For detection of Legionella pneumophila
- Detects Legionella pneumophila with equal or greater accuracy than traditional spread plate culture methods.
- Delivers definitive culture results in 7 days without additional confirmation steps.
- Simple culture test setup and read significantly reduce laboratory workflow.
- Easy-to-use platform, similar to that of the Colilert Test.
- Received NF Validation by AFNOR Certification, reference number IDX 33/06-06/19
- Specified as a recommended method in the Standing Committee of Analysts “Blue Book” publication
- Any brown colour and/or turbidity indicates a positive for Legionella pneumophila.
- Platform similar to that of the Colilert-18 Test: Ready-to-use reagents, no media preparation.
- Used with Quanti-Tray/Legiolert for Most Probable Number (MPN) enumeration.
- Confirmed results in 7 days without additional steps.
- Streamlined workflow with less than 2 minutes of hands-on time.
- Quality control procedure can be done in 15 minutes.
- Specifically detects Legionella pneumophila, the primary cause of Legionnaires’ disease.1
- Any brown colour and/or turbidity indicates a positive and minimises subjective result interpretation.
Why test for Legionella pneumophila?
99% of Legionnaires' disease cases in the United Kingdom and 97% of cases in the European Union are caused by L. pneumophila.2
How the Legiolert Test works
The Legiolert Test detects Legionella pneumophila in water samples. This test is based on a bacterial enzyme detection technology that signals the presence of Legionella pneumophila through utilisation of a substrate present in the Legiolert reagent. L.pneumophila cells grow rapidly and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the Legiolert reagent. Actively growing strains of L. pneumophila use the added substrate to produce a brown colour indicator. The Legiolert Test detects L. pneumophila at 1 organism in 100 mL within 7 days.
How to use
Learn how to use the Legiolert Test
100 ml protocol
Measure hardness of potable water sample and add corresponding Legiolert supplement.
Add reagent to water sample and shake to dissolve.
Pour sample into Quanti-Tray/Legiolert.
Pour sample into Quanti-Tray/Legiolert.
Read results: Any brown and/or turbid wells are positive for Legionella pneumophila.
Quanti-Tray/Legiolert provides Most Probable Number (MPN) results up to 2,272 per 100 mL sample.
The following instructions are for use with nonpotable water samples.
Add reagent to sterile diluent.
Treat nonpotable sample with Legiolert pretreatment.
Add pretreated sample to reagent mixture.
Pour sample into Quanti-Tray/Legiolert.
Frequently asked questions
The Legiolert test detects Legionella pneumophila in potable and nonpotable water samples. This test is based on a bacterial enzyme-detection technology that signals the presence of Legionella pneumophila through utilization of a substrate present in the Legiolert reagent. Legionella pneumophila cells grow rapidly and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the Legiolert reagent. Actively growing strains of Legionella pneumophila use the added substrate to produce a brown color indicator. The Legiolert test detects Legionella pneumophila at 1 organism in 100 mL within 7 days.
The Legiolert test is designed to specifically detect the primary causative agent of Legionnaires’ disease, which is Legionella pneumophila.
When using the protocol for potable water, the Legiolert test detects Legionella pneumophila at ≥1 organisms/100mL. When using the protocol for nonpotable water, the Legiolert test detects Legionella pneumophila at ≥1 organisms/mL (≥1000 organism/1 L).
Any wells with a brown color and/or turbidity are positive for Legionella pneumophila. No other colors are positive for Legionella pneumophila.
There is no comparator for the Legiolert test. For comparison, use a negative control when interpreting results.
Potable water samples are incubated at 39°C (± 0.5°C) for 7 days. Nonpotable water samples are incubated at 37°C (± 0.5°C) for 7 days. Do not remove trays completely from incubator prior to final read. Results can be read any time on the 7th day.
No, false-positive results due to bacteria other than Legionella pneumophila and/or reduced Legionella pneumophila detection can occur at temperatures other than 39°C (± 0.5°C) for potable samples and 37°C (± 0.5°C) for nonpotable samples.
The Legiolert test requires a humidity level that ensures ≤15% sample volume loss in the Quanti-Tray/Legiolert wells. Appropriate humidity can typically be achieved by placing a pan of water on the bottom of the incubator so that it covers approximately 80% of the bottom interior surface. Alternatively, a non-humidified incubator may be used by incubating Quanti-Tray/Legiolert in a container that traps moisture.
Yes, if the results are positive. An inoculated Legiolert test sample that is positive before 7 days is a confirmed positive test for L. pneumophila. However, for an accurate quantitative determination of L. pneumophila in a sample, the results should be read at 7 days. Do not remove trays completely from incubator prior to final read.
Yes, if the results are negative. If an inoculated Legiolert test sample is inadvertently incubated for more than 7 days, the lack of brown color and turbidity is a valid negative test result. However, brown color and/or turbidity that develops after 7 days is not a valid positive test result; the test should be repeated or verified.
No, the Legiolert Test can only be used with Quanti-Tray/Legiolert and it must be incubated paper-side down.
If you are unsure whether your water is potable or nonpotable, please contact IDEXX Technical Services at 1-800-321-0207 for assistance.
The Legiolert reagent powder should be very light to light tan in color and free-flowing. If you have any concerns about the color or integrity of the powder, contact IDEXX Technical Services at 1-800-321-0207.
Check with your local, state, and/or federal authorities for proper disposal of bacteriological biohazard materials at your facility.
The Legiolert test is not currently included in Standard Methods. IDEXX will pursue a listing for this test, as appropriate.
IDEXX plans to conduct regulatory trials in countries where Legionella pneumophila is regulated for potable and/or nonpotable water. Please refer to our approval map for updated approvals.
Varied sample temperatures were not validated during the Legiolert test product development. All samples tested were at room temperature before the testing began.
Legionella pneumophila ATCC 33152 (WDCM 00107) or ATCC 33156 (WDCM 00180) are recommended positive control strains. Enterococcus faecalis ATCC 29212 (WDCM 00087) is a recommended negative control strains.
Yes, the Binder incubator sold by IDEXX Water is able to handle the higher humidity required by the Legiolert Test. Appropriate humidity can typically be achieved by placing a pan of water on the bottom of the incubator so that it covers approximately 80% of the bottom interior surface.
Yes, the Legiolert potable and nonpotable protocols have each been designed for optimal performance with different types of water. Testing a nonpotable sample with the potable protocol may provide false-positive results due to bacteria other than Legionella pneumophila. Testing a potable sample with the nonpotable protocol may result in reduced Legionella pneumophila detection due to the pretreatment step and smaller volume of sample tested.
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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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Legiolert (20-test pack)
Product Number: 98-0002710-00
Catalog Number: WLGT-20
Legiolert (100-test pack)
Product Number: 98-0005738-00
Catalog Number: WLGT-100
Product Number: 98-0007740-00
Catalog Number: WLGT-PRE
Product Number: 98-0005745-00
Catalog Number: WLGT-SUP
Quanti-Tray/Legiolert (20 pack)
Product Number: 98-0005796-00
Catalog Number: WQTLGT-20
Quanti-Tray/Legiolert (100 pack)
Product Number: 98-0005754-00
Catalog Number: WQTLGT-100
IDEXX-QC Legionella pneumophila
Product Number: 98-0009287-00
Catalog Number: UN3373-WQC-P
Water Customer Support
IDEXX Technologies Ltd Units 1B & 1C
Newmarket Business Park
Studlands Park Avenue
Newmarket, Suffolk, CB87ER
Tel: 01638 676800
1. Brunette GW, ed. CDC Health Information for International Travel 2016: The Yellow Book. New York, NY: Oxford University Press; 2016.
2. Source: 2014-2016 PHE Data, https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/696376/2016_Annual_Report_final.pdf