Experience with a novel selective medium for isolation of Actinomyces spp. from medical and dental specimens.

A selective medium containing mupirocin and metronidazole was evaluated for the isolation of Actinomyces spp. from clinical material. The study was a one-year prospective comparison of the method with existing methods, which use nonselective media, at a general hospital and a dental hospital. Significantly more Actinomyces spp. were isolated on the selective medium than on nonselective media from both dental specimens and intrauterine contraceptive devices. However, differentiating between Actinomyces spp. and related nonsporulating gram-positive rods remains a slow and sometimes uncertain process which can introduce lengthy delays in reporting.