Keflex represents which generation of cephalosporin?

• A. First generation
• B. Second generation
• C. Third generation
• D. Fourth generation

Answer: (A)

Understanding cephalosporin generations helps you place Keflex in the spectrum. Keflex, or cephalexin, is a first-generation cephalosporin. First-generation cephalosporins are known for strong activity against gram-positive cocci, especially Staphylococcus aureus and Streptococcus species, with only modest activity against gram-negative bacteria. They’re well suited for skin and soft tissue infections and some uncomplicated urinary tract infections, and they’re typically given orally. This profile—excellent gram-positive coverage with limited gram-negative activity and oral use—is characteristic of the first generation, which is why Keflex is categorized there. Later generations broaden gram-negative coverage and, in many cases, reduce gram-positive potency, or introduce activity against different organisms, which is why cephalosporins from those generations aren’t aligned with Keflex’s typical use.