What laboratory tests are recommended for a patient seeking screening for sexually transmitted diseases (STDs), including chlamydia, gonorrhea, syphilis, human immunodeficiency virus (HIV), hepatitis B and C, and herpes simplex virus (HSV)?

Laboratory Testing for STD Screening

For comprehensive STD screening, test for chlamydia and gonorrhea using nucleic acid amplification tests (NAATs), syphilis using reverse algorithm serology (treponemal test followed by RPR), HIV using fourth-generation antibody/antigen testing, hepatitis B surface antigen, hepatitis C antibody, and trichomoniasis in women. 1, 2

Core Testing Panel

Bacterial STIs

• Chlamydia and gonorrhea: Use NAATs on first-catch urine (men) or vaginal swabs (women, preferred over cervical) due to superior sensitivity (86.1%-100%) and specificity (97.1%-100%) 3, 1, 4
• Syphilis: Employ reverse screening algorithm starting with treponemal-specific test (T. pallidum antibody via immunoassay), followed by nontreponemal testing (RPR) to confirm active disease 3, 1, 2
• Trichomoniasis: Test all women using vaginal swab NAAT, as wet mount microscopy misses 30-40% of infections 1, 2

Viral Infections

• HIV: Order fourth-generation testing combining HIV-1/2 antibodies and p24 antigen, which detects infection 2-4 weeks post-exposure versus 3-6 weeks for antibody-only tests 1, 2
• Hepatitis B: Screen with hepatitis B surface antigen (HBsAg); consider adding hepatitis B core antibody and surface antibody for complete immunity assessment 3, 2
• Hepatitis C: Test using hepatitis C antibody 2

Herpes Simplex Virus

• Do not screen asymptomatic patients for HSV, as no evidence demonstrates that treating asymptomatic HSV improves outcomes 1
• Only test when genital lesions are present, using NAAT (preferred over culture for highest sensitivity and HSV typing) 2

Anatomic Site-Specific Testing

Men Who Have Sex With Men (MSM)

Test all three anatomic sites based on reported sexual practices 3, 1:

• Urogenital: Urine NAAT for chlamydia and gonorrhea
• Rectal: Rectal swab NAAT for chlamydia and gonorrhea (frequently asymptomatic; 3.0%-9.8% positivity in asymptomatic patients) 5
• Oropharyngeal: Pharyngeal swab for gonorrhea only (chlamydia pharyngeal testing not recommended) 3, 1

Common pitfall: Relying solely on urogenital testing in MSM misses the majority of extragenital infections, which are asymptomatic in 53%-100% of cases 4

Women

• Vaginal swab NAAT is the preferred specimen for chlamydia and gonorrhea over cervical specimens 1
• Cervical specimens remain acceptable for women under 25 years 3, 1

Population-Specific Screening Requirements

Pregnant Women

Screen at first prenatal visit for 3, 1, 2:

• Syphilis serology (mandatory; repeat in third trimester and at delivery for high-risk women)
• Hepatitis B surface antigen
• HIV
• Chlamydia and gonorrhea (if under 25 years or at increased risk)

No infant should be discharged without determination of the mother's syphilis status at least once during pregnancy 3, 1

HIV-Infected Individuals

Screen every 3-6 months for all bacterial STIs (chlamydia, gonorrhea, syphilis, trichomoniasis) due to increased HIV transmission risk when co-infected 3, 1, 2

High-Risk Populations Requiring Frequent Testing

Screen every 3-6 months for 3, 1:

• MSM with multiple or anonymous partners, methamphetamine use, or sex in conjunction with drug use
• Persons with new or multiple sex partners
• Inconsistent condom users not in mutually monogamous relationships
• Those exchanging sex for money or drugs
• Persons living in communities with high STI prevalence

Annual Screening

• All sexually active women under 25 years: Chlamydia, gonorrhea, HIV, and syphilis 1
• Women 25 years and older with risk factors: Same panel 1
• All sexually active MSM (minimum): Chlamydia, gonorrhea, syphilis, HIV 3, 1

Post-Treatment Management

Mandatory Retesting

Retest at 3 months after treatment for all patients diagnosed with chlamydia or gonorrhea, regardless of whether partners were treated, due to reinfection rates of 25-40% within 3 months 1, 2

Partner Management

• All sexual partners from the past 60 days must be notified, examined, and treated presumptively before test results when indicated 1, 2
• Consider expedited partner therapy where legally permissible 1, 2

Testing Method Specifications

NAAT Advantages

NAATs offer the widest range of specimen types (endocervical swabs, vaginal swabs, male urethral swabs, female and male urine) and have superior sensitivity compared to culture, particularly for chlamydia 3, 6

Important limitation: NAATs for rectal and pharyngeal sites are not FDA-cleared but are validated by many laboratories under CLIA requirements 3

Culture Indications

Culture remains necessary for 3:

• Nongenital sites (rectum and pharynx) when NAATs are unavailable
• Persistent gonococcal infection after treatment (to perform antimicrobial susceptibility testing)

Gram stain is insufficient for ruling out infection in asymptomatic men and should not be used for endocervical, pharyngeal, or rectal specimens 3

Reporting Requirements

Syphilis, gonorrhea, chlamydia, and AIDS are reportable in every state 3, 1, 2. Clinicians must be familiar with local STD reporting requirements, which vary by jurisdiction 3