Predictors of Mortality with Staphylococcus aureus Bacteremia in Elderly Adults

Objectives: To analyze risk factors for early and late mortality in individuals aged 75 and older with Staphylococcus aureus bacteremia (SAB) in Italy. Design: Four-year retrospective observational study (January 2011-December 2014). Setting: Two tertiary care university hospitals in Italy (Santa Maria Misericordia Hospital in Udine, Policlinico Universitario Agostino Gemelli in Rome). Participants: All adults consecutively admitted with SAB. Measurements: Clinical presentation, infection characteristics, and clinical outcomes of individuals aged 75 and older were compared with those of individuals younger than 75. Results: Three hundred thirty-seven cases of SAB were diagnosed during the study period, 118 of which (35%) occurred in those aged 75 and older. Seven- (20.3% vs 9.2%) and 30-day (35.7% vs 20.7%) mortality were significantly higher in elderly than younger adults. Clinical presentation with septic shock, adequacy of empiric antibiotic treatment, and liver cirrhosis were found to be predictors of 7-day mortality in elderly adults with SAB. Risk factors independently associated with 30-day mortality included isolation of methicillin-resistant Staphylococcus aureus (MRSA) and not receiving an infectious disease consultation. Conclusion: Mortality is significantly higher in elderly than in younger adults with SAB, particularly in those presenting with septic shock, liver cirrhosis, or SAB due to MRSA. Additional risk factors for mortality included inappropriate empiric antibiotic treatment and not receiving an infectious disease consultation.