Cefaclor is the chemical structure associated with which antibiotic class?

• A. Cephalosporin
• B. Quinolones
• C. Penicillin
• D. Macrolides

Answer: (A)

Recognizing antibiotic classes by their chemical structure is the key idea. Cefaclor’s structure is characteristic of cephalosporins, which are beta-lactam antibiotics with a beta-lactam ring fused to a six-membered dihydrothiazine ring. This core distinguishes cephalosporins from other beta-lactams like penicillins (which have a beta-lactam ring fused to a thiazolidine ring). Quinolones have a different bicyclic nucleus, and macrolides are built around a large macrocyclic lactone ring. So cefaclor is categorized as a cephalosporin, specifically a second-generation cephalosporin, reflecting its shared core structure and mechanism of inhibiting bacterial cell-wall synthesis.