Branched septate hyphae are found on cornmeal smear, in a case of corneal ulcer. Causative fungus is
**Core Concept**
Fungal corneal ulcers are a significant cause of vision loss worldwide. The diagnosis often relies on the identification of fungal elements on a corneal smear or culture. In this question, the presence of branched septate hyphae on a cornmeal smear indicates a specific type of fungal infection.
**Why the Correct Answer is Right**
The presence of branched septate hyphae is characteristic of Fusarium species, which are common causes of fungal corneal ulcers. These fungi are known to produce melanin, which can lead to a distinctive brown or black discoloration of the cornea. The branched septate hyphae observed on the cornmeal smear are a result of the fungus's ability to produce hyphae with septa, or divisions, within the cell wall.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not match the description of the fungus in question. The presence of branched septate hyphae is not characteristic of Aspergillus species.
**Option B:** This option is incorrect because it does not match the description of the fungus in question. The presence of branched septate hyphae is not characteristic of Candida species.
**Option C:** This option is incorrect because it does not match the description of the fungus in question. The presence of branched septate hyphae is not characteristic of Mucor species.
**Clinical Pearl / High-Yield Fact**
Fusarium species are commonly found in soil and are often associated with contact lens wear or trauma to the eye. The presence of branched septate hyphae on a cornmeal smear is a key diagnostic feature of Fusarium keratitis.
**Correct Answer:** C. Fusarium