Which is a macrolide antibiotic?

Which is a macrolide antibiotic?

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

Answer: (B)

Macrolide antibiotics are defined by their large macrocyclic lactone ring and their mechanism of action: they bind to the 50S subunit of bacterial ribosomes and block translocation, stopping protein synthesis. Erythromycin is a classic example of this class, and azithromycin is another member that shares the same mechanism and target. Clindamycin is a different class (a lincosamide) that also targets the 50S subunit but is structurally distinct from macrolides. Penicillin is a beta-lactam that inhibits cell wall synthesis, not protein synthesis, so it is not a macrolide. So, recognizing the macrolide class comes from identifying the large lactone-ring structure and the 50S ribosomal inhibition of translocation.

Macrolide antibiotics are defined by their large macrocyclic lactone ring and their mechanism of action: they bind to the 50S subunit of bacterial ribosomes and block translocation, stopping protein synthesis. Erythromycin is a classic example of this class, and azithromycin is another member that shares the same mechanism and target. Clindamycin is a different class (a lincosamide) that also targets the 50S subunit but is structurally distinct from macrolides. Penicillin is a beta-lactam that inhibits cell wall synthesis, not protein synthesis, so it is not a macrolide. So, recognizing the macrolide class comes from identifying the large lactone-ring structure and the 50S ribosomal inhibition of translocation.