Multisite clinical evaluation of the iFAST rapid antimicrobial susceptibility test direct from positive blood cultures containing gram-negative organisms

@article{hornsey2026multisite,
  title = {{Multisite clinical evaluation of the iFAST rapid antimicrobial susceptibility test direct from positive blood cultures containing gram-negative organisms}},
  author = {Michael Hornsey and Isobel Taylor and Toby King and Zoe Brown and Daniel Nathan Tomás Cançado and Katie Judd and Eleanor Kuszynski and Rowena Lines and Rhiannon Lyon and Xiang Wang and Allyson Lloyd and Robert Impey and Gareth Ashworth and Maria Gatenby and Alasdair MacGowan and Mahableshwar Albur and Alan Noel and Marie Attwood and Pippa Griffin and Cliodna Brennan and Freddie Oubridge Brock and Jane Stewart and Estíbaliz Alonso-Moreno and Hywel Morgan and Daniel Spencer},
  journal = {Journal of Clinical Microbiology},
  year = {2026},
  month = aug,
  doi = {10.1128/jcm.00558-26},
  url = {https://doi.org/10.1128/jcm.00558-26},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Multisite clinical evaluation of the iFAST rapid antimicrobial susceptibility test direct from positive blood cultures containing gram-negative organisms
AU  - Michael Hornsey
AU  - Isobel Taylor
AU  - Toby King
AU  - Zoe Brown
AU  - Daniel Nathan Tomás Cançado
AU  - Katie Judd
AU  - Eleanor Kuszynski
AU  - Rowena Lines
AU  - Rhiannon Lyon
AU  - Xiang Wang
AU  - Allyson Lloyd
AU  - Robert Impey
AU  - Gareth Ashworth
AU  - Maria Gatenby
AU  - Alasdair MacGowan
AU  - Mahableshwar Albur
AU  - Alan Noel
AU  - Marie Attwood
AU  - Pippa Griffin
AU  - Cliodna Brennan
AU  - Freddie Oubridge Brock
AU  - Jane Stewart
AU  - Estíbaliz Alonso-Moreno
AU  - Hywel Morgan
AU  - Daniel Spencer
PY  - 2026
DA  - 2026/08/31
JO  - Journal of Clinical Microbiology
DO  - 10.1128/jcm.00558-26
UR  - https://doi.org/10.1128/jcm.00558-26
AB  - iFAST is a label-free rapid antimicrobial susceptibility test (AST) that delivers qualitative results in under 4 h from a positive blood culture bottle. The technique measures changes in the electrical properties of thousands of individual bacteria following exposure to antibiotics. We report the diagnostic accuracy from the first clinical study of the iFASTone rapid AST system in three different centers according to ISO 20776-2:2021. Compared to the reference laboratory broth microdilution method, categorical agreement was 97.8% and 97.2% for the Enterobacterales and non-fermenting gram-negative species, respectively. iFAST specificity and sensitivity for the Enterobacterales were 98.2% and 96.8%, respectively, and 96.9% and 98.4% for the non-fermenting species, exceeding the acceptance criteria (≥95% sensitivity and specificity). Reproducibility was assessed with 12 isolates across 3 sites, in triplicate, on 3 separate days, with different operators at each site. Agreement was 95.7%.  IMPORTANCE: Even short delays in the initiation of antimicrobial therapy in patients with bloodstream infections are associated with increased morbidity and mortality. Consequently, current guidelines recommend initiation of empiric antimicrobial therapy within 1 h of presentation. However, empiric broad-spectrum therapy may not always be appropriate and can contribute to the selection of resistant organisms. Antimicrobial susceptibility testing (AST) is therefore critical for antimicrobial stewardship and the timely selection of targeted therapy, but conventional methods typically require 1 to 2 days to generate results. This study evaluated the diagnostic accuracy of iFAST, a new low-cost, label-free rapid AST using 375 Enterobacterales and non-fermenter isolates tested directly from positive blood cultures, according to ISO-20776-2:2021. Compared with broth microdilution, iFAST demonstrated high sensitivity, specificity, and categorical agreement, with a time to result of less than 4 h. These findings support the implementation of iFAST for same-shift AST results.
SN  - 0095-1137
SN  - 1098-660X
ER  -