呼吸机管道定植菌与呼吸机相关性肺炎病原菌的同源性研究

Homology study on colonization bacteria from Ventilator circuit and pathogens of ventilator-associated pneumonia

目的针对ICU中接受机械通气的患者，从基因水平对该类患者呼吸机管道内定植菌与下呼吸道致病菌的同源性进行研究。方法收集机械通气患者上机后〈1d，第3天，第5天，第7天口咽部分泌物、下呼吸道吸出物和呼吸机管道内的冷凝水进行细菌培养，再用RAPDPCR技术进行同源性研究。结果RAPDPCR显示有35.71%患者呼吸机管道内的定植菌与VAP致病菌有同源性表现，有21.42%的患者在具备同源性的基础上，呼吸机管道内细菌定植时间先于下呼吸道。结论呼吸机管道内定植菌的移行是导致VAP发生的重要原因之一；呼吸机管道更换的最佳时间是上机后3-4d。

Objective To aim directly at the patients that receiving mechanical ventilation in ICU, and to study their homology of pathogens of VAP （ventilator-associated pneumonia） and bacteria that ventilator circuit on molecular level. Methods Oropharynx excretion, tracheal aspirate and condensed water in ventilator circuit within 24 hours, the third day, the fifth day and the seventh day from 30 patients were collected to conduct the bacterial culture. Then the homology was studied by RAPD-PCR. Results RAPD-PCR showed most homology of pathogens for VAP and bacteria in ventilator circuit among 35.71% patients in all cases. 21.42% patients＇ times of bacteria colonization in Ventilator circuit were earlier than lower respiratory tract on the basis of homology. Conclusions A possible bacterial origin which translocates from ventilator circuit to low respiratory tract may contribute to the occurrence of VAP. The third day to the forth day are the best times to change the ventilator circuit after mechanical ventilation.