What laboratory tests do you order for a male patient suspected of having a Sexually Transmitted Infection (STI)?

STI Laboratory Testing for Males

For male patients suspected of having a sexually transmitted infection (STI), comprehensive screening should include nucleic acid amplification tests (NAATs) for chlamydia, gonorrhea, and trichomonas, serologic testing for syphilis and HIV, and appropriate site-specific testing based on sexual practices. 1

Core Laboratory Tests for All Male Patients

• First-void urine NAAT for:

  • Chlamydia trachomatis
  • Neisseria gonorrhoeae
  • Consider adding Mycoplasma genitalium and Trichomonas vaginalis to testing panel 2

• Serologic testing for:

  • Syphilis (using treponemal-specific test such as EIA/chemiluminescence immunoassay, followed by nontreponemal test like RPR)
  • HIV
  • Consider Hepatitis B surface antigen (HBsAg) testing

Site-Specific Testing Based on Sexual Practices

• For men reporting receptive anal sex:

  • Rectal swab for NAAT testing of gonorrhea and chlamydia 1

• For men reporting receptive oral sex:

  • Pharyngeal swab for NAAT testing of gonorrhea 1

Additional Testing Considerations

• For patients with genital lesions:

  • NAAT or viral culture for herpes simplex virus (HSV) with type-specific testing (HSV-1 vs HSV-2)
  • Dark-field microscopy or direct fluorescent antibody testing for Treponema pallidum if available

• For high-risk individuals:

  • Consider type-specific HSV-2 serologic testing
  • Consider hepatitis C screening, particularly for men who have sex with men (MSM) 1

Testing Frequency

• Annual screening is recommended for all sexually active patients
• More frequent screening (every 3-6 months) should be considered for patients with:
  • Multiple or anonymous partners
  • Previous STI diagnosis
  • Substance use, especially methamphetamine
  • Unprotected sex outside monogamous relationships
  • Sex work or partners who engage in sex work 3

Important Clinical Considerations

1. Multi-site testing is critical - Testing only urogenital sites would miss many infections, particularly in MSM where asymptomatic rectal carriage is common 1

2. Testing sensitivity varies by site - NAATs have the highest sensitivity (86.1%-100%) and specificity (97.1%-100%) for chlamydia and gonorrhea detection 1

3. Partner testing is essential - 25-40% of treatment "failures" are actually reinfections from untreated partners 1

4. Reporting requirements - Positive tests for chlamydia, gonorrhea, syphilis, and HIV require reporting to public health authorities according to local requirements 1

Common Pitfalls to Avoid

• Failing to test extragenital sites in MSM patients, which can miss a significant number of infections
• Testing only symptomatic patients, as many STIs are asymptomatic
• Not considering antimicrobial resistance, particularly for gonorrhea
• Neglecting to screen partners, which can lead to reinfection
• Overlooking Mycoplasma genitalium, which may be detected in up to 23.9% of male STI clinic attendees 2

By following these comprehensive testing guidelines, clinicians can significantly improve detection rates of STIs in male patients, leading to appropriate treatment and reduced transmission.