[Bactericidal activity of various disinfectants with or without interfering protein substances].

Determination of bactericidal activity of 15 disinfectants by AFNOR standard NF T 72-151 (in distilled water) and AFNOR standard NF T 72-171 (in the presence of protein) provides practical guidelines for optimal use of the different available products. Inhibition by dirt is weak for products composed chiefly of phenol derivatives, while it is very strong for quaternary ammonium compounds as well as chlorine which therefore require prior cleansing of surfaces to be disinfected. Two strains (out of the five indicated by AFNOR standards), i.e. P. aeruginosa and M. smegmatis, are especially resistant when residual organic material is present. According to specific conditions of use, such as whether surfaces are clean or dirty, or whether a hospital or food factory is involved, appropriate AFNOR standards must be chosen to study the activity of disinfectants in various settings and on different strains.