A 24-year-old woman attends the STI clinic with a 2-week history of mucopurulent cervical discharge, dysuria, and lower abdominal pain. Nucleic acid amplification test (NAAT) is positive for *Chlamydia trachomatis* only (gonorrhea negative). What is the drug of choice for chlamydial cervicitis in this patient?

Explanation

## First-Line Treatment of Chlamydial Cervicitis **Key Point:** Doxycycline 100 mg orally twice daily for 7 days is the preferred first-line treatment for uncomplicated chlamydial genital infection in non-pregnant women, as per CDC, WHO, and Indian guidelines. ### Why Doxycycline is Preferred **High-Yield:** Doxycycline is superior because: 1. Excellent intracellular penetration (Chlamydia is an obligate intracellular pathogen) 2. Superior tissue concentration in genital tract 3. Cost-effective and widely available 4. Efficacy >95% for uncomplicated chlamydial infection 5. Well-tolerated with minimal side effects ### Treatment Algorithm for Chlamydia ```mermaid flowchart TD A[Mucopurulent cervical discharge<br/>NAAT positive for Chlamydia]:::outcome --> B{Pregnancy status?}:::decision B -->|Non-pregnant| C[Doxycycline 100 mg BD × 7 days]:::action B -->|Pregnant| D[Azithromycin 1 g single dose<br/>or Amoxicillin 500 mg TDS × 7 days]:::action C --> E[Partner notification<br/>and treatment]:::action D --> E E --> F[Test of cure at 3 weeks<br/>if symptoms persist]:::outcome ``` **Clinical Pearl:** Partner notification and treatment are mandatory. All sexual partners within the preceding 60 days should be treated with the same regimen, even if asymptomatic, to prevent reinfection and reduce transmission. ### Comparative Drug Efficacy and Indications | Drug | Efficacy | Indication | Pregnancy | Duration | Cost | |------|----------|-----------|-----------|----------|------| | **Doxycycline** | >95% | First-line (non-pregnant) | Contraindicated | 7 days | Low | | **Azithromycin** | 90–95% | Pregnancy, allergy to doxycycline | Safe | Single dose | Moderate | | **Ofloxacin** | >95% | Alternative (if doxycycline contraindicated) | Caution | 7 days | Moderate | | **Erythromycin** | 85–90% | Pregnancy (less preferred than azithromycin) | Safe | 7 days | Moderate | **Warning:** Azithromycin monotherapy is NOT first-line in non-pregnant women because emerging resistance (5–10%) is documented. Reserve it for pregnancy, allergy, or intolerance to doxycycline. **Mnemonic:** **DOX for Chlamydia** — **D**oxycycline is the **O**ptimal choice for **X**-ray negative (uncomplicated) chlamydial infection in non-pregnant women. ### Special Considerations - **Pregnant women:** Doxycycline is contraindicated (teratogenic; causes dental staining in fetus). Use azithromycin 1 g single dose or amoxicillin 500 mg TDS × 7 days. - **Allergy to tetracyclines:** Azithromycin 1 g single dose is the alternative. - **Fluoroquinolones (ofloxacin, ciprofloxacin):** Reserved for doxycycline intolerance; not first-line due to lower efficacy and emerging resistance. [cite:Park 26e Ch 8; CDC STI Treatment Guidelines 2021]