Quinupristin and Dalfopristin belong to which antibiotic brand?

• A. Synercid
• B. Zosyn
• C. Primaxin
• D. Unasyn

Answer: (A)

Quinupristin and dalfopristin form a synergistic streptogramin combination that shuts down bacterial protein synthesis. When used together, they bind to the 50S ribosomal subunit in complementary ways, with dalfopristin disrupting initiation and increasing the binding of quinupristin, which then blocks elongation. This cooperative action makes the combo more potent than either drug alone, and it’s packaged under the brand name Synercid. The other brands listed correspond to different antibiotic classes (for example, Zosyn is piperacillin-tazobactam, Primaxin is imipenem-cilastatin, Unasyn is ampicillin-sulbactam), not streptogramins.