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 filtration 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.

Comparison of Traditional Culture Method with DOX System for Detecting Coliform and <i>Escherichia coli</i> from Vegetables

“…E. coli produces the enzyme-␤-glucuronidase, which hydrolyzes MUG to form a fluorescent compound (Venkateswaran et al, 1996). This simple and rapid method was developed to detect coliforms in surface water (Brenner et al,1993;Clark et al, 1991, Clark & El-Shaarawi, 1993Park et al, 1995), drinking water (Coloquhon et al, 1995;Edberg et al, 1989;Rice et al, 1990;Rice et al, 1991), marine water (Manafi et al, 1989;Palmer et al, 1993), wastewater (Feng & Hartman, 1982), fecal material (Rice et al, 1990) and food (Moberg et al, 1988;Poelma et al, 1987). Following the success of the technology described by Venkateswaran et al (1996) and others and because the assay is rapid and sensitive, many companies have produced chromogenic-fluorogenic substrate systems for enumerating coliforms and fecal coliforms.…”

Impedance fingerprint selection of DHA-producing photoautotrophic microalgae

“…The pH of the sterilized medium was then adjusted to pH 7 by using 1 M hydrochloric acid (HCl) and 1 M potassium hydroxide (KOH) before filling inside the anode chamber. The electrolyte potassium hexacynoferrate (III) (K 3 Fe(CN) 6 ) dissolved in KH 2 PO 4 buffer (0.5 M) at neutral pH was used as an electron acceptor in the cathode compartment. Electrochemical measurements via electrochemical impedance spectroscopy (EIS) (HIOKI 3522-50, Japan) were conducted on steadystate open circuit potential distributed with an amplitude of 10 mV at the frequency range of 10 4 to 5× 10 −3 Hz.…”

“…: +886 3 9317497; fax: +886 3 9357025. Colquhoun et al [6] for detection of Escherichia coli in aquatic environments by BIM). The finding indicated that microalgae of the same genus have nearly identical impedance likely due to similar profiles of bio-electrochemical activities.…”

Rapid enumeration ofEscherichia coliin oysters by a quantitative PCR‐ELISA

“…For the identification and enumeration of E. coli in foods, water and environmental samples, several methods, including rapid plate count procedures (García et al 1995), impedance monitoring (Colquhoun et al 1995) and chromogenicfluorogenic substrate technology (Venkateswaran et al 1996;Villari et al 1997), have been developed as alternatives to conventional procedures. Although these techniques may compare favourably with the conventional methods for detec-tion of E. coli, most of the procedures are complex and timeconsuming (Frampton and Restaino 1993;Venkateswaran et al 1996).…”