Capreomycin IIA

Capreomycin IIA is a minor cyclic polypeptide component of the capreomycin antibiotic complex, isolated from Streptomyces capreolus, lacking the β-lysine residue present in major components IA and IB. It contributes to the complex's antibacterial activity, primarily against Mycobacterium tuberculosis, including multidrug-resistant strains, by binding to the 16S rRNA in the bacterial 30S ribosomal subunit to inhibit protein synthesis. This mechanism disrupts bacterial translation, with additional inhibition of the TlyA methyltransferase involved in rRNA modification. Capreomycin, including IIA, is used as a second-line injectable treatment for drug-resistant tuberculosis in combination with other agents, effective against both active and dormant forms of the pathogen. However, its clinical use is limited by significant toxicities, including nephrotoxicity and ototoxicity, particularly in patients with renal impairment. The sulfate form is typically administered, with IIA comprising a small fraction of the active mixture.

Other names

capreomycin IIB (related minor component)delysinyl capreomycin IA

Inhibits protein synthesis by binding to the 16S rRNA of the 30S ribosomal subunit; inhibits 16S/23S rRNA (cytidine-2'-O)-methyltransferase TlyA