1489. Development and implementation of a treatment algorithm for Gram-positive bloodstream infections identified by a Gram-positive nucleic acid microarray assay
Session: Poster Abstract Session: Antimicrobial Stewardship: Role of Diagnostics
Saturday, October 10, 2015
Room: Poster Hall
  • IDWeek_Poster_1489.pdf (115.0 kB)
  • Background: Bloodstream infections are a major cause of morbidity and mortality in the United States, with mortality estimated at up to 40%. The rapid identification of causative organisms and initiation of appropriate antimicrobial therapy are key predictors of mortality. Routine blood culture techniques can take up to 2-3 days for identification and susceptibilities of causative organisms. The Nanosphere Verigene® Gram-positive blood culture assay (BC-GP) is a rapid molecular nucleic acid microarray capable of identifying twelve bacterial targets and three genetic antibiotic resistance markers. 

    Methods: A retrospective chart review was conducted at the University of Minnesota Medical Center, Fairview from October 2014 until December 2014. Patients identified with a possible Gram-positive bloodstream infection by BC-GP were screened for inclusion. Patients were included if they had a mono-microbial Gram-positive bloodstream infection and were admitted to the hospital. Patients were excluded if they were <18 years of age, pregnant, or opted out of the study. 

    Results: A total of 96 positive blood cultures with Gram-positive cocci or bacilli by Gram-stain were analyzed by BC-GP. The organisms identified by the BC-GP assay were Staphylococcus epidermidis 37.5%, Staphylococcus species 18.75%, Enterococcus faecium 9.3%, Staphylococcus aureus 8.3%, Enterococcus faecalis 5.2%, Streptococcus species 4.1%, Streptococcus agalactiae 3.1%, Streptococcus pneumoniae 1%, Streptococcus pyogenes 1% and no targets 14.5%. When compared with routine culture results, BC-GP organism identification and resistance gene identification for mecA and vanA/B were concordant 97.9% (94/96), 95.1% (39/41), and 92.8% (13/14) of the time, respectively. The mean time to BC-GP results was 3 hours, 24 hours sooner than traditional identification and 31 hours sooner than susceptibilities. Mean vancomycin and antipseudomomal antibiotic duration were 3.4 days and 3.7 days, respectively. 

    Conclusion: The BC-GP assay provided rapid accurate identification of Gram-positive bloodstream infections. In order to improve utilization of BC-GP results and decrease broad-spectrum antibiotic use, a treatment algorithm was developed, and made available to the medical staff.

    Brenton Bastian, PharmD, MS1, Kimberly Boeser, Pharm D, BCPS AQ-ID1 and Patricia Ferrieri, MD, FIDSA2, (1)Pharmacy, University of Minnesota Medical Center, Fairview, Minneapolis, MN, (2)Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, Fairview, Minneapolis, MN


    B. Bastian, None

    K. Boeser, None

    P. Ferrieri, None

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