Which bacterial sexually transmitted infection usually affects mucous membranes?

• A. Chlamydia
• B. Syphilis
• C. Human Papillomavirus
• D. Gonorrhea

Answer: (D)

Mucosal involvement is a hallmark pattern of many sexually transmitted infections, and among the bacterial options, one is classically tied to infection of mucous membranes lining the genital tract and other mucosal sites. Neisseria gonorrhoeae adheres to and invades mucosal epithelium, causing inflammation in the urethra, cervix, throat, or rectum. This mucosal tropism—affecting the lining surfaces shared by these sites—explains why gonorrhea is described as a mucosal infection and is the best answer here.

HPV is a virus, not a bacterium, so it isn’t the correct category. Syphilis is caused by Treponema pallidum and can affect mucosal surfaces, but its early presentation is a chancre rather than a broad mucosal infection pattern. Chlamydia is also a mucosal bacterial STI, but gonorrhea is the classic example of a mucosal infection involving multiple mucous membranes, which is why it’s the best fit for this question.