Osaka Institute of Public Health, 1-3-69 Nakamichi, Higashinari, Osaka, 537-0025, Japan.
Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Sci Rep. 2017 Jun 8;7(1):3092. doi: 10.1038/s41598-017-03293-9.
Legionnaires' disease, predominantly caused by the bacterium Legionella pneumophila, has increased in prevalence worldwide. The most common mode of transmission of Legionella is inhalation of contaminated aerosols, such as those generated by cooling towers. Simple, rapid and accurate methods to enumerate L. pneumophila are required to prevent the spread of this organism. Here, we applied a microfluidic device for on-chip fluorescent staining and semi-automated counting of L. pneumophila in cooling tower water. We also constructed a portable system for rapid on-site monitoring and used it to enumerate target bacterial cells rapidly flowing in the microchannel. A fluorescently-labelled polyclonal antibody was used for the selective detection of L. pneumophila serogroup 1 in the samples. The counts of L. pneumophila in cooling tower water obtained using the system and fluorescence microscopy were similar. The detection limit of the system was 10 cells/ml, but lower numbers of L. pneumophila cells (10 to 10 cells/ml) could be detected following concentration of 0.5-3 L of the water sample by filtration. Our technique is rapid to perform (1.5 h), semi-automated (on-chip staining and counting), and portable for on-site measurement, and it may therefore be effective in the initial screening of Legionella contamination in freshwater.
军团病主要由细菌嗜肺军团菌引起，在全球范围内的发病率不断增加。军团菌最常见的传播方式是吸入受污染的气溶胶，例如冷却塔产生的气溶胶。需要简单、快速和准确的方法来对嗜肺军团菌进行计数，以防止该生物的传播。在这里，我们应用微流控装置在芯片上对冷却塔水中的嗜肺军团菌进行荧光染色和半自动计数。我们还构建了一个便携式系统，用于快速现场监测，并使用该系统对快速流过微通道的目标细菌细胞进行计数。荧光标记的多克隆抗体用于选择性检测样品中的嗜肺军团菌血清群 1。使用该系统和荧光显微镜获得的冷却塔水中的嗜肺军团菌计数相似。该系统的检测限为 10 个细胞/ml，但通过过滤浓缩 0.5-3 L 水样后，可以检测到数量较少的嗜肺军团菌细胞（10 到 10 个细胞/ml）。我们的技术快速（1.5 小时）、半自动（芯片上染色和计数）且便于现场测量，因此可能有效用于淡水军团菌污染的初步筛选。
