Table 3b: Oxazolidinones.

Quinupristin/Dalfopristin 1999

• Combination of two semisynthetic pristinamycin derivatives.

• Dalfopristin A interferes with binding of aa-tRNA and inhibits peptide bond formation while Quinupristin B binds at the beginning of the polypeptide exit tunnel where it blocks short peptidyl tRNA chains entering the tunnel at the beginning of polypeptide translation. Both act synergistically to alter rRNA conformation allowing tight binding and inhibiting cell growth.

• Exerts potent in vitro activity against gram positives. Demonstrates activity against VISA and VRSA

• Either Streptogramin A or streptogramin B molecules can be affected by horizontally transferred resistance determinants but not both.

• Approved for serious infections caused by resistance Gram-positives