- Clostridium tetani is a Gram-positive, sporeforming, rod-shaped bacterium that is resistant to temperature modifications, moisture, and chemical disinfectants. C. tetani is strictly anaerobic and dies in the presence of oxygen; however, spores produced by this species are able to withstand oxygenated environments and other harmful environments. The endospores are produced in a swollen sporangium and their shape generally resembles a ‘drumstick‘.