1107. Evaluating Use Of MALDI-TOF For Blood Culture Isolate Identification In A Four Hospital System
Session: Poster Abstract Session: Molecular and Nucleic Acid Testing Diagnostics
Friday, October 9, 2015
Room: Poster Hall
  • MALDITOF poster IDSA 10.7.15.pdf (467.1 kB)
  • Background: Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) is utilized in healthcare settings to analyze blood, respiratory, wound, and urine samples.  MALDI-TOF can be used to identify the organism, followed by Verigene® Gram-Positive Blood Culture Test (BC-GP) to identify resistance markers for Staphylococcus aureus and Enterococcus spp, with significant shortened total time to identification.  Average time to identification and susceptibility results is 48-72 hours for Phoenix™, 2.5 hours for identification and resistance markers using Verigene® BC-GP, and 30 minutes with MALDI-TOF. Cost to run one sample using Verigene® BC-GP is $70, whereas MALDI-TOF is $5.50 per sample.  We validated MALDI-TOF against Phoenix™ using blood samples and determined if MALDI-TOF is effective in impacting patient care and being cost-effective.

    Methods: Retrospective, descriptive, observational study analyzing 113 blood samples collected from October 2014 through April 2015.  Positive blood samples identified by traditional culture method Phoenix™, then analyzed using MALDI-TOF within 48 hours of confirmed positive gram-positive (GP), gram-negative (GN), anaerobe or yeast organism. Reference used to analyze samples is integrated into the BioTyper software version and compared to a research use only database.  Each isolate given a spectral score, evaluated using software, and confirmed correct identification if score value > 2.0 at species level or > 1.7 but < 2.0 at genus level.

    Results: Total of 113 (48GP, 40GN, 14 anaerobe, and 11 yeast) analyzed using MALDI-TOF. Thirty-six (90%) GN, twenty-nine (60%) GP , nine (64%) anaerobe, and three (27%) yeast organisms were correctly identified using MALDI-TOF. Time to identification per organism using MALDI-TOF was 30 minutes. 

    Conclusion: Achieved 90% concordance with GN, 60% with GP, 64% with anaerobes, and 27% with yeast organisms.  Annual cost savings using MALDI-TOF for initial gram-positive identification is approximately $57,000 and dramatically shortens time to identification.  This has a direct positive impact on patient care. 

    Adrienne Kercsak, PharmD, Eva Sullivan, PharmD and Harminder Sikand, PharmD, FCSHP, FASHP, Scripps Mercy Hospital, San Diego, CA


    A. Kercsak, None

    E. Sullivan, None

    H. Sikand, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.