False colour scanning electron micrograph (SEM) of Clostridium perfringens (formerly C. welchii), the anaerobic, Gram-positive, rod-like bacteria that is the causative agent of gas gangrene. C. perfringens is present in soil and the intestines of man. Infection occurs from soil in accidental wounds & from the gut via the skin during surgery through contact with damaged, devitalized tissue. The bacteria multiply and release an exotoxin which digests surrounding muscle and other tissues. Gas & other waste substances act to further reduce blood supply; unless promptly treated with antibiotics, gas gangrene spreads & may be fatal. Magnification: X 4400 at 35mm size.