Synergistic Effect of Quercetin in Combination with Sulfamethoxazole as New Antibacterial Agent: In Vitro and In Vivo Study

TLDR: The in vivo treatment of S. aureus infection with S+Q combination decreased the sulfamethoxazole side effects while increasing its antibacterial activity, which supported the therapeutic use of this combination in humans.

Abstract: The present study was aimed at creating a combination between lower dose of sulfamethoxazole (S) as a broad-spectrum synthetic antibiotic and quercetin (Q), a natural polyphenol to decrease the antibiotic side effects and increase its antioxidant activity. Staphylococcus aureus infected animal model was studied both in vitro and in vivo in comparison to doxycycline (Dox) as standard antibiotic. The in vitro test results indicated that Q exhibited activity alone and in combination with S against tested bacterial strains, while S in low concentration was inactive. The in vivo results revealed that the S+Q combination in mice showed significant improvements in the liver and kidney functions as compared to those in the infected group or S- and Dox-treated groups. Moreover, malondialdehyde level was significantly decreased, while superoxide dismutase and catalase activities were significantly increased in the sera of (S+Q)-treated group in comparison to other treated groups. The spleen recovery in the (S+Q)-treated group was observed with the disappearance of S. aureus colonies as compared to the infected mice. In conclusion, the in vivo treatment of S. aureus infection with S+Q combination decreased the sulfamethoxazole side effects while increasing its antibacterial activity, which supported the therapeutic use of this combination in humans.