Investigation of antimicrobial efficacy of a quaternary ammonium compound-based disinfectant on copper alloy (CuZn23AlCo).

Antimicrobial efficacy tests were carried out using the DGHM carrier test with and without organic soiling [16]. Microbial inocula were dried for either 60 min or 120 min, as indicated. 100 μl disinfectant dilution (diluted to give 0.25% (v/v)) was applied to the different carriers (copper alloy carriers, stainless steel carriers, tile carriers) with a contact time of 2 min. Water controls (wc) were used to observe the influence of the different carriers (application of 100 μl standardized hard-water instead of the disinfectant within the contact time). Microbial survival rates were determined as described in Material and Methods at the intervals indicated and expressed as log CFU/ml. A: Test organism P. aeruginosa. B: Test organism S. aureus. C: Test organism C. albicans. The experiments were repeated at least three times on different days. Mean values are displayed with standard error. The design of the experiments is depicted schematically in S3 Fig.