Clinical Impact of Rapid Molecular Diagnosis of Bloodstream Infections at an Academic Medical Center in New York City

Background: Rapid blood culture identification (BCID) for patients with bacteremia may improve outcomes when implemented with antimicrobial stewardship interventions. The clinical value of BCID in the absence of such interventions is not well understood.

Methods: We conducted a before-after observational study to assess the impact of BCID (FilmArray BCID panel) on antimicrobial use and clinical outcomes between August 2014 and June 2015. Clinical, antimicrobial and demographic data were extracted from the electronic medical record for adult inpatients with a first episode of bacteremia. Institutional guidelines for empiric therapy based on BCID result were developed based on the hospital antibiogram and published prior to implementation. The primary outcomes were time to optimal therapy and time to effective therapy. Secondary outcomes were aggregate days of antimicrobial therapy per patient, hospital length of stay, Clostridium difficile infection and in-hospital mortality.

Results: 396 positive blood culture episodes were included pre-intervention and 293 episodes were included post-intervention. The Charlson comorbidity index, the Pitt bacteremia score and the frequency of immune-compromising conditions were not significantly different between the study periods. Following BCID implementation, the time to optimal therapy was significantly reduced for patients with blood cultures positive for coagulase-negative staphylococci (median time 6.99 versus 30.52 hours; p-value 0.04) and methicillin-susceptible Staphylococcus aureus (20.30 versus 48.29 hours; p-value 0.04). There was a non-significant reduction in time to optimal therapy for patients with blood cultures positive for streptococci (8.40 versus 50.39 hours; p-value 0.10). The time to effective therapy for patients with gram-negative bacteremia, days of antimicrobial therapy per patient and other secondary outcomes were not significantly different between study periods.

Conclusion: BCID improved the time to receipt of optimal therapy for patients with gram-positive bacteremia in the absence of a stewardship intervention, but it did not impact the time to effective antimicrobial therapy in gram-negative bacteremia or other clinical outcomes.