Macrolides

Macrolides are a class of antibiotics derived from Saccharopolyspora erythraea (originally called Streptomyces erythreus), a type of soil-borne bacteria.

Macrolides inhibit protein synthesis in bacteria by reversibly binding to the P site of the 50S unit of the ribosome. Macrolides mainly affect gram-positive cocci and intracellular pathogens such as mycoplasma, chlamydia, and legionella. Erythromycin was the first macrolide discovered; other macrolides include azithromycin, clarithromycin, and roxithromycin.

Their action is primarily bacteriostatic but may be bactericidal at high concentrations, or depending on the type of microorganism.