What is the primary mechanism of action for penicillins and cephalosporins?

Penicillins and cephalosporins primarily function by weakening the bacterial cell wall, which is essential for maintaining the integrity and shape of the bacteria. These antibiotics target the enzymes involved in the synthesis of peptidoglycan, a crucial component of the bacterial cell wall. By inhibiting these enzymes, penicillins and cephalosporins disrupt the construction of the cell wall, leading to the lysis and death of the bacteria, especially in actively dividing cells. This mechanism is particularly effective against gram-positive bacteria, which have a thick peptidoglycan layer that is critical for their survival.

Understanding this primary action is vital as it highlights why these antibiotics are generally more effective against bacteria than against eukaryotic cells, which do not possess cell walls. Other mechanisms listed, such as inhibiting protein synthesis or disrupting metabolic pathways, pertain to different classes of antibiotics, while interference with DNA replication is also characteristic of another group of antimicrobials, emphasizing the unique role of penicillins and cephalosporins in bacterial treatment.