Impact of material properties in determining quaternary ammonium compound adsorption and wipe product efficacy against biofilms

Disinfectant wipes containing quaternary ammonium compounds (QACs) are widely used within health care. Viscose remains a popular material for these products, although limited information is available concerning its impact on performance against biofilms when compared with alternatives. To identify disinfectant wipe materials and surface properties which optimize product performance against biofilms. Biofilm eradication performance of two commercial viscose-QAC wipes was determined against Staphylococcus aureus and Acinetobacter baumannii dry surface biofilms (DSBs) using an ASTM E2967-based procedure. Additionally, five materials were impregnated with a commercial liquid formulation containing didecyldimethylammonium chloride (DDAC). Following 24 h of storage, eradication performance and DDAC content of extracted liquid were determined and compared with material properties, including zeta potential, hydrophobicity and surface area. Under stringent test conditions, eradication of DSBs by commercial products was no greater than equivalent materials impregnated with water. Extract from one viscose-based product contained 89% less DDAC than the impregnation solution, indicating extensive adsorption. Of the other tested materials, viscose performed worst; nearly 70% of DDAC had depleted from material extracts within 24 h. In contrast, DDAC depletion from polypropylene extracts was only 25%, and DSB eradication was >100 times greater than viscose. Biofilm eradication performance against both species correlated with the DDAC content of extracts, which, in turn, correlated with zeta potential and hydrophobicity. Biofilm eradication performance of QAC-based wipes was significantly greater when selecting thermoplastic substrates over viscose. However, these materials are non-sustainably sourced and non-biodegradable. This study highlights a need to develop new wipe products that are more effective against biofilms.