A rapid fluorogenic method for the detection ofEscherichia coliby the production of β‐glucuronidase

Abstract

A medium containing the fluorogenic substrate 4-methylumbelliferyl-beta-D-glucuronide was developed for the isolation and identification of Escherichia coli within 7.5 h and was based on the detection of beta-glucuronidase. Optimum conditions for the rapid development of fluorescent colonies were determined. The optimum temperature was 41.5 degrees C. Development of fluorescence was delayed when carbohydrates were incorporated into the medium. Water samples were used to evaluate the medium by surface plating and membrane filtration. The frequency of false-negative results was 6.1% and false-positives were 3.7% for freshwater samples. The false-positive organisms were identified as Klebsiella spp. and Shigella sonnei. The potential applications of the medium are discussed.

ColiSense, today's sample today: A rapid on-site detection of β-d-Glucuronidase activity in surface water as a surrogate for E. coli

“…CV decreased from 15.6% at the lowest E. coli MPN (624) to 2.6% for the highest E. coli MPN (14,136). These figures agree with the work of Lebaron who in a much more extensive study using the discontinuous 4-MUG method for measuring GUS activity reported CVs less than 15% [25].…”

“…β-D-Galactosidase (GAL) and β-D-Glucuronidase (GUS) have been used as marker enzymes in assays for E. coli [7][8][9][10][11][12][13] while Glucosidase has been used in assays for Enterococci. Of these target enzymes GUS is the most specific, being present in 94-97% of E. coli strains tested [9,14].…”

A medium detecting β-glucuronidase for the simultaneous membrane filtration enumeration of Escherichia coli and coliforms from drinking water

“…Some strains of Shigella and Salmonella possess this enzyme but expression is rare in the other members of the Enterobacteriaceae (Massenti et al 1981). The fluorogenic substrate 4-methylumbelliferyl-~-~-glucuronide (MUG) has been used in M F techniques (Mates & Shaffer 1989;Sarhan & Foster 1991) but suffers from false-negative presumptive E. coli occurrence due to loss of fluorescence (Sarhan & Foster 1991). 5-Bromo-4-chloro-3-indolyl-~-D-ghcuronide (BCIG) is a chromogenic substrate that has been successfully incorporated into media used for direct plating methods (Ogden & Watt 1991).…”

Comparison of LST + MUG broth technique and conventional method for the enumeration of Escherichia coli in foods

“…1997). Rapid identification of E. coli by the MUG system is also used (Sarhan and Foster 1991). MUG was found to be neither inhibitory nor stimulatory to the growth rate of E. coli .…”

“…MUG substrate can be incorporated into other broth media, such as EC broth and brilliant green bile broth, as well as solid media, such as Violet Red Bile (VRB) agar, trypticase soy agar or Petri film (Koburger and Miller 1985;Weiss and Humber 1988;Matner et al 1990;Villari et al 1997). Rapid identification of E. coli by the MUG system is also used (Sarhan and Foster 1991). MUG was found to be neither inhibitory nor stimulatory to the growth rate of E. coli.…”