Macrolide: One in a class of antibiotics that includes Biaxin, Clarithromycin, Ery-Tab, and Erythromycin.

The macrolides inhibit the growth of bacteria and are often prescribed to treat rather common bacterial infections.

In more technical terms, the macrolides are a group of antibiotics produced by various strains of Streptomyces (spore forming bacteria that grow slowly in soil or water as a branching filamentous mycelium similar to that of fungi) and have a complex chemical (macrocyclic) structure. They act by inhibiting protein synthesis, specifically by blocking the 50S ribosomal subunit. They are broad spectrum antibiotics.