Pythium keratitis: clinical course of an emerging scourge

We hereby report two cases of the emerging and devastating Pythium keratitis for their different presentations, prolonged clinical course, and suspicion of recurrence after therapeutic penetrating keratoplasty (TPK). The history, clinical presentation, investigations including smears, cultures, polymerase chain reaction (PCR) and confocal microscopy, the tumultuous course of the infection, and outcome of TPK have been discussed for two cases having this unusual and severe emerging infection. These two cases demonstrate that Pythium keratitis can present as a central reticular or peripheral guttering corneal ulcer with dense infiltration. PCR is a valuable tool for diagnosis. Pythium keratitis has a severe and prolonged clinical course. Response to antibiotics is modest and needs to be closely monitored. It can present with inflammation after TPK that mimics the dreaded recurrence of the infection. Pythium keratitis presents variably and can be suspected from typical clinical and microbiological findings. It needs protracted treatment with close follow-up. Although the infection is known torecur in the therapeutic graft, not all recurrences are what they seem.