Rapid detection of total and viable Legionella pneumophila in tap water by immunomagnetic separation, double fluorescent staining and flow cytometry.
Bottom Line: The recovery is over 85% of spiked Lp SG 1 cells in 1 l of tap water and detection limits are around 50 and 15 cells per litre for total and viable Lp, respectively.In 53% of the water samples from different taps and showers significantly higher concentrations of Lp were detected by flow cytometry.No correlation to the plate culture method was found.
Affiliation: Swiss Federal Institute for Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600, Dübendorf, Switzerland.Show MeSH
Mentions: Since we demonstrated previously that Lp quantification by FCM and IFM agree very well (Füchslin et al., 2010), the spiking counts were determined by FCM. When applying our gating approach for spiked tap water samples it was possible to discriminate Lp cells very well from background signals in the main fluorescence dot plots, i.e., green versus blue fluorescence; the negative controls contained very few background noise events (Fig. 2A and B, and supporting data in Figs S1 and S2). Background noise events (false positives) for total and viable Lp were 26.0 ± 8.0 and 8.0 ± 2.5 events l−1 (n = 15), respectively.
Affiliation: Swiss Federal Institute for Aquatic Science and Technology (Eawag), Überlandstrasse 133, CH-8600, Dübendorf, Switzerland.