IDEXX Colilert-18

How it works

The Colilert-18 test uses a proprietary Defined Substrate Technology (DST) nutrient indicators ONPG and MUG to detect coliforms and E. coli. Coliforms use their β-galactosidase enzyme to metabolize ONPG and change it from colorless to yellow.

E. coli use β-glucuronidase to metabolize MUG and create fluorescence. Since most non-coliforms do not have these enzymes, they are unable to grow and interfere. The few non-coliforms that do have these enzymes are selectively suppressed by the Colilert-18 test’s specifically formulated matrix.

This approach is different from traditional media, which provide a nutrient-rich environment that supports the growth of both target organisms and nontargets. When nontargets grow and mimic target organisms, false positives occur. Growth of nontargets can also suppress target organisms and give false negatives in traditional media. To suppress nontargets, traditional media often include high levels of salts, detergents, or other selective agents that may inadvertently suppress target organisms and give further false negatives.

IDEXX Colilert 18 for Coliform and e.Coli Detection simultaneously detects both total coliforms and e.Coli in water, or faecal coliforms in waste-water, with results in 18 hours. With the Colilert-18 Test, you can read afternoon samples the next morning - before the next day's samples arrive.

The Colilert-18/Quanti-Tray method is a worldwide ISO standard for detecting total coliforms and E. coli in water (ISO 9308-2:2012).

Faster results mean that you can act sooner to prevent the spread of contamination and the extremely low false positives rates reduce the incidence of false alarms giving greater confidence to operations, reduced uncertainty and unnecessary expense.

Easy

• Detects coliforms and E. coli simultaneously in 18 hours.
• Unit-dosed packaging eliminates media preparation.
• No repeat testing due to clogged filters or heterotrophic interference.
• Quality Control (QC) procedure can be done in 15 minutes.
• 100ml samples, 20 or 200 test packs

Rapid

• Less than 1 minute of hands-on time.
• Detects coliforms and E. coli simultaneously in 18 hours or less.
• No confirmations needed.
• No glassware cleaning or colony counting.

Accurate

• Identifies E. coli specifically, eliminating unnecessary public notification due to non-target organisms.
• Suppresses up to 2 million heterotrophs per 100 ml
• Eliminates the subjective interpretation found in traditional methods.
• Detects a single viable coliform or E. coli per sample.

Economical

• Minimises evening and weekend work.
• Up to 12-month shelf life at room temperature

The Colilert-18 test uses proprietary Defined Substrate Technology (DST) nutrient indicators ONPG and MUG to detect coliforms and E. coli. Coliforms use their ß-galactosidase enzyme to metabolise ONPG and change it from colourless to yellow.

E. coli use ß-glucuronidase to metabolise MUG and create fluorescence. Since most non-coliforms do not have these enzymes, they are unable to grow and interfere. The few non-coliforms that do have these enzymes are selectively suppressed by the Colilert-18 test’s specifically formulated matrix.

This approach is different from traditional media, which provide a nutrient-rich environment that supports the growth of both target organisms and nontargets. When nontargets grow and mimic target organisms, false positives occur. Growth of nontargets can also suppress target organisms and give false negatives in traditional media. To suppress nontargets, traditional media often include high levels of salts, detergents, or other selective agents that may inadvertently suppress target organisms and give further false negatives.

Only IDEXX reagents have been validated and are approved for use with Quanti-Tray and Quanti-Tray/2000.