摘要目的:探讨呼吸机相关性肺炎（VAP）患者肠道和肺部微生态结构变化及其之间的相关性。方法:采用前瞻性观察性研究方法，纳入2019年5月1日至2020年5月1日入住宁夏医科大学总医院重症医学科的31例VAP患者，收集患者同一天的粪便及肺泡灌洗液样本，利用16S rRNA测序技术对粪便和肺泡灌洗液样本进行菌群组成及结构的生物学信息分析，综合测序结果及患者临床资料进行统一分析。结果:① VAP患者肺泡灌洗液中菌群α多样性（丰度及多样性）较粪便菌群增高，其中描述菌群丰度的Ace指数、Chao指数及描述多样性的Shannon指数差异有统计学意义〔Ace指数：305.89（214.39，458.66）比204.51（165.15，247.61），Chao指数：259.83（194.20，459.31）比187.67（153.28，234.01），Shannon指数：3.01（2.39，3.54）比2.55（1.86，2.95），均 P<0.05〕，描述多样性的Simpson指数差异无统计学意义〔0.14（0.08，0.27）比0.19（0.10，0.33）， P>0.05〕。②在VAP患者粪便及肺泡灌洗液测序结果中均存在一些肠道相关菌群，如大肠杆菌属、粪肠杆菌属、拟杆菌属及毛螺菌属等，且丰度均较高。③ 31例VAP患者中有20例肺泡灌洗液临床培养发现可疑致病菌，分别为草绿色链球菌6例、大肠杆菌5例、肺炎克雷伯菌3例、鲍曼不动杆菌3例、金黄色葡萄球菌2例、铜绿假单胞菌1例，且与对应的肺泡灌洗液测序一致，其中17例患者粪便测序中也存在这种可疑致病菌。④ 14例患者合并脓毒症，从未发生脓毒症的患者中选取14例进行样本量匹配，结果显示，VAP合并脓毒症组描述肺-肠菌群相关性的Jaccard相似性指数较VAP组显著升高，差异有统计学意义（0.24±0.08比0.19±0.06， P<0.01）。 结论:VAP患者存在一定的肺-肠菌群相关性，在排除来源于环境和上呼吸道微吸入导致的肺部感染外，仍有一部分感染源可能来自于下消化道。

abstractsObjective:To investigate the changes and correlation of intestinal and pulmonary microecological structures in patients with ventilator-associated pneumonia (VAP).Methods:A prospective observational study was conducted. Thirty-one patients with VAP admitted to the department of critical care medicine of General Hospital of Ningxia Medical University from May 1st 2019 to May 1st 2020 were enrolled. Feces and alveolar lavage fluid samples from patients with the same day, feces and alveolar lavage specimen flora composition and the structure of biological information analysis by 16S rRNA sequencing technologies, the comprehensive sequencing results, and clinical data of patients were analyzed.Results:① The diversity (abundance and diversity) of flora in the alveolar lavage fluid of VAP patients was higher than that of fecal flora. Among them, Ace index, Chao index and Shannon index describing the abundance of flora showed statistically significant differences [Ace index: 305.89 (214.39, 458.66) vs. 204.51 (165.15, 247.61), Chao index: 259.83 (194.20, 459.31) vs. 187.67 (153.28, 234.01), Shannon index: 3.01 (2.39, 3.54) vs. 2.55 (1.86, 2.95), all P < 0.05], but there was no significant difference in Simpson index describing diversity [0.14 (0.08, 0.27) vs. 0.19 (0.10, 0.33), P > 0.05]. ② In the sequencing results of feces and alveolar lavage fluid of VAP patients, there were some intestinal related bacteria groups with high abundance, such as Escherichia-Shigella, Faecalibacterium, Bacteroides, and Lachnospira, etc. ③ In 31 VAP patients, suspicious pathogenic bacteria was found in 20 cases (6 cases of Streptococcus viridans, 5 cases of Escherichia coli, 3 cases of Klebsiella pneumoniae, 3 cases of Acinetobacter baumannii, 2 cases of Staphylococcus aureus, 1 case of Pseudomonas aeruginosa), and the same suspected pathogens also existed in the 17 patients' alveolar lavage and waste sequencing. ④ Fourteen VAP patients combined with sepsis, 14 patients without sepsis were selected for sample size matching. The results showed that, Jaccard similarity index to describe lung-correlation of intestinal flora in VAP with sepsis group was significantly elevated, and the difference was statistically significant (0.24±0.08 vs. 0.19±0.06, P < 0.01). Conclusions:There is a certain correlation between pulmonary and intestinal flora in VAP patients. In addition to the exclusion of pulmonary infection caused by environmental and upper respiratory micro-inhalation, the lower digestive tract may also be source of infection.