Impact of rapid molecular testing on clinical outcomes for methicillin-susceptible Staphylococcus aureus bacteremia

Rapid molecular blood culture identification (BCID) enables earlier pathogen identification and targeted antibiotic therapy compared with traditional culture-based methods. Methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia is optimally treated with anti-staphylococcal β-lactam antibiotics; however, delays in bacterial identification frequently result in prolonged empiric anti-methicillin-resistant Staphylococcus aureus (MRSA) therapy. Data evaluating the clinical impact of early MSSA identification remain limited.

This retrospective, single-center, quasi-experimental program evaluation included adult patients with monomicrobial MSSA bacteremia. Patients were grouped based on identification by BCID or conventional culture-based methods. Automatic Infectious Diseases consultation was performed for all patients. The primary outcome was a desirability of outcome ranking incorporating treatment success, acute kidney injury (AKI), and inpatient mortality. Secondary outcomes included time-to-optimal therapy, duration of bacteremia, treatment success, and hospital length of stay.

A total of 300 patients were included (150 per cohort). BCID use was associated with earlier MSSA identification (0.8 vs 2.1 days; P < .001) and earlier initiation of targeted β-lactam therapy (1.9 vs 3.8 days; P < .001). The probability of a more desirable outcome with BCID was 58.5% (95% CI: 52.5% to 64.3%), and more individuals achieved the most desirable outcome (62.0% vs 46.0%; P = .005). AKI occurred less frequently in the BCID group (23.5% vs 44.2%; P < .001).

Incorporation of rapid BCID into an established automatic Infectious Diseases consultation program improved outcomes in MSSA bacteremia by facilitating earlier β-lactam therapy and reducing nephrotoxicity. Antimicrobial stewardship programs should prioritize rapid diagnostics to optimize MSSA management.