Detection of Legionella by quantitative-polymerase chain reaction (qPCR) for monitoring and risk assessment

Table 1 Comparison of culture and qPCR for quantification of Legionella.

				Number of positive samples			Concentrations
				Culture	qPCR		Culture	qPCR
Sampling	Sampling site	Type of sample	No of samples	Legionella spp	Legionella spp	Legionella pneumophila	Legionella spp 10⁴ CFU/L	Legionella spp10⁴ GU/L	Legionella pneumophila 10⁴ GU/L
	Circulation water	B	1	1	1	1	5.5	3.4	3.6
Before the first intervention	Empty apartment	A	0
	Shower hose	A	1	1	1	1	60	26	14
	Circulation water	B	10	10	10	10	0.005 - 1.2 [0.08]	0.77 - 2.9 [1.5]	0.6 - 2.6 [1.1]
After the first intervention	Empty apartment	A	4	4	4	4	1.9 - 33 [19]	2.9 - 24 [8.9]	4.9 - 19 [11]
	Shower hose	A	5	5	5	5	0.8 - 160 [27]	3.5 - 96 [28]	1.1 - 43 [17]
	Circulation water	B	16	0	16	13	BD	0.4-1.9 [0.62]	BD - 2.0 [0.27]
After the second intervention	Empty apartment	A	2	1	2	2	BD - 0.001	3.2 - 55 [29]	3.7 - 68 [36]
	Shower hose	A	8	0	8	8	BD	0.17 - 2.3 [0.95]	0.033 - 3.2 [1.3]

Number of samples and amount of Legionella detected in samples from circulation water, from first flush of taps in empty apartments and from first flush of shower hoses by culture and by Legionella pneumophila and Legionella species qPCR assays before and after interventions. Samples were collected as first flush (A) or after reaching constant temperature (B). BD: Below detection. Median value is given in [..]