A farmer steps on a rusty nail and develops trismus and opisthotonos. Clostridium tetani is suspected. Which morphological feature is characteristic of this organism on Gram stain?
- A Terminal spore giving a drumstick appearance ✓
- B Central spore giving a safety pin appearance
- C Subterminal spore giving a tennis racket appearance
- D Oval central spore wider than the bacillary body
Correct answer: A. Terminal spore giving a drumstick appearance
Explanation
Clostridium tetani is a Gram-positive bacillus with a terminal spore that is wider than the bacillus, giving it a characteristic drumstick appearance. The safety pin appearance is typical of Clostridium biferme. Bacillus species have central oval spores. The terminal spore is the key diagnostic feature for A. tetani.
Reference: Ananthanarayan and Panicker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.