title: Variability of β-lactam susceptibility testing for Streptococcus pneumoniae using 4 commercial test methods and broth microdilution.
abstract: Limited data are available that verify the performance of commercial susceptibility methods for Streptococcus pneumoniae following the 2008 Clinical and Laboratory Standards Institute revision of the β-lactam breakpoints. We compared the performance of Etest, M.I.C. Evaluator (M.I.C.E), Vitek, and Sensititre systems to broth microdilution for S. pneumoniae susceptibility testing of penicillin, ceftriaxone, meropenem, and amoxicillin. Essential agreement was ≥90% for the majority of the β-lactams and methods tested, particularly for penicillin and ceftriaxone. Categorical agreements (CAs) for penicillin using meningeal and nonmeningeal breakpoints were ≥90%; CAs using penicillin oral breakpoints were 84-89%. Ceftriaxone CAs using nonmeningeal and meningeal breakpoints were 68-88% for Etest, M.I.C.E., and Vitek2 with 6-12% very major errors (VMEs) using meningeal breakpoints. Sensititre CAs for ceftriaxone, amoxicillin, and meropenem were ≥90% with no VMEs. In the context of the current guidelines, there exists considerable method-dependent variability in the susceptibility of S. pneumoniae to β-lactams.
authors.affiliation: Provincial Laboratory for Public Health, Alberta Health Services, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Marthe K
authors.initials: MK
authors.lastname: Charles
authors.affiliation: Provincial Laboratory for Public Health, Alberta Health Services, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Byron M
authors.initials: BM
authors.lastname: Berenger
authors.affiliation: Provincial Laboratory for Public Health, Alberta Health Services, Edmonton, AB, Canada; Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada.
authors.forename: LeeAnn
authors.initials: L
authors.lastname: Turnbull
authors.affiliation: Provincial Laboratory for Public Health, Alberta Health Services, Edmonton, AB, Canada; Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada. Electronic address: robert.rennie@albertahealthservices.ca.
authors.forename: Robert
authors.initials: R
authors.lastname: Rennie
authors.affiliation: Provincial Laboratory for Public Health, Alberta Health Services, Edmonton, AB, Canada; Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Jeff
authors.initials: J
authors.lastname: Fuller
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards; D011008:Pneumococcal Infections / Q000175:diagnosis / Q000382:microbiology; D011933:Reagent Kits, Diagnostic / Q000592:standards; D015203:Reproducibility of Results; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D018440:beta-Lactam Resistance; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D011933:Reagent Kits, Diagnostic; D047090:beta-Lactams
keywords: Bacterial susceptibility tests; Beta-lactam resistance; Beta-lactam susceptibility; Evaluation study; Streptococcus pneumoniae