IDEXX has welcomed the publication of a study1 carried out by the Public Health Laboratory of L’Hospitalet in Barcelona, Spain, which compared the IDEXX Legiolert® test with the standard method for detection and enumeration of Legionella (ISO 11731).
Comparing the methods in both potable and non-potable water samples according to the rigorous ISO 17994 protocol, the study found that Legiolert detected more positive results than ISO 11731 and was statistically more sensitive for Legionella pneumophila.
Additionally, Legiolert was compared to ISO 11731 for the detection of all Legionella species, and while ISO 17994 results demonstrate the two methods to be statistically equivalent, Legiolert was found to be more sensitive.
The study found that all Legiolert results were confirmed to be Legionella pneumophila, indicating a specificity of 100% and no false positives. The authors of the study also noted the procedural advantages of Legiolert, and suggest that it is an easier-to-use test that could be performed more frequently than the standard ISO 11731 method.
Legiolert uses bacterial enzyme detection technology to identify and enumerate Legionella pneumophila, the principal cause of Legionnaires’ disease. This latest study is notable because it shows that despite being specific to Legionella pneumophila, Legiolert even outperforms ISO 11731 when other Legionella species results are included.
These results convinced the study authors to utilise Legiolert instead of the traditional plate method whenever possible in order to minimise the risk of Legionnaires´ disease in their community.
Full details of the study can be found here: https://doi.org/10.1016/j.mimet.2021.106242
This latest study confirms conclusions from other trials conducted with Legiolert, which in 2019 received NF Validation by AFNOR certification; and in 2020 was accepted by the UK’s Standing Committee of Analysts (SCA) and is specified as a recommended method in the Committee’s “blue book” publication of “The determination of Legionella bacteria in waters and other environmental samples (2020) – Part 2 – Culture Methods for their detection and enumeration.”
Several international peer-reviewed studies also show it to be more accurate and more sensitive than traditional plate methods, and importantly, these have shown the incidence of false negative results is lower, so dangerous bacteria are less likely to be missed.2-7 Legiolert was designed to identify all serogroups of Legionella pneumophila, not just the most common, serogroup 1. The increased sensitivity of the test means using Legiolert can minimise the risk that a dangerous level of the bacteria would not be detected and controlled before causing disease.
Legiolert uses bacterial enzyme detection technology to identify and enumerate Legionella pneumophila in drinking water and other building water systems. It supplies nutrients which allow any target Legionella pneumophila cells present in a water sample to grow rapidly, and an indicator in the reagent changes colour to signal their presence. The test reagent also contains inhibitors to suppress non-target organisms to avoid overgrowth of other bacteria.
The test is simple to use and requires minimal training and equipment to set up, giving confirmed results in 7 days, around half the time of traditional agar-based methods. Legiolert simplifies and accelerates water testing, reducing risks posed by the potentially fatal Legionnaires’ disease by generating highly reliable data and enabling faster remedial action.
For more information on Legiolert and IDEXX Water please contact:
IDEXX Water UK, Units 1B and 1C, Newmarket Business Park, Studlands Park Avenue, Newmarket, Suffolk CB8 7ER
T: 01638 676800
1 Checa, J., Carbonell, I., Manero, N., & Marti, I. (2021) Comparative study of Legiolert with ISO 11731-1998 standard method-conclusions from a Public Health Laboratory. Journal of Microbiological Methods, 186. https://doi.org/10.1016/j.mimet.2021.106242
2 Spies, K. Pleischl, B., Lange B., Longer, B., Hübner, J., Jurzki, L., Luden, K., Exner, M. International Journal of Hygiene and Environmental Health 221 (2018) 1047–1053. Full text at https://www.sciencedirect.com/science/article/pii/S1438463917306818
3 Sartory, D., Spies, K., Lange, B., Schneider, S. and Langer, B. (2017), Evaluation of a most probable number method for the enumeration of Legionella pneumophila from potable and related water samples. Letters in Applied Microbiology, 64: 271-275. https://doi.org/10.1111/lam.12719
4 Petrisek, R., & Hall, J. (2018) Evaluation of a most probable number method for the enumeration of Legionella pneumophila from North American potable and nonpotable water samples. Journal of Water and Health, 16(1):25–33. https://doi.org/10.2166/wh.2017.118
5 Rech, M.M., Swalla, B.M., & Dobranic, J.K. (2018) Evaluation of Legiolert for Quantification of Legionella pneumophila from Non-potable Water. Current Microbiology, 75:1282–1289 https://doi.org/10.1007/s00284-018-1522-0
6 Barrette, I. (2019) Comparison of Legiolert and a Conventional Culture Method for Detection of Legionella pneumophila from Cooling Towers in Québec, Journal of AOAC INTERNATIONAL, 102(4):1235–1240. https://doi.org/10.5740/jaoacint.18-0245
7 Monteiro, S.N., Robalo, A.M. & Santos, R.J. (2021) Evaluation of Legiolert™ for the Detection of Legionella pneumophila and Comparison with Spread-Plate Culture and qPCR Methods. Current Microbiology, 78, 1792–1797. https://doi.org/10.1007/s00284-021-02436-6
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