Detection of Escherichia coli in potable water using direct impedance technology

Abstract
Direct impedance measurement utilizing a medium previously described as being specific for Escherichia coli and which contains trimethylamine N‐oxide (TMAO) and glucuronic acid was used to detect E. coli in water samples. The system was compared with the Colilert® presence/absence test and the United Kingdom standard membrane nitration technique using membrane lauryl sulphate broth. The impedance method correlated well with both the traditional membrane method (93%) and the Colilert® method (93.95%) for a number of different water types. No interference from Citrobacter spp. (as reported in previous studies) was detected in this study although some Salmonella spp. did give false‐positive results. The data presented here suggest that the use of direct impedance may offer an alternative to conventional methods for the detection of E. coli in water.