SBIR Phase I: Combating Multi-Drug Resistant Gram-negative Healthcare-Associated Infections

The broader impact of this Small Business Innovation Research (SBIR) Phase I project is to develop therapeutic drugs that restore antibiotic sensitivity in bacteria that cause severe infections in patients that are hospitalized or receiving healthcare for another condition. Antibiotics are paramount to modern medicine. In addition to treating infections and controlling their spread, these drugs enable safe surgeris, facilitate childbirth, and provide treatments for diseases such as cancer. However, as microbes evolve and develop resistance, these life-saving drugs are losing effectiveness. Eleven potent and specific small molecules have been identified that restore antibiotic sensitivity in these bacteria. Bloodstream infections and ventilator-associated pneumonia caused by Gram-negative bacteria are two severe healthcare associated infections that despite current treatments cause significant excess mortality (150 deaths/1,000 patients), longer hospital stays, and incremental costs estimated at nearly $50,000 per patient. Developing therapeutics that restore the sensitivity of Multi-Drug Resistant (MDR) Gram-negative pathogens to commonly used, well tolerated antibiotics addresses a major unmet medical need and would be transformative for patients and physicians. This project involves developing small molecules to restore the sensitivity of Multi-Drug Resistant (MDR) Gram-negative bacteria to commonly used, well tolerated antibiotics. The role of bacterial efflux pumps in MDR Gram-negative bacteria is well documented. These pumps are virulence determinants essential for infection, and by exporting antibiotics across the bacterial cell envelope they play a key role in antibiotic resistance. Eleven potent and specific small molecule inhibitors of bacterial efflux pumps (EPIs) have been identified. These EPIs are in early-stage lead optimization and this project involves three foundational assays: cryo-electron microscopy (cryo-EM), membrane permeability, and in vitro antibiotic combination assays, followed by in vitro characterization, safety pharmacology, and liability screening. Cryo-EM provides insight into the mechanism of action and binding of these EPIs to the efflux pump, enabling in-silico docking studies and the design of new analogs. Some prior EPI research failed due to membrane permeabilization, a property that can result in apparent in vitro efficacy. Cryo-EM data together with results from in vitro efficacy and membrane permeability assays allows early deselection of poor-quality compounds, focusing screening studies on the most promising EPIs. This project may provide insights into links between MDR, persister cells, and virulence in Gram-negative pathogens. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.