several hours at 100ºC for upto
10 min at 120ºC.
• Spores of nonproteolytic types of B, E and F are much less resistant to
heat.

15. Toxin:-
•Exotoxin produced- responsible for pathogenicity
•librated during growth.
•Seven types of toxins (A-G).
•Antigenic (light and heavy chain).
•Environmental survival. (Inactivated by heat 100ºC for 20
min ).
•Most potential biological warfare agents.
• Lethal dose= 1-2 g .
Pathogenicity :-
•Cl.botulism is noninvasive and virtually noninfectious.
•Pathogenicity – due to action of toxin ( neurotoxin ).
•Cause “Botulism” in human.

16. Fig :- Mechanism of Botulinum toxin

17. Prevention
•Proper food handling and preparation
•80°C for 10 minutes or longer
•Manufacturers use thermal processes designed to destroy
spores
•Processors add salt or nitrites to reduce growth
Diagnosis and Treatment
Electrodiagnostic testing = repetitive nerve stimulation
Test serum or feces of the patient for the toxin
Mouse neutralization test
48 hours to complete
5-7 days to culture specimens
Neutralized by an antitoxin - only in circulation

18. 3.Clostridium tetani
Fig:- Clostridium. tetani
Introduction:-
• Cl. tetani is the causative organism of
tetanus.
• Gram positive, straight, slender rod with
rounded ends
• Endospore Forming
• Fermentative
• Obligate anaerobe
• Motile by peritrichous flagella
Morphology:-
• Slender rod shape, about 14 µm×0.5µm
• Spores – terminal, spherical in shape
• Like drumstick

19. Classification:-
 Ten serological types have been recognised based on
agglutination (types I to X )
Cultural characteristics:-
•Obligatory anaerobe that grows only in the absence of
oxygen.
•Optimum growth temp.-37ºC & pH – 7.4
Resistance:-
•The resistance of tetanus spores to heat appears to be
subjected to strain differences
•Most are killed by boiling for 10-15 min.

20. Toxins:-
Cl.tetani produce 2 toxins
 tetanus toxin
or tetanospasmin
•The second exotoxin produced tetanolysin-function not
known.
Pathogenicity:-
•Not pathogenic to humans and animals by invasive
infection but by the production of a potent protein toxin .
•It is causative organism of tetanus.

21.  Mechanism of Cl.tetani toxin (Pathogenicity)

22.  Transmition
• C. tetani can live for years as spores in animal feces and soil.
• It enters the human body :- by wound
• Tetanus may follow burns, deep puncture wounds, ear or dental
infections, animal bites, abortion.
• It is the only vaccine-preventable disease that is infectious but not
contagious from person to person.
 Symptoms
• Tetanic seizures (painful, powerful bursts of muscle contraction)
• if the muscle spasms affect the larynx or chest wall, they may cause
asphyxiation
• stiffness of jaw (also called lockjaw)
• stiffness of abdominal and back muscles
• contraction of facial muscles
• fast pulse
• fever
• sweating

23.  Methods of diagnosis
Based on the patient’s account and physical findings that are
characteristic of the disease.
Diagnostic studies generally are of little value, as cultures of
the wound site are negative for C. tetani two-thirds of the
time.
When the culture is positive, it confirms the diagnosis of
tetanus
Tests that may be performed include the following:
 Culture of the wound site (may be negative even if tetanus is
present)
 Tetanus antibody test
 Other tests may be used to rule out meningitis, rabies,
strychnine poisoning, or other diseases with similar
symptoms.

24.  Treatment
•If treatment is not sought early, the disease is often fatal.
•The bacteria are killed with antibiotics, such as penicillin or
tetracycline; further toxin production is thus prevented.
•The toxin is neutralized with shots of tetanus immune
globulin, TIG.
•Other drugs may be given to provide sedation, relax the
muscles and relieve pain.
•Due to the extreme potency of the toxin, immunity does not
result after the disease.

25.  Prevention
•Rigorous hygienic response to injury
•Vaccination
•First 4 immunization shots (DTP: diphtheria-tetanus-
pertussis) given within 2 years
•Every 10 years: booster shot

26.  Conclusion
All Clostridium is an anaerobic bacteria found in soils
and sediments, especially in areas of pollution, Persists in
fecal matter and intestinal tracts of animals and humans.
It’s causes different major diseases in humans & animals.
Using the correct temperatures in cooking, cooling, or
reheating food is crucial to inhibit bacteria growth in food.

27.  Reference
•Book of Microbiology :- R.P. Singh
•Textbook of Microbiology :- Ananthanarayan &
Paniker’s
•Principles of Microbiology (7th edition) :- Prescott.

28. THANK YOU