Evaluation of the Antibacterial Activity of Antibiotics with different Antibacterial Mechanisms using Electrochemical Signals of Heat-Treated Escherichia Coli

Abstract

Electrochemistry with purines as indicators may be a promising new method for antibiotic activity testing. However, the traditional electrochemical detection method (S-LSV) requires a long accumulation time for purines and has low signal intensity. High-temperature treatment of bacterial samples may significantly enhance the signal intensity and speed of detection. However, this process may also impact the structure and metabolism of bacteria. Further research is necessary to determine how electrochemical signals respond to antibiotic antibacterial activity. In this paper, the electrochemical detection method based on heat-treated Escherichia coli (E. coli, H-LSV) was used to investigate the effects of 11 antibiotics with four different antibacterial mechanisms on the electrochemical behavior of E. coli. The results showed that compared to the S-LSV, the electrochemical signal of E. coli detected by the H-LSV increased by 362%, and showed a strong linear relationship with bacterial counts up to 1.88×10⁸ CFU/mL, with a detection limit of 1.15×10⁶ CFU/mL. The electrochemical signal consistently correlated with changes in viable E. coli counts following treatment with the four different antibacterial mechanisms. HPLC analysis further confirmed that the changes in purine contents in bacteria after antibiotic treatment were consistent with the trends in electrochemical signals. The evaluation of antibiotic antibacterial ability by H-LSV showed good consistency with results from plate counting and turbidity methods, but was closer to the results of plate counting. The inhibition rates of antibiotics on E. coli detected by H-LSV and S-LSV also showed high consistency, indicating that short-term high-temperature treatment of E. coli did not affect the response of the bacterium to the inhibitory activity of antibiotics.