目的 探讨儿童非HIV感染重症肺孢子菌肺炎（PCP）的临床特征，旨在提高儿科医师对此病的认识。方法 回顾性分析2018年3月至2021年3月住院的非HIV感染重症肺炎患儿的临床资料。经宏基因组二代测序（mNGS）确诊为PCP的患儿归入病例组，其他呼吸道病原体感染的重症肺炎患儿作为对照组。比较两组间临床特征、预后及并发症差异。结果 共60例纳入研究，男38例、女22例，中位年龄1.6（0.7~4.3）岁。病例组20例，对照组40例。与对照组相比，病例组原发性免疫缺陷、肾脏-结缔组织病、使用免疫抑制剂、使用糖皮质激素≥1月的比例较高，差异有统计学意义（P<0.05）。与对照组相比，病例组肺部啰音比例、上机24小时内P/F值、CD4⁺ T细胞计数、CD4⁺ /CD8⁺较低，上机24小时内OI值较高，合并巨细胞病毒（CMV）、EB病毒（EBV）及其他真菌感染比例较高，差异有统计学意义（P<0.05）。病例组磨玻璃影、条索影比例，气漏发生率、病死率高于对照组，片状实变、胸腔积液比例低于对照组，有创通气时间长于对照组，差异均有统计学意义（P<0.05）。结论 儿童非HIV感染重症PCP起病前多有糖皮质激素、免疫抑制剂使用史或存在原发性免疫缺陷，低氧血症严重、持续时间长，病死率高。胸部CT以弥漫性磨玻璃影、条索影为主要表现。实验室检查提示细胞免疫功能低下。

Objective To investigate the clinical characteristics of severe Pneumocystis pneumonia (PCP) in non-HIV-infected children, and to improve the understanding of such disease among pediatricians. Methods The clinical data of non-HIV-infected children with severe pneumonia hospitalized from March 2018 to March 2021 were retrospectively analyzed. The patients diagnosed with PCP by metagenomic next-generation sequencing (mNGS) were classified into the case group and the patients with severe pneumonia infected by other respiratory pathogens were included in the control group. The clinical characteristics, prognosis and complications were compared between the two groups. Results A total of 60 patients (38 boys and 22 girls) were enrolled in the study, and the median age was 1.6 (0.7-4.3) years. There were 20 patients in the case group and 40 in the control group. Compared with the control group, the proportions of primary immunodeficiency, renal connective tissue disease, use of immunosuppressive agents, and glucocorticoids use ≥1 month in the case group were higher, and the differences were statistically significant (P<0.05). Compared with the control group, the proportion of lung rales, the arterial oxygen pressure/ inhaled oxygen concentration value within 24 hours, CD4⁺ T cell count and CD4⁺ /CD8⁺ in the case group were lower, the oxygenation index within 24 hours was higher, and the proportion of cytomegalovirus (CMV), Epstein-Barr virus (EBV) and other fungal infections were higher in the case group, and the differences were statistically significant (P<0.05). The proportion of ground glass shadow, strip shadow, incidence of air leakage and mortality in the case group were higher than those in the control group, the proportion of patchy consolidation and pleural effusion were lower than those in the control group, and the invasive ventilation time was longer than that in the control group, and the differences were statistically significant (P<0.05). Conclusions Most non-HIV infected children with severe PCP had a history of glucocorticoid and immunosuppressant use or primary immunodeficiency before the onset of the disease. The hypoxemia was severe and long lasting, and the fatality rate was high. The main manifestations of chest CT were diffuse ground glass shadow and strip shadow. Laboratory tests suggested a low cellular immune function.