Unless you've inoculated the specimen and cultured from blood, chances that it may came from technical errors such as improper disinfection of site, or a heavily concentrated specimen. You may want to collect and centrifuge, and suspend it in a broth/agar, depending on your lab protocols. Otherwise, you may utilize selective medium that contain antibiotics for culturing other fungal spp. of your choice, thus inhibiting saprophytic contaminants and less chances of isolating normal fungal flora.