Risk factors for Pseudomonas aeruginosa acquisition in intensive care units: a prospective multicentre study

SummaryBackgroundPseudomonas aeruginosa is a major nosocomial pathogen in intensive care units (ICUs); however, endogenous versus exogenous origin of contamination remains unclear.AimTo identify individual and environmental ICU risk factors for P. aeruginosa acquisition.MethodsA five-month prospective multicentric study was performed in ten French ICUs. Adult patients hospitalized in ICU for ≥24 h were included and screened for P. aeruginosa colonization on admission, weekly and before discharge. P. aeruginosa acquisition was defined by a subsequent colonization or infection if screening swabs on admission were negative. Water samples were obtained weekly on water taps of the ICUs. Data on patient characteristics, invasive devices exposure, antimicrobial therapy, P. aeruginosa water and patient colonization pressures, and ICU characteristics were collected. Hazard ratios (HRs) were estimated using multivariate Cox model.FindingsAmong the 1314 patients without P. aeruginosa on admission, 201 (15%) acquired P. aeruginosa during their ICU stay. Individual characteristics significantly associated with P. aeruginosa acquisition were history of previous P. aeruginosa infection or colonization, cumulative duration of mechanical ventilation and cumulative days of antibiotics not active against P. aeruginosa. Environmental risk factors for P. aeruginosa acquisition were cumulative daily ward ‘nine equivalents of nursing manpower use score’ (NEMS) [hazard ratio (HR): 1.47 for ≥30 points; 95% confidence interval (CI): 1.06–2.03] and contaminated tap water in patient's room (HR: 1.76; CI: 1.09–2.84).ConclusionIndividual risk factors and environmental factors for which intervention is possible were identified for P. aeruginosa acquisition.