Methods: All consecutive patients with detection of P. aeruginosa in blood cultures and hospitalized at the University Hospital Basel, a tertiary academic care center, from 1/2003-12/2013 were included. Baseline characteristics, as well as comorbid conditions, Charlson comorbidity index, systemic inflammatory response syndrome (SIRS) criteria, Pitt bacteremia score, and antibiotic treatment were assessed. Patients with and without definite combination therapy were compared and hazard ratios for death were calculated.
Results: 187 patients with P. aeruginosa BSI were identified. Definite combination therapy was administered in 42.8% (80/187) of all patients, of which 20% (16/80) received a combination of a betalactam and a quinolone and 80% received a combination of a betalactam with an aminoglycoside. The remaining 57.2% (107/187) were treated with betalactam monotherapy. Median treatment duration was 15 days (IQR 12-20 days). The age of patients significantly differed, but comorbid conditions, immunosuppression, receipt of solid organ or stem cell transplant, ICU admission, Pitt bacteremia score were similar between groups. Importantly, receipt of effective empiric treatment was equally distributed between groups. Mortality was significantly lower in patients receiving definite combination therapy in crude and adjusted cox regression analyses (HR 0.26, 95%CI 0.11-0.60, p=0.002 and HR 0.29 95%CI 0.12-0.68, p=0.004, respectively).
Conclusion: This study provides evidence that combination antimicrobial treatment regimens including quinolones or aminoglycosides in addition to betalactams improves survival in P.aeruginosa BSI compared to betalactam monotherapy. However, new antibiotic regimens may be as effective as combination therapy.
M. Weisser, None
R. Frei, None
A. F. Widmer, None
Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.