What is the mechanism of action for Benzylpenicillin?

Benzylpenicillin, also known as penicillin G, works primarily by inhibiting cell wall synthesis in bacteria. The mechanism of action involves binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell wall. These PBPs are critical for the final stages of peptidoglycan synthesis, which is essential for maintaining the structural integrity of the bacterial cell wall.

When benzylpenicillin binds to these proteins, it interferes with the cross-linking of peptidoglycan layers, ultimately leading to a weakened cell wall. As the bacterium attempts to grow and divide, the structural integrity of its cell wall is compromised, making it unable to withstand osmotic pressure. This results in lysis and death of the bacteria.

In contrast, the other mechanisms listed do not accurately describe how benzylpenicillin functions. It does not inhibit protein synthesis, disrupt bacterial metabolism, or inhibit DNA replication, which are relevant mechanisms for other classes of antibiotics. Hence, the correct understanding of benzylpenicillin’s mechanism emphasizes its role in cell wall synthesis inhibition, which defines its efficacy against susceptible bacterial pathogens.