院内肺炎逆行感染途径的实验研究
Experimental study on retrograde route of transmission of nosocomial pneumonia
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摘要:目的 研究胃-咽-下呼吸道逆行感染途径以及观察胃液pH值变化与院内感染性肺炎(Nosocomial Pneumonia, NP)发生的关系。方法 以气管切开或插管病人为研究对象, 用防污染标本刷(PSB)采集标本, 由细菌表型分型直至质粒DNA、酶切、随机引物PCR(RAPD)等基因分型, 前瞻性观察NP的发生情况。结果 11名患者存在逆行感染, NP发生率为22%, 在胃部分离出病原菌1~2d后, PSB在咽部及下呼吸道也检出相同的细菌, 应用质粒图谱、酶切图谱和RAPD等分子生物学技术进行同源性分析, 证明其有很高的同源性。将美兰经胃管注入病人胃内, 1~2d后在咽部及下呼吸道可检出蓝色分泌物。随着胃液pH值升高, 胃内细菌定植增加, NP发生率升高。结论 存在胃-咽-下呼吸道逆行感染途径, NP的发生与胃液pH值显著相关。Abstract:Objective To study the retrograde route of transmission from stomach to oropharynx to lower respiratory tract and observe the relationship between the incidence of nosocomial pneumonia and the pH value of stomch.Methods The study was conducted in patients in requiring mechanical ventilation or tracheostomy, the secretion of lower respiratory tract was collected by protected specimen brush(PSB).The gene typings of the bacterial from lower respiratory tract secretion and gastric aspirates were taken by plasmial profile analysis, restriction andonuclease fingerprint analysis and randomly amplified polymorphism DNA(RAPD)in the same phenotype bacteria.All patients were monitored for development of nosocomial pneumonia.Results In 11(22%)case of nosocomial pneumonia, the identical or ganisms were isolated first in the gastric samples and then one to two days later in tracheal secretion.They were very homologous, exhibiting the same fingerprinting in plasmid profile, endonuclease fingerprint and RAPD.Two days after being perfused into the stomach through masogastric tubes.Methylene blue was found in the secretion of throat and lower respiratory tract.The bacterial counts in gastric aspirates increased significantly with gastric pH.Conclusion The retrograde route of transmission was confirmed to be existed and it was one of the risk factors in nosocomial pneumonia.The occurrence of nosocomial pneumonia was significantly associated with the rise of gastric pH.
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