Case Report: Poor Outcome Despite Aggressive Management in Pythium insidiosum Endophthalmitis

Abstract

Pythium insidiosum is a parasitic oomycete that can cause keratitis and closely resembles fungus, both clinically and morphologically. It requires a trained microbiologist for its differentiation from fungal filaments and has poor response to antifungal therapy. We present a case of primary isolation of the organism from the vitreous cavity in a case of endophthalmitis. The infection spread quickly and involved all the ocular tissues. The eye had poor visual outcome despite a sequence of rapidly completed retinal and corneal surgeries along with initiation of anti-Pythium therapy.

Figure 1.

(A) Slit-lamp picture of Pythium keratitis revealing the typical signs: ring infiltrate and guttering. (B) B-scan picture of day 1 depicting numerous vitreous echoes (C), which started resolving with appropriate anti-Pythium therapy.

Figure 2.

(A) Flat, adherent, velvety growth of P. insidiosum from a vitreous biopsy on blood agar. (B) Broad, aseptate, fungal-like filaments with characteristic ribbon-like folds of P. insidiosum on Gomori methenamine silver stain from growth on blood agar, seen under ×40 magnification by bright-field microscopy. (C) Zoospore formation of P. insidiosum at the margins of infected leaves in induction medium, seen under ×10 magnification by bright-field microscopy. (D) Histopathology showed cut-end and aseptate, ribbon-like filaments of Pythium in the posterior stroma and anterior chamber of the cornea on Grocott-Gomori methenamine silver stain under ×400 magnification.

Figure 3.

(A) Slit-lamp picture of postoperative day 1 after therapeutic keratoplasty. Sutures are intact and the globe is formed. (B and C) B scan revealing decreases in vitreous echoes but the development of retinal detachment. (D) Slit-lamp picture upon the last follow-up. Most of the sutures are removed and the eye is going into phthisis.