DETECTION OF ESCHERICHIA-COLI IN POTABLE WATER USING DIRECT IMPEDANCETECHNOLOGY

Direct impedance measurement utilizing a medium previously described a s being specific for Escherichia coli and which contains trimethylamin e N-oxide (TMAO) and glucuronic acid was used to detect E. coli in wat er samples. The system was compared with the Colilert(R) presence/abse nce test and the United Kingdom standard membrane filtration technique using membrane lauryl sulphate broth. The impedance method correlated well with both the traditional membrane method (93%) and the Colilert (R) method (93.95%) for a number of different water types. No interfer ence from Citrobacter spp. (as reported in previous studies) was detec ted in this study although some Salmonella spp. did give false-positiv e results: The data presented here suggest that the use of direct impe dance may offer an alternative to conventional methods for the detecti on of E. coli in water.