TABLE 3.
Comparison of results of plating and real-time PCR for water samples from spas
| Sample no.a | Free chlorine concn (ppm) | No. of Legionella cells by plating (log10 CFU/100 ml)b | No. of Legionella cells estimated by real-time PCR (log10 CFU/100 ml)c
|
||||
|---|---|---|---|---|---|---|---|
| No EMA treatment | Treatment with EMA
|
||||||
| 1 μg/ml | 5 μg/ml | 10 μg/ml | 20 μg/ml | ||||
| 1 | 1.0 | 1.3 | 3.2 | ND | ND | ND | 1.4 |
| 2 | 0.1 | 2.4 | 2.2 | ND | ND | ND | 1.3 |
| 3 | 0.5 | 1.3 | 2.8 | 1.9 | 1.3 | — | — |
| 4 | 0 | 3.0 | 3.2 | 2.9 | 2.4 | 2.2 | 1.9 |
| 5 | 0.1 | 1.3 | — | — | — | — | — |
| 6 | 3 | <1 | — | — | — | — | — |
| 7 | 2 | <1 | — | — | — | — | — |
| 8 | 0 | 1 | — | — | — | — | — |
| 9 | 2.4 | <1 | — | — | — | — | — |
| 10 | 0 | <1 | — | — | — | — | — |
| 11 | 0 | <1 | — | — | — | — | — |
| 12 | 0 | <1 | — | — | — | — | — |
| 13 | 0 | <1 | — | — | — | — | — |
| 14 | 0 | 2.9 | 3.0 | 3.1 | 3.0 | 2.7 | 1.9 |
| 15 | 0 | 3.8 | 4.0 | 3.9 | 3.8 | 3.1 | 3.0 |
| 16 | 0 | 4.8 | 5.2 | 4.7 | 3.8 | 3.1 | — |
| 17 | 0 | 4.8 | 5.4 | 4.3 | 3.5 | 2.9 | 2.3 |
| 18 | 0 | 4.6 | 5.2 | 4.4 | 3.5 | 2.5 | 2.2 |
| 19 | 0.01 | 5.4 | 5.9 | 5.5 | 5.5 | 4.0 | 3.0 |
| 20 | 2.5 | 3.6 | 5.5 | 4.8 | 3.8 | 3.1 | 2.8 |
| 21 | 3.5 | 1.8 | 5.2 | 3.3 | 2.6 | 2.1 | 1.6 |
| 22 | 6.4 | 1.5 | 4.0 | 3.6 | 3.4 | 1.6 | — |
| 23 | 8.1 | <1 | 3.3 | 1.4 | 1.3 | 0.7 | 0 |
| 24 | 8.2 | <1 | 3.0 | 1.2 | 1.3 | 0.7 | — |
| 25 | 8.3 | <1 | 3.8 | 3.6 | 1.1 | 1 | — |
a
Samples 1, 2, and 7 to 9 were obtained from bathtubs, samples 3 to 5 were from filter tanks, and sample 6 was from a pipeline of public spas. Samples 10 to 17 were obtained from the bathtub and samples 18 to 25 were from the filter tank of a model spa.
b
The number of bacteria was determined by plating cells on GVPC plates.
c
Real-time PCR was performed with primers LEG427F and LEG880R and probe P1. ND, not done; —, not detected.