What is the action of benzathine penicillin in bacterial infections?

Benzathine penicillin acts by inhibiting bacterial cell wall synthesis, which is fundamental to its mechanism of action. Penicillin is a member of the beta-lactam antibiotic class, and it targets specific proteins known as penicillin-binding proteins (PBPs) located on the bacterial membrane. These PBPs are involved in the final stages of peptidoglycan synthesis, which is critical for maintaining the structural integrity of the bacterial cell wall.

When benzathine penicillin binds to these PBPs, it inhibits their enzymatic activity, leading to a weakened cell wall and eventual lysis of the bacteria. This action is particularly effective against rapidly multiplying organisms, as the cell wall is essential for their survival and optimal functioning.

Other options provided involve different mechanisms of action that do not pertain to benzathine penicillin. For instance, the disruption of protein synthesis is characteristic of antibiotics such as tetracyclines or macrolides. The alteration of bacterial DNA replication pertains to agents like fluoroquinolones. Activating the immune response would relate to immunomodulators rather than an antibiotic with a directly bactericidal activity. Thus, the focus of benzathine penicillin on cell wall synthesis distinctly defines its role in treating bacterial infections