Anti-biofilm and Antibacterial Effects of Novel Metal-coordinated Sulfamethoxazole Against Escherichia coli

Background: Escherichia coli has an adaptive metabolism and many strains are resistant to classical antibacterial agents, and due to this resistance, it can cause severe clinical infections. In addition, few novel antibacterial agents have been developed in recent years, which corroborate with antimicrobial resistance. For this reason, innovative antimicrobials with novel targets and modes of action are needed. Objective: The aim of this study was to determine the antibacterial and anti-biofilm activity of metals (mercury, copper, silver, and cadmium) coordinated with sulfamethoxazole (SMZ) against Escherichia coli (ATCC (R) 35218 (TM)). Methods: We used the minimum inhibitory concentration (MIC) technique to evaluate the compound antibacterial properties. Additionally, we verified metal-coordinated SMZ efficacy against bacterial motility, slime production and biofilm formation. We also quantified the bacterial respiratory activity in the presence of those compounds. Results: We showed that metal-coordinated SMZ displayed E. coli antibacterial activities in concentrations are lower than the ones found to SMZ. Besides, metal-coordinated SMZ were able to inhibit biofilm formation and also decrease E. coli motility in lower concentrations than found in a classical antibiotic. All tested compounds stimulated the bacteria respiratory chain, which can be related to the mechanism of their antibacterial activity. Conclusion: Our results suggest that metal-coordinated SMZ enhanced the antibacterial and anti-biofilm activity against E. coli when compared with SMZ free.