Which organism is the most common cause of dendritic ulcers?

The most common cause of dendritic ulcers is indeed Herpes simplex virus (HSV). Dendritic ulcers are a characteristic type of corneal lesion associated with viral keratitis, particularly caused by HSV. The virus can lead to inflammation of the cornea, resulting in the formation of these branching lesions, which resemble dendrites.

In the context of eye health, HSV is a significant pathogen because it can remain dormant in nerve cells and reactivate, leading to recurrent episodes of keratitis. Early recognition and treatment of dendritic ulcers are crucial, as they can lead to complications, including corneal scarring and vision loss if left untreated.

The other organisms listed are associated with different infections or conditions. For instance, Staphylococcus aureus is primarily a bacterial pathogen that causes skin infections, pneumonia, and other serious conditions but is not linked to dendritic ulcers. Escherichia coli is mainly known for gastrointestinal infections and does not typically cause ocular problems. Chlamydia trachomatis is known for causing sexually transmitted infections as well as conjunctivitis but is not responsible for dendritic ulcers. Thus, the association of dendritic ulcers with Herpes simplex clearly establishes it as the correct answer.