Isolation and Identification Methods for <i>Actinomyces israelii</i> Involved in Actinomycosis

Abstract

Purpose: Actinomyces israelii is known as the key species to cause classical actinomycosis. Although A. israelii is frequently isolated from human oral cavities, the distribution of this microorganism has been little reported. The purpose of the present study was to develop selective media (AISM) for the isolation of A. israelii and to assess the prevalence of this organism in the oral cavity. Methods: To examine the bacterial population in the oral cavity, a novel selective medium (AISM) was developed for isolating A. israelii. AISM consists of BHI, yeast extract, agar, ofloxacin, fosfomycin, colistin, and sodium fluoride. Results: A. israelii strains grew well on AISM. A. israelii was detected in all dental plaque samples collected from 20 subjects and the mean number of this organism in the samples was 7.9 × 104 CFU/ml. Conclusion: These results indicated that the selective medium was useful for the isolation of A. israelii and this organism was a part of the normal flora in the human oral cavity.