**2. Results**

Overall, 123 potable water samples were analyzed. Fifty-one of them were positive by plate culture. Among these, 37 (30%) were *L. pneumophila*, typed as serogroups 1 or 2–14 positive, 14 (11.4%) were *Legionella* non-*pneumophila* and 58.6% were negative. Since the Legiolert test is designed for specificity for *L. pneumophila* only, the 14 samples that were positive with non-*pneumophila Legionella* species samples were excluded from further statistical comparisons with Legiolert results.

Legiolert test results derived from 10 mL water samples showed that 34/123 (27.6%) samples were positive for *L. pneumophila*, whereas results from 100 mL water samples detected 37/123 (30%) positive samples, consistent with plate culture results. Among the 37 plate culture positive samples, four showed very low *Legionella* concentrations (50, 150, 300 and 600 CFU/L) and these were found negative by the Legiolert test in both 10 and 100 mL water samples.

As per ISO 17994:2014 [22], eight samples that were positive with the Legiolert 100 mL test and exceeded the MPN count by Legiolert (too numerous to count, TNTC) were excluded from calculations. Thus, Legiolert data were analyzed for each of the 28 or 33 positive samples from the 100 mL and 10 mL tests, respectively, and were compared with plate culture data. Data analysis did not show significant differences in *Legionella pneumophila* detection between the two Legiolert protocols (*p* = 0.83), or between either Legiolert test (Legiolert 10 mL, *p* = 0.82; Legiolert 100 mL, *p* = 0.2) and the plate culture method performed according to ISO 11731:1998 (Table 1).


**Table 1.** Comparison of Legiolert 10 mL and Legiolert 100 mL tests and plate culture according to ISO 17994:2014.
