CLOSTIDIUM PERFRINGENS Laboratory diagnosis and prophylaxis

Harshita thota roll.no 108

Clostidium perfringens causes gas gangrene .

The diagnosis of gas gangrene must be made primarily on clinical grounds as mere presence of clostridia in wounds does not constitute gas gangrene.

Lab diagnosis can be done to Differentiate gas gangrene from anaerobic streptococcal myositis , which may be indistinguishable from it clinically in the early stages

In the later ,gram stained films show large numbers of streptococci and pus cells but not bacilli, contrasting with the scanty pus cells and diverse bacterial flora seen in films from gas gangrene.

1. SPECIMENS 1 Films from : the muscles at the edge of the affected area. the tissue in the necrotic area. exudate in the deeper parts of the wound.

2 Exudates from: the parts where the infection appears most

active . the depths of the wound .They are collected with a capillary pipette or

a swab.3. Necrotic tissue and muscle fragments.

2.MICROSCOPIC EXAMINATIONGram staining is done to distinguish different

species of clostridia .In the slide of :

Clostridium perfringens – large numbers of regularly shaped, gram

positive bacilli without spores are seen.

Clostridium septicum- ‘citron bodies’ and boat- or leaf shaped

pleomorphic bacilli with irregular staining .

Clostridium novyi –

Large bacilli with oval , sub terminal spores are seen.

Clostridium tetani or C.tetanomorphum –

Slender bacilli with round, terminal spores are seen

3 CULTURE

Robertson’s Cooked meat broth-Growth in cooked meat broth is sub cultured in

blood agar after 24-48 hrs

Blood agar-Aerobic and Anaerobic cultures are made on fresh

and heated blood agar , preferably on 5-6% agar to prevent swarming .

Blood agar is incubated anaerobically for 48-72hrs.most strains produce B- haemolysis on blood agar

and few are non haemolytic ..

A plate of serum and egg yolk agar , with clostridium perfringens antitoxin spread on one half , is used for Nagler reaction.

No antitoxin

AntitoxinPresent

Colonies on the half without antitoxin will be surrounded by opacity while the colonies with antitoxin will not show opacity due to neutralization of alpha toxin.

Alpha toxin ( lecithinase c ) splits lecithine into phosphoryl choline and a diglycerate (lipid). The lipid gets deposited around the colonies resulting in opacity.

Exceptions- cl.novyi ,some vibrios , some aerobic spore bearers

Bacterial isolates can be identified by: Morphology Cultural characteristics Biochemical reactions Reverse CAMP test

Toxigenicity of a strain can be done by animal pathogenicity.

PROPHYLAXIS 1. Surgery : All damaged tissue should be removed promptly and

the would should be irrigated with antiseptic solution to remove blood clots , necrotic tissue and foreign materials .

2.Antibiotics :Gas gangrene organisms are susceptible to :MetronidazolePenicillin SulphonamideTetracyclinAmoxycillin

3. Antitoxin: Passive immunization with anti gas gangrene

serum is used prophylactically in extensively soiled wound.

4. Hyperbaric oxygen : it is introduced in the depth of wound to

reduce anaerobiosis .

5.Active immunization : toxiods have been found .used expermentallyNot in practical use .

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