What are the treatment options for a sexually active adult with a sexually transmitted infection (STI), including chlamydia, gonorrhea, syphilis, herpes simplex virus (HSV), and human papillomavirus (HPV)?

Treatment for Sexually Transmitted Infections

For sexually active adults with STIs, treatment must be pathogen-specific: use ceftriaxone 500 mg IM (or 1 g if ≥150 kg) as monotherapy for gonorrhea, doxycycline 100 mg orally twice daily for 7 days for chlamydia, penicillin G benzathine 2.4 million units IM for early syphilis, valacyclovir for genital herpes, and no specific antiviral treatment exists for HPV (only ablative or immunomodulatory therapies for visible warts). 1, 2

Gonorrhea Treatment

• Ceftriaxone monotherapy is now the standard of care, eliminating the previous dual therapy approach 1
• Dosing is weight-based: 500 mg IM for patients <150 kg, or 1 g IM for patients ≥150 kg 1
• Test-of-cure is mandatory for all pharyngeal gonorrhea cases due to higher treatment failure rates at this site 1
• Antimicrobial resistance has eliminated oral treatment options, making intramuscular ceftriaxone the only reliable first-line therapy 2

Chlamydia Treatment

• Doxycycline 100 mg orally twice daily for 7 days is the preferred regimen, replacing azithromycin as first-line therapy 1, 2
• Azithromycin 1 g orally as a single dose remains an alternative but is no longer preferred 3, 4, 5
• Test-of-cure is required for rectal chlamydia if treated with azithromycin (not needed if doxycycline is used) 1
• Single-dose azithromycin ensures 100% compliance but has lower efficacy than doxycycline 6

Coinfection Considerations

• Patients with gonorrhea should be presumptively treated for chlamydia given high coinfection rates 3, 7
• All patients should be tested for syphilis and HIV at the time of STI diagnosis 7

Syphilis Treatment

• Early syphilis (<1 year duration): penicillin G benzathine 2.4 million units IM as a single dose 1, 2
• Late or unknown duration syphilis: penicillin G benzathine 2.4 million units IM weekly for 3 consecutive weeks 1
• Parenteral penicillin remains the drug of choice for all stages of syphilis 5
• Critical pitfall: Perform thorough evaluation for otic, ophthalmic, and neurologic symptoms before treatment, as neurosyphilis can occur at any stage and requires 10-14 days of IV aqueous crystalline penicillin G 1

Genital Herpes (HSV) Treatment

Initial Episode

• Valacyclovir 1 g orally twice daily for 7-10 days 8, 9
• Treatment should be initiated within 72 hours of symptom onset for maximum efficacy 9
• Alternative agents include acyclovir and famciclovir 5, 10

Recurrent Episodes

• Valacyclovir 500 mg orally twice daily for 5 days, initiated within 24 hours of lesion onset or at first sign of prodrome 8, 9
• Patients should have medication on hand to self-initiate treatment immediately 8

Suppressive Therapy

• Valacyclovir for chronic suppression in immunocompetent adults and HIV-infected patients with CD4+ ≥100 cells/mm³ 9
• Reduces transmission risk in discordant couples 9

Symptomatic Management

• Lidocaine 2-5% gel applied to lesions 3-4 times daily provides local pain relief only 8
• Lidocaine has no antiviral activity and does not prevent transmission or recurrence 8
• Systemic antiviral therapy remains mandatory alongside any symptomatic measures 8

Human Papillomavirus (HPV) Treatment

• No specific antiviral medication exists for HPV eradication 10
• Treatment targets visible genital warts only, not subclinical infection 3
• Therapeutic options are either antimitotic (destructive) or immunomodulatory 10
• Most HPV infections are asymptomatic and self-limited 3

Partner Management and Follow-Up

• All sex partners from the past 60 days must be notified, examined, and treated for diagnosed STIs 3, 7
• Patients and partners must abstain from intercourse for 7 days after single-dose therapy or until completion of multi-day regimens 3, 7
• Retesting at 3 months is recommended to detect reinfection, particularly for gonorrhea and chlamydia 7
• Reinfection is common and difficult to distinguish from treatment failure 3

Special Populations

Pregnancy

• Azithromycin or amoxicillin for chlamydia (doxycycline contraindicated) 7
• Penicillin remains essential for syphilis treatment 5
• Valacyclovir and famciclovir are not yet recommended during pregnancy 5

HIV-Infected Patients

• Same treatment regimens as HIV-negative patients for most STIs 3
• Herpes proctitis may be especially severe in HIV-coinfected patients 3
• Fungi and mycobacteria are more likely causes of complications in immunosuppressed patients 3

Screening Recommendations

• Mandatory annual screening for chlamydia and gonorrhea in all sexually active women <25 years 7
• Screen women ≥25 years with risk factors: new/multiple partners, inconsistent condom use, previous STI, or partner with STI 7
• Use nucleic acid amplification tests (NAATs) as the preferred diagnostic method with sensitivity 86.1-100% and specificity 97.1-100% 7, 2