The treatment of actinomycosis comprises a high dose of antibiotics (18-24 million units a day) of intravenous penicillin G over two to six weeks, followed by oral penicillin V at a dose of 2-4 g/day for six to 12 months.
- the risk of actinomyces developing penicillin resistance is low.
- actinomyces is also susceptible to β lactams (including benzylpenicillin, amoxicillin, ceftriaxone, meropenem, and piperacillin-tazobactam), doxycycline, clindamycin, erythromycin, and clarithromycin.
- for patients who are allergic to penicillin¸ doxycycline, minocycline, clindamycin, and erythromycin can be prescribed.
However the modern approach is more individualized and varies according to the site of infection, severity of disease, and the patient’s response to treatment. The initial phase of treatment should cover other bacteria found at the site of infection. Possible first-line regimens include:
- a β lactam and a β lactamase inhibitor such as clavulanate or tazobactam
- this regimen offers additional cover against potential β lactamase producers such as S aureus, Gram negative anaerobes, and Enterobacteriaceae (in abdominal actinomycosis)
- in abdominal actinomycosis –
- a combination of amoxicillin and clavulanic acid with metronidazole (or clindamycin) for strict anaerobes plus an aminoglycoside, such gentamicin, for resistant Enterobacteriaceae.
- piperacillin-tazobactam or a carbapenem (imipenem or meropenem) may be a suitable alternative
Traditionally treatment is recommended for six to 12 months, but may not be needed for all patients. Shorter courses of antibiotics have been reported to be effective in treatment of orocervicofacial, thoracic and pelvic actinomycosis.
Surgical options
- in patients with extensive necrotic tissue, sinus tracts, or fistulas, surgical resection may also be necessary
- may also be needed if malignancy cannot be excluded or if large abscesses or empyemas cannot be drained by percutaneous aspiration
- furthermore surgery may be a valid option for patients who do not respond to medical treatment
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