Actinomycosis is a chronic disease caused by the fungus Actinomyces bovis. It is characterized by the formation of abscesses, sinuses, granulation tissue and brawny, leathery infiltration of the surrounding tissues. A positive diagnosis is made by demonstrating the sulphur granule or by demonstrating the actinomycotic lesion in tissue, microscopically. The microscopic picture of a typical granule may be described as a central mass of branching mycelia, radiating peripherally, and ending, usually, in clubs.
I have been unable to substantiate or contradict the two current theories of the mode of infection: (1) that the organism is carried into the tissue by some foreign material like straw and (2) that the organism is already present in the mouth and that an injury, such as a straw is likely to cause, serves to provide a portal of entry. The source of the disease in this series was evident in only a few cases.
LOUIS P. GOOD. ACTINOMYCOSIS OF THE ABDOMEN. Arch Surg. 1931;22(2):307–313. doi:10.1001/archsurg.1931.01160020130007