Apigenin and Ampicillin as Combined Strategy to Treat Severe Streptococcus suis Infection

Abstract

As an important zoonotic pathogen, Streptococcus suis (S. suis) can cause a variety of diseases both in human and animals, especially Streptococcal toxic shock-like syndrome (STSLS), which commonly appears in severe S. suis infection. STSLS is often accompanied by excessive production of inflammatory cytokines, which is the main cause of host death. Therefore, it is urgent to find a new strategy to relieve the damage caused by STSLS. In this study, we found, for the first time, that apigenin, as a flavonoid compound, could combine with ampicillin to treat severe S. suis infection. Studies found that apigenin did not affect the growth of S. suis and the secretion of suilysin (SLY), but it could significantly inhibit the hemolytic activity of SLY by directly binding to SLY and destroying its secondary structure. In cell assays, apigenin was found to have no significant toxic effects on effective concentrations, and have a good protective effect on S. suis-infected cells. More importantly, compared with the survival rate of S. suis-infected mice treated with only ampicillin, the survival rate of apigenin combined with an ampicillin-treated group significantly increased to 80%. In conclusion, all results indicate that apigenin in combination with conventional antibiotics can be a potential strategy for treating severe S. suis infection.

Canagliflozin Inhibited the Activity of Hemolysin and Reduced the Inflammatory Response Caused by Streptococcus suis

“…After being released by bacteria, hemolysin binds to the surface of host cells to form holes and cause STSLS. The discovery of some drugs [14][15][16][17] with anti-SLY activity gave us a good indication that treatment at 6 h after infection would significantly improve the survival rate of mice. The screening of drugs that target bacterial virulence proteins can have great advantages [18,19].…”