Symptoms include:
Skin discoloration
"Foul, sweet" smelling discharge from lesions formed on skin
Distinctive black, bubble lesions on skin
Necrosis
Fever
Pain following site of surgery or trauma
Lightheadedness
Rapid heart rate
Numbness on affected site
Blisters
Air in subcutaneous tissues
Swelling
Jaundice

Etiology
Clostridium species produce more toxins and exhibit higher degrees of virulence than any other bacterial taxon. Clostridium infections are usually opportunistic, and occur in individuals with serious preexisting medical conditions. However, Clostridium infections are also known to occur in healthy individuals. Four species of Clostridium (Clostridium botulinum, Clostridium perfringens, Clostridium tetani, and Clostridium sordelli) are responsible for most human infections. Since Clostridium is an obligate anaerobe taxon, the bacterium infects hypoxic tissues, which had become anaerobic due to restricted blood flow, degradation of blood vessels, or atherosclerosis. Immunocompromised individuals exhibit higher susceptibility for infection and higher mortality rates. Virulence factors
Members of the Clostridium species exhibit a plethora of virulence factors. Common virulence factors associated with gas gangrene include alpha toxin and theta toxin. Clostridium perfingens causes 80–90% of infections and produces both these toxins. Alpha toxin (α-toxin)Clostridium perfingens alpha toxin is widely associated with gas gangrene as it is its main virulence factor whilst invading its host. Alpha toxin is associated with hemolysis, thus restricting blood flow towards the area of infection. As the surrounding circulatory system collapses, neutrophils and monocytes, eosinophils and basophils cannot reach target areas of infection. The hemolytic activity of alpha toxin produces an anaerobic environment essential for the proliferation of the bacteria. Alpha toxin also exhibits the ability to infiltrate surrounding cellular tissue and cause a cascade of aberrant biochemical activity.
When gas gangrene occurs in such regions as the abdominal cavity, the patient can be treated in a hyperbaric chamber, which contains a pressurized oxygen-rich atmosphere. The oxygen saturates the infected tissues and thereby prevents the growth of the obligately anaerobic clostridia. The growth of C. perfringens is inhibited when the availability of oxygen is equivalent to a partial pressure of around 9–10 kPa (compare to 4–5 kPa in venous blood under normal conditions, with 11–13 kPa in arteries and 21 kPa in air at sea level), so if the treatment is started early, this condition can mostly be cured. Prognosis
Gas gangrene left untreated is a potentially fatal infection. Early diagnosis of the type of infection and species causing the infection will improve prognosis tremendously. Preventative measures are employed universally through medical facilities to stymie bacterial infections in patients. Reducing the susceptibility of infection will promote a better prognosis by practicing good hygiene and preventing the contraction of diseases which produce hypoxia or an immunocompromised state.Following resolution of myonecrosis, patients will often require further care following the deleterious effects caused by the infection. Skin grafts are often required following removal of necrotic tissues. Former patients will still require hyperbaric oxygen therapy to prevent a recurring infection. Epidemiology
Clostridium species are found in abundance in soil, especially soil used for animal husbandry. In medical facilities, it thrives when unhygienic circumstances prevail.