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Asymptomatic bacterial sexually transmitted infections in a man who has sex with men and uses HIV preexposure

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HardScreeningAsymptomatic bacterial sexually transmitted infections in a man who has sex with men and uses HIV preexposure prophylaxisABIM Board

A 31-year-old man presents for routine follow-up while taking daily oral HIV preexposure prophylaxis. He has had four male sexual partners during the past 3 months and intermittently uses condoms. He has engaged in insertive anal intercourse, receptive anal intercourse, and performing oral sex. He was treated for rectal gonorrhea 8 months ago. He currently has no dysuria, urethral discharge, pharyngeal symptoms, rectal pain, or rash. Screening for bacterial sexually transmitted infections 3 months ago was negative. Which of the following is the most appropriate bacterial sexually transmitted infection screening strategy now?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Obtain syphilis serology, urine and rectal nucleic acid amplification testing for gonorrhea and chlamydia, and pharyngeal nucleic acid amplification testing for gonorrhea

This patient should undergo screening now because MSM taking PrEP who have ongoing risk factors, including multiple partners or a recent bacterial STI, warrant screening at approximately 3-month intervals rather than annual screening alone. Testing must also reflect each exposed anatomic site. Insertive intercourse warrants urine testing for urethral gonorrhea and chlamydia; receptive anal intercourse warrants rectal testing for both organisms; and performing oral sex warrants pharyngeal testing for gonorrhea. Routine pharyngeal screening for chlamydia is not recommended. Syphilis serology should also be obtained. A is inappropriate because annual screening is the minimum for lower-risk sexually active MSM, whereas his PrEP use, multiple partners, and prior gonorrhea support more frequent screening. B misses asymptomatic rectal and pharyngeal infections, which urine testing cannot reliably detect. C appropriately covers urethral and rectal exposure but omits pharyngeal gonorrhea screening despite oral exposure. E appears comprehensive but adds routine pharyngeal chlamydia testing, which is not recommended. The absence of symptoms does not reduce the need for site-specific screening because extragenital infections are frequently asymptomatic.

Reference: Clinical Guidance for PrEP (April 30, 2026) — https://www.cdc.gov/hivnexus/hcp/prep/index.html Sexually Transmitted Infections Treatment Guidelines, 2021 (July 23, 2021) — https://www.cdc.gov/std/treatment-guidelines/STI-Guidelines-2021.pdf