Arachnia propionica (Actinomyces propionicus) as an unusual agent in tympanomastoiditis.

The actinomycetes are extremely uncommon causative agents in chronic tympanomastoiditis. Few cases have been reported in the literature, and, before the use of penicillin, the majority of patients died of intracranial extension of their disease. Two patients described in the recent literature could have had their conditions diagnosed preoperatively as cholesterol granuloma. They had intact but immobile or bulging tympanic membranes and histories of intermittent perforations with drainage. The diagnosis was suggested during surgery because of the presence of yellow-green amorphous "sulfur granules" scattered throughout the mastoid. Both patients were well following mastoidectomy and long-term penicillin therapy. The clinical history of a patient with tympanomastoiditis due to Arachnia propionica (Actinomyces propionicus) is discussed. To our knowledge, this is the first case reported of a patient with otic disease due to this strain of the organism.