Clinical characteristics and risk factors of polymicrobial Staphylococcus aureus bloodstream infections
Cheng Zheng, Shufang Zhang, Qingqing Chen, Li Zhong, Tiancha Huang, Xijiang Zhang, Kai Zhang, Hongwei Zhou, Jiachang Cai, Linlin Du, Changming Wang, Wei Cui, Gensheng Zhang
Abstract
BACKGROUND: Although Staphylococcus aureus bloodstream infections (SA-BSI) are a common and important infection, polymicrobial SA-BSI are infrequently reported. The aim of this study was to investigate the clinical characteristics and risk factors of polymicrobial SA-BSI in comparison with monomicrobial SA-BSI. METHODS: A single-center retrospective observational study was performed between Jan 1, 2013, and Dec 31, 2018 at a tertiary hospital. All patients with SA-BSI were enrolled, and their clinical data were gathered by reviewing electronic medical records. RESULTS: A total of 349 patients with SA-BSI were enrolled including 54 cases (15.5%) with polymicrobial SA-BSI. In multivariable analysis, burn injury (adjusted odds ratio [OR], 7.04; 95% confidence interval [CI], 1.71-28.94), need of blood transfusion (aOR, 2.72; 95% CI, 1.14-6.50), use of mechanical ventilation (aOR, 3.11; 95% CI, 1.16-8.30), the length of prior hospital stay (aOR, 1.02; 95% CI, 1.00-1.03), and pneumonia as primary site of infection (aOR, 4.22; 95% CI, 1.69-10.51) were independent factors of polymicrobial SA-BSI. In comparison with monomicrobial SA-BSI, patients with polymicrobial SA-BSI had longer length of ICU stay [median days, 23(6.25,49.25) vs. 0(0,12), p < 0.01] and hospital stay [median days, 50(21.75,85.75) vs. 28(15,49), p < 0.01], and showed a higher 28-day mortality (29.6% vs. 15.3%, p = 0.01). CONCLUSIONS: Burn injury, blood transfusion, mechanical ventilation, the length of prior hospital stay, and pneumonia as a primary site of infection are independent risk factors for polymicrobial SA-BSI. In addition, patients with polymicrobial SA-BSI might have worse outcomes compared with monomicrobial SA-BSI.