What is the treatment for a suspected Sexually Transmitted Infection (STI)?

Treatment for Suspected Sexually Transmitted Infections (STIs)

The recommended approach for suspected STIs is prompt diagnostic testing followed by targeted antimicrobial therapy based on the specific pathogen identified, with empiric treatment often warranted while awaiting test results. 1, 2

Diagnostic Evaluation

• Collect specimens from all sites of potential infection (genital, pharyngeal, rectal) based on sexual exposure history 1
• For genital infections, obtain:
  • Nucleic acid amplification tests (NAATs) for gonorrhea and chlamydia (highest sensitivity and specificity: 86.1%-100%) 2
  • Wet mount and culture of vaginal swab for Trichomonas vaginalis 1
  • Examination of vaginal discharge for bacterial vaginosis and yeast infection if present 1
• Collect blood samples for:
  • Syphilis serology (sequential testing for treponemal and nontreponemal antibodies) 2
  • HIV testing 1
  • Hepatitis B serology 1

Empiric Treatment

For Urethritis/Cervicitis:

• First-line treatment: 3, 4

  • Ceftriaxone 500 mg IM single dose (for patients ≥150 kg: 1 g) for gonorrhea
  • PLUS
  • Doxycycline 100 mg orally twice daily for 7 days for chlamydia

• Alternative regimen (for patients allergic to cephalosporins/tetracyclines): 1

  • Ofloxacin 300 mg orally twice daily for 10 days

For Epididymitis:

• If likely caused by gonorrhea or chlamydia: 1
  • Ceftriaxone 250 mg IM single dose
  • PLUS
  • Doxycycline 100 mg orally twice daily for 10 days

For Vaginal Trichomoniasis:

• Metronidazole 500 mg orally twice daily for 7 days 4

For Syphilis:

• Early syphilis (less than one year): 4
  • Penicillin G benzathine 2.4 million units IM single dose
• Late syphilis (more than one year or unknown duration): 4
  • Penicillin G benzathine 2.4 million units IM weekly for three consecutive weeks

Follow-Up Care

• Test of cure is recommended for: 4
  • All cases of pharyngeal gonorrhea
  • Rectal chlamydia if treated with azithromycin
• Patients should abstain from sexual intercourse until: 1
  • Therapy is completed (7 days after single-dose regimen or after completion of multi-day regimen)
  • Symptoms have resolved
  • Sex partners have been treated

Management of Sex Partners

• All sex partners from the past 60 days should be referred for evaluation and treatment 1
• Partners should be treated for the same infection as the index patient, even if asymptomatic 1
• Expedited partner therapy (providing medication or prescription for partners without clinical evaluation) may be considered where legally permitted 2

Prevention Strategies

• Consistent and correct condom use with all sexual encounters 1
• Pre-exposure vaccination for preventable STIs (hepatitis B, HPV) 1
• Regular screening for asymptomatic infections in high-risk populations 2
• Consider doxycycline post-exposure prophylaxis (doxyPEP) for high-risk individuals, particularly men who have sex with men 5

Special Considerations

Sexual Assault Cases

• Comprehensive STI testing at initial evaluation 1
• Empiric prophylactic treatment is often recommended 1
• Follow-up testing at 2 weeks and 12 weeks post-assault 1

HIV-Positive Patients

• Same treatment regimens as HIV-negative patients for most uncomplicated STIs 1
• May require more aggressive management or specialist consultation for complicated infections 1

Common Pitfalls to Avoid

• Failing to test for all potential pathogens based on exposure sites 1
• Not treating partners, leading to reinfection 1
• Inadequate follow-up, especially for infections with high treatment failure rates 4
• Using inappropriate antimicrobial regimens that don't account for increasing resistance patterns 2
• Not addressing behavioral risk factors that contribute to acquisition and transmission 1