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''Actinomyces naeslundii'' is a Gram-positive, rod-shaped bacterium that occupies the oral cavity. The species has been implicated in periodontal disease, secondary enamel caries and primary root caries. These bacteria are also associated with good oral health. They are some of the first bacteria to occupy the oral cavity and colonize the tooth's surface. It has also been isolated from women with bacterial vaginosis. == Background == Gram-positive, pleomorphic nonspore-forming, nonacid-fast anaerobic or microaerophilic bacilli of the genus ''Actinomyces'' and the order Actinomycetales cause actinomycosis. Actinomycosis is a chronic bacterial disease, characterized by localized swelling with suppuration, abscess formation, tissue fibrosis, and draining sinuses.〔(eMedicine - Actinomycosis : Article Excerpt by Jorge M Quinonez )〕 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. ''A. israelii'', ''A. naeslundii'', ''A. odontolyticus'', (''A. viscosus'' ), and ''A. meyeri'' are the most frequent microorganisms associated with 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. ''Actinomyces'' species are very closely related to ''Nocardia'' species, and at one time, both were considered to be fungal organisms. ''Propionibacterium propionicus'' and related species of bacteria also can cause actinomycosis-like disease. ''Aggregatibacter actinomycetemcomitans'', ''Eikenella corrodens'', species of ''Fusobacterium'', ''Bacteroides'', ''Capnocytophaga'', ''Staphylococcus'', ''Streptococcus'', and ''Enterococcus'' are other bacteria concomitantly isolated with ''Actinomyces'' in clinical specimens of infected human tissues. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Actinomyces naeslundii」の詳細全文を読む スポンサード リンク
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