Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2013

Evaluation of the BacT/ALERT PLUS blood culture media for growth performance and antimicrobial neutralization at peak serum level (#243)

C.H. Ong 1 , S.F. Tee 1 , I. Isnaini 1 , M. Jagadeesan 1 , C.W. Lam 1
  1. Laboratory Medicine, Alexandra Hospital, Jurong Health Services, Singapore

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.

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