To describe the epidemiology of endemic multidrug-resistant Pseudomonas aeruginosa colonizations and infections in critically ill patients.
Prospective study on bacterial strain typing and retrospective cohort study of charts of patients in the intensive care unit (ICU).
Fifty-three patients with P. aeruginosa isolated from clinical cultures in 2001 were selected, divided into those with P. aeruginosa in vitro resistant to at least two classes of antibiotics (multidrug-resistant, n = 18) and those susceptible to all or resistant to only one antibiotic (susceptible, n = 35).
Risk factors for multidrug-resistant P. aeruginosa included maxillary sinusitis, long-dwelling central venous catheters, prolonged use of certain antibiotics, a high lung injury score, and prolonged mechanical ventilation and duration of stay. The frequency of colonization (approximately 50%) versus infection (ie, ventilator-associated pneumonia) did not differ between the groups. On amplified fragment-length polymorphism analysis, 64% of the multidrug-resistant strains had been potentially transmitted via cross-colonization and 36% had probably originated endogenously. ICU mortality was 22% in the multidrug-resistant group and 23% in the susceptible group, although the duration of mechanical ventilation was longer in the former.
Patients with sinusitis who stayed in the ICU longer, were ventilated longer because of acute lung injury, received antibiotics for longer durations, and had long-dwelling central venous catheters ran an elevated risk of acquiring multidrug-resistant P. aeruginosa. These patients did not have a higher mortality than patients with susceptible P. aeruginosa. Prevention of the emergence of multidrug-resistant strains requires changes in infection control measures and antibiotic policies in our ICU.