The enterotoxins produced by enterotoxigenic Escherichia coli (ETEC) cells include heat labile (LT) and heat stable toxins (ST). These toxins cause diarrheal in humans and domestic animals. In this study, we combined LT I and ST II gene specific PCR primers into a multiplex PCR system and used this system for the simultaneous detection of LT I and ST II ETEC cells in tap water and environmental waters. Using Chromocult coliform agar (CCA), we found that tap water and underground water were contaminated with 0-100 CFU / ml of E. coli and coliform cells while the waters from four rivers near Taichung City were contaminated with 102-104 CFU / ml of E. coli and coliform cells. Furthermore, three of the four river waters were contaminated with LT I / ST II and ST II ETEC cells. The high levels of microfloral contamination in these river waters near an urban area should be attended to urgently.

Key words: multiplex PCR, LT I and ST II enterotoxigenic E. coli, environmental waters