title: Newly defined in vitro quality control ranges for oritavancin broth microdilution testing and impact of variation in testing parameters.
abstract: A 9-laboratory M23-A2 quality control (QC) study was performed to evaluate reproducibility of oritavancin MICs against reference strains of Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumoniae using broth microdilution assays in the presence of polysorbate 80. Polysorbate 80 has previously been shown to be required for accurate measurement of oritavancin broth microdilution MICs. Greater than 95% of replicate results (n = 270/organism) fell within the following QC ranges (in micrograms per milliliter): S. aureus ATCC 29213, 0.015 to 0.12; E. faecalis ATCC 29212, 0.008 to 0.03; and S. pneumoniae ATCC 49619, 0.001 to 0.004. Oritavancin MIC QC ranges were, thus, narrow and reproducible. Parameters affecting testing results in the presence of polysorbate 80 were also evaluated. Oritavancin MICs were equivalent to or within 1 doubling dilution of those obtained under standard Clinical and Laboratory Standards Institute testing conditions, regardless of incubation time (18, 24, or 48 h), Ca(2+) concentration, pH, or frozen panel storage time (up to 6 months).
authors.affiliation: Targanta Therapeutics Inc., Saint Laurent, Québec, Canada.
authors.forename: Francis F
authors.initials: FF
authors.lastname: Arhin
authors.forename: Karla
authors.initials: K
authors.lastname: Tomfohrde
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Draghi
authors.forename: Mohana
authors.initials: M
authors.lastname: Aranza
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Parr
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Sahm
authors.forename: Gregory
authors.initials: G
authors.lastname: Moeck
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D013293:Enterococcus faecalis / Q000187:drug effects*; D006020:Glycopeptides / Q000494:pharmacology*; D006801:Humans; D000077427:Lipoglycopeptides; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards*; D011136:Polysorbates; D011786:Quality Control; D012015:Reference Standards; D013211:Staphylococcus aureus / Q000187:drug effects*; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D014640:Vancomycin / Q000031:analogs & derivatives
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D000077427:Lipoglycopeptides; D011136:Polysorbates; C100708:oritavancin; D014640:Vancomycin