Sulfonamide Bioisosteres of Niclosamide Enhance Antibacterial Activity of Colistin and Bacitracin

Multicomponent therapy combining antibiotics with enhancer molecules known as adjuvants is an emerging strategy to combat antimicrobial resistance. Niclosamide is a clinically relevant anthelmintic drug with potential to be repurposed for its inherent antibacterial activity against Gram‐positive bacteria and its ability to potentiate the antibacterial activity of colistin against susceptible and resistant Gram‐negative bacteria. Herein, sulfonamide analogs of niclosamide were prepared and found to enhance colistin activity against Gram‐negative bacteria. The ability of niclosamide and the new sulfonamide analogs to synergize with bacitracin against vancomycin‐resistant Enterococcus faecium was also discovered.