Gas gangrene

Overview
Gas gangrene is a bacterial infection that produces gas within tissues in gangrene. It is a deadly form of gangrene usually caused by Clostridium bacteria. It is a medical emergency.

Features
Gas gangrene can cause myonecrosis, gas production, and sepsis. Progression to toxemia and shock is often very rapid.

Pathophysiology
Gas gangrene is caused by exotoxin-producing Clostridial species (most often Clostridium perfringens), which is mostly found in soil but also found as normal gut flora, and other anaerobes (e.g. Bacteroides and anaerobic streptococci). The exotoxin is commonly found in C. perfringens type A strain and is known as alpha toxin. These environmental bacteria may enter the muscle through a wound and go on to proliferate in necrotic tissue and secrete powerful toxins. These toxins destroy nearby tissue, generating gas at the same time.

A gas composition of 5.9% hydrogen, 3.4% carbon dioxide, 74.5% nitrogen and 16.1% oxygen was reported in one clinical case.

Treatment
Treatment is usually debridement and excision with amputation necessary in many cases. Antibiotics alone are not effective because they don't penetrate ischemic muscles enough to be effective. However, penicillin is given as an adjuvant treatment to surgery. In addition to surgery and antibiotics, hyperbaric oxygen therapy (HBOT) is used and acts to inhibit the growth of and kill the anaerobic C. perfringens.