First case report of fatal Nocardia nova infection in yellow-bibbed lory (Lorius chlorocercus) identified by multilocus sequencing

Abstract

Background: Nocardiosis is often a multi-systemic disease in humans and other mammals. Nocardiosis in birds is uncommon. Laboratory identification of Nocardia to the species level is difficult by traditional phenotypic methods based on biochemical reactions and hydrolysis tests, and is most accurately performed by sequencing multiple gene targets. Case presentation: We report the first case of fatal Nocardia nova infection in a yellow-bibbed lory nestling in an oceanarium diagnosed by multilocus sequencing. Necropsy examination showed effacement of normal sternal musculature with yellowish, firm aberrant material, and diffuse infiltration of the lungs with nodular, tan to yellow foci. Histologically, severe granulomatous inflammation with marked necrosis was observed in the lung, spleen and sternal musculature. Fine, sometimes Gram-positive, 0.5-1 μm wide, branching and beaded filamentous organisms were visible within the lesions. They were acid-fast on Fite-Faraco stain. Tissue samples obtained from the sternum, liver, right lung and right kidney recovered Nocardia species. Sequencing of four gene loci and phylogenetic analysis of concatenated (gyrB-16S-secA1-hsp65) sequences revealed that the isolate was N. nova. Conclusions: We report the first case of N. nova infection in yellow-bibbed lorry (Lorius chlorocercus). The present case is the first one of which the species identity of the isolate was determined by multilocus sequencing. Molecular diagnosis is important for identifying the Nocardia to species level and understanding the epidemiology of nocardiosis in birds.