Controlling Legionella pneumophila growth in hot water systems by reducing dissolved oxygen levels.

IF 1.5 4区 医学 Q4 ENVIRONMENTAL SCIENCES Journal of Occupational and Environmental Hygiene Pub Date : 2024-03-01 Epub Date: 2024-03-06 DOI:10.1080/15459624.2024.2313580
J David Krause
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Abstract

Legionella pneumophila, the leading cause of Legionnaires' disease in the United States, is found in lakes, ponds, and streams but poses a health risk when it grows in building water systems. The growth of L. pneumophila in hot water systems of healthcare facilities poses a significant risk to patients, staff, and visitors. Hospitals and long-term care facilities account for 76% of reported Legionnaires' disease cases with mortality rates of 25%. Controlling L. pneumophila growth in hot water systems serving healthcare and hospitality buildings is currently achieved primarily by adding oxidizing chemical disinfectants. Chemical oxidants generate disinfection byproducts and can accelerate corrosion of premise plumbing materials and equipment. Alternative control methods that do not generate hazardous disinfection byproducts or accelerate corrosion are needed. L. pneumophila is an obligate aerobe that cannot sustain cellular respiration, amplify, or remain culturable when dissolved oxygen (DO) concentrations are too low (< 0.3 mg/L). An alternative method of controlling L. pneumophila growth by reducing DO levels in a hot water model system using a gas transfer membrane contactor was evaluated. A hot water model system was constructed and inoculated with L. pneumophila at DO concentrations above 0.5 mg/L. Once the model system was colonized, DO levels were incrementally reduced. Water samples were collected each week to evaluate the effect of reducing dissolved oxygen levels when all other conditions favored Legionella amplification. At DO concentrations below 0.3 mg/L, L. pneumophila concentrations were reduced by 1-log over 7 days. Under conditions in the hot water model system, at favorable temperatures and with no residual chlorine disinfectant, L. pneumophila concentrations were reduced by 1-log, indicating growth inhibition by reducing DO levels as the sole control measure. In sections of the model system where DO levels were not lowered L. pneumophila continued to grow. Reducing dissolved oxygen levels in hot water systems of healthcare and other large buildings to control L. pneumophila could also lower the risk of supplemental chemical treatment methods currently in use.

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通过降低溶解氧水平控制嗜肺军团菌在热水系统中的生长。
嗜肺军团菌是美国军团病的主要病因,它存在于湖泊、池塘和溪流中,但在建筑供水系统中生长时会对健康造成威胁。嗜肺军团菌在医疗保健设施热水系统中的生长对病人、员工和访客构成重大风险。在报告的军团病病例中,医院和长期护理机构占 76%,死亡率高达 25%。目前,控制嗜肺军团菌在医疗保健和酒店大楼热水系统中生长的主要方法是添加氧化型化学消毒剂。化学氧化剂会产生消毒副产物,并可能加速前提冷热水管道材料和设备的腐蚀。我们需要不会产生有害消毒副产品或加速腐蚀的替代控制方法。嗜肺叶球菌是一种必须的气生微生物,当溶解氧浓度过低(< 0.3 mg/L)时,它无法维持细胞呼吸、扩增或保持培养能力。通过使用气体传输膜接触器降低热水模型系统中的溶解氧水平,评估了一种控制嗜肺菌生长的替代方法。构建了一个热水模型系统,并在溶解氧浓度高于 0.5 毫克/升时接种嗜肺菌。一旦模型系统被定殖,溶解氧水平就会逐渐降低。每周收集水样,以评估在所有其他条件都有利于军团菌扩增的情况下降低溶解氧水平的效果。当溶解氧浓度低于 0.3 毫克/升时,嗜肺军团菌的浓度在 7 天内降低了 1-log。在热水模型系统中,在温度适宜且无余氯消毒剂的条件下,嗜肺军团菌的浓度降低了 1-log,这表明通过降低溶解氧水平作为唯一的控制措施抑制了嗜肺军团菌的生长。在溶解氧水平没有降低的模型系统区域,嗜肺菌继续生长。降低医疗保健和其他大型建筑热水系统中的溶解氧水平以控制嗜肺菌,还可以降低目前使用的辅助化学处理方法的风险。
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来源期刊
Journal of Occupational and Environmental Hygiene
Journal of Occupational and Environmental Hygiene 环境科学-公共卫生、环境卫生与职业卫生
CiteScore
3.30
自引率
10.00%
发文量
81
审稿时长
12-24 weeks
期刊介绍: The Journal of Occupational and Environmental Hygiene ( JOEH ) is a joint publication of the American Industrial Hygiene Association (AIHA®) and ACGIH®. The JOEH is a peer-reviewed journal devoted to enhancing the knowledge and practice of occupational and environmental hygiene and safety by widely disseminating research articles and applied studies of the highest quality. The JOEH provides a written medium for the communication of ideas, methods, processes, and research in core and emerging areas of occupational and environmental hygiene. Core domains include, but are not limited to: exposure assessment, control strategies, ergonomics, and risk analysis. Emerging domains include, but are not limited to: sensor technology, emergency preparedness and response, changing workforce, and management and analysis of "big" data.
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