Spore specie of clostridium bacteria that produces a toxin that causes blood poisoning, gas gangrene, and the infection of wounds. Its toxin also leads to a type of food poisoning that is typically mild for healthy adults but a serious danger for elderly, infirmed people, or very young children. Known also as Welch’s Bacillus. Notated also as C. perfringens or Clos. perfringen.