RISKS AND ROUTES FOR VENTILATOR-ASSOCIATED PNEUMONIA WITH PSEUDOMONAS-AERUGINOSA

In a prospective study, we screened specimens from 190 mechanically ve ntilated patients hospitalized in a surgical intensive care unit, and from the environment to assess risks and routes of colonization/infect ion. Specimens from various sites were collected on admission and once a week throughout each patient's stay. All P. aeruginosa isolates wer e typed by determination of DNA patterns. Data were collected from pat ients to identify risk factors. In vitro production of exoenzymes of d ifferent strains were compared. Forty-four patients were colonized wit h P. aeruginosa on the bronchopulmonary tract and 13 suffered from pne umonia. The 7-d and 14-d Kaplan-Meier rates of colonization were 2.21 and 7.03%. Twenty-one patterns of bronchopulmonary tract isolates were isolated from single patients and 10 from several patients. The lower airway was often the first site of colonization. The contribution of environment to patient colonization appeared to be small. The length o f hospitalization, the previous use of third-generation cephalosporins less effective against P., aeruginosa, and chronic obstructive pulmon ary disease were the most significant predictors of colonization/infec tion. The in vitro exoprotein production was not correlated with the p resence of pneumonia. Our study may be useful in identifying which pat ients in the mechanically ventilated population are at greater risk of P. aeruginosa pneumonia.