冷却塔军团菌污染：危险因素和控制措施评估（翻译有奖）
Legionella species colonization in cooling towers: Risk factors and assessment of control measuresAmerican Journal of Infection Control
Volume 38, Issue 1, Pages 50-55 (February 2010)
Background
Cooling towers can be colonized by Legionella spp, and inhalation of aerosols generated by their operation may cause Legionnaires' disease in susceptible hosts. Environmental investigations of Legionnaires' disease outbreaks linked with cooling towers have revealed poorly maintained systems, lack of control measures, and failure of system equipment. The purpose of this study was to identify Legionella-contaminated cooling towers, identify risk factors for contamination, and assess the effectiveness of control measures.
Methods
A total of 96 cooling towers of public buildings were registered and inspected, and 130 samples were collected and microbiologically tested. Microbiological test results were associated with characteristics of cooling towers, water samples, inspection results, and maintenance practices.
Results
Of the total 96 cooling towers examined, 47 (48.9%) were colonized by Legionella spp, and 22 (22.9%) required remedial action. A total of 65 samples (50.0%) were positive (≥ 500 cfu L−1), and 30 (23%) were heavily contaminated (≥ 104 cfu L−1). Of the 69 isolates identified, 55 strains (79.7.%) were L pneumophila. Legionella colonization was positively associated with the absence of training on Legionella control (relative risk =1.66; P=.02), absence of regular Legionella testing (RR=2.07: P=.002), absence of sunlight protection (RR=1.63: P=.02), with samples in which the free residual chlorine level in the water sample was<0.5mg/L (RR=2.23; P=.01), and with total plate count (P=.001). Colonization was negatively associated with chemical disinfection (RR=0.2; P=.0003) and with the presence of a risk assessment and management plan (RR=0.12; P=.0005). A statistically significant higher age (P=.01) was found in legionellae-positive cooling towers (median, 17 years; interquartile range =5.0 to 26.0 years) compared with noncolonized cooling towers (median age, 6 years; IQR=1.0 to 13.5 years). After the 22 legionellae-positive cooling towers were disinfected with chlorine, 2 (9%) of them remained positive for Legionella spp with a concentration≥1000 cfu L−1.
Conclusions
Cooling towers can be heavily colonized by Legionella spp and thus present a potential risk for infection. This study demonstrates the importance of a risk assessment and management plan. Water chlorination effectively reduces legionellae contamination. Proper training of cooling tower operators is paramount.
Key Words: Legionella, cooling tower, factor, disinfection, risk assessment 缺乏常规管理和日光照射是冷却塔军团菌污染的危险因素。 本帖最后由 潮水 于 2010-4-10 21:36 编辑
冷却塔可携带军团菌属，吸入了其运作时产生的气溶胶可能导致易感者感染军团病。军团病的暴发与冷却水塔的关系显示与操作系统维护不良、缺乏控制的措施和机器运行故障等因素相关。本研究旨在确定冷却塔军团菌污染情况，找出相关危险因素，并评估控制措施的有效性。
本次共登记检查了96座公共建筑的冷却塔，采集了130个样本进行微生物培养。培养结果（的差异）显示与冷却塔类型特征、塔内水样、视察所见和水塔保养密切相关。
在96个被检测的冷却塔中，有47个 (48.9%) 有军团菌属定植，22个（22.9%）急需（清洁）补救措施。有65个 (50.0%)样本显示阳性 (≥ 500 个 /L-1？) ，30 (23%)个严重污染 (≥ 104 个/L-1？)。在69个标本分离出的菌株中，55 株 (79.7.%)是嗜肺性军团菌。军团菌定植显然与以下因素相关：与缺乏（对该菌）积极防范措施相关（相对风险 =1.66；P =0. 02)；与缺乏定期军团检测相关 (RR = 2.07： P = 0.02)；与缺乏阳光（照射）措施相关 (RR =1.63：P = 0.02；与水样本中的氯残余浓度（过低）<0.5mg/l相关 (rr=2.23; p=0.01)；与（检验计算的）平皿总数相关 (p=.001).。本次阴性结果显示与以下因素相关：与化学消毒液（浓度？）相关(rr=0.2; p=.0003)；，与实行检查控制制度相关(rr=0.12; p=.0005).我们还发现了一个有统计学意义的相关因素——塔龄（使用年限）(p=0.01)，在军团菌阳性的标本中（平均17年，四位分数值 =5.0 to 26.0年)，而军团菌定植阴性的样本中 (塔龄平均6年; iqr=1.0 to 13.5 年). （我们）对军团菌阳性塔使用含氯消毒剂进行消毒处理后, 有2 (9%)仍然阳性，菌落数≥1000 cfu l−1？.
结论：冷却塔存在军团菌定植的隐患和引发（人）感染的风险。本研究阐述对冷却塔进行定期检查和维护制度的重要性，水中含氯消毒剂成分可以有效减低军团菌的污染。适当的冷却塔操作培训也（对减低这种污染）很重要。
cfu l−1？这个单位怪怪的，请哪位老师解释解释. 应该是细菌菌落数的单位CFU/L 回复 4# 天师
如果只是cfu/l就明白，但后面还有一个-1就搞不明白了，而且从文中的情况来看，有这个单位的数字越大，污染情况就越轻的感觉。比如文中说，阳性标本≥500cfu/L-1 ，严重污染≥104cfu/L-1，经消毒后仍阳性的≥1000cfu/L-1，所以感觉它不是我们平常的每升菌落形成单位的意思。天师老师的英文了得，我也只是业余爱好而已，请多多指导。 cfu L−1其实CFU/L ，英文都是这么表达的，而不是cfu/L-1 本帖最后由 潮水 于 2010-4-10 21:39 编辑
回复 3# wjllulu
不好意思，原文中的104其实是104，复制原文的时候没有上标让你产生了误解。cfu L−1就是cfu/L。 又学到了一些知识，谢谢！。。。。
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