A simple patch test (empty tablet cover patch test) demonstrating ornidazone as offending agent in a patient of fixed drug eruption: Report of a clinical case, a new modified technique and systematic review of literature.

A 49-year-old male presented with the complaints of sudden-onset redness and watering of both the eyes following the intake of fixed drug combination of ofloxacin-ornidazole for diarrhea. Following this, he developed redness of both the lips and blisters in the upper lip. He also developed erythematous macules in the medial aspects of the right lower thigh and ventral aspects of the right leg. Ocular examination showed conjunctival redness with diffuse corneal punctate epithelial erosions in both the eyes. The patient had a similar history affecting the same region 1 year back following the intake of the same combination medicine. To find out the specific inciting agent and owing to unavailability of Finn chamber, we developed a new modified skin patch test using empty tablet cover with three chambers, incorporated with ornidazole, Vaseline (petroleum jelly), and ofloxacin, respectively, and applied on the healed affected lesions. Modified patch test was positive for ornidazole at 48 h. Ornidazole-induced fixed drug eruption (FDE) affecting cornea is a rare and unique in our case report. The patient was then educated about the offending medication and advised to avoid in the future. We also conducted a systematic review of FDEs associated with ornidazole exposure. We searched PubMed and Google Scholar with specific keywords to finally retrieve 14 case reports of ofloxacin induced FDEs, which were further reviewed.