STD Screening for a 39-Year-Old Sexually Active Man
A 39-year-old sexually active man should receive annual screening at minimum for chlamydia, gonorrhea, syphilis, and HIV, with testing frequency increased to every 3–6 months if he has multiple partners, new partners, or other high-risk behaviors. 1
Core Screening Panel
All sexually active men require the following baseline tests:
- Chlamydia and gonorrhea – First-catch urine specimen tested by nucleic acid amplification test (NAAT), which has superior sensitivity (86-100%) and specificity (97-100%) compared to culture 2, 1
- Syphilis – Both nontreponemal test (RPR or VDRL) and treponemal test (EIA or CIA) performed together 1
- HIV – Laboratory-based antigen/antibody combination test for all patients aged 13-64 years 2, 3
- Hepatitis B – Serologic testing (HBsAg and antibodies) if not previously vaccinated 1, 2
- Hepatitis C – Screening if additional risk factors present, including drug use or multiple partners 1, 2
Site-Specific Testing Based on Sexual Practices
Testing must be tailored to anatomic sites of exposure:
- Receptive anal intercourse – Rectal swab NAAT for both chlamydia and gonorrhea (if laboratory has validated the assay) 1, 2
- Receptive oral sex – Pharyngeal swab NAAT or culture for gonorrhea only; pharyngeal chlamydia testing is not recommended due to lack of clinical utility 1
- Insertive intercourse – Urine NAAT covers urethral infections 1
The CDC emphasizes that failing to test exposure-specific sites (pharynx, rectum) misses a substantial proportion of infections, particularly in men who have sex with men. 4
Screening Frequency Algorithm
Annual screening (minimum):
- All sexually active men with any sexual activity in the past year should receive comprehensive testing at least once annually 1, 2
Every 3–6 months screening (high-risk indicators):
Increase screening frequency if any of the following are present: 1, 2
- Multiple or anonymous sexual partners
- New sexual partners
- Substance use during sex (especially methamphetamine)
- Prior STI diagnosis
- Unprotected sex outside a mutually monogamous relationship
- Exchange of sex for drugs or money, or partners who engage in these behaviors
- Partner with known STI or high-risk behaviors
- Recent relationship dissolution or life changes promoting high-risk behaviors
Research demonstrates that among HIV-infected MSM reporting condomless sex, STI positivity increases significantly with number of partners: 0% with 1 partner, 3.0% with 2-3 partners, and 6.7% with 4+ partners for gonorrhea. 5
Special Considerations for Men Who Have Sex With Men
MSM require comprehensive anatomic-site testing annually at minimum: 1
- Urine/urethral NAAT for chlamydia and gonorrhea
- Rectal NAAT for chlamydia and gonorrhea (when receptive anal intercourse occurs)
- Pharyngeal NAAT or culture for gonorrhea (when receptive oral intercourse occurs)
- Syphilis serologic testing
- HIV testing
- Hepatitis A vaccination recommended 2
MSM with higher-risk profiles require screening every 3–6 months. 1 Studies show that repeat testers demonstrate increasing risk behaviors over time, with linear increases in risk scores up to the 17th test, identifying them as the highest-risk candidates for intensive prevention. 6
Retesting After Positive Results
Mandatory 3-month retest for any positive chlamydia or gonorrhea result, even if the partner was treated, due to reinfection rates of 25-40%. 1, 2 Research confirms high reinfection rates: 25% of previously infected individuals experience reinfection within 3.6 months for chlamydia, 6 months for gonorrhea, and 4.8 months for trichomonas. 4
Common Pitfalls to Avoid
- Testing only urine specimens in MSM – This misses the majority of rectal and pharyngeal infections, which are often asymptomatic. 1, 4
- Accepting patient self-report of "always using condoms" – Condom effectiveness studies show inconsistent findings due to variations in actual versus reported use and correct versus incorrect use. 4
- Single annual screening for high-risk individuals – Men with ongoing risk factors require 3–6 month intervals, not annual testing. 1, 2
- Skipping syphilis treponemal testing – Both nontreponemal and treponemal tests must be performed together for accurate diagnosis. 1
- Not retesting after treatment – The 3-month retest is mandatory regardless of partner treatment status due to extremely high reinfection rates. 1, 2
Among HIV-infected MSM in care who reported condomless sex, subsequent STI testing was not documented in up to 25% of patients during the following year, representing a significant gap in preventive care. 5