Pseudalert 250

24-hour detection of Pseudomonas aeruginosa

Pseudalert 250

  • Delivers definitive results with no additional confirmation steps.
  • Minimizes the risk of false positives from non-target organisms.
  • Same easy-to-use platform as the Colilert 250 test.
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Overview

Easy
  • Blue fluorescence indicates a positive result.
  • Same familiar platform as the Colilert 250 test:Ready-to-use reagents, no media preparation.
  • Convenient unit-dosed packaging.
  • No toxic compounds.
Rapid
  • Definitive results in 24 hours.
  • Less than 1 minute of hands-on time for streamlined testing work flow.

Accurate
  • Specifically detects Pseudomonas aeruginosa, reducing the risk of false positives from non-target organisms.
  • Results are definitive without additional confirmation steps.
  • Simple blue fluorescent change minimizes subjective result interpretation.
  • Liquid enrichment optimizes recovery.

Science

How the Pseudalert 250 test works

The Pseudalert 250 test detects the presence of Pseudomonas aeruginosa in bottled water samples.

The test is based on a bacterial enzyme detection technology that signals the presence of P. aeruginosa through the hydrolysis of a substrate in the Pseudalert 250 reagent. P. aeruginosa cells rapidly grow and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the Pseudalert 250 reagent. Actively growing strains of P. aeruginosa have an enzyme that cleaves the substrate in the reagent to produce blue fluorescence under ultraviolet light.

The Pseudalert 250 test detects P. aeruginosa at 1 cfu per 250 mL sample within 24 hours.

How to Use

Learn how to use the Pseudalert 250 test

Learn how to use Pseudalert
Learn how to use the Pseudalert test
 

Step-by-step guide to using the Pseudalert 250 test

Presence/Absence (P/A)

Step 1

Add reagent to sample (sample will turn yellow), and then incubate at 38°C ± 0.5°C for 24–28 hours.

Step 2

Read under ultraviolet (UV) light. Blue fluorescence indicates presence of P. aeruginosa. See the Pseudalert Quick Reference Guide (PDF) for tips on reading fluorescence.

 

Q & A

Frequently asked questions and answers

What water types can be tested with the Pseudalert 250 test?
The Pseudalert 250 test is designed specifically for bottled water samples. Bottled water samples are defined as samples taken from any point in the manufacturing of bottled water (from the original water to the finished product). The Pseudalert 250 test was specifically formulated and tested to ensure it would detect stressed P. aeruginosa in these samples.

How does the Pseudalert 250 test work?
The Pseudalert 250 test is based on a bacterial enzyme detection method that signals the presence of Pseudomonas aeruginosa through the hydrolysis of an enzyme substrate. P. aeruginosa cells rapidly grow and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the Pseudalert reagent. Actively growing strains of P. aeruginosa have an enzyme that cleaves the substrate in the reagent to produce blue fluorescence under ultraviolet light. The Pseudalert 250 test detects P. aeruginosa at 1 cfu per 250 mL sample within 24 hours.

What is the detection limit of the Pseudalert 250 test?
The Pseudalert 250 test detects Pseudomonas aeruginosa at 1 cfu per 250 mL.

Is there a comparator for the Pseudalert 250 test?
There is no comparator for the Pseudalert 250 test. For comparison, use a negative control when interpreting results.

What is the incubation time and temperature for samples tested with the Pseudalert 250 test?
Water samples are incubated at 38°C ± 0.5°C for 24 hours, and results are valid up to 28 hours.

Can I incubate at a temperature other than the recommended 38°C?
No. Breakthrough of non-target organisms can occur at temperatures other than 38°C ±0.5°C.

Are results valid prior to 24 hours?
Yes, if the results are positive. An inoculated Pseudalert test presence/absence sample that is positive for Pseudomonas aeruginosa before 24 hours is a confirmed positive test for P. aeruginosa. However, for an accurate quantitative determination of P. aeruginosa in a sample, the results should be read at 24–28 hours of incubation.

Are results valid after 28 hours?
Yes, if the results are negative. If an inoculated Pseudalert test sample is inadvertently incubated for over 28 hours, lack of blue fluorescence is a valid negative test result. However, blue fluorescence that develops after 28 hours is not a valid positive test result; the test should be repeated or verified.

Which vessels should I use with the Pseudalert 250 test?
For presence/absence testing, use a sterile, transparent, non-fluorescing vessel. For the Quanti-Tray and Quanti-Tray/2000 systems, any sterile vessel can be used.

What are the recommended storage conditions for the Pseudalert 250 test?
Store the Pseudalert 250 test at 2°C–30°C away from light.

What color and consistency should the Pseudalert 250 reagent powder be?
The Pseudalert 250 reagent powder should be tan in color; it should be dry and free-flowing. Any concerns about the color or integrity of the reagent powder should be directed to IDEXX Technical Support at +1-800-321-0207 or by email at water@idexx.com.

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Resources & Product Information

Resources

IDEXX Water has reference materials and approval documents to support the many products in our water portfolio. Find the document(s) you need by selecting the link below.


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Product information

Pseudalert 250 test (20-test pack)
Catalog Number: WPSE25020I

IDEXX Water Customer Support

Corporate Headquarters
IDEXX Laboratories, Inc.
One IDEXX Drive
Westbrook, Maine 04092 USA

Tel: 1-800-321-0207
Fax: 1-207-556-4630

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