The significance of the surface wetting capacity of disinfectant formulations on the sporicidal activity against Clostridioides difficile

Clostridioides difficile infection (CDI) remains the leading infectious cause of antibiotic-associated diarrhoea, representing a substantial burden on healthcare systems worldwide. C. difficile spores can persist on environmental surfaces for months and require sporicidal disinfection for effective elimination. The high surface (interfacial) tension of disinfectant formulations may limit their sporicidal efficacy. Evidence suggests that the hydrophobicity of spore surfaces plays a significant role in the transmission and persistence of CDI. The aim of this study was to determine and compare the wetting properties of two disinfectant formulations based on chlorine dioxide on selected test surfaces, including both hydrophobic and hydrophilic materials, and to evaluate the sporicidal activity of these formulations against C. difficile spores in accordance with EN 17846. Two disinfectant formulations based on chlorine dioxide, with identical concentrations of the active substance, were investigated: one containing a surfactant and one without. Wettability measurements were performed on selected solid materials with differing hydrophilic and hydrophobic properties. Seven surfaces were analysed: parafilm (a thin film of specially processed, highly purified paraffin mounted on a roll of waxed paper), glass, ceramic (a commercial glazed ceramic tile), aluminium, PVC flooring (a commercial product), PVC Forex (foamed PVC), and 316 stainless steel. Sporicidal activity was evaluated on PVC carriers using the EN 17846 four-field test under clean conditions with a 15-min contact time. The chlorine dioxide–based disinfectant containing a surfactant demonstrated the most favourable wetting properties. However, wettability varied considerably across the tested surfaces and decreased in the following order: glass > ceramic > PVC > aluminium > stainless steel > > PVC Forex > parafilm. The addition of a surfactant resulted in a greater reduction of C. difficile spores, with a log 10 reduction factor of 5.39, compared with 4.22 for the formulation without surfactant. The addition of appropriately selected surfactants reduced surface tension and improved the wettability of the tested materials. Under the EN 17846 test conditions on PVC carriers, the surfactant-containing formulation showed a numerically higher reduction in C. difficile spores than the formulation without surfactants. Further replicated studies on additional healthcare-relevant surfaces are required to confirm whether improved wettability translates into greater sporicidal efficacy across different materials.