Cefalexin belongs to which antibiotic class?

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

Answer: (A)

Cefalexin is a cephalosporin, a class of beta-lactam antibiotics. Cephalosporins share the core beta-lactam structure and work by inhibiting bacterial cell wall synthesis through binding penicillin-binding proteins, leading to cell lysis. Cefalexin, as a first-generation cephalosporin, has good activity against gram-positive cocci and modest activity against some gram-negative bacteria, making it suitable for skin and soft tissue infections and similar indications. This distinguishes it from macrolides, which inhibit the 50S ribosomal subunit to stop protein synthesis, from penicillins as a related but distinct class, and from quinolones, which inhibit DNA gyrase/topoisomerase. Hence, cefalexin belongs to the cephalosporin class.