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Validation of Rapid Antimicrobial Susceptibility Testing directly from blood cultures using WASPLab®, including Colibrí™ and Radian® in-Line Carousel

Journal Contribution - Journal Article

With the increase in antimicrobial resistance, fast reporting of antimicrobial susceptibility testing (AST) results is becoming increasingly important. EUCAST developed a method for rapid AST (RAST) directly from the broth of positive blood cultures (BC). Inhibition zones are read after 4, 6, and 8 h, with specific breakpoints per time point. We evaluated the RAST method based on EUCAST disk diffusion methodology with inoculation of BC broth using WASPLab® (inclusive Colibrí™ and Radian®). Forty-nine non-duplicate strains were tested: Escherichia coli n = 17, Klebsiella pneumoniae n = 7, Pseudomonas aeruginosa n = 4, Acinetobacter baumannii n = 2, Staphylococcus aureus n = 10, Enterococcus faecalis n = 6, and Enterococcus faecium n = 3. Results were compared to direct AST and standardized AST. Good categorical agreement was obtained at all time points for all groups, except P. aeruginosa. RAST cut-offs for extended-spectrum β-lactamase (ESBL)-producing Enterobacterales enabled the detection of all included ESBL isolates (n = 5) at all time points, except for 1 E. coli ESBL after 4 h. RAST cut-offs for carbapenemase-producing Enterobacterales enabled the detection of only one carbapenemase after 6 h. However, all carbapenemases (n = 3) were correctly detected after 8 h. Two methicillin-resistant S. aureus were included; both were correctly categorized as cefoxitin-resistant at 6 and 8 h. At 4 h, there was insufficient growth for inhibition zone interpretation. EUCAST RAST is a fast supplementary tool for direct AST of positive BC. WASPLab® provides a significant advantage as pictures are made automatically implicating that we are not strictly bound to the time points for inhibition zone interpretation.
Journal: European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology
ISSN: 0934-9723
Issue: 5
Volume: 41
Pages: 733-739
Publication year:2022
  • DOI: https://doi.org/10.1007/s10096-022-04421-8
  • ORCID: /0000-0001-6234-3285/work/112704879
  • ORCID: /0000-0003-2937-1705/work/112704740
  • ORCID: /0000-0002-6217-1695/work/112704120
  • ORCID: /0000-0002-7756-3691/work/112703876
  • Scopus Id: 85125267043
  • WoS Id: 000761134100001