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

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

Prospective cohort study.

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

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

Prospective patient surveillance and data collection.

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.

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.