Mechanisms of Action for Common Antibiotics

Cephalosporins

Cephalosporins are beta-lactam antibiotics that inhibit bacterial cell wall synthesis. They bind to penicillin-binding proteins (PBPs) on the bacterial cell membrane, disrupting the final stages of cell wall synthesis and causing cell lysis.

Macrolides

Macrolides inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit. This prevents the elongation of the polypeptide chain, thereby halting protein synthesis.

Quinolones

Quinolones (including fluoroquinolones) inhibit bacterial DNA replication by targeting DNA gyrase and topoisomerase IV, enzymes responsible for supercoiling and unwinding DNA during replication. This leads to DNA fragmentation and cell death.

Penicillins

Like cephalosporins, penicillins are beta-lactam antibiotics that inhibit bacterial cell wall synthesis by binding to PBPs. This disrupts cell wall formation, causing bacterial lysis.

Aminoglycosides

Aminoglycosides bind to the 30S subunit of bacterial ribosomes, causing misreading of mRNA and inhibiting protein synthesis. They can also cause bacterial cell membrane disruption.

Tetracyclines

Tetracyclines inhibit protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the ribosome, thus blocking the addition of amino acids to the growing peptide chain.