Streptogramins are a type of antibiotic that inhibit protein synthesis in bacteria by binding to the 50S ribosomal sub-unit, in a similar way to macrolides and lincosamides.
They are produced naturally by certain subspecies of Streptomyces bacteria. Streptogramins include two structurally unrelated components, streptogramin group A (dalfopristin) and streptogramin group B (quinupristin). A mixture of group A and group B causes a 10 to 100-fold greater bacterial growth inhibition than the individual components given alone, and the combination is considered bactericidal. Streptogramins are mostly only effective against gram-positive bacteria.
Quinupristin and dalfopristin are marketed in a fixed 30:70 ratio as Synercid which is administered by injection. Side effects may include severe stomach pain, diarrhea that is watery or bloody; pain, bruising, swelling, or severe irritation around the IV needle; jaundice (yellowing of the skin or eyes); a seizure (convulsions); irregular...