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.

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.

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.

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

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.

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.

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

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.

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.

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.

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.

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.

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

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

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®.