目的 了解儿童重症社区获得性肺炎（CAP）的病原分布及细菌耐药情况，为临床诊疗提供依据。方法 选取2016年住院治疗的522例重症CAP患儿为研究对象。按照年龄分为婴儿组（28 d~，n=402），幼儿组（1岁~，n=73），学龄前期组（3岁~，n=35），学龄期组（≥ 6岁，n=12）；按照发病季节分为春季组（3~5月份，n=120），夏季组（6~8月份，n=93），秋季组（9~11月份，n=105），冬季组（12~2月份，n=204）。采集所有患儿气道深部痰液标本，采用phoenix-100全自动细菌鉴定系统进行菌种鉴定及药敏试验；采用直接免疫荧光法检测呼吸道7种病毒；采用荧光定量PCR技术检测肺炎支原体（MP）和沙眼衣原体（CT）。结果 522例重症CAP患儿中，419例（80.3%）病原体检出阳性，其中混合感染190例（45.3%）；共检出病原体681株，包括细菌371株（54.5%），病毒259株（38.0%），真菌12株（1.8%），MP 15株（2.2%），CT 24株（3.5%）。细菌、病毒、MP、真菌感染分别在不同年龄组间分布比率比较差异有统计学意义（P < 0.05）。病毒感染发生率在不同季节间比较差异有统计学意义（P < 0.05），且在冬季高发。肺炎链球菌对红霉素、四环素、克林霉素耐药率高达85%以上；金黄色葡萄球菌对青霉素、红霉素、克林霉素的耐药率达50%以上；但两者对万古霉素、利奈唑胺均敏感。流感嗜血杆菌对头孢克洛、头孢呋辛等的耐药率达60%以上，但对头孢噻肟敏感；大肠埃希菌、肺炎克雷伯菌对氨苄西林、头孢噻肟、头孢曲松等的耐药率达60%以上，但对碳青霉烯类抗生素、酶抑制剂复方制剂敏感。结论 重症CAP患儿感染主要病原体为细菌，混合感染较普遍，且细菌耐药情况严峻。

Objective To investigate the distribution of pathogens and bacterial resistance in children with severe community-acquired pneumonia (CAP). Methods A total of 522 children with severe CAP who were hospitalized in 2016 were enrolled as study subjects. According to their age, they were divided into infant group (402 infants aged 28 days to 1 year), young children group (73 children aged 1 to 3 years), preschool children group (35 children aged 3 to 6 years), and school-aged children group (12 children aged ≥ 6 years). According to the onset season, all children were divided into spring group (March to May, 120 children), summer group (June to August, 93 children), autumn group (September to November, 105 children), and winter group (December to February, 204 children). Sputum specimens from the deep airway were collected from all patients. The phoenix-100 automatic bacterial identification system was used for bacterial identification and drug sensitivity test. The direct immunofluorescence assay was used to detect seven common respiratory viruses. The quantitative real-time PCR was used to detect Mycoplasma pneumoniae (MP) and Chlamydia trachomatis (CT). Results Of all the 522 children with severe CAP, 419 (80.3%) were found to have pathogens, among whom 190 (45.3%) had mixed infection. A total of 681 strains of pathogens were identified, including 371 bacterial strains (54.5%), 259 viral strains (38.0%), 12 fungal strains (1.8%), 15 MP strains (2.2%), and 24 CT strains (3.5%). There were significant differences in the distribution of bacterial, viral, MP, and fungal infections between different age groups (P < 0.05). There were significant differences in the incidence rate of viral infection between different season groups (P < 0.05), with the highest incidence rate in winter. The drug-resistance rates of Streptococcus pneumoniae to erythromycin, tetracycline, and clindamycin reached above 85%, and the drug-resistance rates of Staphylococcus aureus to penicillin, erythromycin, and clindamycin were above 50%; they were all sensitive to vancomycin and linezolid. The drug-resistance rates of Haemophilus influenzae to cefaclor and cefuroxime were above 60%, but it was sensitive to cefotaxime. The drug-resistance rates of Escherichia coli and Klebsiella pneumoniae to ampicillin, cefotaxime, and ceftriaxone were above 60%, but they were sensitive to carbapenems and compound preparation of enzyme inhibitors. Conclusions Bacteria are the main pathogens in children with severe CAP and mixed infection is prevalent. The drug-resistance rates of these pathogenic bacteria are high.