What is the recommended treatment for an adult patient diagnosed with uncomplicated Chlamydia (Chlamydia trachomatis)?

Treatment of Uncomplicated Chlamydia in Adults

For uncomplicated chlamydial infection in non-pregnant adults, treat with either azithromycin 1 g orally as a single dose or doxycycline 100 mg orally twice daily for 7 days, both achieving cure rates of 97-98%. 1, 2

First-Line Treatment Options

• Azithromycin 1 g orally as a single dose achieves a 97% microbial cure rate and offers the critical advantage of directly observed therapy, eliminating compliance concerns entirely 1, 2
• Doxycycline 100 mg orally twice daily for 7 days achieves a 98% microbial cure rate, costs less than azithromycin, and has extensive clinical experience supporting its use 1, 2

Choose azithromycin when compliance with a 7-day regimen is questionable or unpredictable follow-up is anticipated. 1, 3 This is particularly important in populations with erratic health-care-seeking behavior, where single-dose therapy prevents treatment failure from non-adherence. 1

Choose doxycycline when cost is a primary concern and the patient can reliably complete 7 days of twice-daily dosing. 2 Multiple randomized controlled trials demonstrate equivalent efficacy between these two regimens, with similar rates of mild-to-moderate gastrointestinal side effects (17-20%). 2, 4

Alternative Treatment Regimens

Use these alternatives only when patients cannot tolerate first-line options: 1, 2

• Erythromycin base 500 mg orally four times daily for 7 days 1, 2
• Erythromycin ethylsuccinate 800 mg orally four times daily for 7 days 1, 2
• Levofloxacin 500 mg orally once daily for 7 days 1, 2
• Ofloxacin 300 mg orally twice daily for 7 days 1, 2

Avoid erythromycin as first-line therapy—gastrointestinal side effects frequently cause poor compliance, making it less effective in real-world practice despite adequate in vitro activity. 2, 3 Fluoroquinolones (levofloxacin, ofloxacin) show 88-94% efficacy but lack clinical trial validation for chlamydia, offer no compliance advantage over doxycycline due to 7-day dosing, and cost more without superior outcomes. 1

Treatment During Pregnancy

Pregnant women require different regimens because doxycycline and all fluoroquinolones are absolutely contraindicated due to fetal harm. 1, 2

Preferred treatment in pregnancy: 1, 2

• Azithromycin 1 g orally as a single dose (first choice) 1, 2
• Amoxicillin 500 mg orally three times daily for 7 days (alternative) 1, 2

Alternative regimens for pregnant patients who cannot tolerate preferred options: 1, 5

• Erythromycin base 500 mg orally four times daily for 7 days 1, 5
• Erythromycin ethylsuccinate 800 mg orally four times daily for 7 days 1
• For reduced tolerance: Erythromycin base 250 mg orally four times daily for 14 days 5

Critical contraindication: Never use erythromycin estolate in pregnancy—it causes drug-related hepatotoxicity. 1

Pregnant women always require test-of-cure 3-4 weeks after treatment completion, preferably by culture, because alternative regimens have lower efficacy and higher gastrointestinal side effects that compromise compliance. 1

Implementation for Maximum Effectiveness

Dispense medication on-site and directly observe the first dose whenever possible to maximize compliance. 1, 2 This is especially critical for azithromycin single-dose therapy, where witnessed administration guarantees treatment completion. 1

Patients must abstain from all sexual intercourse for 7 days after initiating treatment (regardless of regimen) and until all sex partners have been treated. 1, 3 Failure to observe this restriction leads to reinfection rates up to 20%. 1

Partner Management

All sex partners from the previous 60 days must be evaluated, tested, and empirically treated—even if asymptomatic. 1, 2 If the last sexual contact occurred more than 60 days before diagnosis, still treat the most recent partner. 1, 2

Failing to treat sex partners results in reinfection in up to 20% of cases, negating the initial treatment and perpetuating transmission. 1

Concurrent Gonorrhea Considerations

If gonorrhea is confirmed or prevalence is high in your patient population (20-40% coinfection rates), treat presumptively for both infections: 3

• Ceftriaxone 250 mg IM single dose PLUS azithromycin 1 g orally single dose 1

Do not wait for test results if compliance with return visits is uncertain in high-prevalence populations—treat presumptively to prevent treatment failure. 1

Follow-Up and Test-of-Cure

Test-of-cure is NOT recommended for non-pregnant patients treated with azithromycin or doxycycline who are asymptomatic, due to cure rates of 97-98%. 1, 2 Perform test-of-cure only if: 1, 2

• Therapeutic compliance is questionable
• Symptoms persist after treatment
• Reinfection is suspected

Never test before 3 weeks post-treatment—nucleic acid amplification tests yield false-positives from dead organisms that persist after successful treatment. 1

Mandatory reinfection screening: Retest ALL women approximately 3 months after treatment, regardless of whether partners were reportedly treated. 1, 2 Reinfection rates reach 39% in some adolescent populations, and repeat infections carry elevated risk for pelvic inflammatory disease, ectopic pregnancy, and tubal factor infertility compared to initial infection. 1, 6

Common Pitfalls to Avoid

• Do not use levofloxacin or ofloxacin as first-line therapy—they are designated alternative regimens with inferior evidence, no compliance benefit, and higher cost 1
• Do not prescribe doxycycline, ofloxacin, levofloxacin, or any fluoroquinolone to pregnant women—these are absolutely contraindicated 1, 2
• Do not skip partner treatment—this is the primary cause of reinfection and treatment failure 1
• Do not perform test-of-cure in the first 3 weeks—you will get false-positives from dead organisms 1
• Do not forget 3-month reinfection screening in women—this detects clinically significant reinfections that increase PID risk 1