Infection Route Analysis of Ventilator Associated Pneumonia

Abstract

Abstract Objective A prospective study was conducted in a tertiary care center to identify the risk factors of ventilator associated pneumonia (VAP) through phenotypic and molecular biological methods. Methods The patients who were mechanically ventilated in the respiratory intensive care unit (RICU) and the neurological internal intensive care unit (NICU) were enrolled in our study, and samples were collected from the lower respiratory tract, oropharynx and stomach. Other samples, including the environmental air, swabs of nurses’ hands, subglottic secretion and ventilator circuit, were also collected. Microorganisms in the collected samples were recovered and identified at species level by biochemical detection. Genetic relationship of dominant species was further characterized by pulsed field gel electrophoresis (PFGE). Results Out of 48 enrolled patients, 22 cases developed VAP and bacterial cultures were recovered from the lower respiratory tract samples of 14 cases. The average hospitalization time with VAP was significantly longer than that of patients without VAP (P < 0.05). Among the recovered bacteria cultures, multidrug-resistant Pseudomonas aeruginosa and Stenotrophomonas maltophilia were dominant. It was more likely that subglottic secretion and gastric juice samples contained the same isolates as recovered in the lower respiratory tract by PFGE analysis. Conclusions Mechanical ventilation in RICU and NICU was a high risk factor for VAP development. Special emphasis of VAP prophylaxis should be paid on subglottic secretion and gastric juice reflux.