Comparative study of Legiolert with ISO 11731-1998 standard method-conclusions from a Public Health Laboratory

Published on 01/11/2022 | by Waterline Admin

Checa J, Carbonell I, Manero N, Martí I.

J Microbiol Methods. 2021 Jul;186:106242. doi: 10.1016/j.mimet.2021.106242. Epub 2021 May 18. PMID: 34019935.



  • Legiolert and the standard method detected a similar percentage of positive samples, with Legiolert being slightly higher (31 vs 30%) and detecting higher concentrations of Legionella within the samples.
  • ISO 17994:2014 analysis of the potable water samples found Legiolert was more sensitive than the standard at detecting Legionella, even when complete Legionella species (L. spp.) results were considered for both methods.
  • The comparison is significantly more in favour of Legiolert when only L. pneumophila results are considered. Each confirmation run with material extracted from positive Legiolert wells contained L. pneumophila, giving the method a specificity of 100%.
  • Although statistical results for non-potable waters are not included because of the low number of samples, the two methods trended towards equivalence.

Conclusions: Relative to the Standard method, Legiolert has a greater sensitivity and selectivity, and appears to have higher recovery for L. pneumophila, and equivalent recovery when L. spp. is included in the comparison. Legiolert also has high specificity. The procedural advantages of Legiolert allow laboratories to save on resources, costs, and time and consequently to test more frequently. In conclusion, the study finds IDEXX Legiolert a suitable alternative to ISO 11731:1998.



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