目的:分析宏基因组二代测序(mNGS)技术在重症肺炎病原菌未明患者中的应用价值。方法:回顾性分析扬州大学附属医院2019年6月至2020年2月采用肺泡灌洗液mNGS技术辅助诊疗的重症肺炎病原菌未明患者8例的临床资料，包括肺泡灌洗液涂片、培养、mNGS检测等结果，分析患者的临床特点与mNGS检测情况。依据mNGS结果并结合临床医师的判断，将是否明确为病原菌分为病原菌确定组、病原菌未确定组，比较两组辛普森菌群多样性指数。结果:8例患者中，男5例，女3例；年龄范围41～71岁，中位年龄62.5岁。除1例患者无慢性疾病外，其余患者合并糖尿病、慢性阻塞性肺疾病、肾脏移植等。8例患者mNGS检测阳性，3例患者常规检测阳性。病原菌确定组(n n＝5)与病原菌未确定组(n n＝3)辛普森菌群多样性指数比较，差异有统计学意义[(0.398±0.222)比(0.763±0.061)，n t＝2.709，n P＝0.035]。2例患者mNGS检测阳性与常规检测阳性结果不同。3例卡氏肺孢子虫mNGS检测阳性患者的核酸序数为120～15 580，相对丰度为24.6%～99.8%。n 结论:肺泡灌洗液mNGS技术有助于医师快速、全面掌握病原菌信息，特别适用于重症肺炎病原菌未明患者。“,”Objective:To evaluate the application value of metagenomic next-generation sequencing(mNGS) for patients with severe pneumonia of unknown pathogen.Methods:The clinical data of 8 patients with unknown pneumonia pathogens who were assisted by the alveolar lavage fluid mNGS technology treated in Affiliated Hospital of Yangzhou University from June 2019 to February 2020 were retrospectively analyzed, including alveolar lavage fluid smear, culture, and the sequencing result.The clinical characteristics and mNGS detection results were comprehensively analyzed.According to the results of mNGS and the judgment of the clinician, the patients were divided into confirmed pathogens group and undetermined pathogens group, and the Simpson's diversity index of two groups was compared.Results:Among 8 cases, there were 5 males and 3 females, and the median age was 62.5 years (ranged from 41 to 71 years). All of them had chronic diseases except 1 case, including diabetes, chronic obstructive pulmonary disease and kidney transplantation.mNGS was positive in 8 patients, and conventional test was positive in 3 patients.The comparison of the Simpson's diversity index between the identified pathogenic group and the undetermined pathogenic group showed statistically significant difference [(0.398 ± 0.222) vs.(0.763 ± 0.061),n t=2.709, n P=0.035]. The positive results of mNGS were different from that of conventional test in 2 patients.The nucleic acid number in 3 cases of Pneumocystis carinii with mNGS positive results ranged from 120 to 15 580, with genomic coverage rates from 24.6% to 99.8%.n Conclusion:mNGS can help physicians acquire information of the pathogenic bacteria quickly and comprehensively, especially for patients with unknown pneumonia pathogenic bacteria.