Pristinamycin is a streptogramin group antibiotic used primarily for the treatment of staphylococcal infections, and to a lesser extent streptococcal infections. It is marketed in Europe by Sanofi-Aventis under the trade name "Pyostacine". 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 is a depsipeptide.

PSM01: Pristinamycin IA [CAS # 3131-03-1] (also known as Mikamycin IA; Ostreogrycin B; Streptogramin B; Vernamycin Ba)

PSM02: Quinupristin [CAS # 120138-50-3]

PSM03: Pristinamycin IIA [CAS # 21411-53-0] (also known as Mikamycin A; Ostreogrycin A; Staphylomycin M1; Streptogramin A; Vernamycin A; Virginiamycin M1)

PSM04: Dalfopristin [CAS # 112362-50-2]

Synercid® (quinupristin and dalfopristin powder for injection) I.V., a streptogramin antibacterial agent for intravenous administration, is a sterile lyophilized formulation of two semisynthetic pristinamycin derivatives, quinupristin (derived from pristinamycin I) and dalfopristin (derived from pristinamycin IIA) in the ratio of 30:70 (w/w).