Keflex (cephalexin) works by targeting the bacterial cell wall, which is the protective outer layer that gives bacteria their shape and structural integrity. As a first-generation cephalosporin, Keflex belongs to the beta-lactam family of antibiotics, which means it has a special chemical structure that allows it to interfere with bacterial cell wall construction. Think of bacterial cell walls like the framework of a house - they're essential for keeping the bacteria intact and functioning properly. Keflex works by binding to specific proteins called penicillin-binding proteins (PBPs) that bacteria use like construction workers to build and maintain their cell walls. When Keflex attaches to these proteins, it's like removing the construction crew from a building site, making it impossible for bacteria to repair or build proper cell walls. Without functional cell walls, bacteria become weak and eventually burst due to the pressure from their internal contents, much like a balloon that loses its structural integrity. What makes Keflex particularly effective is its strong activity against gram-positive bacteria, especially Staphylococcus aureus and Streptococcus pyogenes, which are the most common causes of skin and soft tissue infections in children. Unlike some newer antibiotics that try to cover many different types of bacteria, Keflex is specifically optimized to work very well against these common pediatric pathogens. The drug has excellent penetration into skin and soft tissues, which is why it's so effective for treating conditions like cellulitis, impetigo, and wound infections. Once Keflex reaches the infection site, it maintains effective concentrations for several hours, which is why it can be dosed two to four times daily depending on the severity of the infection.