Which Chlamydia trachomatis serovars are responsible for trachomatous infection of the eye?

Question

Accepted Answer

D. Serovars A, B, Ba, and C. ## Chlamydia trachomatis Serovars and Eye Disease

**Key Point:** Trachoma is caused exclusively by Chlamydia trachomatis serovars A, B, Ba, and C. These are the only serovars that produce chronic keratoconjunctivitis and lead to blindness if untreated.

### Serovar Classification by Disease

| Serovars | Disease | Clinical Features |
|----------|---------|-------------------|
| **A, B, Ba, C** | **Trachoma** | Chronic keratoconjunctivitis, trichiasis, entropion, blindness |
| D–K | Inclusion conjunctivitis | Acute mucopurulent discharge, self-limited |
| L1, L2, L3 | Lymphogranuloma venereum | Genital ulcers, inguinal lymphadenopathy |

**High-Yield:** Serovars A, B, Ba, and C are endemic in developing countries (particularly Africa, Middle East, South Asia) and cause repeated infections leading to scarring and blindness. These are the only serovars that produce the pathognomonic Arlt's line (horizontal pannus) and conjunctival scarring.

**Clinical Pearl:** Serovars D–K cause acute follicular conjunctivitis (often neonatal inclusion conjunctivitis acquired during birth) but do NOT cause chronic trachoma or blindness. They are self-limited and respond to antibiotics without sequelae.

**Mnemonic:** **ABC = Always Blindness Causing** (serovars A, B, Ba, C cause trachoma and blindness); **DEF = Don't End in Fibrosis** (serovars D–K do not cause chronic scarring).

![Trachoma diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/4220.webp)

Answer

A. Serovars M, N, O, and P

Answer

B. Serovars D, E, F, G, H, I, J, and K

Answer

C. Serovars L1, L2, and L3

Which Chlamydia trachomatis serovars are responsible for trachomatous infection of the eye?

Explanation

Chlamydia trachomatis Serovars and Eye Disease

Serovar Classification by Disease

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Serovars	Disease	Clinical Features
A, B, Ba, C	Trachoma	Chronic keratoconjunctivitis, trichiasis, entropion, blindness
D–K	Inclusion conjunctivitis	Acute mucopurulent discharge, self-limited
L1, L2, L3	Lymphogranuloma venereum	Genital ulcers, inguinal lymphadenopathy