Clinical characteristics, risk factors, and outcomes of patients with polymicrobial Pseudomonas aeruginosa bloodstream infections

BACKGROUND: Previous studies on polymicrobial Pseudomonas aeruginosa bloodstream infections (Pa-BSIs) are dated, and it is necessary to reanalyze polymicrobial Pa-BSIs. The aim of this study was to investigate clinical characteristics and risk factors for polymicrobial Pa-BSI in comparison with monomicrobial Pa-BSI. METHODS: A double-center retrospective observational study was performed between January 1, 2013 and June 30, 2022, in two tertiary hospitals. All patients with Pa-BSI were enrolled, and their clinical data were collected by reviewing electronic medical records. RESULTS: A total of 278 patients with Pa-BSI were enrolled, including 77 patients (27.7%) with polymicrobial Pa-BSI. Compared with monomicrobial Pa-BSI, the main source of polymicrobial Pa-BSI was pneumonia (49.4% vs 31.3%, p < 0.01), whereas the main source of monomicrobial Pa-BSI was primary BSIs (21.9% vs 2.6%, p = 0.04). In multivariate analysis, a history of cerebrovascular accident (CVA) (adjusted odds ratio [OR], 3.62; 95% CI, 1.46-8.92) was independently associated with polymicrobial Pa-BSI. Primary BSI was associated with monomicrobial Pa-BSI (OR, 0.08; 95% CI, 0.02-0.38). Patients with polymicrobial Pa-BSI had a longer intensive care unit (ICU) length of stay after onset of BSI than those with monomicrobial Pa-BSI (2 [2, 16] vs 13 [3.75, 29], p = 0.02). CONCLUSION: Patients with Pa-BSI and the presence of CVA need to be alert to the possibility of polymicrobial BSI occurrence. Prolonged ICU stay and pneumonia as a source of BSI warrant clinician attention for polymicrobial Pa-BSI, and primary BSIs are likely associated with monomicrobial BSIs.