Introduction: This study aims to evaluate the growth performance and detection of commonly isolated blood pathogens in the new resin based blood culture media BacT/ALERT FA Plus and FN Plus developed by bioMerieux (BM) in comparison to our current method (Becton Dickinson BACTEC Plus bottles) (BD). We also compared the efficacy of antimicrobial neutralization between BM and BD by time of detection for organism recovery in the presence of antimicrobial agents.
Material and Method: All aerobic and anaerobic blood culture
bottles from BM and BD were inoculated with healthy donor’s blood. For growth
performance studies, the bottles were inoculated with Clostridium
perfringens, Haemophilus influenzae and Streptococcus
pneumoniae from ATCC strains. For antimicrobial
neutralization studies, ATCC strains were inoculated with selected
antimicrobials i.e. Staphylococcus aureus with
Vancomycin, Escherichia coli with ceftriaxone, and Bacteroides
fragilis with imipenem. The bottles were incubated in their respective
instrument for up to 5 days. The aerobic and anaerobic media
from each system were evaluated and testing was done in triplicate. For all
positively flagged bottles, a direct gram stain and
subculture onto solid media were performed before incubating in appropriate
conditions. Organism identification was done using Vitek MS.
Results: The growth performance between BM and BD is comparable. Antimicrobial neutralization was evaluated on the basis of time to detection.
Both systems were able to neutralize vancomycin. Neither system was able to
recover Escherichia coli in the presence of ceftriaxone and BD's Plus
anaerobic bottle failed to recover Bacteroides fragilis in the
presence of imipenem.
Conclusion: In this study, the performance of
bacterial growth detection for the two bottle types was comparable. With
the antimicrobial and bacteria combination tested, BM was better in its ability
to recover Bacteroides fragilis in the presence of imipenem.