Impact of human wound exudate on the bactericidal efficacy of antiseptic products in quantitative suspension according to the European standard (DIN EN 13727)

By default, antimicrobial efficacy of antiseptics used in wound management is tested in vitro under standardized conditions according to DIN EN 13727, with albumin and sheep erythrocytes used as organic challenge. However, it is not clear whether these testing conditions do adequately reflect the wound bed environment. Therefore, the aim of this study was to compare the efficacy of different antiseptic products based on octenidine dihydrochloride (OCT), polyhexamethylene biguanide (PHX), and povidone-iodine under challenge with human wound exudate instead of standardized organic load in an in vitro setting according to DIN EN 13727. Bactericidal efficacy of the tested products was reduced to different extend when challenged with human wound exudate compared to standardized conditions. Overall, OCT-based products showed the necessary germ count reductions at the shortest exposure times (e.g., 15 seconds for octenisept®). PHX-based products were the least efficient. In addition to the protein content, other components of wound exudates, such as the microflora, seem to influence the efficacy of antiseptics. This study demonstrates that standardized in vitro test conditions only partly reflect actual wound bed conditions. Consequences for an amendment of existing test methods adapting organic load requirements and the feasibility of standardization of wound exudates are to be discussed.