Iboxamycin (OPP-3) is an orally bioavailable, synthetic antibacterial compound [1
]. Structurally, IBX is built on a oxepanoproline scaffold that is linked to the aminooctose residue of clindamycin
. X-ray crystallography shows that IBX binds to the large ribosomal subunit in the bacteria (more effectively than clindamycin) and disrupts translation initiation. Iboxamycin is a novel broad-spectrum agent that is active against Gram-positive and Gram-negative bacteria including ESKAPE pathogens that express resistance-conferring Erm and Cfr ribosomal RNA methyltransferase enzymes.