Streptogramins

What are Streptogramins?

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 site; jaundice (yellowing of the skin or eyes); seizures(convulsions); an irregular heart rate; sudden numbness or weakness; severe headache; slurred speech; or problems with balance.

Streptogramins are a group of cyclic peptide antibiotics that inhibit, like macrolides and lincosamides, the synthesis of bacterial proteins. They are derivatives of the naturally occurring pristinamycin. The later developed derivatives quinupristin and dalfopristin are used in a fixed combination.

There are two types of streptogramins: streptogramin A (dalfopristin) and streptogramin B (quinupristin). Individually, both A and B streptogramins inhibit bacterial growth (bacteriostatic).

The streptogramins consist of mixtures of two structurally distinct compounds, type A and type B, which are separately bacteriostatic, but bactericidal in appropriate ratios. These antibiotics act at the level of inhibition of translation through binding to the bacterial ribosome.