Identification of small molecules that antagonize diguanylate cyclase enzymes to inhibit biofilm formation

Bacterial biofilm formation is responsible for numerous chronic infections, causing a severe health burden. Many of these infections cannot be resolved, as bacteria in biofilms are resistant to the host's immune defenses and antibiotic therapy. New strategies to treat biofilm-based infections are critically needed. Cyclic di-GMP (c-di-GMP) is a widely conserved second-messenger signal essential for biofilm formation. As this signaling system is found only in bacteria, it is an attractive target for the development of new antibiofilm interventions. Here, we describe the results of a high-throughput screen to identify small-molecule inhibitors of diguanylate cyclase (DGC) enzymes that synthesize c-di-GMP. We report seven small molecules that antagonize these enzymes and inhibit biofilm formation by Vibrio cholerae. Moreover, two of these compounds significantly reduce the total concentration of c-di-GMP in V. cholerae, one of which also inhibits biofilm formation by Pseudomonas aeruginosa in a continuous-flow system. These molecules represent the first compounds described that are able to inhibit DGC activity to prevent biofilm formation.