Redox potential as a diagnostic tool to investigate growth of various clinical pathogens

Introduction: Through their oxidative metabolism, bacteria reduce the redox potential of their environment. It is thus possible to detect a bacterial growth by measuring the redox potential of the culture broth. Methods: We have determined the oxydoreduction curves (shape and kinetics) of different pathogens at serial initial concentrations. Material: We have used basic potentiometers associated to combined redox electrodes with an Ag/AgCl reference. Repeated measurements have been performed on a strirred Tryptic Soya broth maintained at 37°C. Results: We have shown that there is a linear correlation between the initial germs concentration and the time needed to observe a diminution of the potential (in mV). Additionally, the shape and kinetics of the curves are reproductible and specific to the microbial species. We have equally studied the effect of different concentrations of antibiotics on the variation of the redox potential. Conclusions: These preliminary studies show that there is a big “potential” for the use of electrochemistry for qualitative and quantitative diagnosis of a bacterial infection and its associated antibiotics resistances. If proven implementable, this technique would offer the consequent advantages of being low-cost and faster than actual diagnosis methods.