Question
Chlamydial conjunctivitis.
Answer
Chlamydial conjunctivitis is caused by Chlamydia trachomatis, an obligate intracellular bacterium, and presents in two clinically distinct forms depending on the serovar involved.
Trachoma (serovars A, B, Ba, C): a chronic follicular keratoconjunctivitis, endemic in areas with poor hygiene/overcrowding; repeated reinfection causes conjunctival scarring, entropion, and trichiasis (inward-turning eyelashes), which abrade the cornea, leading to corneal opacification and blindness — a leading infectious cause of preventable blindness worldwide.
Inclusion conjunctivitis (serovars D–K): sexually transmitted serovars causing:
- Adult inclusion conjunctivitis — acquired via genital-eye contact/autoinoculation, presents as an acute mucopurulent follicular conjunctivitis.
- Neonatal inclusion conjunctivitis (ophthalmia neonatorum) — acquired during passage through an infected birth canal, presenting typically 5–14 days after birth with purulent discharge and lid swelling; can be complicated by pneumonitis.
Laboratory diagnosis: Giemsa-stained conjunctival scrapings showing characteristic intracytoplasmic inclusion bodies (Halberstaedter-Prowazek bodies); direct fluorescent antibody (DFA) test; enzyme immunoassay for chlamydial antigen; nucleic acid amplification tests (PCR) — now the most sensitive and preferred method; cell culture (McCoy cells) — reference standard but slow and technically demanding.
Treatment: systemic azithromycin (single dose) or doxycycline (topical therapy alone is inadequate as the infection is not confined to the eye); erythromycin for neonates (also treats concurrent chlamydial pneumonitis); treatment of sexual partners for the genital-serovar forms; mass azithromycin distribution and facial hygiene/environmental improvement (SAFE strategy) for trachoma control.