A Case of Corneal Ulcer Caused by Stenotrophomonas maltophilia in a Healthy Patient

Purpose: To report a case of corneal ulcer caused by Stenotrophomonas maltophilia monomicrobial infection in an otherwise healthy patient, devoid of underlying medical conditions or predisposing factors.Case summary: A 48-year-old male patient, who was normally healthy without a history of systemic disease, eye trauma, and eye surgery, presented with acute left eye pain that had manifested one day prior. Ophthalmic examination revealed conjunctival injection, corneal edema, and localized corneal ulceration in the left eye. Suspecting infectious keratitis, diagnostic procedures including gram staining, bacterial and fungal cultures, and antibiotic susceptibility testing were promptly instituted. Bacterial culture identified S. maltophilia, prompting an eight-week course of topical gatifloxacin therapy. The subsequent clinical course exhibited improvement, with lingering corneal haziness and the restoration of visual acuity to 1.0.Conclusion: The case featuring the single detection of S. maltophilia, known to cause hospital-acquired opportunistic infections, emphasizes the importance of culture and antibiotic susceptibility testing in the treatment of keratitis. Remarkably, in a patient with a normal immune status and in the absence of factors predisposing to S. maltophilia infections, there were no discernible causative factors damaging the ocular surface environment.