2004年2月，旧金山公用事业委员会〔PUC〕 将其剩余饮用水消毒剂从氯气改为 一氯胺，以达到新的消毒副产品标准 将水输送给客户。在转换之前 乔治亚州亚特兰大市疾病控制中心（CDC）联系了临时市政局，提出了一项建议 研究新型消毒剂对人体军团菌感染的影响 饮用水分配系统。其他当地卫生机构也在接受调查 对这个问题感兴趣，最终成立了一个研究小组，包括 加利福尼亚州卫生服务部的代表 [DHS]、加州新发感染计划[CEIP]和旧金山 旧金山公共卫生部[DPH]。53栋建筑中的场地被拆除 每次取样六次: 在转化为 一氯胺和三次转化后。自从军团菌 众所周知，细菌在大型建筑的生物膜中存活和繁殖 有着广泛的热水系统，只有至少三层的建筑 故事符合抽样条件。在每一个时间点，我们都收集了一杯水 来自一次热水器和四对水和生物膜的样本 水槽水龙头或淋浴头的样本。温度、pH值、游离态和游离态 在每个地点测量总余氯。样本被送往 军团菌培养疾病控制中心。实验室测试对这些人的身份一无所知 建筑物。在转化为一氯胺之前，37（70%）的 样本建筑曾有一次或多次被军团菌感染 1405份样本中有347份（24%）培养出军团菌。转换后，5 （9%）的建筑曾被殖民，1420个样本中只有12个（<1%） 结果呈阳性。建筑物内军团菌定植的减少 表明一氯胺的残留消毒效果优于游离消毒 氯气用于限制热水系统中这些细菌的生长。仅包含摘要。

In February 2004, the San Francisco Public Utilities Commission [PUC] changed its residual drinking water disinfectant from chlorine to monochloramine in order to achieve new disinfectant byproduct standards in water delivered to its customers. Prior to the conversion, the Centers for Disease Control [CDC] in Atlanta, Georgia contacted the PUC with a proposal to study the effect of the new disinfectant on the occurrence of Legionella in the drinking water distribution system. Other local health agencies were also interested in this issue, which resulted in a final study team that included representatives from the State of California Department of Health Services [DHS], the California Emerging Infections Program [CEIP], and the San Francisco Department of Public Health [DPH]. Sites in 53 buildings were sampled six times each: three times before the conversion to monochloramine and three times after the conversion. Since Legionella bacteria are known to survive and multiply within biofilms in large buildings with extensive hot water systems, only buildings that were at least three stories were eligible for sampling. At each time point, we collected a water sample from the primary water heater and four paired water and biofilm samples from sink faucets or showerheads. Temperature, pH, and free and total chlorine residual were measured at each site. Samples were sent to CDC for Legionella culture. Laboratory testing was blinded to the identities of the buildings. Prior to the conversion to monochloramine, 37 (70%) of sampled buildings were colonized with Legionella on one or more occasion and 347 (24%) of 1,405 samples grew Legionella. After the conversion, 5 (9%) of buildings were ever colonized and only 12 (<1%) of 1,420 samples were positive. The reduction of Legionella colonization within buildings suggests that monochloramine provides better residual disinfection than free chlorine for limiting the growth of these bacteria in hot water systems. Includes abstract only.