Which antibiotic is a bacteriostatic protein synthesis inhibitor that binds the 50S ribosomal subunit?

Which antibiotic is a bacteriostatic protein synthesis inhibitor that binds the 50S ribosomal subunit?

• A. Gentamicin
• B. Tetracycline
• C. Ciprofloxacin
• D. Erythromycin

Answer: (D)

Antibiotics that inhibit protein synthesis work by targeting bacterial ribosomes, and their effect can be bacteriostatic or bactericidal depending on the class. Macrolides, such as erythromycin, bind to the 50S ribosomal subunit and block the translocation step of protein elongation. This stops the growth of the peptide chain and typically yields a bacteriostatic effect at standard doses. In contrast, drugs like gentamicin bind the 30S subunit and cause misreading of mRNA, usually producing a bactericidal outcome. Tetracycline also targets the 30S subunit and is generally bacteriostatic by preventing tRNA attachment. Ciprofloxacin targets DNA gyrase, not the ribosome, and is bactericidal due to its effect on DNA replication. Therefore, the antibiotic that is a bacteriostatic protein synthesis inhibitor binding the 50S subunit is erythromycin.

Antibiotics that inhibit protein synthesis work by targeting bacterial ribosomes, and their effect can be bacteriostatic or bactericidal depending on the class. Macrolides, such as erythromycin, bind to the 50S ribosomal subunit and block the translocation step of protein elongation. This stops the growth of the peptide chain and typically yields a bacteriostatic effect at standard doses.

In contrast, drugs like gentamicin bind the 30S subunit and cause misreading of mRNA, usually producing a bactericidal outcome. Tetracycline also targets the 30S subunit and is generally bacteriostatic by preventing tRNA attachment. Ciprofloxacin targets DNA gyrase, not the ribosome, and is bactericidal due to its effect on DNA replication.

Therefore, the antibiotic that is a bacteriostatic protein synthesis inhibitor binding the 50S subunit is erythromycin.