Which of the following is NOT an example of a Macrolide?

• A. Erythromycin
• B. Clindamycin
• C. Clarithromycin
• D. Azithromycin

Answer: (B)

Macrolides are a class of antibiotics defined by a large macrocyclic lactone ring with attached sugar molecules, and they exert their effect by binding to the 50S ribosomal subunit to block translocation during protein synthesis. Common examples include erythromycin, clarithromycin, and azithromycin. Clindamycin, while it also targets the 50S subunit, belongs to a different chemical class called lincosamides, based on its distinct structure. Because the question is about chemical classification, clindamycin is not a macrolide despite some overlapping antibacterial effects. The other drugs listed are macrolides, so they fit the category.