Actinomyces

Actinomyces

Ass.prof. Dr. nebras Al- Dabagh
Morphology and Physiology:
Facultatively or strictly anaerobic Gram-positive bacilli
Bacteria with fungi-like structures:
Form delicate filaments (often called hyphae or mycelia as per the structures formed by the true fungi) and aerial filaments which may branch, fragment into spores, or become pigmented

Actinomyces actually means "ray fungus" in Greek

Actinomyces are true bacteria due to the lack of mitochondria and a nuclear membrane, reproduction by cell fission and susceptibility to penicillin but not to antifungal chemotherapeutic agents
Actinomyces are morphologically similar to Nocardia except that they Actinomyces are not acid-fast
Grow slowly in culture and cause infections that are slow to develop and tend to be chronic
Epidemiology and Clinical Syndromes:
Normal flora of the upper respiratory, gastronintestinal and femal genital tracts
Low virulence potential, only causing opportunistic disease following disruption of mucosal barriers by trauma, surgery or infection

Actinomycosis:
May occur as acute pyogenic infection or more commonly as a chronic infection that is both suppurative and granulomatous Characterized by multiple abscesses and interconnecting sinus tracts that contain granules of microcolonies imbedded in tissue elements
Microcolonies are macroscopic masses of filamentous bacterial cells that are "cemented" together by calcium phosphate

Known as sulfur granules due to their yellow or orange appearance
Chronic suppuration results in granuloma formation and a fibrotic "walling off" of the lesion .Ultimately resulting in bone involvement

Five major clinical forms of actinomycoses based on site of infection:
1. cervicofacial actinomycosis (most common form): associated with poor oral hygiene, an invasive dental procedure or oral trauma that is characterized by tissue swelling with fibrosis and draining sinus tracts along the jawline
2. thoracic actinomycosis: associated with aspiration into the lungs and dissemination of the organisms into surrounding tissues
3. abdominal actinomycosis: associated with abdominal surgery or intestinal trauma
4. pelvic actinomycosis: primary infection associated with intrauterine devices in women and secondary infection associated with spread from abdominal actinomycosis
5. cerebral actinomycosis: associated with secondary spread from another infected site and most commonly characterized by a single brain abscess

Treatment and Prevention:
Surgical debridement and long-term antibiotic therapy (susceptible to penicillin)
Maintain good oral hygiene
Prophylactic antibiotics prior to invasive oral or abdominal surgical procedures