Antibiotic Treatment for Sexually Transmitted Diseases
For gonorrhea, use ceftriaxone 500 mg IM (≥150 kg body weight) or 250 mg IM (<150 kg); for chlamydia, use doxycycline 100 mg orally twice daily for 7 days; for syphilis, use benzathine penicillin G 2.4 million units IM as a single dose for early syphilis or three weekly doses for late/unknown duration syphilis. 1
Gonorrhea Treatment
The treatment landscape for gonorrhea has evolved significantly due to antimicrobial resistance. Ceftriaxone monotherapy is now the standard of care, eliminating the previous dual therapy approach 1. The dosing is weight-based:
- ≥150 kg body weight: 500 mg IM
- <150 kg body weight: 250 mg IM
This represents a critical shift from older guidelines that recommended 125 mg doses 2, 3. The increased dosing addresses emerging resistance patterns and provides adequate therapeutic coverage.
Important Caveats for Gonorrhea:
- Quinolones (ciprofloxacin, ofloxacin) are no longer recommended due to widespread resistance 4, 5, 6
- Pharyngeal gonorrhea requires test-of-cure 7-14 days after treatment 1
- Spectinomycin (2 g IM) remains an alternative for patients with cephalosporin allergies, though it's only 52% effective for pharyngeal infections 2
Chlamydia Treatment
Doxycycline 100 mg orally twice daily for 7 days is the preferred first-line treatment 1, 7. This represents a change from previous guidelines that listed azithromycin 1 g as co-equal 3, 5.
Alternative Regimens:
- Azithromycin 1 g orally single dose: Reserved for compliance concerns or specific populations (pregnancy) 5
- Levofloxacin 500 mg daily for 7 days 8
- Erythromycin base 500 mg four times daily for 7 days (less effective, more GI side effects) 5
Key Points:
- Test-of-cure is recommended for rectal chlamydia treated with azithromycin 1
- No test-of-cure needed after doxycycline unless symptoms persist 5
- Rescreen at 3 months due to high reinfection rates 4, 5
Syphilis Treatment
Penicillin remains the only proven effective treatment for syphilis, with no acceptable alternatives in pregnancy 9, 10.
Treatment by Stage:
- Early syphilis (<1 year duration): Benzathine penicillin G 2.4 million units IM single dose 1
- Late/unknown duration syphilis: Benzathine penicillin G 2.4 million units IM weekly for 3 consecutive weeks 1
- Neurosyphilis, ocular, or otic syphilis: Aqueous crystalline penicillin G IV for 10-14 days 1
Critical Considerations:
- Thoroughly evaluate for neurologic, ophthalmic, and otic symptoms at any stage—these complications require extended IV therapy 1
- Penicillin-allergic patients must be desensitized if pregnant 2, 9
- Ceftriaxone plus doxycycline combinations show inferior efficacy compared to standard penicillin therapy 11
Dual Therapy Considerations
Always treat presumptively for chlamydia when treating gonorrhea due to high coinfection rates (up to 31% in some populations) 2, 11. The recommended approach:
- Ceftriaxone (for gonorrhea) PLUS
- Doxycycline 100 mg twice daily for 7 days (for chlamydia)
This dual coverage addresses the 31.2% chlamydia coinfection rate and provides additional coverage against other pathogens 11.
Special Populations
Pregnancy:
- Gonorrhea: Ceftriaxone only (avoid quinolones and tetracyclines) 2
- Chlamydia: Azithromycin 1 g single dose or erythromycin 2, 10
- Syphilis: Benzathine penicillin G (desensitize if allergic—no alternatives exist) 9, 10
HIV-Positive Patients:
- Use same regimens as HIV-negative patients 2
- Monitor closely for treatment response
Partner Management
All sexual partners within 60 days of symptom onset or diagnosis must be evaluated and treated 2. Expedited partner therapy is cost-effective and reduces reinfection rates 7. Patients should abstain from sexual activity for 7 days after single-dose therapy or until completion of multi-day regimens 8, 5.
Resistance Surveillance
The evidence consistently emphasizes that antimicrobial resistance is an evolving threat 6, 12, 13. Clinicians should:
- Culture and perform susceptibility testing for treatment failures
- Report resistant cases to local health departments 5
- Stay updated on regional resistance patterns