Which organism is classically implicated in tetanus and is commonly found in puncture wounds?

• A. Staphylococcus aureus
• B. Clostridium tetani
• C. Clostridium botulinum
• D. Streptococcus pyogenes

Answer: (B)

Tetanus is caused by the neurotoxin tetanospasmin produced by Clostridium tetani, an obligate anaerobic, spore-forming gram-positive rod commonly found in soil and in contaminated puncture wounds. Puncture wounds create a low-oxygen environment that allows this organism to germinate and produce toxin. Tetanospasmin travels to the central nervous system and blocks the release of inhibitory neurotransmitters like GABA and glycine, leading to unopposed excitatory activity and the characteristic rigid, spasmodic paralysis seen in tetanus. This organism is classically implicated in tetanus, distinguishing it from Staphylococcus aureus (a common skin wound pathogen), Clostridium botulinum (botulism with flaccid paralysis), and Streptococcus pyogenes (GAS infections such as pharyngitis or cellulitis).