Background
Actinomycosis is a chronic bacterial disease. Localized swelling with suppuration, abscess formation, tissue fibrosis, and draining sinuses characterize this disease. Gram-positive, pleomorphic nonspore-forming, nonacid-fast anaerobic or microaerophilic bacilli of the genus Actinomyces and the order Actinomycetales cause actinomycosis. Actinomyces species are very closely related to Nocardia species, and at one time, both were considered to be fungal organisms.
Infections of the oral and cervicofacial regions are the most commonly recognized infections; however, the thoracic region, abdominopelvic region, and the central nervous system also frequently can be involved. Actinomyces israelii, A. naeslundii, A. odontolyticus, A. viscosus, and A. meyeri most frequently cause human actinomycosis. A. gerencseriae also may cause disease in humans. Three coryneform bacteria now have been added to the Actinomyces genus and are thought to be potential causes for disease: A. neuii, A. radingae, and A. turicensis. A. radicidentis, a recently described species, has been isolated with polymerase chain reaction from patients with endodontic infections. Actinomyces species grow well in enriched media with brain-heart infusion and may be aided in growth by an atmosphere of 6-10% ambient carbon dioxide. They grow best at 37°C. Colonies can appear at three to seven days, but, to ensure that no growth is missed, cultures should be observed for up to 21 days.
Propionibacterium propionicus and related species of bacteria also can cause actinomycosis-like disease. Other bacteria frequently isolated from clinical specimens concomitantly with Actinomyces in human infection include Aggregatibacter actinomycetemcomitans and Eikenella corrodens, and species of Fusobacterium, Bacteroides, Capnocytophaga, Staphylococcus, Streptococcus, and Enterococcus.
Read more about this topic: Actinomyces Naeslundii
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