CHARACTERIZATION OF SOME ACTINOMYCES-LIKE ISOLATES FROM HUMAN CLINICAL SPECIMENS - RECLASSIFICATION OF ACTINOMYCES-SUIS (SOLTYS-AND-SPRATLING) AS ACTINOBACULUM-SUIS COMB-NOV AND DESCRIPTION OF ACTINOBACULUM-SCHAALII SP-NOV

Five strains of a hitherto unknown Actinomyces-like bacterium were iso lated from human clinical sources, including blood cultures. Biochemic al and chemotaxonomic characterization indicated that the strains were distinct from previously described Actinomyces and Arcanobacterium sp ecies. A comparative 16S rRNA gene sequence analysis demonstrated that the undescribed strains constitute a new subline within the Actinomyc es-Arcanobacterium species complex. The closest known relative of the isolates was found to be Actinomyces suis, although a 16S rRNA sequenc e divergence value of approximately 6% clearly demonstrated that the u nknown bacterium represents a distinct species. Based on the results o f the present and earlier phylogenetic investigations, it is proposed that Actinomyces suis should be reclassified in a new genus, the genus Actinobaculum, as Actinobaculum suis comb. nov. In addition, a new sp ecies, Actinobaculum schaalii, is proposed for the Actinomyces-like ba cterium from human sources. The type strain of Actinobaculum schaalii is CCUG 27420.