A macrolide antibiotic produced by Streptomyces ambofaciens. The drug is effective against gram-positive aerobic pathogens, N. gonorrhoeae, and staphylococci. It is used to treat infections caused by bacteria and Toxoplasma gondii.

A macrolide originally discovered as product of Streptomyces ambofaciens, with antibacterial and antiparasitic activities. Although the specific mechanism of action has not been characterized, spiramycin likely inhibits protein synthesis by binding to the 50S subunit of the bacterial ribosome. This agent also prevents placental transmission of toxoplasmosis presumably through a different mechanism, which has not yet been characterized.