Samantha Iyaloo
National Institute for Communicable Diseases (NICD), South Africa
Title: Staphylococcus aureus bacteremia: risk factors associated with death
Biography
Biography: Samantha Iyaloo
Abstract
Background: Staphylococcus aureus bacteremia (SAB), especially when caused by methicillin-resistant S. aureus (MRSA), is associated with increased patient morbidity, death and increased healthcare costs. Modifiable risk factors for death are important to identify and incorporate into interventions to reduce the burden of illness. This study aimed to describe the risk factors associated with death among patients with MRSA vs. methicillin-sensitive S. aureus (MSSA) bacteremia. Methods: We undertook a retrospective study of patients admitted to three hospitals in Gauteng province, South Africa, from September 2012-July 2014. Patients with SAB were recruited through active, enhanced, laboratory-based surveillance. Demographic, clinical and laboratory data were collected by face-to-face interviews, chart and laboratory record reviews using standardized case report forms. Statistical analysis was conducted using STATA 13. Survival analysis was performed using univariate and multivariate Cox proportional hazards regression analysis and Kaplan-Meier (KM) survival curves to compare MRSA and MSSA risk factors for death. Results: During the 23-month period, a total of 589 cases of SAB were detected with an overall case-fatality rate of 30.2% (178/589). The adjusted KM survival curves showed a higher mortality rate in patients with MRSA vs. MSSA. The incidence for MRSA vs. MSSA-associated deaths was 23.3 and 12.9 deaths per 1000 patient-days respectively from the collection date of the first positive specimen. Increasing age (OR: 1.02, 95%CI: 1.01-1.03), diabetes mellitus (OR: 3.18, 95%CI: 1.19-8.53), a history of smoking (OR: 6.06 95%CI: 1.32-5.06) and any antibiotic use within two months preceding admission (OR: 2.62, 95%CI: 1.36-5.06) were risk factors for death in the multivariate Cox model in the MRSA sub-group. HIV infection (OR: 2.60, 85%CI: 1.24-5.44), cerebrovascular accidents (OR: 3.76, 95% CI: 1.20-11.78) and fever (OR: 0.60, 95% CI: 0.37-0.97) were associated with deaths in the MSSA sub-group in the multivariate Cox model. Conclusions: The incidence and the risk factors for death in patients with MRSA and MSSA were remarkably different. Identification of predictors for death among patients with MRSA and MSSA bacteremia can help prioritize the management of these patients.