Pseudalert^™ is easy to use, rapid and accurate

Easy

• Fluorescence of wells or vessel indicates a positive result
• Same familiar platform as the Colilert® Test:
  • Ready-to-use reagents, no media preparation
  • Convenient unit-dosed packaging
  • No toxic compounds
• Use with Quanti-Tray® or Quanti-Tray®/2000 for most probably number (MPN) enumeration
  

Rapid

• Definitive results in 24 hours
• Less than 1-minute of hands-on time for streamlined testing work flow
  

Accurate

• Reduced risk of false positives; Pseudalert specifically detects Pseudomonas aeruginosa
• Results are definitive without additional confirmation steps
• Simple fluorescent color change minimizes subjective result interpretation

Scientific Basis: How Pseudalert™ Works

The Pseudalert test detects the presence of Pseudomonas aeruginosa in bottled-, pool- or spa-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 reagent. 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.

Pseudalert detects P. aeruginosa at 1 cfu in either 100-mL or 250-mL samples within 24 hours for non-carbonated water samples and within 26 hours for carbonated-water samples.

How to Use Pseudalert™
Note: If using carbonated water, please refer to the package insert (PDF) for sample preparation instructions.
Presence/Absence (P/A)
Step 1.  Add reagent to sample (sample will turn yellow), and then incubate 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.
Quantification
Step 1.  Add reagent to sample (sample will turn yellow).
Step 2. Add IDEXX Antifoam Solution to vessel.
Step 3. Pour sample into Quanti-Tray or Quanti-Tray/2000.
Step 4. Seal using a Quanti-Tray® Sealer, and then incubate for 24–28 hours.
Step 5. Read under ultraviolet (UV) light, count blue fluorescent wells and refer to MPN table. See the Pseudalert Quick Reference Guide (PDF) for tips on reading fluorescence.

Pseudalert Questions and Answers

• What water types can be tested with the Pseudalert™ Test?

  The Pseudalert Test is designed specifically for bottled-, pool- and spa-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). Extensive studies were done on Pseudomonas aeruginosa stressed by the various chemicals and cleaning agents used in pools and spas, to mimic the impact of treatment. Pseudalert was specifically formulated and tested to ensure it would detect stressed P. aeruginosa in these samples.

• How does Pseudalert work?

  Pseudalert 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.

  
  

  Pseudalert detects P. aeruginosa at 1 cfu in either 100-mL or 250-mL samples within 24 hours for noncarbonated-water samples and within 26 hours for carbonated-water samples.

• Why does Pseudalert detect only Pseudomonas aeruginosa and not other Pseudomonas species?

  Pseudomonas aeruginosa is the only Pseudomonas species known to cause health issues. For this reason, regulations in many countries apply specifically to P. aeruginosa detection.

• What is the detection limit of Pseudalert?

  Pseudalert detects Pseudomonas aeruginosa at 1 cfu/100 mL or 1 cfu/250 mL.

• Is there a comparator for Pseudalert?

  There is no comparator for Pseudalert. For comparison, use a negative control when interpreting results. You can also refer to the Pseudalert Quick Reference Guide (PDF) for tips on reading results.

• What is the incubation time and temperature for samples tested with Pseudalert?

  Non-carbonated water samples are incubated at 38°C ±0.5°C for 24 hours, and results are valid up to 28 hours. Carbonated-water samples are incubated at 38°C ±0.5°C for 26 hours, and the results are valid up to 28 hours.

• Can I incubate at a different temperature, such as 36°C?

  No. Breakthrough of nontarget organisms can occur at temperatures other than 38°C ±0.5°C.

• Why do presence/absence (P/A) carbonated–water samples need to be incubated in a water bath while those in the Quanti-Tray® and Quanti-Tray®/2000 do not?

  The presence of carbonation has been shown to slow down the growth and detection of Pseudomonas aeruginosa in the Pseudalert prescence/absence (P/A) test. Incubating the Pseudalert P/A sample solution in a water bath helps to facilitate the release of residual carbonation not released during the degassing step and supports optimal growth of the bacteria. The design of Quanti-Tray and Quanti-Tray/2000 inherently helps release resolved carbonation.

• Are results valid prior to 24 hours?

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

• Can either a 51-well Quanti-Tray or a 97-well Quanti-Tray/2000 be used with Pseudalert?

  Yes, both the Quanti-Tray and Quanti-Tray/2000 can be used with Pseudalert in the 100 mL format but not the 250-mL format.

• Which vessels should I use with Pseudalert?

  For presence/absence testing, use a sterile, transparent, nonfluorescing vessel. For the Quanti-Tray and Quanti-Tray/2000 systems, any sterile vessel can be used.

• What are the recommended storage conditions for Pseudalert?

  Store Pseudalert at 2°C–30°C away from light.

• What color and consistency should the Pseudalert powder be?

  The Pseudalert reagent powder should be tan in color and free flowing. If you have any concerns about the color or integrity of the powder, contact IDEXX Technical Services.

• Why is antifoam solution needed when testing samples with Pseudalert in the Quanti-Tray or Quanti-Tray/2000?

  The mixing of sample and reagent can create foaming. IDEXX Antifoam Solution is needed to help the foaming subside before sealing the sample in the Quanti-Tray or Quanti-Tray/2000.