Hospital mortality for patients with bacteremia due to Staphylococcus aureus or Pseudomonas aeruginosa

Abstract

Study objectives: To evaluate the relationship between hospital mortality and bloodstream infections due to Staphylococcus aureus or Pseudomonas aeruginosa.

Design: Prospective cohort study.

Setting: A 1,400-bed, university-affiliated urban teaching hospital.

Patients: Between December 2001 and September 2002, 314 patients with bacteremia due to S aureus or P aeruginosa were prospectively evaluated.

Intervention: Prospective patient surveillance and data collection.

Results: Thirteen patients (4.1%) received inadequate initial antibiotic treatment. Fifty-four patients (17.2%) died during hospitalization. Hospital mortality was statistically greater for patients with bloodstream infections due to P aeruginosa (n = 49) compared to methicillin-sensitive S aureus (MSSA) [n = 117; 30.6% vs 16.2%, p = 0.036] and methicillin-resistant S aureus (MRSA) [n = 148; 30.6% vs 13.5%, p = 0.007]. Multiple logistic regression analysis identified the lack of response to initial medical treatment (adjusted odds ratio [AOR], 2.69; 95% confidence interval [CI], 1.83 to 3.94; p = 0.010) and endocarditis (AOR, 4.62; 95% CI, 2.45 to 8.73; p = 0.016) as independent determinants of hospital mortality. Patients with bloodstream infections due to P aeruginosa were statistically more likely to be nonresponders to early medical treatment compared to patients with MSSA (73.5% vs 11.1%, p < 0.001) and MRSA (73.5% vs 16.9%, p < 0.001) bloodstream infections.

Conclusions: These data suggest that bloodstream infections due to P aeruginosa have a greater risk of hospital mortality compared to bloodstream infections due to S aureus despite adequate antibiotic treatment.