Clostridium

Clostridium

Spore forming bacteria:

The spore –bearing organisms are gram positive, non-acid fast, may be motile , aerobic or anaerobic and may be capsulated or non –capsulated.

Classification of spore – forming bacteria:

Spore forming bacteria three types:

Spore forming bacteria

1.  Gram –positive bacilli.         2. Gram –positive cocci              3. Gram-negative coccobacilli.

-          Bacillus anthraces.               –Sporosarcina spp.                           –Coxiella burnetti.

-          Bacillus subtilis

-          Clostridium tetani.

Clostridium tetani:

Habitat: Soil is the usual habitat. In man, they found in intestine.

Morpholoty:

Shape                   : Rod shaped with rounded end.

Size                      : 2-5 µm

Flagella                : pertrichous flagella present.

Spore                   : Present.

Capsule                : Absent.

Motility               : Motile.

Staining               : They are gram –positive bacilli & non-acid fast.

Cultural character:

1. Anaerobic
2. Optimum temperature: 37°C
3. Growth on:

1. Agar streak : colonies are thin transparent film.
2. Anaerobic agar plate culture: light ,flocky & cloudy colonies,
3. Agar stab : surface growth negative , growth occur along the line of inoculating wire.
4. Blood agar: Haemolysis occur.
5. Brain meat medium : Digestion of the medium slowly & blackening.
6. Cooked meat medium  slight turbid growth with gas formation.
7. Coagulated agar medium :liquefaction of medium.
8. Gelatin stab : liquefaction & blackened.
9. Litmus silk: precipitation of casein.
10. Serum agar: Small & transparent colonies.
11. On blood agar: Haemolysis colonies.
12. On cooked meat medium .

1. Turbidity of the medium.
2. Blackening of meat.

O. On Loffler’s serum slope: softened.

Biochemical character:

1. Sugars are not fermented.
2. Milk is not coagulated .
3. In dole is produced.
4. Gelatin is liquefied.
5. Coagulated serum is softened.
6. Iron- gelatin is blackened.

Clinical features: 

After incubation period: 6-10 days-

1. Lock jaw (trismus )due to masseter muscle spasm.
2. Rises sardonic us due to spasm of facial muscle.
3. Opistohotonus due to marked trunk muscle spasm.

Laboratory diagnosis of tetanus:

Principle: Finding out of the causative organism confirms the diagnosis of tetanus.

Steps:

1. Specimen collection : Wound swab .
2. Microscopic examination : On Gram staining .

Finding: Gram –positive bacilli (tennis racket appearance)

3. Isolation &identification from culture:

1. On Robertson’s cooked meat media.

Finding: turbidity of medium& blackening of meat.

2. On blood agar: Haemolysis colonies.
3. On Loffler’s serum slope: softened.

4. Other tests:

-          Agglutination test.

-          Toxigenicity test.

Animal inoculation test.