[Investigation of Legionella contamination in artificial water environment of public places and identification of its pathogenic types in Shanghai from 2011 to 2018].

ABSTRACT

Objective: To understand the epidemiological and pathogenic characteristics of Legionella in artificial water environment of public places in Shanghai from 2011 to 2018, and to provide scientific basis for the prevention and control of Legionellosis. Methods: A total of 4 817 samples of artificial water environment were collected from 31 public places in Huangpu, Jing'an, Xuhui and Songjiang districts of Shanghai from 2011 to 2108. Epidemiological characteristics of the collected years and months, regional and site types, and sample types were analyzed. After treatment, culture and isolation of the collected water samples, the positive samples were analyzed for Legionella typing characteristics. Results: The positive rate of Legionella pneumophila was 21.57% (1 039/4 817), of which 96.25% (1 000/1 039) was single type, 84.31% (876/1 039) was Legionella pneumophila type 1, followed by Legionella pneumophila type 7 and 6, which accounted for 4.72% (49/1 039) and 3.75% (39/1 039), respectively, and 29 (29/1 039) were multi-type positive. Further typing. From May to October, the highest positive rates were found in July and August, 27.61%(222/804)and 28.61% (230/804)respectively. There were significant differences between different months (P<0.001); the highest positive rates were found in central air-conditioning cooling water and chilled water (32.40%) and there were significant differences among different water samples (P<0.001). Legionella pneumophila type 1, type 7 and type 6 were the main diversity distribution characteristics in artificial water environment of different regions, different time, different places and different types of public places. Legionella pneumophila type 1 accounted for the highest proportion, and the proportion of positive samples under different epidemiological characteristics was more than 71.64%. Conclusion: There is relatively serious pollution of Legionella pneumophila type 1 in the artificial water environment of public places in Shanghai. It is necessary to strengthen the disinfection of cooling water/freezing water of central air conditioning in public places in July and August every year.