Metabolic and serologic differentiation of Actinomyces bovis and anaerobic diphtheroids.

It is frequently a difficult task to differentiate Actinomyces bovis from "anaerobic diphtheroids" of questionable pathogenicity. Diphtheroids, isolated from normal and pathological tissues, resemble A. bovis morphologically and in some cultural characteristics. These similarities and lack of suitable criteria for their definitive identification have been responsible for the errors in separating "anaerobic diphtheroids" from A. bovis and vice versa. Taxonomists have been divided in their opinions regarding the classification of the genus Actinomyces. Erikson (1940) and Thompson (1950) believed the genus Actinomyces could be separated into 2 species depending upon their source, A. bovis (bovine) and Actinomyces israeli (human), by means of morphological andbiochemical criteria. Rosebury et al. (1944) felt there was insufficient evidence for this separation. Slack (1955, personal communication), using an agglutination-adsorption technique, found that separation of the genus Actinomyces into antigenic groups could not be associated with their host source. Erikson and Porteous (1955) expressed some doubt regarding their earlier conclusions when they discovered some smooth strains previously identified as A. bovis of bovine origin were actually "anaerobic diphtheroids." There is a limited amount of literature available on the classification of the "anaerobic diphtheroids," and many investigators note the present classification scheme is inadequate. Differences in opinion have been expressed regarding the pathogenicity of these microorganisms. Fleisher (1952), Prevot and Tardieux (1953), Seeliger (1953), and Linzenmeier (1954) believed these diphtheroids may be responsible for certain pathological conditions in man; however, Kassel and Rottino (1955) commented that most of these organisms could be eliminated if more careful techniques were used in collecting specimens and