Staphylococcus aureus Bacteremia Among Patients Receiving Maintenance Hemodialysis: Trends in Clinical Characteristics and Outcomes

ABSTRACT Rationale & Objective Staphylococcus aureus (S. aureus) bacteremia (SAB) is associated with morbidity and mortality in patients receiving maintenance hemodialysis (HD). We evaluated changes in clinical and bacterial characteristics, and their associations with clinical outcomes following SAB in this population over a 21-year period. Study Design Prospective cohort study. Setting & Participants 453 hospitalized, non-neutropenic, adults receiving maintenance HD who developed monomicrobial SAB between 1995 and 2015. Exposures Clinical characteristics and bacterial genotype. Outcomes All-cause and SAB-attributable mortality, persistent bacteremia, and metastatic infection complications. Analytical Approach Proportions of participants experiencing each outcome were calculated overall and by calendar year. Secular trends were estimated using binomial risk regression, a generalized linear model with the log link function for a binomial outcome. Associations with outcomes were estimated using logistic regression. Results Over the 21-year study period, patients receiving maintenance HD experienced significant increases in age- and diabetes-adjusted SAB-attributable mortality (0.45% per year, 95% confidence interval [CI] 0.36, 0.46), persistent bacteremia (0.86% per year, 95% CI 0.14, 1.55), metastatic infection complications (0.84% per year, 95% CI 0.11, 1.56), and infection with the virulent S. aureus clone USA300 (1.47% per year, 95% CI 0.33, 2.52). Over time, the suspected source of SAB was less likely to be a central venous catheter (-1.32% per year, 95% CI -2.05, -0.56) or arteriovenous (AV) graft (-1.08% per year, 95% CI -1.54, -0.56), but more likely to be a non-vascular access source (1.89% per year, 95% CI 1.29, 2.43). Patients with a non-vascular access suspected source of infection were more likely to die as a result of their S. aureus infection (Odds Ratio [OR] =3.20, 95% CI 1.36, 7.55). The increase in USA300 infections may have contributed to the observed increase in persistent bacteremia (OR=2.96, CI 1.12, 7.83) but did not explain the observed increases in SAB-attributable mortality (OR=0.83, CI 0.19, 3.61) or metastatic complications (OR=1.34, CI 0.53, 3.41). Limitations Single-center, inpatient cohort. Conclusions The clinical and molecular epidemiology of SAB in HD-dependent patients has changed over time, with an increase in SAB-attributable mortality and morbidity despite a decline in catheter-related infections.