Capreomycin sulfate is a salt of a complex of cyclic pentopeptides isolated from Streptomyces capreolus, first reported in 1962. The sulfate salt is the most commonly accessible formulation of capreomycin and is used for pharmaceutical applications. The complex has two major components, IA and IB, with an exocyclic lysine residue and two minor delysinyl components, IIA and IIB. Capreomycin is a potent antibiotic with activity against mycobateria, Gram positive and Gram negative organisms. Capreomycin acts by binding to the 23S ribosomal subunit, disrupting protein synthesis.