Tracking Inhibitory Alterations during Interstrain <i>Clostridium difficile</i> Interactions by Monitoring Cell Envelope Capacitance

Abstract

Global threats arising from the increasing use of antibiotics coupled with the high recurrence rates of <i>Clostridium difficil</i>e (<i>C. difficile</i>) infections (CDI) after standard antibiotic treatments highlight the role of commensal probiotic microorganisms, including nontoxigenic <i>C. difficile</i> (NTCD) strains in preventing CDI due to highly toxigenic <i>C. difficile</i> (HTCD) strains. However, optimization of the inhibitory permutations due to commensal interactions in the microbiota requires probes capable of monitoring phenotypic alterations to <i>C. difficile</i> cells. Herein, by monitoring the field screening behavior of the <i>C. difficile</i> cell envelope with respect to cytoplasmic polarization, we demonstrate that inhibition of the host-cell colonization ability of HTCD due to the S-layer alterations occurring after its co-culture with NTCD can be quantitatively tracked on the basis of the capacitance of the cell envelope of co-cultured HTCD. Furthermore, it is shown that effective inhibition requires the dynamic contact of HTCD cells with freshly secreted extracellular factors from NTCD because contact with the cell-free supernatant causes only mild inhibition. We envision a rapid method for screening the inhibitory permutations to arrest <i>C. difficile</i> colonization by routinely probing alterations in the HTCD dielectrophoretic frequency response due to variations in the capacitance of its cell envelope