Actinomycosis is an indolent, slowly progressive infection caused by anaerobic or microaerophilic bacteria primarily of the genus Actinomyces (e.g., A. israelii). This diagnosis should be considered when a chronic progressive process with masslike features crosses tissue boundaries, a sinus tract develops, and/or the pt has evidence of a refractory or relapsing infection despite short courses of antibiotics. Most infections are polymicrobial, but the role of other species in the pathogenesis of the disease is unclear.

Actinomycosis is associated with poor dental hygiene, use of intrauterine contraceptive devices (IUCDs), and immunosuppression. Its incidence is decreasing, probably as result of better dental hygiene and earlier initiation of antibiotic treatment.

The agents of actinomycosis are members of the normal oral flora and are commonly cultured from the GI and female genital tracts. Disease occurs only after disruption of the mucosal barrier. Local infection spreads contiguously in a slow, progressive manner, ignoring tissue planes. In vivo growth produces clumps called grains or sulfur granules. Central necrosis of lesions with neutrophils and sulfur granules is virtually diagnostic of the disease. The fibrotic walls of the mass are often described as “wooden.”

• Oral-cervicofacial disease: Infection starts as a soft tissue swelling, abscess, or mass, often at the angle of the jaw with contiguous extension to the brain, cervical spine, or thorax. Pain, fever, and leukocytosis are variable.
• Thoracic disease: The pulmonary parenchyma and/or pleural space is usually involved. Chest pain, fever, and weight loss occur. CXR shows a mass lesion or pneumonia. Cavitary disease or hilar adenopathy may occur, and >50% of pts have pleural thickening, effusion, or empyema. Lesions cross fissures or pleura and may involve the mediastinum, contiguous bone, or the chest wall.
• Abdominal disease: The diagnosis is challenging and may not be made until months after the initial event (e.g., diverticulitis, bowel surgery). The disease usually presents as an abscess, mass, or lesion fixed to underlying tissue and is often mistaken for cancer. Sinus tracts to the abdominal wall, perianal region, or other organs may develop and mimic inflammatory bowel disease. Involvement of the urogenital tract can present as pyelonephritis or perinephric abscess.
• Pelvic disease: Pelvic actinomycosis is often associated with IUCDs. The presentation is indolent and may follow removal of the device. Pts have fever, weight loss, abdominal pain, and abnormal vaginal bleeding. Endometritis progresses to pelvic masses or tuboovarian abscess. When there are no symptoms and actinomycosis-causing organisms are isolated, it is not clear whether an IUCD should be removed, but the pt should be carefully observed over time.
• Miscellaneous sites: Actinomycosis can involve musculoskeletal, soft tissue, CNS, and other sites. Hematogenous dissemination is rare and usually involves lungs and liver.

Aspirations, biopsies, or surgical excision may be required to obtain material for diagnosis. Microscopic identification of sulfur granules in pus or tissues makes the diagnosis. Sulfur granules can occasionally be grossly identified from draining sinus tracts or pus. Cultures require 5-7 days but may take 2-4 weeks to become positive and are often rendered useless by prior antibiotic treatment.

Like nocardiosis, actinomycosis requires prolonged treatment. For serious infection, IV therapy for 2-6 weeks (usually with penicillin) followed by oral therapy for 6-12 months (e.g., with penicillin or ampicillin) is suggested. If treatment is extended beyond the point of resolution of measurable disease (as quantified by CT or MRI), relapse is minimized.

penicillin G 18-24mil units IV/d x 2-6 wks, then amoxicillin 500-750mg PO three times a day/four times a day x 6-12 mos; oral therapy alone may be adequate.
penicillin G potassium 10-20 million units/day IV divided q4-6hr x 6 weeks, (근화 페니실린주 5백만x4) may follow with penicillin V

doxycycline 100mg twice daily IV x 2-6 wks, then 100mg PO twice daily x 6-12mos; erythromycin 500mg PO four times a day x 6-12 mos.
Clindamycin 600mg IV q 8h x 2-6 wks, then 300mg PO four times a day x 6-12 mos.

clarithromycin, azithromycin, imipenem, cefotaxime/ceftriaxone.
Not active: metronidazole, TMP-SMX, ceftazidime, aminoglycosides, oxacillin, fluoroquinolones.

Surgery usually reserved for suspected neoplasm, to establish diagnosis, lesion in vital area (epidural, CNS, etc) or unresponsiveness to abx.
Surgical procedures: debulking, excision of fistula tracts, abscess drainage.

• 출처: http://emedicine.medscape.com/article/211587-medication#2