Pythium and Acanthamoeba Co-infection: A Rare Case of Mixed Keratitis

Abstract

Oomycete Pythium insidiosum and protozoan Acanthamoeba are rare but fulminant causes of keratitis, with co-infection reported only once previously, posing significant diagnostic and therapeutic challenges. We report the case of a young female who presented with defective vision following ocular exposure to carrom powder, with a best-corrected visual acuity of 6/36. Slit-lamp examination revealed an active stromal infiltrate with tentacular margins and limbal involvement. Microbiological evaluation demonstrated Acanthamoeba cysts on Gram stain with growth on non-nutrient agar and Pythium growth in blood agar. The patient was treated with hourly topical polyhexamethylene biguanide 0.04% and azithromycin 1% eye drops along with therapeutic penetrating keratoplasty. With one episode of graft rejection at the 18-month follow-up, the patient maintains clear graft with 6/18 uncorrected vision and best-corrected visual acuity of 6/6 ^P at the 8-year follow-up. Early diagnosis and timely surgical intervention can result in favorable visual outcomes even in such rare and aggressive co-infections.