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Mode of action:


Inhibition of protein synthesis. Streptogramins irreversibly  bind to the 50S ribosomal subunit.  Group A streptogramins prevent peptide bond formation during chain elongation step, while group B components cause the release of incomplete peptide chains from the 50S ribosomal subunit.






Streptomyes virginiae.


Spectrum of activity:

Narrow spectrum; mainly Gram positive bacteria


Effect on bacteria:


Group A or Group B – Bacteriostatic

Group A and Group B - Bacteriocidal


Examples of applications in Veterinary Medicine:

Used largely as a growth promotant for livestock, but has also been used to prevent laminitis in horses.



Virginiamycin has been developed largely as a growth promoter and is still used in many countries. It has been banned by European Union since 1999. 





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