The suppression effect of SCH-79797 on Streptococcus mutans biofilm formation

SCH-79797 was recently shown to be a broad-spectrum antibacterial agent with a dual-bactericidal mechanism. However, its anti-biofilm effect remains unknown. To investigate the effect of SCH-79797 on the biofilm formation of the cariogenic Streptococcus mutans Crystal violet staining, colony forming units count and MTT assays (for cell metabolic activity) revealed that S. mutans biofilm formation was significantly suppressed. In addition, virulence factors, including extracellular polysaccharides (investigated by bacterial/exopolysaccharide staining and the anthrone method) and acid production (investigated by lactic acid and supernatant pH detection) were also inhibited significantly. Moreover, the biofilm inhibitory effect of SCH-79797 was mediated through its repression of bacterial growth and not by a bactericidal effect, which was verified by growth curve and bacterial live/ dead staining, respectively. Quantitative real-time PCR results disclosed that SCH-79797 affected bacterial acid production and tolerance, polysaccharide synthesis and remodeling, biofilm formation and quorum sensing-related gene expression. In addition, SCH-79797 showed good biocompatibility as determined by cytotoxicity assays. SCH-79797 had an anti-biofilm effect and showed application prospects in the control of dental caries.