AN UNUSUAL ASPERGILLUS SP SECTION TERREI ISOLATE IN A CASE OF SYSTEMIC ASPERGILLOSIS IN DOG

INTRODUCTION: Canine aspergillosis in its systemic form represents a serious disease often resulting in a fatal outcome. Aspergillus terreus has been reported as the most frequent agent, with the German Shepherd being the most commonly affected breed. Occasionally, A. versicolor, A. alabamensis, and A. deflectus are reported in some cases. we report a case of discospondylitis in an 8-year-old female German Shepherd with severe neck pain, lameness of the forelimb, and progressive pelvic limb proprioceptive ataxia and paresis. MATERIALS AND METHODS: The dog was referred to the University veterinary Hospital of Alma Mater Studiorum - University of bologna. The MRI revealed severe and diffuse changes in signal intensity of the intervertebral discs and multiple lytic lesions, confirming the suspicion of discospondylitis and C6-C7 epidural empyema. Urinary sediment was obtained for both microscopic examinations using MGG staining and culture on Sabouraud medium with Chloramphenicol (SAb-CAF) at 26°C for several weeks. The colonies were observed both macroscopically and microscopically and processed for DNA extraction. Sequencing of ITS rDNA and benA genes was performed for molecular identification. RESULTS AND CONCLUSIONS: Microscopic examination of the urinary sediment stained with MGG revealed the presence of short hyphae with chlamydospores. Cultures exhibited slow growth and an atypical rugose appearance, with hyphae bearing numerous terminals and intercalary chlamydospores, but no conidial structures were observed. Sequencing of the ITS region identified the genus as Aspergillus, while benA sequences showed 100% similarity with Aspergillus floccosus (section Terrei). Subsequent passages on SAb CAF led to a morphological mutation in the peripheral sector, resulting in flat colonies with a dusty cinnamon brown surface. Microscopic examination revealed septate hyphae bearing solitary conidia or short conidiophores, with biseriate phialides on the upper half of vesicles and chains of round conidia, typical features of A. terreus. This transformation persisted in subsequent subcultures. Antifungal therapy with Itraconazole was started. After 16 months the dog presented with non-ambulatory paraparesis due to suspension of therapy, and euthanasia was performed due to a rapid worsening of clinical signs. This case highlighted that urine specimens can be highly indicative and minimally invasive. Additionally, the identification of A. floccosus, not previously described in systemic mycoses of dogs, confirms that Aspergillus spp. involved in canine systemic aspergillosis often belong to the section Terrei. Furthermore, the atypical morphology of the fungus made identification challenging. Previous studies have described the presence of morphological mutations in A. terreus as an adaptation of the fungus to changed environmental conditions, which significantly differ from laboratory growth conditions in terms of nutrient availability and physiological factors (Jukic et al., 2017. Antimicrob Agents Chemother, 61:12).