Clinical characteristics and therapeutic outcomes of hematogenous vertebral osteomyelitis caused by methicillin-resistant Staphylococcus aureus

Objective: To evaluate the clinical characteristics and therapeutic outcomes of patients with hematogenous vertebral osteomyelitis (HVO) caused by methicillin-resistant Staphylococcus aureus (MRSA). Methods: We performed a cohort study of adult patients diagnosed with S. aureus HVO at a tertiary-care hospital over a 7-year period. Results: Of the 139 patients with S. aureus HVO, MRSA caused 62 (44.6%) cases. In multivariate analysis, compared with methicillin-susceptible S. aureus (MSSA), MRSA was associated with a higher risk of persistent bacteremia (≥7 days) (8.40 fold; P<0.001) and relapse (4.83 fold; P=0.03), and increased hospital stay (1.69 fold; P=0.001). Among the MRSA cases, relapse rates differed according to duration of antibiotics: 41.7% (4-6 weeks), 25.0% (6-8 weeks), and 5.6% (≥8 weeks) ( P=0.007). Bacteremia was more likely to persist for ≥7 days in patients with an initial vancomycin trough <15mg/L than in those with an initial trough ≥15mg/L (79.3% vs. 20.0%; P=0.001). Conclusions: MRSA HVO was associated with more frequent persistent bacteremia (≥7 days) and relapse, and longer hospital stay compared to MSSA HVO. Antibiotic therapy for ≥8 weeks and targeting a vancomycin trough of ≥15mg/L may be benefit patients with MRSA HVO.