Three quantitative methods to continuously monitor Legionella in spring water / 中华预防医学杂志

<p><b>OBJECTIVE</b>To compare the detection effect of Legionella pollution in spring water by three methods, namely traditional plating method, fluorescent quantitation PCR method and ethidium monoazide (EMA) fluorescent quantitation PCR method.</p><p><b>METHODS</b>Every month (except May), we collected 11 water samples from the 5 selected hot spring pools in one hot spring resort in Beijing in 2011. A total of 121 water samples were collected, and then were detected by the above three methods qualitatively and quantitatively.</p><p><b>RESULTS</b>In our study, the Legionella pollution rate was separately 74.4% (90/121), 100.0% (121/121) and 100.0% (121/121) by the above three methods. The quantitative value of Legionella in the 121 water samples detected by the three methods were around 0.10-216.00 colony-forming units (CFU)/ml, 1.47-1557.75 gene units (GU)/ml and 0.20-301.69 GU/ml, respectively. The median (25th and 75th percentiles) was 75.30 (32.51-192.10) GU/ml, 36.46 (16.08-91.21) GU/ml and 5.30 (0.00-33.70) CFU/ml, respectively. The difference in the quantitative value of Legionella detected by the three methods showed statistical significance (χ(2) = 187.900, P < 0.01). The quantitative value of Legionella detected by fluorescent quantitation PCR method was the highest, followed by the value Legionella detected by EMA-fluorescent quantitation PCR method and traditional plating method.</p><p><b>CONCLUSION</b>The sensitivity of the PCR methods was higher than traditional plating method, in detecting Legionella pollution in spring water, especially the EMA- fluorescent quantitation PCR method, which was more suitable for detecting Legionella in water.</p>

Study on the status of pollution by Legionella species in hot spring vacation center and the related factors / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the pollution status of Legionella species in hot spring vacation center and the related factors.</p><p><b>METHODS</b>Field surveys were performed in four big hot spring vacation centers of Changping district. Uniform questionnaires was used and colony count was made together with the isolation of Legionella species from hot spring water based on mip gene typing.</p><p><b>RESULTS</b>47 isolates of Legionella pneumophila (Lp) from 87 samples showed 4 serotypes as Lp1, Lp6, Lp12, Lp5 with percent of 57.45%, 21.28%, 14.89%, 6.38% respectively. The hot spring centers controlled the temperature of recycled water between 34-47 degrees C by hot water heating and filtrating system. All the isolates were cultured from the hot water with temperature between 34-44 degrees C: 56.75% (21/37) in high temperature (40-47 degrees C) and 61.90% (26/42) in low temperature (34-39.9 degrees C). There were no statistically significant difference between the high and the low temperature samples (P > 0.05). In the four hot spring vacation centers, the pH value was under control at 6.4-7.3 and the ambient temperature was under control between 26-28 degrees C. The humidity was controlled between 56% -69% relative humidity, which were the best growing conditions for the Legionella species. Disinfectors as chlorine deviratives was used in the four hot spring vacation centers. Though the concentration of chlorine in the water was 0.3-0.5 mg/L, 14.29%-48.00% of the samples were still positive of having Legionella species.</p><p><b>CONCLUSION</b>The pollution of Legionella species was considered to be quite serious in the four hot spring vacation centers and the predominant serotype was Lp1. The pH and temperature of the hot spring water, ambient temperature and humidity and the way of heating up the water were the best conditions for the growth of Legionella species in these centers. Because of the high temperature of the hot spring water, chlorine of the disinfector volatilized quickly, affecting the effect of disinfection. The result revealed that water temperature achieving 44 degrees C could have had the effect of prevention.</p>