A screeningmodel, based on flow cytometric and other techniques, was developed to assess the influence of methylamines on the viability of enterotoxigenic Escherichia coli. Results show a decrease of ETEC viability after exposure to glycine, sarcosine and imethylglycine, but not betaine, under alkaline conditions (pH 9,0-10,0), due to a disturbance of bacterial pH homeostasis mechanisms.