胃腔定植菌在内肺炎患者发病机制中的作用

研究医院内肺炎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例患采集到２３７份胃液、咽拭子标本。胃腔分离革兰阴性杆菌菌株数多于口咽部。

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 cultured 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 5GNB (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.