From the FDA Drug Label
Clindamycin has been shown to be active against most of the isolates of the following microorganisms, both in vitro and in clinical infections... Anaerobic bacteria... Actinomyces israelii At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for clindamycin against isolates of a similar genus or organism group... Anaerobic bacteria... Actinomyces israelii
The antibiotic treatment for Actinomyces israelii infection is clindamycin 1.
- Clindamycin is active against Actinomyces israelii in vitro.
- The efficacy of clindamycin in treating clinical infections due to Actinomyces israelii has not been established in adequate and well-controlled clinical trials, but it is indicated for the treatment of serious infections caused by susceptible anaerobic bacteria 1.
From the Research
The recommended antibiotic treatment for Actinomyces israelii infection is high-dose intravenous penicillin G for 2-6 weeks, followed by oral penicillin V or amoxicillin for 6-12 months. Specific regimen:
- Initial therapy: Penicillin G 18-24 million units IV daily, divided into 6 doses, for 2-6 weeks
- Followed by: Penicillin V 2-4 g orally daily, divided into 4 doses, or Amoxicillin 1.5-3 g orally daily, divided into 3 doses, for 6-12 months For penicillin-allergic patients, alternatives include:
- Doxycycline 100 mg orally twice daily
- Erythromycin 500 mg orally four times daily
- Clindamycin 300-450 mg orally four times daily The prolonged treatment duration is necessary due to the organism's slow growth and the presence of extensive tissue fibrosis, which can limit antibiotic penetration, as noted in a study from 2. Surgical debridement may be required in addition to antibiotic therapy for extensive or complicated infections, as seen in a case report from 3. Monitor patients for clinical improvement and potential side effects of long-term antibiotic use, and adjust the duration of therapy based on clinical response and the extent of the infection, as suggested by the findings of 2. It is also important to consider the potential for cast-forming Actinomyces israelii, as reported in a case of canaliculitis from 4, and the need for surgical exploration and removal of casts in some cases. Overall, the treatment approach should be individualized based on the severity and extent of the infection, as well as the patient's response to therapy, as discussed in the literature review from 5.