a rod-shaped, obligate anaerobe which stains Gram positive in fresh cultures; established cultures may stain Gram negative. During vegetative growth, the organism cannot survive in the presence of oxygen, is heat-sensitive and exhibits flagellar motility. As the bacterium matures, it develop a terminal spore, which gives the organism its characteristic appearance. C. tetani spores are extremely hardy as they are resistant to heat and most antiseptics. The spores are distributed widely in manure-treated soils and can also be found on human skin.