呼吸机相关肺炎内源性感染途径的分子流行病学研究

Endogenous Infection Route in Ventilator-associated Pneumonia:the Molecular Epidemiological Study

目的 用分子流行病学方法研究呼吸机相关肺炎 (VAP)内源性感染途径在VAP发病机制中的作用 ,为探索和发展全新的VAP预防措施提供理论依据。方法 通过前瞻性队列研究 ,动态采集重症监护病房 (ICU)人工气道 (artificialairway ,AA)包括气管插管或气管切开患者胃腔、口咽部、下呼吸道标本行病原菌培养和药敏试验 ;筛选VAP患者中下呼吸道、胃液和 (或 )咽拭子标本中所分病原菌生化反应结果相同并有先后定植次序者 ;通过PFGE方法分析这些病原菌是否具有同源性。结果 98例人工气道机械通气患者中 5 2例发生VAP ;表型分析 5 2例VAP患者有 13例下呼吸道病原菌呈现胃腔→口咽部→下呼吸道的逆向定植次序 ;3例出现胃腔→下呼吸道的定植次序 ;病原菌的PFGE同源性分析表明ICU中 5 2例VAP患者有 15例 (其中 14例为晚发性VAP)存在胃腔→下呼吸道逆向内源性感染途径 ,占VAP发病总数的 2 8 8% ;PFGE技术方法为分析病原菌同源性的有效方法。结论 病原菌的PFGE同源性分析表明ICU中VAP患者存在胃腔→下呼吸道逆向内源性感染途径。

OBJECTIVE To evaluate the role of endogenous infection route in the pathogenesis of ventilator-associated pneumonia (VAP) by molecular epidemiological methods, in order to explore and develop new prophylactic procedures of VAP. METHODS A prospective cohort study was made in artificial airway patients included trachea-intubated or tracheotomied ones in intensive care unit (ICU). Pathogen cultivation and antibiotic sensitivity test of the samples collected dynamically from gastric cavity, oropharynx and lower respiratory tract were made. The bacteria isolated from lower respiratory tract, oropharynx and/or gastric juice showed same biochemical characteristics and colonization order, the isolates were analyzed by pulse field gel electrophoresis (PFGE) to study their homology. RESULTS (1) Fifty two cases of the total 98 intubated patients supported by mechanical ventilation developed VAP. (2) The reverse stomach-pharynx-lower respiratory tract colonization order was found in 13 cases of the total 52 VAP patients and stomach-lower respiratory tract order in 3 cases by phenotypic analysis. (3) The reverse endogenous stomach-lower respiratory tract infection route was verified in 15 cases(among them 14 cases were late-onset VAP) of the total 52 VAP patients by PFGE analysis, with the incidence of 28.8%. (4) PFGE method was proved to be an effective method for homologous analysis of microorganism. CONCLUSIONS The PFGE homologous analysis of pathogen might show that the reverse stomach-lower respiratory tract infection route could exist in VAP patients in ICU.