[Verification of the effectiveness of neutralization in the in vivo study of antiseptics]

Well defined controls of the effectiveness of antiseptic neutralizing agents in vitro already exist (Afnor Standards for antiseptics and disinfectants). Conversely, there is currently no standard method for verifying how effectively such agents neutralize antiseptics which have been applied to the skin. We describe a method in which the neutralizing solution is first applied to the antiseptic-treated skin and then filtered to remove skin flora. The effect of the neutralizing agent is then checked using a test organism (Staphylococcus epidermidis ATCC 14990) in parallel with four controls: viability of the test organism (T1), activity of the untreated antiseptic (T2), non-bactericidal effect of the neutralizing agent (T3) and of skin secretions (4). Skin sampling was carried out using Gaschen's bag method for the hands and the Williamson and Kligman method modified by Fleurette for other sites. Twelve soaps and/or antiseptics were studied. In each case, activity of the antiseptic (T2) was confirmed, except when the product under study was a non-bactericidal soap. Bacterial counts obtained in controls T3 and T4 and in the neutralization test itself were always greater than 80% of the control value (T1). Occasionally, the counts in the neutralization test exceeded 100% of the T1 value, probably because of the dispersal effect of the triton X100 present in the neutralizing solution. This method thus offers a means of standardizing the study of antiseptics in vivo. In addition, the test organism, Staphylococcus epidermidis, is more representative of the skin flora than the bacterial strains recommended by Afnor for in vitro studies.