| Objective:To investigate the contamination of legionella and amoeba in hospital water distribution systems, and to analyze the associated risk factors. Methods:193 water samples from the water distribution systems of 8 hospitals in Shanghai were collected. The water samples were cultured for legionella species and amoeba, and latex agglutination test were used to identify the serogroups of legionella. Meanwhile, the temperature and pH value were tested and associated factors of water distribution systems were collected. Results:Among the 8 sampling hospitals,7 (87.5%) were contaminated by legionella species,7 hospitals were detected with high level contamination of legionella species, while 2 hospitals were detected with high level contamination of legionella pneumophila (contamination rate≥30%). From 193 water samples that have been collected,83 (43.0%) were positive for legionella species, including 33 for legionella pneumophila.166 in 193 samples had isolated amoeba (86.0%). Among 83 legionella positive samples, as many as 63 samples had the concentration≥103 cfu/l and 22 samples≥104 cfu/l.26 water samples were collected from the intensive care unit (ICU), 11 were positive for legionella species, and 6 for legionella pneumophila. All samples from ICU had the concentration≥103 cfu/l. In the risk factors analysis for legionella contamination, the contamination of amoeba, lack of disinfection of distribution systems, use of galvanized Steel Pipe and use of tank for water distribution were independent risk factors. Conclusions:Most of the investigated hospitals have high levels contamination and high concentration of legionella species in Shanghai, which would likely to acquire legionellosis. Active surveillance of water distribution systems and hospital acquired legionellosis should be conducted and disinfection of the water distribution systems should be considered.Objective:To classify 25 strains of Legionella pneumophila serogroup 1 (LP1) from shanghai using genotyping methods, reveal the relationship between 25 strains and compare the results of 3 genotyping methods. Methods:25 strains of LP1 were subtyped using pulse field gel electrophoresis (PFGE), sequence based typing (SBT) and PCR of repetitive chromosomal elements (Rep-PCR). Genotyping results of PFGE and Rep-PCR were classified as dendrogram, and results of SBT were submitted to the SBT website, a ST number can be given according to the sequence uploaded. Results: 24 strains belong to 6 PFGE genotypes, of which 21 belong to A/B/E predominant genotypes. SBT classified 25 strains of LP1 into 7 catalog, most of the strains belong to the ST-1 and ST-780. Two unique SBT types were also confirmed in shanghai, China (ST-780 and ST-784). Rep-PCR classified 24 strains of LP1 into 4 blocks. Strains have the similarity≥98.6% belong to the same type of LP1. Block A consisted of 11 strains of LP1, which were isolated from hospital No.1, hospital No.2 and hospital No.6, can be divided into 7 types according to the similarity. Block B consisted of 6 strains mainly isolated from hospital No.5, can divided into 4 types according to the similarity and electrophoresic bands.The existing of predominant strains and sporadic strains were also been detected in the water distribution systems in Shanghai, the different hospitals shared the same genotype, and strains of the same hospital may belong to different genotypes. Among the three genotyping methods, SBT and Rep-PCR could save a lot of time, and were easy to operate. SBT had the most accurate results as the method was based on the direct sequencing of the 7 loci, and made it convenient to compare the results among laboratories, although the price was a bit higher. PFGE gave the best resolution of the strains, but it depended on the experiences of the operator and was different to compare the results with each other. Conclusions:Because different hospitals shared the same genotype, and strains of the same hospital may belong to different genotypes, Molecular study should be conducted during epidemiological study of hospital acquired legionellosis. SBT provide the most accurate results of subtype while PFGE provide the best resolution.
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