Project description:BACKGROUND:Few cases of scedosporiosis have been reported in animals, but the true prevalence is probably underestimated due to a lack of awareness. Scedosporiosis in dogs has often been associated with localized infection (i.e., nasal infection, eumycetoma, or keratomycosis) or, in rare cases, disseminated infections. CASE PRESENTATION:This case report describes the clinical and pathological features and the diagnostic process of a rare systemic and fatal fungal infection in a dog caused by Scedosporium apiospermum. A 10-month-old female Maremmano-Abruzzese sheepdog showing weakness, lethargy, lateral decubitus, miosis and muscular rigidity was presented. Rodenticide poisoning was clinically suspected for the differential diagnosis. However, postmortem examinations revealed the presence of a swollen and soft subcutaneous nodule located near the right inguinal breast, which was associated with massive enlargement of the inguinal lymph nodes and small disseminated, cream-colored nodules in the kidneys and mesentery. Multiple fungal pyogranulomas were observed upon histological examination. Fungal isolation from the kidneys, breast and inguinal lymph nodes was performed. The internal transcribed spacer (ITS) sequences from the fungal colony DNA were searched in BLAST in the NCBI GenBank for species identification. The sequences of the fungi isolated from the kidney and breast cultures showed 100% sequence identity with sequences from Scedosporium apiospermum. CONCLUSIONS:This report shows that Scedosporium apiospermum may act as a primary pathogen in young and apparently healthy dogs and represents an important pathogen that should be considered during the diagnostic process, particularly when a fungal infection is suspected.
Project description:An extracellular proteinase produced by the filamentous fungus Scedosporium apiospermum has been purified and characterized. Initially, in vitro conditions for enzyme synthesis were investigated. The highest yield of enzyme production was obtained when the fungus was cultivated in modified Czapek-Dox liquid medium supplemented with 0.1% bacteriological peptone and 1% (w/v) glucose as the nitrogen and carbon sources respectively. Purification to homogeneity of the proteinase was accomplished by (NH4)2SO4 precipitation, followed by gel filtration through Sephadex G-75 and finally affinity chromatography through immobilized phenylalanine. Analysis of the purified enzyme by SDS/PAGE revealed a single polypeptide chain with an apparent molecular mass of 33 kDa. Further investigation of its physical and biochemical properties disclosed numerous similarities with those of the previously described serine proteinase of Aspergillus fumigatus. The enzyme was not glycosylated and its pI was 9.3. Proteinase activity was optimum between 37 and 50 degrees C and at pH 9.0, but remained high within a large range of pH values between 7 and 11. The inhibition profile and N-terminal amino acid sequencing confirmed that this enzyme belongs to the subtilisin family of serine proteinases. In agreement with this, the specific synthetic substrate N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide proved to be an excellent substrate for the proteinase with an estimated Km of 0.35 mM. Like the alkaline proteinase of A. fumigatus, this enzyme was able to degrade human fibrinogen, and thus may act as a mediator of the severe chronic bronchopulmonary inflammation from which cystic fibrosis patients suffer.