Successful Medical Management of Presumptive Pythium insidiosum Keratitis

To describe the previously unreported successful treatment of presumptive Pythium keratitis (PK) with medical therapy alone.

A 42-year-old female homemaker presented to us with a 15-day history of pain and redness in the right eye after a trivial injury. Her vision was 20/80 at presentation. Slit-lamp biomicroscopy revealed a central, dense and dry-looking, grayish-white infiltrate reaching mid stroma. The infiltrate had feathery margins and was surrounded by multiple tentacle-like lesions and peripherally expanding pinhead-sized subepithelial lesions. The contralateral eye was essentially normal. Diagnostic corneal scraping on smears revealed broad, aseptate, hyaline filaments with ribbon-like folds; very characteristic of Pythium species. Confocal imaging revealed fungal filaments. Based on corroborative evidence, a diagnosis of presumptive PK was made. She was administered a combination therapy consisting of eye drop linezolid 0.2% 1 hourly, azithromycin 1% 2 hourly, atropine sulfate 1% thrice daily, and oral azithromycin 500 mg once daily for 3 days in a week.

After initial worsening in the form of stromal expansion, regression of pinhead-sized lesions was seen with onset of scarring by as early as day 4 of intense medical therapy. The tentacle-like lesions did not worsen. On day 8, significant resolution was noted with scarring, and by the end of 2 weeks, the entire stromal lesion had scarred and complete resolution of expanding tentacles was observed in 3 weeks.

Presumptive Pythium keratitis of the patient completely resolved with antibacterial treatment alone. It is pertinent for ophthalmologists to be aware of this new treatment regimen.