目的：探讨人类免疫缺陷病毒（human immunodeficiency virus, HIV）/获得性免疫缺陷综合征（acquired immunodeficiency syndrome,AIDS）患者（统称people living with HIV, PLWH）合并肺部感染的病原学特征，评估宏基因组二代测序（metagenomic next-generation sequencing, mNGS）技术在诊断中的价值。方法：回顾性纳入322例PLWH合并肺部感染患者，收集其临床资料与支气管肺泡灌洗液，分别进行传统病原学检测[涂片、培养、聚合酶链反应（polymerase chain reaction, PCR）]和mNGS检测，比较不同方法的病原体检出率、报告周期及检出病原学特征，并分析不同CD4⁺T淋巴细胞水平下的病原学变化。结果：322例患者中，男性占80.1%（258/322），中位年龄为35岁，CD4⁺T淋巴细胞中位数61（22，205）个/μL， HIV RNA 载量中位数1 343（0，159 423）拷贝/mL。mNGS成功检测294例，共检出病原体93种/786例次。病原体以病毒（34.4%，32种）为主，最常见为巨细胞病毒（cytomegalovirus, CMV）（44.7%）、耶氏肺孢子菌（40.4%）、EB病毒（14.6%）、结核分枝杆菌复合群（11.2%）、新型冠状病毒（9.0%）、黄曲霉/米曲霉（8.7%）。传统方法综合灵敏度为64.0%，mNGS为91.0%，差异具有统计学意义（P<0.001）。mNGS报告周期显著短于传统方法。CD4⁺T淋巴细胞<200个/μL的AIDS期患者病原体检出数量最多（648例次）。结论：PLWH合并肺部感染以CMV、耶氏肺孢子菌、结核分枝杆菌、新型冠状病毒及曲霉菌为主，不同免疫状态下感染的病原学种类不同，低CD4患者易受耶氏肺孢子菌、 CMV 等机会性病原体感染，随着CD4计数增加，病毒和真菌仍是主要的病原体类型，但细菌检出比例相对增加。mNGS可显著提高PLWH合并肺部感染患者的病原体检出率。

Objective To discuss the etiological characteristics of patients with human immunodeficiency virus (HIV) / acquired immunodeficiency syndrome (AIDS) [collectively referred to as people living with HIV (PLWH)] complicated with pulmonary infection, and to evaluate the diagnostic value of metagenomic next-generation sequencing (mNGS) technology. Methods A retrospective study was conducted on 322 PLWH with pulmonary infection, whose clinical data and bronchoalveolar lavage fluid samples were collected. All samples underwent both conventional etiological tests [smear, culture, polymerase chain reaction (PCR)] and mNGS. The pathogen detection rates, reporting times, and detected etiological characteristics were compared between the two methods. Etiological variations under different CD4⁺ T lymphocyte levels were also analyzed. Results Among the 322 patients, 80.1% (258/322) were male, with a median age of 35 years. The median CD4⁺ T lymphocyte count was 61 (22, 205) cells/µL, and the median HIV RNA load was 1 343 (0, 159 423) copies/mL. mNGS was successfully performed on 294 patients, detecting a total of 93 pathogen species across 786 instances. Viruses were the predominant pathogens (34.4%, 32 species), with the most common being cytomegalovirus (CMV, 44.7%), Pneumocystis jirovecii (40.4%), Epstein-Barr virus (14.6%), Mycobacterium tuberculosis complex (11.2%), coronavirus disease 2019(COVID-19)(9.0%), and Aspergillus flavus/A. oryzae(8.7%). The overall sensitivity of conventional methods was 64%, with a statistically significant difference (P<0.001) compared to 91.0% for mNGS. The reporting time of mNGS was significantly shorter than of conventional methods. Patients at the AIDS stage, whose CD4⁺ T lymphocytes<200 cells/µL, had the highest total number of detected pathogens (648 instances). Conclusions Pulmonary infections in PLWH are primarily caused by CMV, P. jirovecii, M. tuberculosis complex, COVID-19, and Aspergillus species, with the etiological spectrum varying according to immune status. Patients with low CD4 counts are susceptible to opportunistic pathogens such as Pneumocystis jirovecii and CMV. As the CD4 count increases, viruses and fungi remain the predominant types of pathogens, but the proportion of bacterial detection relatively increases. mNGS can significantly improve the pathogen detection rate in PLWH with pulmonary infection.