Identifying new risk factors for Pseudomonas aeruginosa pneumonia in intensive care units: experience of the French national surveillance, REA-RAISIN.

Pseudomonas aeruginosa is an important pathogen of complicated pneumonia in intensive care units (ICUs). Our objective was to determine 'patient' and 'ward' risk factors for P. aeruginosa pneumonia among patients with nosocomial pneumonia in ICU. Data from the 2004-2006 prospective French national nosocomial infection surveillance in ICUs (REA-RAISIN) were used, including patients admitted for >48 h in ICU and who developed nosocomial pneumonia. Only first pneumonia was considered and categorised as either P. aeruginosa pneumonia or other micro-organism pneumonia. Multilevel logistic regression model (patient as first level and ward as second) with P. aeruginosa pneumonia as binary outcome was performed. Of 3,837 included patients from 201 different wards, 25% had P. aeruginosa pneumonia. P. aeruginosa was significantly more frequent in late onset pneumonia. Higher probability of P. aeruginosa pneumonia was associated with higher age and length of mechanical ventilation, antibiotics at admission, transfer from a medical unit or ICU, and admission in a ward with higher incidence of patients with P. aeruginosa infections. Lower probability of P. aeruginosa was associated with traumatism and admission in a ward with high patient turnover. Our analyses identified a patient's profile and some ward elements that could make suspect P. aeruginosa in case of nosocomial pneumonia.