Disinfection of surfaces contaminated with Clostridioides difficile endospores using NaCl-derived electrochemically activated solutions

Clostridioides difficile is transmitted through endospores. Most disinfection procedures for these structures deploy high concentrations of chlorine-derived compounds such as sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC). However, these substances are linked to undesired Public Health and Environmental issues. To compare the efficacy of NaCl-derived electrochemically activated solutions (ECAS, 0.18% w/v NaOCl, pH=9.6-10.3), commercial bleach (5000 ppm, 2.83% w/v NaOCl, pH=5.6), and 1000 ppm NaDCC (pH=6.8) to inactivate C. difficile endospores on surfaces using a standard quantitative test (EPA MO-21-03). Ten representative reference and field strains from Multi-locus Sequence Typing (MLST) Clades 1 to 5 were assayed (n=10). Irrespective of the phylogenetic background of the strains, ECAS showed comparable or better log reduction values (mean=3.22, CI: 0.40-5.56) than bleach (mean=2.74, CI: 0.12-5.50) and NaDCC (mean=2.02, CI: 0.10-5.12). Cyclic voltammetry measurements revealed similar electrochemical behaviors and open-circuit potentials for ECAS and NaOCl. Congruently, similar morphologies for spores treated with these two compounds were observed by transmission electron microscopy. A factorial design demonstrated that exposure time, but not activation time, influenced ECAS efficacy. These results demonstrate a functional equivalence of ECAS and NaOCl and suggest a common mechanism of action for both substances.