How do beta-lactams exert their antimicrobial effects?

Beta-lactams exert their antimicrobial effects primarily by inhibiting cell wall synthesis. These antibiotics, which include penicillins and cephalosporins, specifically target the bacterial cell wall's peptidoglycan layer. During bacterial growth and replication, beta-lactams prevent the transpeptidation enzyme from forming cross-links in this layer, which is essential for maintaining the integrity and strength of the cell wall.

As a result, the weakened cell wall cannot withstand the osmotic pressure within the bacterial cell, leading to cell lysis and death. This mechanism of action is particularly effective against actively dividing bacteria, as they are continually synthesizing and remodeling their cell walls. The specificity of beta-lactams for bacterial cell wall synthesis makes them an important class of antibiotics with minimal effects on human cells, which do not have a cell wall.