Prototheca wickerhamii infection of a corneal graft.

Algae are generally noninfectious agents in mammals, with few known pathogenic algae. Prototheca is an achlorophylic nonphotosynthetic algae, globally ubiquitous, and readily isolated from rivers, lakes, ponds, and soil. Although canine and bovine protothecosis have been reported more widely, infections in humans are rare, particularly in patients with an intact immune system. The majority of protothecal infections in humans is associated with Prototheca wickerhamii. We report an unusual case of P. wickerhamii infection in an immunocompetent corneal transplant patient.