Antibiotics Groups - Streptogramins

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Antibiotic groups
Virginamycin

1. Antibiotics Groups Streptogramins

2. Streptogramins Group The streptogramins include: Virginiamycin It is produced by a mutant strain of Streptomyces virginiae . It is a natural mixture of factor M and factor S Its antibacterial activity is synergistically optimum when the M:S ratio is approximately 4 : 1 Pristinamycin It is a combination of quinupristin ( streptogramin B) and dalfopristin ( streptogramin A) in a 30:70 ratio.

3. Mechanism of Action - Spectrum Gram positive The antibacterial activity of the streptogramins is attributed to the inhibition of protein synthesis. Virginiamycin bind to 50S ribosomal subunits and inhibiting the formation of peptide bonds during protein synthesis. Pristinamycin bind to the 50 S ribosomal subunit at different sites located in close proximity, thereby interfering with the formation of polypeptide chains .

4. Resistance Pristinamycin the mechanisms of resistance to class A streptogramins and class B streptogramins are different. Class A streptogramins, active efflux of drug from the bacterial cell as well as drug inactivation by acetyltransferases contribute to resistance. Class B streptogramins, the most common, due to methylation of the target 23 S ribosomal RNA, while a less common mechanism involves enzymatic cleavage of a structural ring in the drug.

5. Indications Virginiamycin To improve daily live weight gain and feed conversion efficiency in feedlot and grazing cattle, broilers, turkeys, and pigs in several countries. Banned in the EU in 1999 and in Australia in 2005. In feedlot cattle, it also reduces the incidence and severity of liver abscessation. To reduces the risk of fermentative lactic acidosis in cattle and sheep fed high-concentrate diets. To reduce the risk of laminitis in horses on high grain diets.