Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel.
Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany.
Water Res. 2015 Jun 15;77:119-132. doi: 10.1016/j.watres.2015.03.010. Epub 2015 Mar 25.
Bacteria of the genus Legionella cause water-based infections, resulting in severe pneumonia. To improve our knowledge about Legionella spp. ecology, its prevalence and its relationships with environmental factors were studied. Seasonal samples were taken from both water and biofilm at seven sampling points of a small drinking water distribution system in Israel. Representative isolates were obtained from each sample and identified to the species level. Legionella pneumophila was further determined to the serotype and genotype level. High resolution genotyping of L. pneumophila isolates was achieved by Multiple-Locus Variable number of tandem repeat Analysis (MLVA). Within the studied water system, Legionella plate counts were higher in summer and highly variable even between adjacent sampling points. Legionella was present in six out of the seven selected sampling points, with counts ranging from 1.0 × 10(1) to 5.8 × 10(3) cfu/l. Water counts were significantly higher in points where Legionella was present in biofilms. The main fraction of the isolated Legionella was L. pneumophila serogroup 1. Serogroup 3 and Legionella sainthelensis were also isolated. Legionella counts were positively correlated with heterotrophic plate counts at 37 °C and negatively correlated with chlorine. Five MLVA-genotypes of L. pneumophila were identified at different buildings of the sampled area. The presence of a specific genotype, "MLVA-genotype 4", consistently co-occurred with high Legionella counts and seemed to "trigger" high Legionella counts in cold water. Our hypothesis is that both the presence of L. pneumophila in biofilm and the presence of specific genotypes, may indicate and/or even lead to high Legionella concentration in water. This observation deserves further studies in a broad range of drinking water systems to assess its potential for general use in drinking water monitoring and management.
军团菌属的细菌引起基于水的感染，导致严重肺炎。为了提高我们对军团菌属生态的认识，研究了其流行情况及其与环境因素的关系。从以色列一个小型饮用水分配系统的七个采样点采集了季节性水样和生物膜样本。从每个样本中获得代表性分离株，并鉴定到种水平。进一步确定嗜肺军团菌的血清型和基因型水平。通过多位点可变数串联重复分析（MLVA）对嗜肺军团菌分离株进行高分辨率基因分型。在所研究的水系统中，军团菌平板计数在夏季较高，即使在相邻的采样点之间也高度可变。在七个选定的采样点中有六个点存在军团菌，计数范围为 1.0×10(1) 到 5.8×10(3) cfu/l。在存在生物膜的点，水中的军团菌计数明显更高。分离的军团菌的主要部分是血清群 1 的嗜肺军团菌。还分离到血清群 3 和圣西缅军团菌。军团菌计数与 37°C 时的异养平板计数呈正相关，与氯呈负相关。在采样区域的不同建筑物中鉴定出 5 种 MLVA 基因型的嗜肺军团菌。“MLVA 基因型 4”的特定基因型的存在与高军团菌计数一致，并似乎“触发”冷水中的高军团菌计数。我们的假设是，嗜肺军团菌在生物膜中的存在和特定基因型的存在，可能指示甚至导致水中的高军团菌浓度。这一观察结果值得在广泛的饮用水系统中进一步研究，以评估其在饮用水监测和管理中的潜在用途。
