What are the treatment options for Chlamydia (sexually transmitted infection) and trichomoniasis (STI)?

Treatment of Chlamydia and Trichomoniasis

Chlamydia Treatment

For uncomplicated genital chlamydia, treat with either azithromycin 1 g orally as a single dose OR doxycycline 100 mg orally twice daily for 7 days, both with approximately 97-98% efficacy. 1, 2

First-Line Regimens

• Azithromycin 1 g orally as a single dose is preferred when compliance is questionable, follow-up is unpredictable, or directly observed therapy is needed 1, 2
• Doxycycline 100 mg orally twice daily for 7 days is equally effective, costs less, and has extensive clinical experience 1, 2
• Meta-analyses confirm equal efficacy between these two regimens for genital chlamydial infections 2, 3

Alternative Regimens (when first-line options cannot be used)

• Erythromycin base 500 mg orally four times daily for 7 days 4
• Erythromycin ethylsuccinate 800 mg orally four times daily for 7 days 4
• Ofloxacin 300 mg orally twice daily for 7 days 4
• Levofloxacin 500 mg orally once daily for 7 days 1

Important caveat: Erythromycin causes frequent gastrointestinal side effects that lead to poor compliance, making it a less desirable option 4, 2

Pregnancy Considerations

• Azithromycin 1 g orally as a single dose is the preferred treatment during pregnancy 1, 2
• Amoxicillin 500 mg orally three times daily for 7 days is an alternative 1, 2
• Doxycycline, ofloxacin, and levofloxacin are contraindicated in pregnancy 1, 5
• Pregnant women require test-of-cure 3 weeks after treatment completion due to potential maternal and neonatal complications 5

Pediatric Dosing

• Children ≥8 years weighing >45 kg: Azithromycin 1 g orally as a single dose OR doxycycline 100 mg orally twice daily for 7 days 1
• Children <45 kg: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses daily for 14 days 1
• Avoid non-culture tests (EIA, DFA) in children due to false-positive results from cross-reaction with other organisms 1

Critical Management Steps

• Dispense medications on-site when possible and directly observe the first dose to maximize compliance 1, 2
• Patients must abstain from all sexual intercourse for 7 days after single-dose therapy or until completion of a 7-day regimen, and until all sex partners complete treatment 1, 2, 5
• All sex partners from the preceding 60 days must be evaluated, tested, and treated simultaneously to prevent reinfection 1, 5
• Test all patients for gonorrhea, syphilis, and HIV at the initial visit 1

Follow-Up and Retesting

• Test-of-cure is NOT recommended for patients treated with recommended regimens unless compliance is questionable, symptoms persist, or reinfection is suspected 1, 2
• Retest all women approximately 3 months after treatment due to high reinfection rates (84-92% of recurrent infections are reinfections, not treatment failures) 1, 5
• If testing earlier than 3 weeks after treatment, false-positives may occur from dead organisms 5

Recurrent Chlamydia

• Treat recurrent chlamydia with the same first-line regimens as initial infection (azithromycin 1 g single dose or doxycycline 100 mg twice daily for 7 days) 5
• Treatment failure rates with recommended regimens are extremely low: 0-3% in males and 0-8% in females 2, 5
• Most recurrences (84-92%) represent reinfection from untreated or new partners, not antibiotic resistance 5
• The single most important factor in preventing recurrence is treating all sexual partners 5

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Trichomoniasis Treatment

For trichomoniasis, treat with either metronidazole 2 g orally as a single dose OR tinidazole 2 g orally as a single dose, taken with food. 6, 7

First-Line Regimens

• Tinidazole 2 g orally as a single dose with food is FDA-approved for trichomoniasis in both females and males 6
• Metronidazole 2 g orally as a single dose is also effective for symptomatic trichomoniasis 7
• Both medications should be taken with food to minimize gastrointestinal side effects 6

Critical Management Steps

• Sexual partners must be treated simultaneously with the same dose to prevent reinfection, as trichomoniasis is a sexually transmitted disease 6, 7
• Patients must avoid alcoholic beverages during treatment and for 3 days afterward when taking tinidazole 6
• Asymptomatic male partners should be treated even with negative cultures, as the organism is difficult to isolate from male carriers 7

Alternative Dosing for Tinidazole

• Tinidazole 2 g orally once daily for 2 days with food (for bacterial vaginosis, but may be considered) 6
• Tinidazole 1 g orally once daily for 5 days with food (for bacterial vaginosis, but may be considered) 6

Special Considerations

• For patients unable to swallow tablets, tinidazole tablets may be crushed in artificial cherry syrup (stable for 7 days at room temperature) 6
• Rule out other pathogens including Chlamydia trachomatis, Neisseria gonorrhoeae, Candida albicans, and Herpes simplex virus before diagnosing trichomoniasis 6
• Asymptomatic female partners should be treated when the organism is associated with endocervicitis, cervicitis, or cervical erosion 7