Nusrat Jahan Maha - Followers Questions

Gas gangrene, also called myonecrosis, is a type of wet gangrene that is caused predominantly by **Clostridium perfringens** bacteria. The pathogenesis of gas gangrene involves the entry of bacteria into an ischemic wound, which provides anaerobic conditions for the bacteria due to a lack of blood supply. The bacteria then multiply in the dead tissue and produce exotoxins such as alpha toxin (lecithinase), which lyses erythrocytes, platelets, leukocytes, endothelial cells, fibroblasts, and muscle cells.

The local effects of gas gangrene include necrosis of muscle and subcutaneous fat, thrombosis of blood vessels, marked edema which further compromises blood supply to the region, and gas production by fermentation of glucose. Systemic effects include hemolysis and cardiovascular abnormalities. The exotoxins further create more anaerobic conditions suitable for clostridium to proliferate and spread. Death may occur due to septic shock and unintentionally damaging effects of the immune response.

Gangrene comes in two forms:
1. Dry, and
2. Wet.
**Dry gangrene** occurs when the blood supply to the tissue is cut off. The area becomes dry, shrinks, and turns black. The main causes of dry gangrene include diabetes, arteriosclerosis, trauma, frostbite, injury, or tobacco addiction.

On the other hand, **wet gangrene** occurs if bacteria invade this tissue. This makes the area swell, drain fluid, and smell bad. Wet gangrene mainly results from venous obstruction associated with infections.