Patterns of colonization by Pseudomonas aeruginosa in intubated patients: a 3-year prospective study of 1,607 isolates using pulsed-field gel electrophoresis with implications for prevention of ventilator-associated pneumonia

Objective To identify routes and patterns of colonization with Pseudomonas aeruginosa in intubated patients to design strategies of prevention for respiratory infection.Design and setting Prospective and observational study in the 16-bed intensive care unit of a teaching hospital.Patients and participants Ninety-eight intubated patients were investigated over a 3-year period. Those ventilated less than 72 h were excluded.Measurements and results Samples from the tap water from each patients room, stomach, oropharynx, subglottic secretions, trachea, and rectum were collected when the patient was intubated, and then three times per week. Pulsed-field gel electrophoresis was performed to type the strains. We identified 1,607 isolates pertaining to 35 different pulsotypes. Overall 54.2% of patients presented colonization, and tracheal colonization was present in 30.5%. Ten patients had colonization at intubation, and four of these developed ventilator-associated pneumonia (VAP) after a mean of 4±2 days. ICU-acquired colonization occurred in 31 patients, and 4 of these developed VAP after a median of 10±5 days. P. aeruginosa was isolated from the rooms tap water in 62.4% of samples. More than 90% of tap water samples had pulsotypes 1 and 2, which were frequently isolated in the stomach (59%) but were only rarely associated with VAP.Conclusions Although colonization/infection with P. aeruginosa in intubated patients tends to be endogenous, exogenous sources should not be ruled out. A combination of early identification (and eradication) of airways colonization by P. aeruginosa plus infection control measures targeted to reduce cross-contamination should be the basis to prevent pulmonary infection.This work was supported in part by a grant from the FIS 96/146