Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina Universidad de Chile, and 2Servicio Médico Legal, Santiago, Chile.
Clin Infect Dis. 2010 Feb 1;50(3):347-53. doi: 10.1086/649868.
Increasing reports of Pneumocystis DNA in noninvasive respiratory specimens from immunocompetent asymptomatic adults and the characteristic lung tropism of Pneumocystis suggest that asymptomatic pulmonary infections with Pneumocystis occur after primary infection. However, studies searching for Pneumocystis in the autopsied lungs of healthy immunocompetent adults have not met with success.
Lungs of people who died of violent causes (accidents, homicide, and suicide) and of nonviolent causes (diseases causing a rapid demise in the street) in Santiago, Chile-for whom an autopsy was legally required-were examined for Pneumocystis by nested polymerase chain reaction (PCR) DNA amplification of the mitochondrial large subunit ribosomal RNA-specific P. jirovecii gene and immunofluorescent microscopic analysis. Lung tissue concentration methods and analysis of approximately 3% of the weight of the right upper lobe (RUL) were needed to reach the sensitivity threshold of the assays. Individuals determined to be P. jirovecii negative after analysis of 3% of the RUL weight in the violent death group were confirmed to be negative by analyzing additional tissue, totaling 6%-7% of the RUL weight.
P. jirovecii was identified by nested PCR in 50 (64.9%) of 77 individuals (34 [61.8%] of 55 in the violent death group and 15 [78.9%] of 19 in the nonviolent death group; P > .05) and additionally by microscopic analysis in all individuals who tested positive for P. jirovecii DNA in the violent death group. Analysis of tissue beyond 3.0% of the RUL weight for the individuals who tested negative yielded consistently negative results.
A mild P. jirovecii pulmonary infection is prevalent in more than half of the general adult population. Our results strengthen the concept that immunocompetent adults develop frequent self-limited reinfections throughout life and participate in the circulation of P. jirovecii as an infective reservoir for susceptible individuals.
越来越多的报道表明，免疫功能正常的无症状成人的非侵入性呼吸道标本中存在肺孢子菌 DNA，且肺孢子菌具有特征性的肺部嗜性，这提示初次感染后可能会发生无症状性肺孢子菌感染。然而，在免疫功能正常的健康成人尸检肺中寻找肺孢子菌的研究并未取得成功。
对智利圣地亚哥因暴力（意外、凶杀和自杀）和非暴力（在街头迅速死亡的疾病）原因死亡且法律要求进行尸检的人群的肺进行研究，通过巢式聚合酶链反应（PCR）DNA 扩增线粒体大亚基核糖体 RNA 特异性的肺孢子菌 jirovecii 基因和免疫荧光显微镜分析来检测肺孢子菌。需要进行肺组织浓度方法检测，并且分析右肺上叶（RUL）的大约 3%，才能达到检测方法的灵敏度阈值。在对暴力死亡组的 RUL 重量的 3%进行分析后，确定为肺孢子菌阴性的个体，通过分析另外的组织（总共占 RUL 重量的 6%-7%）来进一步确认阴性。
通过巢式 PCR 在 77 名个体中的 50 名（64.9%）（暴力死亡组 34 名[61.8%]，非暴力死亡组 15 名[78.9%]；P＞0.05）和所有在暴力死亡组中 PCR 检测为肺孢子菌 DNA 阳性的个体中通过显微镜分析均鉴定出肺孢子菌。对 RUL 重量的 3.0%以上的组织进行分析，结果均为阴性。
超过一半的普通成年人群存在轻度的肺孢子菌肺部感染。我们的结果进一步证实，免疫功能正常的成年人在一生中会频繁发生自限性再感染，并且作为易感个体的感染源参与肺孢子菌的传播。
