Session: Poster Abstract Session: Diagnostics: Bacteremia
Thursday, October 27, 2016
Room: Poster Hall
Background: Successful detection of bloodstream pathogens in blood cultures is diminished when antibiotics are present in the blood. Blood culture bottles containing antibiotic adsorbent materials are recommended to address this problem. Recently bioMerieux introduced a new antibiotic adsorbing resin to replace activated charcoal in its blood culture bottles. The ability of this new resin to adsorb antibiotics and decrease time to detection (TTD) was compared with the resin bottles produced by Becton Dickenson (BD). Methods: BD BACTEC Plus Aerobic/F bottles and bioMerieux BacT/Alert FA Plus bottles were compared for their ability to remove vancomycin (VANC), oxacillin (OXA), micafungin (MFN), and ampicillin (AMP) (at peak serum concentration), thus allowing the growth and detection of Staphylococcus aureus, Candida albicans or Enterococcus faecalis. After three time points, medium containing remaining antibiotic was removed from each bottle, serially diluted, and inoculated with organism in a 96 well plate. Adsorption of antibiotics was indicated by a decrease in the number of two-fold dilutions of medium containing antibiotic needed to allow microbial growth. Results: The BacT/Alert FA Plus resin bottles were reproducibly better than the BD resin bottles at removal of VANC, OXA, and MFN as measured by at least one lower dilution needed to allow microbial growth. To determine how removal of antibiotics affected TTD we spiked each bottle (performed in triplicate) with 10 ml of whole blood, peak serum concentration of antibiotic, and approximately 60 CFU/ml of organism. Bottles were mixed and loaded into respective instruments for incubation. Adsorption of antibiotics was demonstrated by a decrease in TTD, indicating a more favorable environment for microbial growth. A statistically significant lower TTD (p<0.05) was observed in BacT/Alert FA Plus bottles compared to BACTEC Plus Aerobic/F bottles each containing S. aureus/OXA and E. faecalis/AMP. A lower mean TTD (but not statistically significant) was also seen in bottles containing S. aureus/VANC or C. albicans/MFN. Conclusion: BacT/Alert FA Plus bottles demonstrated enhanced ability to remove antibiotics and allow microbial growth compared to the BACTEC Plus Aerobic/F bottles.