A case of keratitis by mixed infection of Proteus mirabilis and Colletotrichum Jructicola

Purpose : Keratitis caused by combined infection of bacteria and fungus is common, however, it is difficult to identify both of them. We report a case of keratitis by mixed infection of Proteus mirabilis and Colletotrichum fructicola. Case : The patient was a 70-year-old man, who felt the entrance of a foreign body in the right eye in the course of cargo handling of rice in late October 2019. After 2-3 days, he felt eye pain in the right eye ; however, he used steroid and anti-glaucoma eye drops at home without hospital visit. In early November 2019, he visited a local ophthalmic clinic because of decreased vision, was referred to Tottori University Hospital, and diagnosed withm hypopyon ulcer in the right eye. At the first examination, corneal scrapings were provided to microscopic examination of smear, laboratory culture, and real-time PCR (bacteria, fungi), and antibiotics was started. Although hypopyon had been reduced after the start of antibiotic therapy, pimaricin eye drops was added at 4 days after hospitalization because of fungal elements observed in smear. Afterward, the right eye had been gradually improved and scarred after one and half months. The results of laboratory culture were Proteus mirabilis and fungus, which was identified as Colletotrichum fructicola by PCR direct sequence methods. Conclusions : We should consider both bacteria and fungi as causative agents, in case of injury by plants or crops. Microscopic examination of smear is important to recognize the existence of mixed infection earlier than culture. To our best knowledge, this is the first report on keratitis caused by Colletotrichum fructicola.