How do macrolide antibiotics such as erythromycin affect bacteria?

Macrolide antibiotics, such as erythromycin, function as antimicrobial agents by targeting the protein-building machinery of susceptible bacteria.12

Specifically, these drugs bind to a specific subunit of bacterial ribosomes, which are the essential sites for protein synthesis. By binding to these subunits, macrolides inhibit the formation of proteins necessary for bacterial function and survival.1

The effect on the bacteria depends largely on the concentration of the drug and the specific type of microorganism:
* Bacteriostatic effect: In most cases, this inhibition of protein synthesis prevents bacterial growth and reproduction.12
* Bactericidal effect: At higher concentrations, the disruption of protein synthesis can be severe enough to cause direct cell death.12

While these agents are highly effective against various pathogens, some bacteria have developed resistance through mutations that alter the ribosomal binding site, the production of drug-inactivating enzymes, or the activation of drug efflux proteins.1