The genus of the organism that causes tetanus is which?

• A. Bacillus
• B. Staphylococcus
• C. Streptococcus
• D. Clostridium

Answer: (D)

Tetanus is caused by a toxin produced by a bacterium in the genus Clostridium. These organisms are obligate anaerobes that form hardy endospores and are commonly found in soil and contaminated wounds. The toxin, tetanospasmin, travels to the nervous system and blocks the release of inhibitory neurotransmitters like GABA and glycine, leading to unopposed muscle contraction and the characteristic rigid, spasmodic tension of tetanus.

Other genera listed are associated with different infections. Bacillus includes species such as B. anthracis and B. cereus, Staphylococcus with skin and soft-tissue or bloodstream infections, and Streptococcus with strep throat and other diseases. None of these cause tetanus, which is specifically linked to Clostridium tetani.