Evaluation of the BD PhoenixTM automated system for determining antimicrobial susceptibility against carbapenem-resistant Enterobacteriaceae compared to broth microdilution.
Int J Antimicrob Agents. 2019 May 06;:
Authors: Haffler ZJ, Kulengowski B, Ribes JA, Burgess DS
PURPOSE: Carbapenem-resistant Enterobacteriaceae (CRE) are increasingly widespread in the healthcare system, resulting in infections associated with mortality of up to 50%. Many laboratories utilize automated systems to identify CRE isolates and determine susceptibility. The aim of this study is to evaluate the categorical agreement between the automated system BD PhoenixTM and the gold standard - broth microdilution - in determining minimum inhibitory concentrations of CRE METHODOLOGY: We evaluated the activity of amikacin, aztreonam, cefepime, ceftazidime, ertapenem, gentamicin, levofloxacin, meropenem, nitrofurantoin, piperacillin-tazobactam, and tobramycin on 125 CRE isolates collected from an academic medical center. We determined categorical agreement between BD PhoenixTM and broth microdilution, as well as the rates of minor error, major error, and very major error.
RESULTS: BD PhoenixTM significantly overestimates susceptibility of CRE isolates for amikacin, aztreonam, cefepime, ceftazidime, gentamicin, levofloxacin, meropenem, nitrofurantoin, and tobramycin compared to gold-standard broth microdilution. Overall categorical agreement of 76% between testing methods indicates a potential diminished ability of BD PhoenixTM to accurately predict resistance in highly drug-resistant isolates. All tested antimicrobials had increased rates of very major error rates compared to previous literature.
CONCLUSIONS: We conclude that BD PhoenixTM has a diminished ability to determine susceptibility for CRE isolates. Further studies are warranted in order to validate BD PhoenixTM susceptibility testing in highly resistant CRE isolates. The mechanism by which isolates are resistant to carbapenems does not impact BD Phoenix's ability to determine susceptibility.
PMID: 31071467 [PubMed - as supplied by publisher]