Colilert-18

Easy

• Ease of use simplifies training.
• 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.

Rapid

• Under 1 minute 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

• Minimizes evening and weekend work.
• Up to 15-month shelf life at room temperature.

Flexible

• Can be used for presence/absence (P/A) or quantification testing with Quanti-Tray and Quanti-Tray/2000.

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