Figure 34-1
.Pathogenesis and disease sites of three major forms of actinomycosis
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(From Slack JM, Gerencser MA: Actinomyces, Filamentous Bacteria: Biology and Pathogenicity. p. 95. Burgess, Minneapolis, 1975, with permission.)
). These lesions discharge pus containing the organisms (Fig. 34-2). In long-standing cases, the organisms are found in firm, yellowish granules called sulfur granules (Fig 34-3). The disease is usually divided into three major clinical types, cervicofacial, thoracic, and abdominal, but primary infections may involve almost any organ. Secondary spread of the disease is by direct extension of an existing lesion without regard to anatomic barriers. Hematogenous secondary spread of the organisms, except from thoracic lesions, is not common.
Actinomycosis is almost always a mixed infection; a variety of other oral bacteria can be found in the lesion with Actinomyces or P propionicus. The role of these associated bacteria is not clear. It has been shown that succinic acid produced by Actinomyces can promote the growth of some Gram -ve anaerobes. Also, in experimental infections, Eikenella corrodens and Actinobacillus actinomycetemcomitans enhance the virulence of Actinomyces. The mycelial masses of Actinomyces reduce the rate of penetration of antibiotics and may physically protect the associated bacteria. In addition, associated organisms which produce ß-lactamases can complicate treatment. Therefore, the dense granules of Actinomyces and the presence of associated bacteria can enhance the virulence of the infection and influence the mode of use of antibiotics, thereby adding to the difficulty of treating the disease.
Cervicofacial infections involve the face, neck, jaw, or tongue and usually occur following an injury to the mouth or jaw or a dental manipulation such as extraction. The disease begins with pain and firm swelling along the jaw and slowly progresses until draining sinuses are produced.
Thoracic actinomycosis results from aspiration of pieces of infectious material from the teeth and may involve the chest wall, the lungs, or both. The symptoms are similar to those of other chronic pulmonary diseases, and the disease is often difficult to diagnose. Thoracic disease may spread extensively to adjacent tissues or organs and often disseminates through the bloodstream, resulting in abscesses in distant sites such as the brain.
Abdominal actinomycosis is often associated with abdominal surgery, accidental trauma, or acute perforative gastrointestinal disease. Persistent purulent drainage after surgery or abdominal masses resembling tumors may be the first sign of infection.
Actinomycosis may affect almost any organ. For example, Actinomyces and P propionicus cause a lacrimal canaliculitis with concretions in the canaliculi that are persistent. A naeslundi i and A odontolyticus can also infect the eyes. In recent years, Actinomyces and P propionicus have been isolated with increasing frequency from female pelvic infections associated with wearing an intrauterine contraceptive device. There has been considerable interest in the possible role of Actinomyces in human periodontal disease and root surface caries. Evidence suggests that these bacteria are not involved in the more destructive forms of periodontal disease. Actinomyces naeslundii and possibly other species may be involved in gingivitis and mild forms of periodontitis. They may also facilitate colonization of the gingivae through coaggregation with Gram -ve anaerobes. Actinomyces naeslundii has also been associated with root surface caries and can be the predominant organism in some lesions.
