Eleven cases of actinomycosis have been observed and the exudate studied by direct smear and by staining.
Organized granules occurred in exudate from nine of the cases, “clubs” being present in three of the nine.
Exudate from two of the cases showed branching filaments only without organization into granules.
Cultures were obtained from seven cases, four being isolated under a microaerophilic environment, the others in aerobic culture.
Five of these have been compared with A. asteroides, A. hominis and A. bovis from the American Type Culture Collection. One, A is undoubtedly A. asteroides, two D and E are probably A. hominis and the remaining two B and C are described but not assigned to a definite species since they each show certain characteristics either of A. asteroides, A. hominis or of A. bovis.
The importance of an early recognition of human actinomycosis is mentioned and the difficulties of laboratory diagnosis and of classification of the recovered organisms discussed.