Which statement about macrolides is true?

Which statement about macrolides is true?

• A. Macrolides are always bactericidal.
• B. Macrolides are generally bacteriostatic but can be bactericidal at high concentrations.
• C. Macrolides inhibit DNA replication.
• D. Macrolides disrupt cell walls.

Answer: (B)

Macrolides block protein synthesis by binding to the 50S ribosomal subunit and preventing translocation. Because this stops bacteria from making new proteins rather than directly causing rapid cell death, they are usually bacteriostatic. However, at high concentrations or against certain organisms, they can be bactericidal. They do not inhibit DNA replication, nor do they disrupt cell walls—effects seen with other antibiotic classes. This combination—predominantly static activity with potential bactericidal action in specific situations—is what makes the true statement that macrolides are generally bacteriostatic but can be bactericidal at high concentrations.

Macrolides block protein synthesis by binding to the 50S ribosomal subunit and preventing translocation. Because this stops bacteria from making new proteins rather than directly causing rapid cell death, they are usually bacteriostatic. However, at high concentrations or against certain organisms, they can be bactericidal. They do not inhibit DNA replication, nor do they disrupt cell walls—effects seen with other antibiotic classes. This combination—predominantly static activity with potential bactericidal action in specific situations—is what makes the true statement that macrolides are generally bacteriostatic but can be bactericidal at high concentrations.