Case of isolated Rhizobium radiobacter contact lens-related infectious keratitis: A plant microbe now emerging as a human pathogen

PURPOSE: To report a case of contact lens-related infectious keratitis caused by the Gram-negative plant pathogen Rhizobium radiobacter. OBSERVATIONS: A 26-year old lady with history of contact lens use presented with three weeks history of right eye redness and pain, with the left eye also being involved in the past week. Slit lamp examination of the right eye demonstrated multiple faint subepithelial and stromal infiltrates with no overlying epithelial defect, and no anterior chamber activity. Anterior segment optical coherence tomography demonstrated multiple hyper-reflective foci scattered at various depths of the corneal stroma. Corneal scrapings grew Rhizobium radiobacter, and culture-directed antibiotic therapy with topical gentamicin and levofloxacin resulted in slow clinical improvement of the R. radiobacter keratitis without visual sequelae. CONCLUSIONS AND IMPORTANCE: We have described the clinical features, microbial susceptibilities, and response to treatment in a case of R. radiobacter infectious keratitis. R. radiobacter has recently emerged as a source for several ocular and systemic infections and was identified in a series of polymicrobial keratitis cases. Our case report of monomicrobial R. radiobacter keratitis adds to the sparse literature on this uncommon but potentially sight-threatening infection.