Cicatrising trachoma is seen in
**Core Concept**
Cicatrising trachoma is a chronic form of trachoma, a leading cause of preventable blindness worldwide, characterized by scarring and inflammation of the tarsal conjunctiva. It is caused by the bacterium Chlamydia trachomatis, which leads to a chronic inflammatory response and subsequent fibrosis.
**Why the Correct Answer is Right**
The correct answer is Chlamydia trachomatis, as it is the causative agent of cicatrising trachoma. The bacterium infects the conjunctival epithelial cells, leading to an immune response that results in inflammation, scarring, and ultimately, cicatrisation (scarring) of the tarsal conjunctiva. This scarring can lead to entropion (inversion of the eyelid) and trichiasis (growth of eyelashes towards the globe), which can cause further irritation and potentially lead to blindness.
**Why Each Wrong Option is Incorrect**
**Option A:** Chlamydophila pneumoniae - This is another species of Chlamydia, but it is not associated with cicatrising trachoma. Chlamydophila pneumoniae is a respiratory pathogen that causes pneumonia and other respiratory infections.
**Option B:** Staphylococcus aureus - This is a common cause of bacterial conjunctivitis, but it is not associated with cicatrising trachoma.
**Option C:** Haemophilus influenzae - This is a common cause of conjunctivitis, but it is not associated with cicatrising trachoma.
**Clinical Pearl / High-Yield Fact**
Cicatrising trachoma is a leading cause of preventable blindness in the developing world, particularly in areas with poor sanitation and hygiene. Early diagnosis and treatment with antibiotics, such as azithromycin, can prevent progression to cicatrisation and subsequent blindness.
**Correct Answer:** C. Chlamydia trachomatis.