for mbbs 2nd prof

1. CLOSTRIDIUM PERFRINGENES
MORPHOLOGY –
- Gram + ve bacilli
- 4-6 um x 1um
- Capsulated, non motile
- Spore formation can be induced on special media.
- Arranged in singles or in chains & pleomorphic
- Appearace – Boat or leaf shaped
CULTURE –
- Grow best in carbohydrate containing media (glucose blood agar).
- Anaerobic
- pH – 5.5 – 8.0
- Temp. – 20 – 50 degree
- Target haemolysis on blood agar by theta toxin.
- Liquid media cooked meat broth (CMB) also used.
CLASSIFICATION –
- These are classified ito five types A to E.
BIOCHEMICAL REACTION –
- Ferment glucose, sucrose, lactose, maltose production of acid and gas.
- Indole – Negative, H2S is formed.
- MR - +ve, VP – negative
- Nagler rxn – see on p.no.- 231
- Reverse camp test – see on p.no. - 232
PATHOGENESIS –
1. Gas Gangrene – Cl.perfringens type A is the predominant bacterial agent causing Gas Gangrene. Incubation
period varies from 6 hours to 6 weaks.
2. Food poisoning – some strains of type A produce food poisoning. Incubation period varies from 8 – 12 hours.
3. Necrotizing enteritis – A severe and fatal necrotizing jejunitis is caused by type c strins of cl.perfringens.
4. Other infections – These include gangrenous appendicitis, urogenital infections, brain abscess, meningitis,
panophthalmitis, and puerperal infections.
LAB DIAGNOSIS –
- Direct microscopy
- Culture
- Animal pathogenicity

2. CLOSTRIDIUM TETANI
MORPHOLOGY –
- Gram positive bacillus
- 4 – 8 um x 0.5 um
- Appearance – drumstick
- Non – capsulated
- Motile
CULTURE –
- Obligate anaerobe
- Grow better in enriched media with blood or serum
- Temp – 37 degree
- pH – 7.4
- alpha haemolysis on blood agar
BIOCHEMICAL REACTION –
- Proteolytic
- It does not ferment any sugar
- Forms indole,
- MR & VP – Negative
- H2S r not formed
- Nitrates are not reduced
TOXINS –
- TETANOLYSIN – It is heat labile n oxygen labile toxin which causes lysis of erythrocytes of several animal
species, specially rabbit n horse.
- TETANOSPASMIN – It is heat labile n oxygen stable, powerful neurotoxin and rapidly gets destroyed by
proteolytic enzymes. It is protein in nature. It is responsible for clinical manifestations of tetanus.
PATHOGENESIS –
The tetanus toxin specially blocks synaptic inhibition in spinal cord. The abolition of spinal inhibition leads to
uncontrolled spread of impulses initiated anywhere in the central nervous system.
LAB DIAGNOSIS –
- Microscopy
- Culture
- Toxigenecity test