How long do you typically treat mixed infections involving Actinomyces such as empyema or abdominal abscesses when adequate source control has been achieved?  

In cases like this, shorter course of treatment can be given. In a case where there is no concern for residual mass, invasive disease or fistulous disease, treatment can be anywhere from 2 to 6 weeks. I would generally recommend at least 3 weeks for an empyema with Actinomyces as the cause provided ...

When adequate source control has been achieved (e.g, complete drainage or removal of infected tissue), mixed infections involving Actinomyces—such as empyema or abdominal abscesses—can usually be treated for a shorter duration than classic actinomycosis. 3-6 weeks of therapy for empyema ...