Different Effects of Six Antibiotics and Ten Traditional Chinese Medicines on Shiga Toxin Expression byEscherichia coliO157:H7

Abstract

This study compared the effects of ten types of traditional Chinese medicines (TCMs) and six different antibiotics onE. coliO157:H7 Shiga toxin gene (stx2) mRNA expression level based on real-time PCR and the expression level of Stx toxin using an ELISA quantitative assay. We also compared their effects on the induction of the SOS response. The results clearly indicated that all ten TCMs had negative results in the SOS response induction test, while most TCMs did not increase the levels ofstx2mRNA and the Stx toxin. Some TCMs did increase the mRNA levels of thestx2gene and the Stx toxin level, but their increases were much lower than those caused by antibiotics. With the exception of cefotaxime, the six antibiotics increased the Stx toxin level and increased thestx2gene mRNA level. With the exceptions of cefotaxime and tetracycline, the antibiotics increased the SOS induction response. These results suggest that TCMs may have advantages compared with antibiotics, when treatingE. coliO157:H7; TCMs did not greatly increase Stx toxin production and release.