We investigated the effects of detergent treatment on the susceptibility of attached Escherichia coli and Listeria monocytogenes to subsequent disinfectant treatment. The results demonstrate that, in E. coli, detergents that increase susceptibility to BAC increase membrane permeability. In L. monocytogenes, detergents that reduce susceptibility to BAC lower cell surface hydrophobicity. Detergents, therefore, can influence the sensitivity of pathogenic food borne micro-organisms to BAC. Journal of Applied Microbiology (2008).