Fungal keratitis complicating the diagnosis of Acanthamoeba keratitis

A 42-year-old woman was referred to an emergency department. She had an unresponsive corneal ulcer that was initially diagnosed as <i>Herpes simplex</i> virus keratitis. Later, the microbiological studies revealed fungal keratitis. Although the patient was given topical antifungal medication, the clinical presentation did not support improvement. Despite using antifungal medication, the infiltration continued to progress, and the patient underwent therapeutic penetrating keratoplasty (T-PKP). Corneal tissue was collected and sent for histopathologic and molecular examination. The results revealed the presence of both <i>Acanthamoeba</i> T4 subgroup and <i>Fusarium</i> sp. This case emphasizes the importance of considering <i>Acanthamoeba</i> infection in progressive and non-responsive infectious keratitis, especially fungal specimens. Polymerase chain reaction (PCR) is an appropriate laboratory molecular diagnostic test for accurate diagnosis <i>of Acanthamoeba</i> keratitis.