title: Multi-center and multi-method evaluation of in vitro activities of ceftaroline against S. aureus.
abstract: This five-site study was performed to assess the reproducibility of ceftaroline MIC and disk results for Staphylococcus aureus. Three commercial broth microdilution, three gradient diffusion and ceftaroline 5μg disk diffusion methods were compared to a reference broth microdilution method against challenge isolates (n = 41) and isolates collected at four European sites (n = 30/site). For four MIC methods (Sensititre and three gradient diffusion methods), 99.0% of consolidated MIC results were within +/- 1 dilution of the reference MIC. Categorical agreement rates based on EUCAST breakpoints for the challenge isolates were 75.6-100% and for disk testing were 78.0-92.7%. There was no clear distinction between isolates with MIC results of 1 and 2mg/L with regard to variation in MIC or molecular genotyping results. The addition of an intermediate category for isolates with MIC results of 2mg/L would help to identify these isolates as borderline susceptible/non-susceptible isolates.
authors.affiliation: Laboratory Specialists, Inc., Westlake, OH. Electronic address: lkoeth@labspec.org.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Koeth
authors.affiliation: Analyse Biolab GmbH and Johannes Kepler University, Linz, Austria.
authors.forename: Petra
authors.initials: P
authors.lastname: Apfalter
authors.affiliation: Institute of Medical Microbiology, University Hospital Münster, Münster, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Becker
authors.affiliation: Niguarda Ca' Granda Hospital, Milan, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gesu
authors.affiliation: University Hospital Marqués de Valdecilla-Instituto de Investigación Marqués de Valdecilla (IDIVAL), Department of Molecular Biology, University of Cantabria, Santander, Spain; AstraZeneca, Waltham, MA.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
authors.affiliation: AstraZeneca, Waltham, MA.
authors.forename: Sushmita D
authors.initials: SD
authors.lastname: Lahiri
authors.affiliation: AstraZeneca, Waltham, MA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Alm
authors.affiliation: AstraZeneca, Waltham, MA.
authors.forename: Jane
authors.initials: J
authors.lastname: Ambler
authors.affiliation: AstraZeneca, Waltham, MA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Iaconis
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D013211:Staphylococcus aureus / Q000187:drug effects*; D000097583:Ceftaroline
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D000097583:Ceftaroline
keywords: Antimicrobial susceptibility testing; Broth microdilution; Ceftaroline; Disk diffusion; Gradient diffusion; Method comparison