Enterolert 250*

Accurately detects enterococci in 24 hours

Detects enterococci in a 250 mL format.
More accurate and specific compared to ISO 7899-2 and MoDW 2006, part 5.
Same easy-to-use platform as Colilert 250.

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Overview

Easy

Ready-to-use media.
Simple procedure.
Unit-dosed packaging eliminates media preparation.
Reagent contains no toxic compounds.

Rapid

Confirmed results in 24 hours.
Simplified quality control.
Less than 1 minute of hands-on time.

Accurate

More accurate when compared to ISO 7899-2 on all samples.
Liquid enrichment ensures optimized recovery.
Eliminates subjective interpretation of results determined by traditional methods.

Science

How the Enterolert 250 Test works

The Enterolert 250 Test uses proprietary Defined Substrate Technology (DST) nutrient indicator to detect enterococci. The Enterolert 250 Test provides confirmed presence/absence results in 24 hours. The Enterolert 250 Test utilizes orth-nitrophenyl-ß-D-glucoside as a nutrient indicator and incorporates a specifically designed blue background color in its formulation.

When the substrate is metabolized by enterococci, the sample turns from blue to green to indicate detection. Any change from the original color to green is considered a positive result. No ultraviolet light source is required. The Enterolert 250 Test detects enterococci at 1 cfu in 250 mL bottled water samples in 24 hours.

How to use

Presence/Absence

Step 1

Add reagent to sample, shake to mix and then incubate at 41 ± 1°C for 24 hours; results are valid for up to 28 hours of incubation.

Step 2

Blue indicates negative for enterococci. Green indicates positive for enterococci.

Frequently asked questions

Store at 2–30°C and away from light.

The Colilert comparator is a liquid color and fluorescence reference. Its purpose is to assist in distinguishing a minimal positive from a negative test result.

At 24–28 hours, any yellow color or fluorescence equal to or greater than the comparator is considered a positive test result.

The Colilert 250 reagent powder should be should be white to off-white in color; it should be dry and free-flowing. Any concerns about the color or integrity of the powder should be directed to IDEXX Technical Support.

Yes, if they are negative. If an inoculated Colilert 250 Test sample is inadvertently incubated over 28 hours, lack of yellow color is a valid negative test; a yellow color after the 28 hours is not valid and should be repeated or verified.

Yes, if they are positive. An inoculated Colilert 250 sample that is positive for coliforms and E. coli before 24 hours is a valid positive test for both coliforms and E. coli. If the sample is positive before 24 hours for coliforms only, the sample is a valid positive test for coliforms. However, the sample should be incubated for a longer period (up to 24 hours, but not greater than 28 hours total time) to determine whether E. coli are present.

The reagent system was designed to suppress noncoliform ONPG or MUG positive bacteria for at least 28 hours. If incubation extends past 28 hours, it is possible that such bacteria will overcome the Colilert 250 Test’s suppression system and react with ONPG or MUG. When incubation exceeds 28 hours, only negative results are valid. Positive results must be confirmed or revalidated and resampled.

No, the Colilert 250 Test works only with 250 mL of sample, so it cannot be used with the Quanti-Tray or Quanti-Tray/2000, which require 100 mL of sample.

Check with your local, state, and/or federal authorities for proper disposal of bacteriological biohazard materials at your facility.

The Colilert 250 test detects total coliforms and E. coli at 1 organism/250 mL.