Stenotrophomonas maltophilia keratitis treated with trimethoprim-sulfamethoxazole

An 84 year-old woman with persistent epithelial defect and a dense stromal infiltrate post-corneal transplantation. According to the microbiological results, it was due to a Stenotrophomonas maltophilia (S. maltophilia) resistant to all antibiotics except trimethoprim-sulfamethoxazole (TMP/SMX). Healing was achieved after three weeks of treatment with oral and topical TMP/SMX. S. maltophilia is an opportunistic microorganism rarely described in ophthalmology. It is associated with conjunctivitis, keratitis, scleritis, dacryrocystitis, cellulitis, and endophthalmitis with significant morbidity. Treatment is complicated because of its resistances to broad-spectrum antibiotics. TMP/SMX monotherapy can be considered an option of treatment for this type of keratitis.