Isolation of Aspergillus caninus (Synonym: Phialosimplex caninus) from a Canine Iliac Lymph node

Aspergillus caninus (synonym: Phialosimplex caninus) is an anamorphic fungus species associated with systemic infections in dogs that has been transferred from the genus Phialosimplex to Aspergillus. Here, we report the first case of canine A. caninus infection in Japan. A castrated Japanese Shiba Inu (6 years old; weight, 12.5 kg) was referred to the Yamaguchi University Animal Medical Center, Yamaguchi, Japan, in June 2017 showing vitality loss and depression. Computed tomography revealed iliac and splenic hilum lymphopathies, and histologic examination of an iliac lymph node by biopsy revealed granulomatous lesions with numerous oval to round yeast-like fungal cells. Aspergillus caninus was isolated from the biopsy samples, and in vitro susceptibility tests of the isolate to the antifungal drugs amphotericin B (AMB), fluconazole (FLZ), itraconazole (ITZ), voriconazole (VRZ), and micafungin (MCF) were performed by the E-test method. The isolate from this dog exhibited a minimal inhibitory concentration of < 0.002 µg/ml to AMB, > 256 µg/ml to FLZ, < 0.002 µg/ml to ITZ, < 0.002 µg/ml to VRZ, and < 0.002 µg/ml to MCF, indicating that the isolate was not susceptible to FLZ and susceptible to AMB, ITZ, VRZ, and MCF. Since the response of the patient dog to ITZ and VRZ treatments was poor, more aggressive management using combination therapies of ITZ with other antifungals may be necessary for treating canine A. caninus infection in dogs.