Risk factors and clinical outcomes of nosocomial multi-drug resistant Pseudomonas aeruginosa infections

Risk factors for multi-drug resistant Pseudomonas aeruginosa (MDRP) infections were investigated using a case-control study design involving MDRP patients (N = 44) and controls (N = 68). A retrospective cohort study was performed to study the predictive factors of clinical outcome in MDRP patients. Multivariate analysis demonstrated that previous exposure to imipenem/meropenem odds ratio (OR), 44.8] and mechanical ventilation (OR 8.2) were risk factors for nosocomial infections of MDRP. Of 44 cases of MDRP infections, 20 patients died directly from P. aeruginosa infections. Pulsed-field gel electrophoresis (PFGE) analysis on serial isolates from three patients showed that profiles of isolates from the same patient were closely related or indistinguishable. Multivariate analysis demonstrated that patients with adverse clinical outcomes were more likely to have been treated with mechanical ventilation (OR 12.8), and more likely to have MDRP resistance patterns that did not change during treatments (OR 26.5). We concluded that mechanical ventilation and previous exposure to imipenem/meropenem were independent risk factors for MDRP infections, while mechanical ventilation and antibiotic resistance switch were predictive factors of outcomes of MDRP infections.