[Contamination status and molecular biological characteristics of Legionella in cooling water samples from different places in Wuxi city].
OBJECTIVE
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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Wuxi Center for Disease Control and Prevention, Wuxi 214023, China.
Qi
Q
Zhang
Rong
R
Chen
Yong
Y
Xiao
Bin
B
Liu
Tian
T
Qin
Zhu-Jun
ZJ
Shao
Wei-Jie
WJ
Zhou
D000389:Air Conditioning; D000818:Animals; D002478:Cells, Cultured; D004783:Environmental Microbiology; D007875:Legionella / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification*; D016952:Legionella pneumophila / Q000254:growth & development / Q000302:isolation & purification; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D012703:Serotyping; D014871:Water Microbiology