What is the mechanism of action of penicillin in bacteria?

Penicillin works primarily by inhibiting the synthesis of bacterial cell walls, which is essential for the structural integrity and survival of bacteria. This mechanism hinges on its ability to block the enzyme transpeptidase, also known as penicillin-binding proteins (PBPs). Transpeptidase is crucial for forming cross-linkages between the peptidoglycan strands in the bacterial cell wall.

By binding to this enzyme, penicillin prevents the formation of these cross-links, leading to a weakened cell wall that cannot withstand osmotic pressure. As a result, the bacteria can undergo lysis and die, especially in environments where they are exposed to osmotic imbalance. This action is particularly effective against Gram-positive bacteria, which rely heavily on their cell wall for stability. Understanding this specific mechanism highlights the importance of penicillin as a beta-lactam antibiotic and illustrates how it targets vital processes necessary for bacterial growth and division.