Department of Pathology, University of Otago.
Clin Infect Dis. 2013 Nov;57(9):1275-81. doi: 10.1093/cid/cit504. Epub 2013 Jul 29.
Legionnaires' disease cannot be clinically or radiographically distinguished from other causes of pneumonia, and specific tests are required to make the diagnosis. Currently, testing occurs erratically and, instead, clinicians rely on empiric treatment strategies and ignore public health implications of the diagnosis. We aimed to measure the increase in case detection of Legionnaires' disease following the introduction of routine polymerase chain reaction (PCR) testing of respiratory specimens. PCR is the most sensitive diagnostic tool for Legionnaires' disease.
In a quasi-experimental study in Christchurch, New Zealand, we compared the number of cases of Legionnaires' disease requiring hospitalization diagnosed during a 2-year period before the introduction of a routine PCR testing strategy (November 2008-October 2010) with a similar period after the introduction (November 2010-October 2012). With this testing strategy, all respiratory specimens from hospitalized patients with pneumonia sent to the region's sole tertiary-level laboratory were tested for Legionella by PCR, whether requested or not.
During November 2008 to October 2010, there were 22 cases of Legionnaires' disease compared with 92 during November 2010 to October 2012. Of 1834 samples tested since November 2010, 1 in 20 was positive, increasing to 1 in 9 during peak Legionella season (November to January). Increasing bacterial load was associated with increasing disease severity.
In our region, the burden of Legionnaires' disease is much greater than was previously recognized. Routine PCR testing provides results within a clinically relevant time frame and enables improved characterization of the regional epidemiology of Legionnaires' disease.
军团病在临床上或放射学上无法与其他肺炎病因区分，需要进行特定的检测才能做出诊断。目前，检测结果并不稳定，因此临床医生依赖经验性治疗策略，忽视了诊断对公共卫生的影响。我们旨在测量引入常规聚合酶链反应（PCR）检测呼吸道标本后军团病病例检测的增加。PCR 是军团病最敏感的诊断工具。
在新西兰克赖斯特彻奇进行的一项准实验研究中，我们比较了在引入常规 PCR 检测策略之前的 2 年期间（2008 年 11 月至 2010 年 10 月）和之后的类似时期（2010 年 11 月至 2012 年 10 月）住院的军团病病例数量。采用这种检测策略，地区唯一的三级实验室对所有住院肺炎患者的呼吸道标本进行 Legionella 检测，无论是否要求进行检测。
在 2008 年 11 月至 2010 年 10 月期间，有 22 例军团病病例，而在 2010 年 11 月至 2012 年 10 月期间，有 92 例。自 2010 年 11 月以来，共检测了 1834 个样本，阳性率为 1/20，在 Legionella 高发季节（11 月至 1 月）增加到 1/9。细菌负荷增加与疾病严重程度增加相关。
在我们的地区，军团病的负担比以前认识到的要大得多。常规 PCR 检测可在临床相关时间范围内提供结果，并能够更好地描述该地区军团病的流行病学。
