Actinomycosis is a chronic suppurative disease caused by anaerobic filamentous bacteria in the order Actinomycetales.
The disease occurs worldwide and is mostly seen in tropical regions such as Asia, Africa, central & south America.
Males are more frequently affected.
The principal agent of actinomycosis in humans is Actinomyces israelii - a gram-positive, branching, anaerobic or microaerophilic bacterium.
This organism occur as commensals in the mouth and "sulphur" granules are commonly found in the tonsillar crypts of healthy persons.
The actinomycetes are ordinarily of low pathogenicity.
Underlying disease and interruption of mucocutaneous barriers predispose a person to actinomycosis by providing a medium in which these endogenous organisms can invade, proliferate and disseminate.
Unlike nocardiosis, actinomycosis does not occur preferentially in patients with defective immunity.
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Patients present with painless swelling of foot and is usually not associated with fever.
The organism produce chronic destructive lesions of deep soft tissue and bones, most commonly of the limbs.
Infection commonly occurs in the foot of bare-footed persons.
Primary skin infections may develop after human bites.
Based on the anatomic site of lesions four clinical forms of actinomycosis are recognized:
(i) Cervicofacial
-
Most commonly involved is the cervicofacial area, where the disease is
often a sequel to dental caries, periodontal disease, or injury to the
oral mucosa, such as tooth extraction.
The localized lesion enlarges, abscesses form, and draining sinus tracts
which ruptures with formation of
sinuses through which "sulfur grains" are discharged.
If untreated, the infection may extend into the mandible, paranasal sinuses, orbit, cranial bones, and thorax, where it may then disseminate to the central nervous system, skin, and other bones.
(ii) Thoracic
-
Infection occurs due to aspiration of infective material.
(iii) Abdominal - Abdominal actinomycosis is frequently mistaken clinically for advanced malignancy. It may result from direct extension of a thoracic infection but is more commonly seen as a consequence of a ruptured appendix or bowel perforation by swallowed foreign bodies, such as toothpicks or needles.