Tetanus is a neurologic disorder, characterized by increased muscle tone and spasms, that is caused by tetanospasmin, a powerful protein toxin elaborated by Clostridium tetani. Tetanus occurs in several clinical forms, including generalized, neonatal, and localized disease. †A contributor to HPIM since the 12th edition, Dr. Abrutyn passed away on February 22, 2007. Etiologic Agent C. tetani is an anaerobic, motile, gram-positive rod that forms an oval, colorless, terminal spore and thus assumes a shape resembling a tennis racket or drumstick. The organism is found worldwide in soil, in the inanimate environment, in animal feces, and occasionally in human.