胃腔定植菌在医院内肺炎患者发病机制中的作用

目的研究医院内肺炎（ＮＰ）发病机制和病原体来源。方法动态对比胃腔、口咽部、下呼吸道菌群构成、定植次序，调查影响定植的因素。结果５２例患者采集到２３７份胃液、咽拭子标本。胃腔分离革兰阴性杆菌（ＧＮＢ）菌株数多于口咽部（７７株：５１株）。其中胃腔肠杆菌科细菌明显多于口咽部（４６株：２４株）、且定植早１～２天。１０例患者发生ＮＰ，３例观察到ＧＮＢ从胃腔→口咽部→呼吸道的定植次序并致肺炎。结论胃腔ＧＮＢ可能是引起ＮＰ的重要来源，尤其是肠杆菌科细菌肺炎。

Gastric colonization and its effect on pathogenesis of nosocomial pneumonia

Objective To study the gastric colonization and its effect on development of nosocomial pneumonia(NP). Methods We investigated the microorganism ( mainly pathogens) constitution, isolating sequences and risk factors in gastric, oropharyngeal and lower respiratory tract flora. Microbiologic cultures of serially taken samples of gastric aspirates, oropharyngeal swabs and bronchoalveolar lavages (BALs) or sputums were performed at the time of ICU admission and subsequently every morning in 52 surgical patients with nasogastric tube. Etiologic diagnosis of NP was based on quantitative culture of BAL or sputum. Sequences of colonization were examined by comparing isolates of the same species with concordance of minimum inhibitory concentration values to 12 antibiotics. Results A total of 237 pairs of gastric and oropharyngeal specimens were taken. 77 strains of gram negative bacilli (GNB) isolated from stomach, more than the number of GNB isolated from oropharynx (51 strains) , P =0.007. Comparing the species, Enterobacteriaceae isolated from stomach was much more than that from oropharynx (46 vs 24 strains, P =0.004), and in most instances stomach colonization was before oropharynx colonization one to two days. Isolating rates of Pseudomonas were the same in both kinds of specimens. On contrast, Acinetobacter colonization in oropharynx was much more than that in stomach (10 vs 3 strains, P =0.049).Risk factors for GNB colonization in stomach included increased gastric pH, medications inhibiting gastric acid secretion (such as cimitidine, omeprazole), and systemic use of cephalosporins. 10 patients developed NP and 5 GNB ( Enterobacter cloacae 2, Pseudomonas aeruginosa 2, Acinetobacter anitratum 1) isolated from BAL or sputum in 4 of 10 patients. A sequence of colonization from the stomach to the respiratory tract leading to pneumonia was observed in 3 patients. Conclusions It was suggested that the stomach is likely to be an important source of pathogens leading to NP, especially Enterobacteriaceae pneumonia.