(177b) Monitoring Microbial Hunger Games: Dielectrophoretic Monitoring of Inter-Strain C.Difficile Antagonisms

Clostridium difficile (C.difficile) infection (CDI) is a global toxin-mediated intestinal disease that is commonly attributed to exposure to pathogenic C.difficile strains following the elimination of healthy microflora in the gut by broad-spectra antibiotics.  An emerging body of scientific and clinical studies has demonstrated that CDI rates can be controlled through promoting antagonistic inter-strain interactions on pathogenic C.difficile strains by pre-colonization with non-toxigenic C.difficile and other probiotic microorganisms, due to ensuing competition for the same nutrient and colonization niche. The emerging interest in restoration of a healthy microbiota to treat CDI highlights the need to understand and optimize the complex and dynamic interaction between the commensal polymicrobial environment and pathogenic C.difficile strains. Current methods to monitor the alterations in C.difficile colonization following culture within environments including non-toxigenic C.difficile and other probiotic microorganisms utilize cumbersome adhesion assays on human epithelial cell lines (HCT8). These are time consuming, thereby limiting the permutations of interactions that can be studied and do not provide direct information on the causes underlying the alterations in colonization. S-layer glycoproteins are part of the cell wall envelope in gram positive and gram negative bacteria, and are integral to surface recognition, gut colonization, host-pathogen adhesion and virulence. Hence, alterations in colonization properties of pathogenic C.difficile strains due to dynamical interactions with non-toxigenic C.difficile and other probiotic microorganisms are likely to alter the S-layer on the cell wall envelope. We demonstrate here that these alterations in the S-layer on the cell wall envelope of pathogenic C.difficile strains due to interactions with non-toxigenic C.difficile cause systematic alterations in call wall capacitance [1], thereby enabling their facile monitoring within just as few minutes, based on the characteristic shifts in their dielectrophoretic frequency spectra. We compare the influence of static versus dynamic co-culture methods on alterations in C.difficile colonization and benchmark this dielectrophoretic method versus conventional adhesion assays. In this manner, we envision the application of this microfluidic platform towards optimization of polymicrobial therapies to arrest CDI.

[1] Y.-H. Su, C. Warren, R.L. Guerrant, N.S. Swami; “Dielectrophoretic monitoring and inter-strain separation of intact Clostridium difficile based on their S(surface)-layers”, Anal Chem (2014), 86, 10855–10863.