Nocardia keratitis mimicking superior limbic keratoconjunctivitis and herpes simplex virus

PURPOSE: Nocardia keratitis is a rare type of infectious keratitis and may mimic other corneal diseases and lead to delay in diagnosis. This case illustrates how Nocardia often escapes accurate diagnosis due to its insidious onset, variable clinical manifestations, and unusual characteristics on cultures. OBSERVATION: The patient presented with an epithelial defect and superior pannus and scarring, which was misdiagnosed as superior limbic keratoconjunctivitis (SLK) and herpes simplex virus (HSV) keratitis. Repeat corneal scraping cultures, smears, and conjunctival biopsy were necessary to elucidate the diagnosis. It can be effectively treated with the intravenous preparation of trimethoprim-sulfamethoxazole 80 mg/mL (brand name SEPTRA) used topically as eye drops. CONCLUSION: The diagnosis of Nocardia keratitis relies on a high clinical suspicion and a prompt corneal scraping with culture. Due to its potential for rapid resolution with early therapy, it is important to isolate Nocardia early in its disease course. IMPORTANCE: Topical amikacin had been the standard of care for Nocardia keratitis for many years. However, recently there is increasing resistance of Nocardia to amikacin. SEPTRA offers an alternative therapy. Nocardia keratitis mimics other infectious and inflammatory etiologies so rapid diagnosis and treatment is critical in the prevention of long-term complications.