RX-05

RX-05 is a novel, next-generation macrolide antibiotic originally developed by Rib-X Pharmaceuticals (now Melinta Therapeutics). It was designed using a structure-based drug design platform to overcome common mechanisms of macrolide resistance, such as ribosomal methylation (encoded by *erm* genes) and efflux pumps (encoded by *mef* genes). RX-05 binds to the 50S ribosomal subunit, specifically targeting the peptidyl transferase center and the peptide exit tunnel to inhibit bacterial protein synthesis. It has demonstrated potent in vitro activity against a broad spectrum of Gram-positive pathogens, including methicillin-resistant *Staphylococcus aureus* (MRSA) and multi-drug resistant *Streptococcus pneumoniae*. The program was primarily investigated for indications such as community-acquired bacterial pneumonia (CABP) and complicated skin and soft tissue infections (cSSTI), but development appears to have been discontinued in favor of other candidates in the developer's pipeline.