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

Abstract

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 Oropbarynx 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. Key words: VAP (Ventilator-associated pneumonia); Ventilator circuit; Homology; RAPD-PCR(Randomly amplified polymorphic DNA)