Actinomyces spp and Propionibacterium propionicus (previously Arachnia propionica) are members of a large group of pleomorphic Gram-positive bacteria, many of which fhave some tendency toward mycelial growth. Both are members of the oral flora of humans or animals. Actinomyces species, in particular, are major components of dental plaque. A israelii, A gerencseriae (previously A israelii serotype II), and P propionicus cause actinomycosis in humans and animals. Other species of Actinomyces can be involved in mixed anaerobic and other infections, where they may not always play an obviously pathogenic role. In addition, some coryneform bacteria (diphtheroids) isolated from clinical samples, which had been placed into the Centers for Disease Control Coryneform groups 1, 2 and E, have been identified as new species of Actinomyces.
Copyright © 1996, The University of Texas Medical Branch at Galveston.