3. General features
• Anaerobic, sporing, bulging spores
• Kloster = spindle
• Saprophytes – soil, water
• Or live in GIT – C. tetani, C. perfringens
• Cause three major diseases : Tetanus, Gas
gangrene and food poisoning
• All are motile except C. perfringens & C. tetani
type VI
4. Classification
Tetanus : C. tetani
Acute colitis: C. difficile
Food poisoning:
GE – C. perfringens type A
Necrotizing enteritis – C. p. type C
Botulism – C. botulinum
Gas gangrene:
Established pathogens: C.
perfringens, C. Septicum, C. novyi
Less pathogenic: C. histoliticum, C.
fallax
Doubtful path: C. bifermentans, C.
sporogens
PerSeN has HiFi BiSness
5. Culture
• Macintosh – Fildes jar
• CMB (unsat. Free fatty acids consume O2
catalysed by haemetin, and low redox pot d/t
sulpjydrl groups)
• Gaspacks
• All spores die in autoclave
• Halogens and 2% glutraldehyde kill spores
effectively
6. C. Perfringens (welchii)
• Capsulated & NM, Subterminal spores
• M/I cause of gas gangrene, causes food
poisoning & necrotizing enteritis
• Commensal in GIT
• Soil & dust
• Spores rarely seen in cultures or tissues &
absent spores characteristic feature
• Glucose BA – Target haemolysis
Alpha toxin
Theta toxin
7. Biochemical reactions
• Sacchrolytic I pink
• G/L/S – acid + gas
• Abundant H2S
• Stormy fermentation reaction: litmus milk –
lactose ferm. Leads to acid production – color
changes blue to red – acid clots milk – gas
disrupts the clot
8. Classification
• 12 types of toxins
• Alpha, beta, epsilon & iota (αβει)
• Type A : α,
• Type B : α, β,ε
• Type C : α, β
• Type D : α, ε
• Type E : α, ι
• Alpha – m/I : gas gangrene & food poisoning
9. Alpha toxin
• Phospholipidase (lecithinase C)
• Lecithin – part of mammalian cells walls
• Heat stable, lethal, dermonecrotic, hemolytic
• Hot – cold lysis
• Naegler’s reaction
• Reverse CAMP test
10. Pathogenesis
• Gas gangrene 6h 6 wks , anaerobic cellulitis,
myonecrosis
• Food poisoning: type A, 8-12 hrs, meat,
poultry – like enterotoxin of V. cholerae
• Necrotic enteritis
11. Diagnosis = clinical
Lab diagnosis
Gram stain: GPB without spores, pleomorphic GPB (Citron bodies, leaf or
boat shapes) in C. septicum, large GPB & oval subterminal spores – C. novyi
Culture: heated BA , CMB
Colony morphology, biochemical reactions, reverse CAMP test etc.
Animal pathogenicity , RCM i/m GP – death – heart, spleen
Food poisoning: RCM inculated - heated @ 100 C x 30 m – cooled –
incubated @ 37 C x overnight – s/c on selective media – S. A . above
13. Cl. Tetani
• Soil and GIT
• Terminal spores – drumstick appearance
• Non capsulated, motile except type VI
• Grows on BA,NA,CMB, Thioglycoslate broth
• CMB- Black, BA – Swarming,
• Iridescence – greenish fluorescence on MA
• No sugars fermented
14. • Spores survive in soil for years
• Ten serological types based on flagellar (H) Ag
• Type VI – non-flagellated
• All produce same toxin
• Toxins:
– Tetanolysin (heat & O2 labile, lysis RBC &
WBC),
– Tetanospasmin (heat labile, O2 stable,
powerful neurotoxin, rapidly destroyed by
proteolytic enzymes, plasmid coded,
neutralized by AB
15. Pathogenesis
• Little invasiveness
• Toxin – acts presynaptically – blocks synaptic
inhibition in spinal cord – continuous spread
of spread of impulses – muscles rigidity &
spasm
• Diagnosis – clinical grounds
• Lab diagnosis – GPB with terminal spores
• Cl. tetanomorphium & Cl. spheroides – similar
apperance on GS – hence GS unreliable
16.
17.
18. Lab diagnosis
• Only for confirmation
• Gram stain – drumstick GPB
• Culture: sample – Fresh BA + Poly B –
swarming
• CMB x 3 tubes – 1st – 80° C X 15 m, 2nd 80° C x
5 m and 3rd unheated (kills vegetative
bacteria) – s/c daily x 4 days
• 02 ml CMB – mice tail – rigidity in 2 – 4 days –
ascending paralysis – death
19. Prophylaxis
• Surgical debridement – prevent anaerobiasis
• Antibiotics – destroy or inhibit bacterial load
• Immunization – vaccination with toxoid, ATS
or combined
• Protect patients from light & noise
• Clinical attacks don’t provide protection
20. Cl. Botulinum
• Botulus = sausages
• Soil, manure, vegetables
• Strict aerobes grow on ordinary media
• Large fimbriate irregular colonies
• GPB with sub-terminal highly resistant spores
• Classification based on toxin produced – 8
types A (most toxic), B, C 1- 3, D, E, F, G
21. Toxin
• Exotoxin - Blocks production of Acetylycholine
@ synapses & Neuromucular junctions
• Protoxin Protease active form
• Once bound cant be inactivated
