Staphylococcus aureus VCF files: Risk Factors for Recurrent Staphylococcus aureus Bacteremia

Background: To understand the clinical, bacterial, and host characteristics associated with recurrent Staphylococcus aureus bacteremia (R-SAB), patients with R-SAB were compared to contemporaneous patients with a single episode of SAB (S-SAB).
Methods: All SAB isolates underwent spa genotyping. All isolates from R-SAB patients underwent Pulsed-Field Gel Electrophoresis (PFGE). PFGE-indistinguishable pairs from 40 patients underwent whole genome sequencing (WGS). Acute phase plasma from R-SAB and S-SAB patients was matched 1:1 for age, race, gender, and bacterial genotype and underwent cytokine quantification using 25-analyte multiplex bead array. Results: R-SAB occurred in 69 (9.1%) of the 756 study patients. Of the 69 patients, 30 experienced relapse (43.5%) and 39 reinfection (56.5%). Age, race, hemodialysis dependence, presence of foreign body, MRSA, and persistent bacteremia were individually associated with likelihood of recurrence. Multivariate risk modeling revealed that African American (AA) hemodialysis patients were nearly two times more likely (OR = 9.652 [5.402 – 17.418]) than White hemodialysis patients (OR = 4.53 [1.696 – 10.879]) to experience R-SAB. WGS confirmed PFGE interpretations in all cases. Median RANTES levels in acute phase plasma from the initial episode of SAB were higher in R-SAB than in matched S-SAB controls ( P = 0.0053, False Discovery Rate < 0.10).   
Conclusion: This study identified several risk factors for R-SAB. The largest risk for R-SAB is among AA hemodialysis patients. Higher RANTES levels in R-SAB compared to
matched controls warrants further study.