Stewardship Approach for Optimizing Antimicrobial Therapy through Use of a Rapid Microarray Assay on Blood Cultures Positive for Enterococcus Species

Enterococci are a major cause of bloodstream infections in hospitalized patients and have limited antimicrobial treatment options due to their many resistance mechanisms. Molecular technologies have significantly shortened the time to enterococcal isolate identification compared with conventional methods. We evaluated the impact of rapid organism identification and resistance detection with the Verigene Gram-positive blood culture microarray assay on clinical and economic outcomes for patients with enterococcal bacteremia. A single-center preintervention/postintervention quasiexperimental study compared inpatients with enterococcal bacteremia from 1 February 2012 to 9 September 2012 (preintervention period) and 10 September 2012 to 28 February 2013 (postintervention period). An infectious disease and/or critical care pharmacist was contacted with the microarray assay results, and effective antibiotics were recommended. The clinical and economic outcomes for 74 patients were assessed. The mean time to appropriate antimicrobial therapy was 23.4 h longer in the preintervention group than in the postintervention group (P = 0.0054). A nonsignificant decrease in the mean time to appropriate antimicrobial therapy was seen for patients infected with vancomycin-susceptible Enterococcus isolates (P = 0.1145). For patients with vancomycin-resistant Enterococcus bacteremia, the mean time to appropriate antimicrobial therapy was 31.1 h longer in the preintervention group than in the postintervention group (P < 0.0001). In the postintervention group, the hospital length of stay was significantly 21.7 days shorter (P = 0.0484) and mean hospital costs were $60,729 lower (P = 0.02) than in the preintervention group. The rates of attributed deaths in the two groups were not statistically different. Microarray technology, supported by pharmacy and microbiology departments, can decrease the time to appropriate antimicrobial therapy, the hospital length of stay, and health care costs.