Which antibiotic is a commonly used example of a bacteriostatic agent?

• A. Penicillin
• B. Amoxicillin
• C. Ciprofloxacin
• D. Tetracycline

Answer: (D)

Bacteriostatic agents halt bacterial growth rather than killing bacteria outright. Tetracycline fits this pattern because it binds to the 30S ribosomal subunit and blocks the attachment of aminoacyl-tRNA, preventing protein synthesis. Without new proteins, bacteria can’t grow or divide, allowing the immune system to clear the infection rather than relying on rapid killing.

In contrast, penicillins and amoxicillin disrupt cell wall synthesis and are typically bactericidal, leading to bacterial death. Ciprofloxacin targets DNA replication by inhibiting DNA gyrase and topoisomerase IV, which also tends to be bactericidal. Therefore, tetracycline is the classic example of a bacteriostatic antibiotic.