Distribution of uidA gene sequences in Escherichia coli isolates in water sources and comparison with the expression of beta-glucuronidase activity in 4-methylumbelliferyl-beta-D-glucuronide media

Article Abstract:

The fluorigenic substrate 4-methylumbelliferyl-beta-D-glucuronide (MUG) is commonly used for the detection of Escherichia coli through its ability to detect activity of beta-glucuronidase (GUR), which is encoded by uidA. GUR activity is tested in minimal medium o-nitrophenyl-beta-D-galactopyranoside (MMO)-MUG. The validity of MMO-MUG and two other E. coli detection kits, Colilert and Colquik, were tested by examining 449 strains of E. coli for the presence of the uidA gene. The results showed that uidA levels did not correlate well with beta-glucoronidase activity or with the results of Colilert and Coliquik.

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Detection of virulence factors in culturable Escherichia coli isolates from wa ter samples by DNA probes and recovery of toxin-bearing strains in minimal o-n itrophenol-beta-D-galactopyranoside-4-methylumbelliferly-beta-D-glucuronide me dia

Article Abstract:

Minimal o-nitrophenol-beta-D-galactopyranoside-4-methylumbelliferyl-beta-D glucoronide (MMO-MUG) media, which was designed for the detection of virulent strains of Escherichia coli, was evaluated by comparing results of molecular genetic analyses to those obtained using MMO-MUG. The hybridization probes consisted of sequences detecting different toxins, adherence factors and the fimbrial antigen. The results of the genetic analyses showed that 13% of E. coli isolated from treated and raw water sources contain one or more virulence factors. The MMO-MUG media failed to detect more than 50% of these isolates.

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Evaluation of commercial presence-absence test kits for detection of total coliforms, Escherichia coli, and other indicator bacteria

Article Abstract:

The capacity of various commercial presence-absence (P-A) test kits for detecting the presence of totalcoliforms and Escherichia coli was evaluated. Corollary to this study was the comparison of the Ministry of Environment (MOE) P-A test procedure to the Colilert and Coliquik test kits. Comparison of the Colilert, Coliquik, Hatch Disposable or Hachi Vial tests to the MOE P-A tests and the total coliform MF tests were made by using m-Endo agar LES as m-TEC agar was used to compare themwith fecal coliform tests. Three out of the four commercial products tested demonstrated good recovery levels.

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