Actinomyces naeslundii

Species of bacterium

Actinomyces naeslundii under a microscope

Actinomyces naeslundii is a species of Gram-positive bacteria within the genus Actinomyces. It is a facultatively anaerobic organism that is part of the normal microbiota of the human oral cavity and gastrointestinal tract.

Characteristics

Actinomyces naeslundii is characterized by its filamentous, branching morphology, which is typical of the genus Actinomyces. These bacteria are non-motile and do not form spores. They are known for their ability to form biofilms, particularly in the oral cavity, where they contribute to the formation of dental plaque.

Habitat

A. naeslundii is commonly found in the human mouth, particularly in the gingival crevices and on the surfaces of teeth. It is also present in the gastrointestinal tract and can be isolated from the vagina and respiratory tract.

Role in Disease

While A. naeslundii is generally considered a commensal organism, it can be an opportunistic pathogen. It is associated with periodontal disease and can contribute to the development of actinomycosis, a chronic infection characterized by the formation of abscesses and sinus tracts. Actinomycosis can affect various parts of the body, including the oral cavity, lungs, and gastrointestinal tract.

Clinical Significance

In the context of dental health, A. naeslundii plays a role in the early stages of dental plaque formation. It adheres to the tooth surface and provides a substrate for other bacteria to colonize, leading to the development of complex biofilms. These biofilms can contribute to dental caries and gingivitis.

Laboratory Identification

A. naeslundii can be identified in the laboratory by its characteristic morphology and growth patterns. It is a Gram-positive rod that forms branching filaments. It can be cultured on media such as blood agar, where it forms small, white colonies. Biochemical tests and molecular methods, such as 16S rRNA sequencing, can be used for definitive identification.

Prevention and Treatment

Good oral hygiene practices, including regular brushing and flossing, can help prevent the overgrowth of A. naeslundii and the formation of dental plaque. In cases of actinomycosis, treatment typically involves prolonged courses of antibiotics, such as penicillin.

Related pages

• Actinomyces
• Actinomycosis
• Dental plaque
• Periodontal disease