Actinomyces israelii
المؤلف:
Cornelissen, C. N., Harvey, R. A., & Fisher, B. D
المصدر:
Lippincott Illustrated Reviews Microbiology
الجزء والصفحة:
3rd edition , p193-194
2025-07-30
484
Actinomyces israelii is part of the normal oral and intestinal flora in humans. The organism is a strict anaerobe.
1. Clinical significance: Actinomycosis is an infection in which a chronic suppurative abscess leads to scarring and disfigurement. The infection is probably initiated by accidental introduction of organisms into the underlying soft tissue during conditions of sufficient anaerobiasis to support their growth. About half of the cases have a cervicofacial location and are associated with poor dental hygiene and/or tooth extraction (“lumpy jaw”). Other cases involve the lung and chest wall, cecum, appendix, abdominal wall, and pelvic organs. The lesion (mycetoma) begins as a hard, red, relatively nontender swelling that develops slowly, becomes filled with liquid, and ruptures to the surface, discharging quantities of pus. It also spreads laterally, draining pus through several sinus tracts.
2. Laboratory identification: The most typical and diagnostic finding in actinomycosis is the presence of “sulfur granules” in the draining pus. These are small, firm, usually yellowish particles, which, in fact, do not contain sulfur. When examined under the micro scope, sulfur granules appear as microcolonies composed of filaments of the organism embedded in an amorphous, eosinophilic material thought to be antigen–antibody complexes. The organism can be grown anaerobically on enriched media, such as thioglycollate broth or blood agar. Growth is slow, often requiring 10 to 14 days for visible colonies.
. Treatment: Penicillin G is the treatment of choice for actinomycosis, although a number of antibiotics (clindamycin, erythromycin, and tetracycline) have been shown to have clinical effect.
Treatment must be maintained for weeks to months and may be accompanied by surgical debridement and/or drainage. No significant resistance to penicillin G has been reported. [Note: Good oral hygiene is an important preventive measure.]
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