title: Development of a national EUCAST challenge panel for antimicrobial susceptibility testing.
abstract: A challenge panel of bacterial strains useful for clinical laboratories to validate their European Committee on Antimicrobial Susceptibility Testing (EUCAST) antimicrobial susceptibility test (AST) system was established. A total of 117 strains, obtained from Belgian Reference Centres (n = 57) and from routine clinical samples (n = 60) was selected based on resistance pattern. These strains were analysed in seven different laboratories by three different automated AST systems (Vitek (n = 2), Phoenix (n = 2) and Microscan (n = 2)) and by disc diffusion from five different manufacturers (Rosco (n = 2), Becton-Dickinson (n = 2), Biomérieux (n = 1), Bio-rad (n = 1) and i2a (n = 1)). To select the challenge panel, selection criteria were set for categorical agreement between the different systems and the number of very major errors, major errors and minor errors. Very major and major errors for at least two antibiotics were observed in 43% of all strains, leading to the exclusion of these strains from the selected panel. In only 10% of all tested strains was there 100% categorical agreement for all antibiotics. Finally, 28 strains (14 Gram-positive and 14 Gram-negative) covering a wide spectrum of resistance mechanisms were selected. Pilot-testing of this challenge panel in 20 laboratories mainly confirmed the results of the validation study. Only six strains withheld for the pilot study could not be used as challenge strain due to an overall (very) major error rate of >5% for a particular antibiotic (n = 5) or for two antibiotics (n = 1). To conclude, this challenge panel should facilitate the implementation and use of EUCAST breakpoints in laboratories.
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium; Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium. Electronic address: stefanie.desmet@uzleuven.be.
authors.forename: S
authors.initials: S
authors.lastname: Desmet
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium; Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Verhaegen
authors.affiliation: Belgian Reference Laboratory of Multi-resistant Enterobacteriaceae and Multi-resistant Pseudomonas and Acinetobacter, CHU Dinant-Godinne UCL-Namur, Belgium.
authors.forename: Y
authors.initials: Y
authors.lastname: Glupzcynski
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium; Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Van Eldere
authors.affiliation: Belgian Reference Centre for Streptococcus agalactiae, Department of Clinical Microbiology, University Hospital of Liege, Liege, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Melin
authors.affiliation: Belgian Reference Laboratory of Enterococcus spp, Streptococcus pyogenes and other beta-hemolytic streptococci non-group B, University Hospital Antwerp, Antwerp, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Goossens
authors.affiliation: Department of Laboratory Medicine, Universitair Ziekenhuis Brussel, Brussels, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Piérard
authors.affiliation: Department of Laboratory Medicine, Sint-Jozefskliniek, Izegem, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Declercq
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium; Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Lagrou
authors.affiliation: Clinical Laboratory of Microbiology OLVZ Aalst, Aalst, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Boel
authors.affiliation: Department of Laboratory Medicine, Jessa Hasselt, Hasselt, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Cartuyvels
authors.affiliation: Belgian Reference Laboratory of Staphylococcus aureus, Hopital Erasme, Brussels, Belgium.
authors.forename: O
authors.initials: O
authors.lastname: Denis
authors.affiliation: Department of Laboratory Medicine, AZ Sint-Lucas Brugge, Brugge, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Vandewal
authors.affiliation: Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium; Department of Microbiology and Immunology, KU Leuven - University of Leuven, Leuven, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Saegeman
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D001424:Bacterial Infections / Q000175:diagnosis / Q000382:microbiology; D005060:Europe; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents
keywords: Antibiotic; Antimicrobial susceptibility testing; Automated susceptibility testing; Challenge panel; EUCAST; MIC breakpoints; Zone diameter breakpoints