Gas gangrene is an infectious condition, usually affected in the wounded muscle masses contaminated with an anaerobic bacterium called Clostridium perfringens. It is the condition of necrosis of the muscles, where the bacteria produce an exotoxin and creates gas in the muscle tissues. Type A strains cause occasional food poisoning.
They are sporulating in nature and spores are seen suspended in air, soil, dust, etc. The spores are killed by boiling within five minutes. They are known to produce four types of toxins; alpha, beta, epsilon and iota. All Clostridial infections normally do not cause gas gangrene. They only contaminate the wound resulting in anaerobic cellulitis. When muscle tissues are invaded, it leads to gas gangrene. Gangrenous appendicitis is also a serious condition associated with it which causes intestinal blockage, toxemia and shock.
The normal civilians are generally affected by this disease through street accidents or any type of accidents which involves the damage of muscle tissues. It is a fatal form of necrosis. After a major road accident or any other type of injury, the Clostridia sp. present in the environmental dust, pieces of clothes, fragments of soil and even in the normal flora of human skin, invades into the crushed muscles and starts to generate exotoxins.
Three main types of gas gangrene have been recognized;
1. Simple wound contamination
1) Tissues below the wound are not attacked
2) No toxins are produced
3) Wound healing is delayed
2. Anaerobic cellulitis
1) Disease progresses slowly starting from a gas blister leading to an involvement of the appendage in a widespread manner.
2) Fascial planes are invaded
3) Muscle tissues are not attacked
4) Little amount of toxin is produced
3. Gas gangrene or Anaerobic myositis
1) Most critical condition
2) Disease develops with increasing pain, tenderness and edema of the affected area.
3) Healthy muscular tissues are attacked
4) Exotoxins are produced copiously
5) Low oxygen tension inside the wounds creates favorable conditions for the multiplication of the bacteria resulting in gangrene.
6) Mashing and shredding of the tissues and arteries around it creates an anoxic condition inside the muscle.
7) Blood supply to this area will be reduced
8) Dropping of pH in the muscles and certain chemical changes like carbohydrate degradation and release of amino acids from proteins results in anaerobic conditions favoring the multiplication of anaerobes.
9) Myoglobin and hemoglobin gets reduced causing them to stop carrying oxygen.
10) Multiplication of Clostridia results in toxin production and further damage of the tissues.
11) The erythrocytes undergo lysis leading to hemolytic anemia and hemoglobinuria.
12) Gas is produced plentifully
13) Signs of toxemia persists
14) Slim watery discharge oozes out from the wound
15) Toxemic condition become deep
16) Death occurs due to circulatory failure.
Surgery is the only effective treatment for gas gangrene. Therapeutic steps including antibiotics have to be followed in order to recover completely. Removal of damaged tissues is carried out along with blood clots, necrotized tissues and other foreign materials if present. The drugs normally preferred is metronidazole to be given before surgery and also continuing for 24 hours in 8 hour intervals. A combination of metronidazole, gentamycin and amoxycillin are advised. Passive immunization is also done using ‘anti-gas gangrene serum’ in some places. But their efficacy has not been clinically proved, so the use is being limited.