Diagnostic Challenges in Nocardia Keratitis.

OBJECTIVE

To present a case of diagnostic confusion in Nocardia keratitis in a contact lens wearer and to illustrate the characteristic clinical findings of this rare entity.

METHODS

Case report of Nocardia keratitis that was mistaken for acanthamoeba, herpetic, and fungal keratitis in three tertiary corneal referral centers before the correct diagnosis of Nocardia infection was made.

RESULTS

A 29-year-old contact lens wearer was referred to our hospital for a contact lens-associated bacterial keratitis, not improving under standard bacterial treatment. Biomicroscopy revealed a circular corneal ulcer and pinhead lesions arranged in a wreath pattern. Initial scraping revealed no positive cultures and confocal microscopy findings were suspicious for fungal keratitis. Only after a poor response to protozoal and fungal treatment, and a negative herpes serology, Nocardia was suspected. This suspicion was confirmed with a positive culture and the topical amikacin and ciprofloxacin were started. The infiltrate responded promptly and resolved, leaving a small corneal scar and a good visual recovery.

CONCLUSION

Because of its infrequent occurrence and its variable clinical picture, Nocardia keratitis is easily misdiagnosed. Although a rare entity, this infection should be added to the differential diagnosis in contact lens-related keratitis not responding to first-line antibiotics and presenting with patchy anterior stromal infiltrates.