Bilateral tonsillectomy is performed on an otherwise healthy 11-year-old female with recurrent upper respiratory tract infections. On pathologcal examination of the tonsils, numerous small, yellow granules are noted. A granule crushed between two slides have a dense, gram-positive center and numerous branching filaments at the periphery. The granules are most likely composed of which of the following organisms?
Actinomyces israelii Aspergillus fumigatus Blastomyces dermatitidis Candida albicans