Hybrid antibiotics targeting the bacterial ribosome

Antimicrobial resistance remains a formidable challenge to modern medicine, with bacterial resistance mechanisms increasingly eroding the utility of clinically important antibiotics. While recent efforts have expanded the antibacterial pipeline, the development of resistance in priority pathogens continues to exceed the pace of new drug development. One emerging strategy to overcome resistance is the rational design of hybrid antibiotics that engage multiple binding sites. Here we describe the design, synthesis, and microbiological and structural characterization of hybrid antibiotics of azithromycin, tedizolid, and chloramphenicol that span the peptidyltransferase center (PTC) and nascent peptide exit tunnel (NPET). We characterize the binding of five such hybrids to the bacterial ribosome by cryo-electron microscopy, granting insight into their molecular mechanisms of action. We identify a hybrid of azithromycin and tedizolid that is active against a diverse panel of Gram-positive bacteria, including strains with both macrolide and oxazolidinone resistance mechanisms. These results extend our understanding of ribosome inhibition and demonstrate that the rational design of dual-action antibiotics can restore or even enhance antibacterial efficacy against resistant strains. In a broader context, this work offers a promising framework for developing next-generation therapeutics to combat multidrug-resistant pathogens and reinvigorate the dwindling antibiotic pipeline.