Pathology · single question
A sexually active patient presents with a painless ulcer (chancre) on the lip. Which organism is the likely cause?
Show answer and explanation
Correct answer: A. Treponema pallidum (syphilis)
- A. Correct. A painless, indurated chancre at an oral site of inoculation is primary syphilis caused by Treponema pallidum.
- B. HSV causes painful grouped vesicles/ulcers, not a painless chancre.
- C. Candida causes white pseudomembranous plaques, not a chancre.
- D. S. aureus causes pyogenic infections, not a syphilitic chancre.