Gas gangrene results from infection by Clostridium perfringens ( welchii ) and other Clostridium species. The organism, a Gram – positive, anaerobic spore – forming bacillus such as Clostridium tetani, also produces powerful exotoxins. It is a rare but devastating infection characterized by muscle necrosis and systemic toxicity due to the elaboration and release of toxins. It usually follows wounding with trauma or surgery and requires factors contributing to tissue hypoxia like foreign bodies, vascular insufficiency or occurs as a complication of amputation. The organisms are found in soil and in faeces.
Clostridium perfringens is responsible for over 80% of cases. More than one species can be isolated or polymicrobial infection with other microorganisms can occur.
It is characterized by fulminant local and systemic manifestations. Patients may appear normal at early state. Clinical features include:
- Sudden and persistent severe pain at wound site.
- Localized tense edema, pallor and tenderness
- Gas noted on palpation or radiographs
- Progressive brownish discoloration of skin and hemorrhagic bullae formation
- Dirty brown discharge with offensive, sweetish odor
- Severe systemic manifestations including fever, tachycardia, hemolytic anemia, hypotension, renal failure and finally death
- Gram’s stain from the discharge can be diagnostic
In the established case, all involved tissue must be excised. Involvement of all muscle groups in a limb is an indication for amputation, which in the lower limb may mean a disarticulation at the hip. High – dose penicillin is given, and other supportive measures as required. Hyperbaric oxygen therapy, to eliminate the anaerobic environment, has been used with varying degrees of success. The value of antiserum against gas gangrene, as either a prophylactic or curative measure, is not proven.
Adequate excision of wounds removes both the organisms and the dead tissues which are essential for their anaerobic growth. Seriously contused wounds (such as those produced by a gunshot) or contaminated wounds are left open and lightly packed with gauze. Delayed primary suture can then safely be performed after 5 – 6 days, by which time the wound is usually healthy and granulating. The dangers of primary closure of contaminated wounds has been learned and forgotten after every war and catastrophe since 1914.
Penicillin is given in all heavily contaminated wounds and to patients undergoing amputation of an ischaemic leg.