ABSTRACT
Actinomyces are Gram-positive filamentous bacteria which are part of the resident oral flora, colonizing especially the gingival crevices and the tonsils in the absence of clinical disease. Actinomyces may also colonize the vagina and gastrointestinal tract. Actinomycosis is a chronic disease caused by several species of Actinomyces, the most common of which are A. israelii, A. gerencseriae, A. naeslundi, A. viscosus, A. odontolyticus and A. meyeri. Actinomycosis develops when the microorganism is introduced into surrounding tissue and is characterized by the formation of suppurative abscesses that usually result in draining sinuses. Because of radial growth of the bacterium, colonies form in tissue, surrounded by a marked inflammatory response which gives rise to firm yellowish granules (‘sulfur granules’). These may be extruded with draining pus. While three major categories of infection (cervicofacial, thoracic, abdominal) are well recognized, actinomycosis may develop in any organ or body site, e.g. the eye (lacrimal canaliculitis) and the female pelvis in association with the presence of an intrauterine contraceptive device. Actinomycosis may occur in conjunction with other bacterial species such as Actinobacillus actinomycetemcomitans and Eikenella corrodens.
