Bilateral nocardial endophthalmitis in a prothonotary warbler (Protonotaria citrea).

A 7-year-old captive female prothonotary warbler (Protonotaria citrea) died following chronic feather and weight loss. At necropsy, the right eye had a 2 x 2 x 1 mm corneal plaque of inspissated yellow-tan material and edema of the lower eyelid. Microscopically, both eyes exhibited diffuse, severe pyogranulomatous endophthalmitis with retinal necrosis and detachment. Numerous intralesional branching, gram-positive, beaded, filamentous bacteria formed a thick mat attached to the retinal pigmented epithelium and extending into the pecten. Bacteria were strongly acid-fast positive by Fite's stain but only occasionally acid-fast positive by Ziehl-Neelsen staining, a characteristic consistent with a Nocardia spp. Infected regions demonstrated positive in situ hybridization reactivity with a probe complementary to the 16S rRNA gene of Nocardia spp. There was no evidence of primary bacterial infection in the other organs examined.