Which common sexually transmitted infections should I screen for in sexually active adults?

STI Screening Recommendations for Sexually Active Adults

Screen all sexually active women ≤24 years annually for chlamydia and gonorrhea, and test all sexually active men who have sex with men (MSM) annually for chlamydia, gonorrhea, and syphilis at all exposure sites. 1

Core Screening Panel by Population

Women ≤24 Years

• Annual screening mandatory for chlamydia and gonorrhea using nucleic acid amplification tests (NAATs) on vaginal swab (including self-collected), endocervical swab, or urine, regardless of reported risk behaviors 2, 1
• HIV screening should be performed at least once for all sexually active individuals aged 15-65 years, with annual rescreening for those at increased risk 1, 3
• Syphilis screening is not routinely recommended for heterosexual women unless risk factors are present (multiple partners, partner with STI history, drug use) 2, 1
• Trichomoniasis screening is not routine but should be considered for women with high-risk behaviors (multiple partners, new partner, history of STIs, sex work, drug use) 2, 1

Women >25 Years

• Screen annually only if risk factors present: new sex partner, partner with concurrent partners, inconsistent condom use, history of STIs, commercial sex work, illicit drug use, or partner who uses drugs 2, 4
• The USPSTF explicitly recommends against routine screening in low-risk women over 24 years, as harms may outweigh benefits in low-prevalence populations 4, 5

Men Who Have Sex with Men (MSM)

• Annual screening minimum for chlamydia, gonorrhea, and syphilis at all anatomic sites based on sexual practices 2, 1
• Site-specific testing is critical: urethral/urine NAAT for insertive intercourse, rectal NAAT for receptive anal intercourse, pharyngeal NAAT for receptive oral sex 2, 1, 6
• Increase to every 3-6 months if higher risk factors present: multiple or anonymous partners, sex with drug use, or partners engaging in high-risk behaviors 2, 1
• HIV and syphilis screening should be performed at least annually, with more frequent screening (every 3-6 months) for those at highest risk 2, 1

Heterosexual Men

• Routine screening is not universally recommended for asymptomatic heterosexual men without risk factors 2, 1
• Consider annual screening in high-prevalence settings (≥2% prevalence): jails, juvenile corrections facilities, STD clinics, high school clinics, adolescent clinics 2, 1
• Screen men with high-risk behaviors: multiple partners, inconsistent condom use, substance use during sex, history of recent STIs 1

High-Risk Screening Frequency (Every 3-6 Months)

Increase screening frequency to every 3-6 months for any individual with the following risk factors 2, 1:

• Multiple or anonymous sexual partners
• Sex in conjunction with illicit drug use
• Partners who engage in high-risk behaviors
• History of recent STIs
• Sex work or exchanging sex for money/drugs
• MSM status

Post-Treatment Rescreening

Rescreen all individuals 3 months after treatment for chlamydia or gonorrhea, regardless of whether partners were treated, due to high reinfection rates 2, 1

• If 3-month rescreening is not possible, retest at the next healthcare visit within 12 months 2, 1
• Consider rescreening females previously diagnosed with trichomoniasis 3 months after treatment 2, 1

Testing Methodology

Specimen Collection

• NAATs are the preferred test for chlamydia and gonorrhea due to superior sensitivity (86.1%-100%) and specificity (97.1%-100%) 7, 5
• For women: vaginal swabs (including self-collected) are as sensitive as endocervical specimens and preferred for patient comfort 4
• For men: first-catch urine sample is the standard specimen 6
• Collect specimens based on sexual practices: pharyngeal swabs for receptive oral sex, rectal swabs for receptive anal intercourse 1, 6

Syphilis Testing

• Use sequential testing algorithm: both nontreponemal test (RPR/VDRL) and treponemal test (EIA/CIA) are required for diagnosis 6, 7

Critical Pitfalls to Avoid

• Failing to test exposure-specific sites (pharynx, rectum) misses a substantial proportion of infections, particularly in MSM 6
• Testing too early after exposure: bacterial STIs may not produce sufficient concentrations for detection immediately; repeat testing at 1-2 weeks if initial tests negative and no presumptive treatment given 6
• Accepting patient self-report of "always using condoms" as sufficient reassurance—condom effectiveness varies widely due to inconsistent and incorrect use 6
• Not rescreening at 3 months after positive test and treatment—reinfection occurs rapidly (within 3.6 months for chlamydia, 6 months for gonorrhea) in 25% of previously infected individuals 6

Special Considerations

HIV-Infected Individuals

• Screen for syphilis at initiation of care and periodically thereafter based on risk 1
• Screen all HIV-infected women for trichomoniasis and all women ≤25 years for chlamydia 1
• Retest in 3 months for those found positive for gonorrhea, chlamydia, or trichomoniasis due to high reinfection rates 1

Pregnant Women

• All pregnant women should be tested for hepatitis B, HIV, and syphilis 3
• Pregnant women ≤24 years and older women with risk factors should be tested for gonorrhea and chlamydia 2, 3
• Retest in third trimester if continued risk or if initial test was positive 2