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Leptotrichosis. Lumpy jaw (also found in cattle). Streptotrichosis. Ray fungus. Ger: Aktinomycose (Strahlen Pffzkrankheit durch Actinomyces). Fr: Actinobacillose. Sp: Actinomicose. Actinomicosis


Actinomycosis is an infection with one of the Actinomyces species, most commonly Actinomyces israelii, causing a chronic pyogranulomatous reaction characterized by multiple nodular swellings, tissue destruction, and multiple discharging sinuses. These sinuses discharge puscontaining organisms, either as invisible filaments or in colony forms, the so-called grains or white or yellow "sulfur granules."

Geographic Distribution

The distribution of actinomycosis is worldwide.

Epidemiology and Pathology

These pathogenic, grain-forming, filamentous bacilli are anaerobic and are normal human flora. They frequently colonize the surface and spaces around teeth and the tonsillar crypts. They are possible involved in the formation of dental plaques. They are seldom found elsewhere unless there is an active infection, and then almost always on previously injured tissue. The characteristic grains or sulfur granules are a matrix of bacterial filaments and cellular debris. The filaments branch, are gram positive, are usually aligned at right angles, and have intermediary gram-negative segments. They may be associated with other anaerobic bacteria: it has been suggested that these associated bacteria are necessary to initiate an infection. At the edge of the grains, the hyphae are aligned radially and are sometimes coated with Splendore Hoeppli material, which contains immune complexes, fibrin, and cellular debris. It is important that these actinomyces are differentiated from the aerobic Nocardia because treatment differs.

Actinomycosis was first recognized in 1877 in cattle (A. bovis), and recognition in humans (A. israelii) followed 3 years later; the organism for each is different. There is no racial or sexual predisposition; but actinomycosis is uncommon in children under the age of 10 years.
Actinomycosis is almost always a chronic, fibrosing suppurating infection. There are commonly multiple abscesses of different sizes, with sinus tracts which may interconnect with other abscesses or lead to the skin (Fig. 6.2). The abscesses are limited in size by fibrous tissue. In most patients the sulfur grains (Fig. 6.3) are numerous and easily recognized, but in a few patients a careful search is necessary. Actinomycosis spreads by contiguous expansion and does not respect tissue planes (Fig. 6.4). The fibrosis and infection may produce tumor-like masses, which clinically have been mistaken for malignancy (e. g., within the chest or a frozen pelvis). The destructive process can be severe and disfiguring.



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