Evaluation of BACTEC PLUS Resin Media with the BACTEC 9240 system

Abstract

BACKGROUND: The rapid detection of pathogenic organisms in blood samples is essential for the diagnosis and management of septic patients. However, patients with suspected sepsis could have received an empirical antimicrobial therapy before cultures were taken, therefore, it is of paramount importance to increase the yield of blood cultures from such patients. A new BACTEC PLUS(TM) Aerobic/F and PLUS(TM) Anaerobic/F (Becton Dickinson Diagnostic Instrument System, Sparks, Maryland, USA.) containing nonionic adsorbing resin and cationic exchange resin designed for use with BACTEC 9240 blood culture system was evaluated for their improvement of the detection of microorganisms in blood culture specimens. METHODS: S. aureus (ATCC25923) and E. coli (ATCC 25922) were utilized in this study. Ten different antimicrobials representing a variety of categories (vancomycin, ciprofloxacin, imipenem, aztreonam, gentamicin, ampicillin/sulbactam, cefazolin, cefoxitin, cefotaxime and ceftriaxone) were tested at achievable serum levels in BACTEC PLUS/F media and in Standard/F media for adsorption of antimicrobials by resins in the media. Test medium vials were inoculated with bacterial suspensions and antimicrobials. After inoculation the growth values of the organisms were measured with the BACTEC 9240 system. RESULTS : All resin bottles containing the antimicrobials except aztreonam and standard anaerobic bottles containing imipenem, gentamicin and ampicillin/sulbactam showed growth. When resin vials examined for the growth values of the microorganisms, the anaerobic bottles revealed a shorter time to grow. CONCLUSIONS : The use of BACTEC PLUS medium, instead of resin-free standard medium, may neutralize the antimicrobials such as cephalosporin, quinolone or glycopeptides. However its cost is more expensive. For cost-effectiveness, the resin medium should be adopted in patients receiving empirical antimicrobial treatment and/or new admissions.