What is the best course of treatment for a patient with recurrent Chlamydia (sexually transmitted infection), who was previously treated with doxycycline (Doxycycline) and has had unprotected sex with the same partner, likely resulting in reinfection?

Recurrent Chlamydia After Doxycycline Treatment

Treat this patient immediately with doxycycline 100 mg orally twice daily for 7 days again, as this is almost certainly reinfection from the untreated partner, not treatment failure. 1, 2

Understanding the Clinical Scenario

This is a reinfection case, not treatment failure. The key distinction is critical:

• Doxycycline has 97-98% efficacy for chlamydia when compliance is adequate 1, 2
• Reinfection from untreated partners occurs in up to 20% of cases when partner treatment fails 2
• The patient explicitly had unprotected sex with the same individual, making reinfection the overwhelmingly likely explanation 3, 1

Immediate Treatment Plan

Retreat with doxycycline 100 mg orally twice daily for 7 days 1, 4

• This is the same regimen as initial treatment because the infection is new, not resistant 1, 2
• Dispense medication on-site and directly observe the first dose to maximize compliance 1, 2
• Alternative option is azithromycin 1 g orally as a single dose if compliance with 7-day regimen is questionable 1, 2

Critical Partner Management (The Root Problem)

The partner MUST be treated simultaneously, or this cycle will continue indefinitely:

• Treat all sex partners from the preceding 60 days, even if previously "treated" 3, 1, 2
• Verify the partner actually completed their full course of antibiotics the first time 1
• Consider expedited partner therapy (EPT) if the partner won't come in—this reduces retreatment rates by 45% 5
• Both patient and partner must abstain from all sexual contact for 7 full days after initiating treatment AND until both have completed their full courses 3, 1, 2

Common Pitfall to Avoid

Do not assume treatment failure and switch antibiotics unnecessarily. The evidence shows:

• True doxycycline treatment failure is extremely rare (0-3% in males, 0-8% in females) when compliance is adequate 1
• The patient's history of sex with the same untreated/inadequately treated partner makes reinfection the diagnosis 3, 1
• Switching to alternative agents like fluoroquinolones (levofloxacin, moxifloxacin) is inappropriate here—these are reserved for documented treatment failures with proper compliance, not reinfection 1, 2

Mandatory Sexual Abstinence Instructions

Emphasize the 7-day abstinence rule with crystal clarity:

• No sexual contact of any kind for 7 days after starting treatment 3, 1, 2
• Abstinence must continue until the partner completes treatment too 3, 1
• Explain that having sex before both complete treatment guarantees another reinfection 3, 1

Follow-Up Testing Strategy

Do NOT perform test-of-cure unless specific circumstances exist:

• Test-of-cure is not recommended for non-pregnant patients treated with recommended regimens 1, 2
• If testing is done, wait at least 3 weeks post-treatment to avoid false-positives from dead organism DNA 3, 1
• Mandatory retest at 3 months regardless of partner treatment status, as reinfection rates reach 39% in some populations 1, 2

Additional STI Screening

Test for other sexually transmitted infections now:

• Screen for gonorrhea, syphilis, and HIV at this visit 2
• Coinfection with gonorrhea is common, and if present, requires ceftriaxone 250 mg IM plus the chlamydia treatment 2

Why Not Switch Antibiotics?

The evidence does not support changing regimens in this scenario:

• Recent high-quality studies show doxycycline and azithromycin have equivalent efficacy (97-98%) for genital chlamydia 1, 2
• For anorectal chlamydia specifically, doxycycline is actually superior to azithromycin (97% vs 76% cure rate) 6, 7
• Fluoroquinolones like levofloxacin have lower efficacy (88-94%) and lack clinical trial validation for chlamydia 2
• The problem here is reinfection, not antibiotic resistance 3, 1

Documentation and Counseling

Document the following in the medical record:

• Confirmed reinfection due to unprotected sex with likely untreated partner 1, 2
• Explicit counseling on 7-day abstinence and partner treatment 3, 1, 2
• Plan for 3-month retest 1, 2
• Offer HPV vaccination if age-appropriate 2