Pristinamycin is an antibiotic used primarily in the treatment of staphylococcal infections, and to a lesser extent streptococcal infections. It is a streptogramin group antibiotic, similar to virginiamycin, derived from the bacterium Streptomyces pristina spiralis. Pristinamycin is a mixture of two components that have a synergistic antibacterial action. Pristinamycin IA is a macrolide, and results in pristinamycin having a similar spectrum of action to erythromycin. Pristinamycin IIA (streptogramin A) is a depsipeptide.