Which clinical sign is most characteristic of chlamydial trachomatis conjunctivitis in adults?

Explanation

## Chlamydial Trachomatis Conjunctivitis — Clinical Features **Key Point:** Follicular conjunctivitis with preauricular lymphadenopathy is the hallmark of chlamydial trachomatis infection in adults (inclusion conjunctivitis). ### Morphology of Conjunctival Lesions | Lesion Type | Appearance | Associated Condition | Location | |-------------|-----------|----------------------|----------| | **Follicles** | Small, translucent, avascular nodules (0.5–1 mm) | Chlamydial, viral, allergic conjunctivitis | Lower tarsal, fornix | | **Papillae** | Larger, vascularized elevations (>1 mm) with central vessel | Bacterial, allergic, vernal conjunctivitis | Upper tarsal (vernal), lid margin | | **Giant papillae** | Papillae >1 mm, often ≥3 mm | Vernal keratoconjunctivitis, contact lens reaction | Upper tarsal conjunctiva | | **Pseudomembrane** | Fibrinous exudate, easily peeled off | Acute bacterial (gonorrhea, pneumococcus), viral | Palpebral conjunctiva | **High-Yield:** Follicles = avascular, translucent nodules; papillae = vascularized, opaque elevations. This distinction is critical for diagnosis. ### Chlamydial Trachomatis (Serovars D–K) — Adult Inclusion Conjunctivitis 1. **Onset:** 1–2 weeks after exposure (sexually transmitted) 2. **Symptoms:** Mild to moderate foreign body sensation, mucopurulent discharge 3. **Signs:** - Follicular conjunctivitis (lower tarsal and fornix) - Preauricular lymphadenopathy (pathognomonic) - Mild chemosis and hyperemia - **Absence of corneal involvement** (unlike keratitis) 4. **Systemic involvement:** Urethritis, cervicitis, or urethral syndrome in sexual partner 5. **Diagnosis:** Nucleic acid amplification test (NAAT), PCR, or direct immunofluorescence 6. **Treatment:** Azithromycin 1 g single dose or doxycycline 100 mg BD × 7 days (systemic); topical antibiotics are adjunctive [cite:Kanski's Clinical Ophthalmology 9e Ch 3] **Clinical Pearl:** Preauricular lymphadenopathy in the setting of follicular conjunctivitis is virtually diagnostic of chlamydial infection. Always screen for sexually transmitted infections (STIs) and treat the sexual partner. **Mnemonic:** **FLACC** — Follicles, Lymphadenopathy (preauricular), Absence of pseudomembrane, Chlamydia, Chronic (often >3 weeks if untreated).