Clinical, morphological, and molecular characterization of Penicillium canis sp. nov., isolated from a dog with osteomyelitis

Infections caused by Penicillium species are rare in dogs, and the prognosis in these cases is poor. An unknown species of Penicillium was isolated from a bone lesion in a young dog with osteomyelitis of the right ilium. Extensive diagnostic evaluation did not reveal evidence of dissemination. Resolution of lameness and clinical stability of disease were achieved with intravenous phospholipid-complexed amphotericin B initially, followed by long-term combination therapy with terbinafine and ketoconazole. A detailed morphological and molecular characterization of the mold was undertaken. Sequence analysis of the internal transcribed spacer revealed the isolate to be closely related to Penicillium menonorum and Penicillium pimiteouiense. Additional sequence analysis of β-tubulin, calmodulin, minichromosome maintenance factor, DNA-dependent RNA polymerase, and prerRNA processing protein revealed the isolate to be a novel species; the name Penicillium canis sp. nov. is proposed. Morphologically, smooth, ovoid conidia, a greenish gray colony color, slow growth on all media, and a failure to form ascomata distinguish this species from closely related Penicillium species.