Factors associated with antimicrobial resistance and mortality in pneumococcal bacteremia

We conducted a multicenter, retrospective cohort study of patients with Streptococcus pneumoniae bacteremia to determine factors associated with antibiotic resistance and mortality. Risk factors were identified using multivariate logistic regression. There were 1574 patients at 34 sites enrolled. Compared to isolates from patients not receiving an antibiotic before the index blood culture, patients receiving an antibiotic were less likely to harbor an antibiotic susceptible organism. Susceptibility to penicillin decreased from 78% (95% confidence interval [CI] 75-80) to 49% (95% CI 39-59); to cefotaxime/ceftriaxone, from 92% (95% CI 90-93) to 82% (95% CI 72-89); and to macrolide, from 84% (95% CI 82-87) to 55% (95% CI 41-68). Factors associated with macrolide non-susceptibility include: > 24 h of antibiotic therapy at time of the index culture (odds ratio [OR] 4.0), residing in southern U.S. (OR 1.7), and having an antibiotic allergy (OR 1.7). Harboring an antibiotic non-susceptible strain (OR 1.4) and male sex (OR 1.4) were associated with increased risk of mortality, whereas black race (OR 0.6) and evidence of focal infection (OR 0.6) were associated with decreased risk.