Infections in intensive care unit adult patients harboring multidrug-resistant Pseudomonas aeruginosa: implications for prevention and therapy

The purpose of this paper was to report the burden and characteristics of infection by multidrug-resistant Pseudomonas aeruginosa (MDR-PA) in clinical samples from intensive care unit (ICU) adults, and to identify predictors. This was a retrospective observational study at four medical-surgical ICUs. The case cohort comprised adults with documented isolation of an MDR-PA strain from a clinical specimen during ICU stay. Multivariate analysis was performed to identify predictors for MDR-PA infection. During the study period, 5667 patients were admitted to the ICU and P. aeruginosa was isolated in 504 (8.8%). MDR-PA was identified in 142 clinical samples from 104 patients (20.6%); 62 (43.6%) of these samples appeared to be true infections. One hundred and eighteen (83.1%) isolates were susceptible only to amikacin and colistin, and 13 (9.2%) were susceptible only to colistin. Overall, the MIC50 to meropenem was 16 μg/mL and the MIC90 was >32 μg/mL, with 60.4% of respiratory samples being MIC >32 μg/mL to meropenem. Independent predictors for MDR-PA infection were fever/hypothermia [odds ratio (OR) 9.09], recent antipseudomonal cephalosporin therapy (OR 6.31), vasopressors at infection onset (OR 4.40), and PIRO (predisposition, infection, response, and organ dysfunction) score >2 (OR 2.06). This study provides novel information that may be of use for the clinical management of patients harboring MDR-PA and for the control of the spread of this organism.