Actinomyces - Bacteriology

ACTINOMYCES

BACTERIOLOGY

Actinomyces are Gram-positive bacilli that grow slowly (4 – 10 days) under microaerophilicor strictly anaerobic conditions. The organisms typically appear as elongated Gram-positive rods that branch at acute angles and often show irregular staining. In pus the most character-istic form is the sulfur granule. This yellow – orange granule, named for its gross resem-blance to a grain of sulfur, is a small colony (usually < 0.3 mm) of intertwined branching Actinomyces filaments solidified with elements of tissue exudate.

Species of Actinomyces are distinguished on the basis of biochemical reactions, cul-tural features, and cell wall composition. Most human actinomycosis is caused by Actino-myces israelii, but other species have been isolated from typical actinomycotic lesions.Propionibacterium propionicum originally classified with the Actinomyces, can produceclinically similar disease. Other species of Actinomyces have been associated with dental and periodontal infections .