Kool J L, Buchholz U, Peterson C, Brown E W, Benson R F, Pruckler J M, Fields B S, Sturgeon J, Lehnkering E, Cordova R, Mascola L M, Butler J C
Epidemic Intelligence Service, Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Epidemiol Infect. 2000 Dec;125(3):599-608. doi: 10.1017/s095026880000474x.
An epidemiological and microbiological investigation of a cluster of eight cases of Legionnaires' disease in Los Angeles County in November 1997 yielded conflicting results. The epidemiological part of the investigation implicated one of several mobile cooling towers used by a film studio in the centre of the outbreak area. However, water sampled from these cooling towers contained L. pneumophila serogroup 1 of another subtype than the strain that was recovered from case-patients in the outbreak. Samples from two cooling towers located downwind from all of the case-patients contained a Legionella strain that was indistinguishable from the outbreak strain by four subtyping techniques (AP-PCR, PFGE, MAb, and MLEE). It is unlikely that these cooling towers were the source of infection for all the case-patients, and they were not associated with risk of disease in the case-control study. The outbreak strain also was not distinguishable, by three subtyping techniques (AP-PCR, PFGE, and MAb), from a L. pneumophila strain that had caused an outbreak in Providence, RI, in 1993. Laboratory cross-contamination was unlikely because the initial subtyping was done in different laboratories. In this investigation, microbiology was helpful for distinguishing the outbreak cluster from unrelated cases of Legionnaires' disease occurring elsewhere. However, multiple subtyping techniques failed to distinguish environmental sources that were probably not associated with the outbreak. Persons investigating Legionnaires' disease outbreaks should be aware that microbiological subtyping does not always identify a source with absolute certainty.
1997年11月，对洛杉矶县8例军团病病例群进行了流行病学和微生物学调查，结果相互矛盾。调查的流行病学部分表明，疫情爆发地区中心一家电影制片厂使用的几座移动冷却塔中的一座有嫌疑。然而，从这些冷却塔采集的水样中所含嗜肺军团菌血清1型的亚型，与疫情中从病例患者身上分离出的菌株不同。在所有病例患者下风向的两座冷却塔的样本中，含有一种军团菌菌株，通过四种分型技术（AP-PCR、PFGE、单克隆抗体和MLEE），该菌株与疫情菌株无法区分。这些冷却塔不太可能是所有病例患者的感染源，而且在病例对照研究中，它们与患病风险无关。通过三种分型技术（AP-PCR、PFGE和单克隆抗体），此次疫情菌株也与1993年在罗德岛州普罗维登斯市引起疫情的嗜肺军团菌菌株无法区分。由于最初的分型是在不同实验室进行的，所以实验室交叉污染的可能性不大。在本次调查中，微生物学有助于将此次疫情群与其他地方发生的无关军团病病例区分开来。然而，多种分型技术未能区分可能与此次疫情无关的环境来源。调查军团病疫情的人员应意识到，微生物学分型并不总是能绝对确定地识别出感染源。
