PDF(Pubmed)
Abstract：
Legionella is the causative agent of Legionnaires\' disease, and its prevalence in potable water is a significant public health issue. Water stagnation within buildings increases the risk of Legionella. However, there are limited studies investigating how stagnation arising through intermittent usage affects Legionella proliferation and the studies that are available do not consider viable but non culturable (VBNC) Legionella. This study used a model plumbing system to examine how intermittent water stagnation affects both VBNC and culturable Legionella. The model plumbing system contained a water tank supplying two biofilm reactors. The model was initially left stagnant for ≈5 months (147 days), after which one reactor was flushed daily, and the other weekly. Biofilm coupons, and water samples were collected for analysis at days 0, 14 and 28. These samples were analysed for culturable and VBNC Legionella, free-living amoebae, and heterotrophic bacteria. After 28 days, once-a-day flushing significantly (p < 0.001) reduced the amount of biofilm-associated culturable Legionella (1.5 log10 reduction) compared with weekly flushing. However, higher counts of biofilm-associated VBNC Legionella (1 log10 higher) were recovered from the reactor with once-a-day flushing compared with weekly flushing. Likewise, once-a-day flushing increased the population of biofilm-associated Vermamoeba vermiformis (approximately 3 log10 higher) compared with weekly flushing, which indicated a positive relationship between VBNC Legionella and V. vermiformis. This is the first study to investigate the influence of stagnation on VBNC Legionella under environmental conditions. Overall, this study showed that a reduction in water stagnation decreased culturable Legionella but not VBNC Legionella.
摘要：
军团菌是军团菌病的病原体，它在饮用水中的流行是一个重要的公共卫生问题。建筑物内的水停滞会增加军团菌的风险。然而,有有限的研究调查了通过间歇性使用引起的停滞如何影响军团菌增殖，并且现有的研究没有考虑可行但不可培养的军团菌（VBNC）。这项研究使用了一个模型管道系统来研究间歇性水停滞如何影响VBNC和可培养军团菌。模型管道系统包含一个水箱，可供应两个生物膜反应器。该模型最初停滞了约5个月（147天），之后每天冲洗一个反应堆，另一个每周。生物膜优惠券,在第0、14和28天收集水样进行分析。对这些样本进行了可培养和VBNC军团菌分析，自由生活的变形虫，和异养细菌。28天后,与每周冲洗相比，每天一次的冲洗显着（p<0.001）减少了与生物膜相关的可培养军团菌的数量（减少1.5log10）。然而,与每周冲洗相比,每天冲洗一次从反应器中回收的生物膜相关VBNC军团菌计数较高(高1log10).同样，与每周潮红相比，每天一次的潮红增加了与生物膜相关的VermamoebaVermiformis的数量（大约高3log10），表明VBNC军团菌与V.vermiformis呈正相关。这是首次研究环境条件下停滞对VBNC军团菌的影响。总的来说,这项研究表明，水停滞的减少减少了可培养的军团菌，而不是VBNC军团菌。
