Beta-lactam pharmacology review Which one of the following antibiotics contains a beta-lactam ring as its defining pharmacophore?

Introduction / Context:
Beta-lactams are the most widely used antibacterial agents. Recognizing which drugs carry the beta-lactam ring is essential for understanding mechanism, resistance (for example, beta-lactamases), and allergy cross-reactivity.

Given Data / Assumptions:

• Beta-lactams inhibit cell wall synthesis by binding penicillin-binding proteins.
• The defining motif is a four-membered beta-lactam ring.
• Only one option should clearly be a beta-lactam in this set.

Concept / Approach:
Penicillins, cephalosporins, carbapenems, and monobactams are beta-lactams. Tetracycline (polyketide), erythromycin (macrolide), vancomycin (glycopeptide), and chloramphenicol (amphenicol) lack the beta-lactam ring and have distinct mechanisms.

Step-by-Step Solution:
Identify the class carrying a beta-lactam ring: penicillins.Exclude non–beta-lactam classes (tetracyclines, macrolides, glycopeptides, amphenicols).Select “Penicillin.”

Verification / Alternative check:
Structural diagrams and pharmacology references confirm penicillin’s four-membered beta-lactam fused to a thiazolidine ring.

Why Other Options Are Wrong:
They target protein synthesis (30S/50S) or cell wall via non–beta-lactam scaffolds (vancomycin), not via beta-lactam PBPs binding.

Common Pitfalls:
Assuming all cell wall–active drugs are beta-lactams. Vancomycin is cell wall–active but not a beta-lactam.

Final Answer:
Penicillin.