Search

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.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.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, P0.01). 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.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.

To investigate the contamination state of Legionella in cooling water samples from different places in Wuxi city and reveal the molecular biological characteristics of Legionella strains.112 parallel water samples (500 ml each) were collected from 56 sites in Wuxi city during year 2009 - 2010. The samples were used for Legionella test and quantitative culture. The isolated Legionella strains were used for serotyping, pulsed-field gel electrophoresis (PFGE), sequence-based typing (SBT), and intracellular growth were tested.The positive proportion of Legionella was 39. 3% (22/56) among all sampling sites. A total of 29 Legionella strains were isolated, and the serotypes include LP1, LP3, LP5 and LP6. LP1 serotype was the major one with a proportion of 65.5% (19/29). 29 Legionella strains got 17 PFGE types. There were 10 SBT types among 10 Legionella strains with different PFGE types. Comparing to LP1 strain (ATCC 33152), WX2011062 (LP6) and WX2011067 (LP5) had strong intracellular growth ability in mouse peritoneal macrophages J774 cell line (the amount of intracellular bacteria on day 0 after infection were (5.5 +/- 1.32) x 10(5), (3.9 +/- 0.60) x 10(5), (7.8 +/- 0.76) x 10(5) CFU/ml, respectively; the amount of intracellular bacteria on day 3 after infection were (58.3 +/- 1.61) x 10(5), (2700.0 +/- 655.74) x 10(5), (3066.7 +/- 208.17) x 10(5) CFU/ml, respectively).The Legionella contamination existed in cooling water samples from different places in Wuxi city. Legionella strains isolated showed high genetic variation. Some Legionella strains had vigorous intracellular growth ability.

To analyze the characteristics of Sequence-based Typing (SBT) of the Serotype 1 Legionella pneumophila (Lp1) isolated from environmental water in China, and then create a preliminary database.A total of 82 strains of Lp1 isolated from environmental water in 9 provinces of China between 2005 and 2008 were genotyped by SBT method and Pulsed-field Gel Electrophoresis (PFGE) method. The results of the two different typing methods were then compared by cluster analysis, adopting BioNumerics version 5.1 software.By SBT method, the 82 strains of Lp1 were divided into 22 ST types, of which 17 new types and one new allele was discovered. The dominant type was ST-1 type, found in 8 provinces, accounting for 46.3% (38/82). ST-1, ST-150, ST-154, ST-159, ST-160 and ST-630 types were found in more than 2 isolated-sites; while more than 2 different ST types were found in 5 isolated-sites, as site B4, B5, B6, S3 and S8. In cluster analysis, 15 ST types were grouped into three complexes (ST-1 complex, ST-154 complex and ST-149 complex); and the other 7 ST types were not assigned complex. By PFGE method, 46 banding patterns were observed. As a result of the combination of the two methods, the 82 isolates strains could be divided into 54 molecular types, which showed a reliable accordance in the cluster analysis between the two methods.The SBT of the Lp1 in environmental water in China was unique. From the study, a preliminary SBT database was set up.