Impact of Xpert® MRSA/SA blood culture PCR test on antimicrobial utilization at a large teaching hospital

Administering appropriate antimicrobial treatment as soon as possible is critical in improving patient outcomes. The implementation of a rapid molecular diagnostic test for detection and identification of pathogens in blood stream infections (BSI) may allow for reduced time to intervention, thereby leading to potential reductions in hospital costs and improved patient outcomes.

This was a retrospective study of patients admitted to an 870-bed hospital with a blood culture positive for methicillin-susceptible Staphylococcus aureus (MSSA). The primary outcome was days of antimicrobial treatment with activity against methicillin-resistant S. aureus (MRSA). Secondary outcomes included time to MSSA identification, time to discontinuation of anti-MRSA treatment, and proportion of patients receiving targeted anti-MSSA therapy within 24 hours of Gram stain result.

158 patients with MSSA BSI were included (76 pre-intervention and 82 post intervention). Following implementation of the Xpert® MRSA/SA blood culture test, the duration of anti-MRSA therapy was significantly reduced (median days (IQR): 2.7 (0.55) vs 1.67 (1.51), p < 0.001). Post-intervention also saw significantly shorter time to MSSA identification and a significantly higher proportion of patients receiving targeted anti-MSSA therapy within 24 hours of Gram stain.

Implementation of the Xpert® MRSA/SA Blood Culture assay was associated with reduced duration of anti-MRSA therapy and more rapid initiation of targeted MSSA therapy. These results demonstrate antimicrobial stewardship benefits of rapid diagnostics in a real-world hospital setting. These findings support the use of rapid diagnostics in antimicrobial stewardship strategies to optimize care for hospitalized patients with MSSA bloodstream infections.