呼吸机相关性肺炎（VAP）是医院获得性肺炎(HAP)中最主要的类型。在ICU中发病率高，病死率高。申请人前期发现，VAP发病前后，患者肺部菌群紊乱，部分使用过儿茶酚胺的患者，肺部条件致病菌明显增多。利用“培养组”方法从患者肺泡灌洗液分离得到104株菌，选其中2株进行体外培养，发现儿茶酚胺促进表皮葡萄球菌(S.epi)增殖，且此S.epi能诱发小鼠肺炎。结合儿茶酚胺在ICU的高使用频率及其调节菌群的特性，然而其对肺部菌群的影响尚不明确。我们提出科学假说：肺部儿茶酚胺含量变化改变肺部菌群组成从而诱发肺损伤。本项目拟基于临床样本、小鼠肺炎模型，通过宏基因组测序、免疫学指标、肺部通透性指标检测：1.明确肺部“儿茶酚胺作用核心菌群”；2.阐明儿茶酚胺通过“核心菌群”诱发肺损伤的机制。该项目将从肺部菌群角度，给出ICU患者儿茶酚胺用药的潜在风险评估的流程，并为预防VAP感染提供新思路。

Ventilator-associated pneumonia (VAP), known with high morbidity and high mortality in ICU, is the most commonly seen hospital acquired pneumonia with great clinical importance. The applicant discovered that microbiota disorder appeared in VAP, as supported by the finding that opportunistic pathogen significantly accumulated in some of the catecholamine-treated patients. Out of 104 bacterial strains obtained from bronchoalveolar fluid of patients using culturomics, we selected 2 strains and revealed that catecholamine promoted the proliferation of S.epi, which induced pneumonia in mice. In spite of the high utilization frequency in ICU and proven effect in moderating microbiota, catecholamine’s effect on lung microbiota remained uncharacterized. On the basis of clinical samples, this project aimed to illustrate the following by using metagenome sequencing, immunological assay and mouse pneumonia model: 1). Core microbiome targeted by catecholamine 2). Mechanism of pneumonia induced by immunological reactions due to changes in catecholamine-targeting Core Microbiome. From the perspective of lung microbiota, this project will provide important clues for assessment of potential risk in treating ICU patients with catecholamine, and prevention of VAP.