title: An international, prospective, multicenter evaluation of the combination of AdvanDx Staphylococcus QuickFISH BC with mecA XpressFISH for detection of methicillin-resistant Staphylococcus aureus isolates from positive blood cultures.
abstract: Sepsis caused by Staphylococcus aureus is a major health problem worldwide. Better outcomes are achieved when rapid diagnosis and determination of methicillin susceptibility enable early optimization of antimicrobial therapy. Eight large clinical laboratories, seven from the United States and one from Scotland, evaluated the combination of the Staphylococcus QuickFISH BC and the new mecA XpressFISH assay (both AdvanDx, Woburn, MA, USA) for the detection of methicillin-resistant S. aureus in positive blood cultures. Blood cultures flagged as positive by automated blood culture instruments and demonstrating only Gram-positive cocci in clusters on Gram stain were tested by QuickFISH, a 20-min assay. If only S. aureus was detected, mecA XpressFISH testing followed. The recovered S. aureus isolates were tested by cefoxitin disk diffusion as the reference method. The QuickFISH assay results were concordant with the routine phenotypic testing methods of the testing laboratories in 1,211/1,221 (99.1%) samples and detected 488/491 S. aureus organisms (sensitivity, 99.4%; specificity, 99.6%). Approximately 60% of the samples (730) contained coagulase-negative staphylococci or nonstaphylococci as assessed by the QuickFISH assay and were not tested further. The 458 compliant samples positive exclusively for S. aureus by the QuickFISH assay were tested by the mecA XpressFISH assay, which detected 209 of 211 methicillin-resistant S. aureus organisms (sensitivity, 99.1%; specificity, 99.6%). The mecA XpressFISH assay also showed high reproducibility, with 534/540 tests performed by 6 operators over 5 days achieving reproducible results (98.9% agreement). The combination of the Staphylococcus QuickFISH BC and mecA XpressFISH assays is sensitive, specific, and reproducible for the detection of methicillin-resistant S. aureus and yields complete results in 2 h after the blood culture turns positive.
authors.affiliation: Detroit Medical Center University Laboratories, Detroit, Michigan, USA.
authors.forename: H
authors.initials: H
authors.lastname: Salimnia
authors.affiliation: Detroit Medical Center University Laboratories, Detroit, Michigan, USA mfairfax@dmc.org.
authors.forename: M R
authors.initials: MR
authors.lastname: Fairfax
authors.affiliation: Detroit Medical Center University Laboratories, Detroit, Michigan, USA.
authors.forename: P
authors.initials: P
authors.lastname: Lephart
authors.affiliation: Cedars Sinai Medical Center, Los Angeles, California, USA.
authors.forename: M
authors.initials: M
authors.lastname: Morgan
authors.affiliation: University of Washington, Seattle, Washington, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Gilbreath
authors.affiliation: University of Washington, Seattle, Washington, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Butler-Wu
authors.affiliation: Royal Infirmary, Edinburgh, United Kingdom.
authors.forename: K E
authors.initials: KE
authors.lastname: Templeton
authors.affiliation: Royal Infirmary, Edinburgh, United Kingdom.
authors.forename: F J
authors.initials: FJ
authors.lastname: Hamilton
authors.affiliation: Columbia University Medical Center, New York, New York, USA.
authors.forename: F
authors.initials: F
authors.lastname: Wu
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: R
authors.initials: R
authors.lastname: Buckner
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: D
authors.initials: D
authors.lastname: Fuller
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Davis
authors.affiliation: Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Abdelhamed
authors.affiliation: Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, Ohio, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Jacobs
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: A
authors.initials: A
authors.lastname: Miller
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: B
authors.initials: B
authors.lastname: Pfrommer
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Carroll
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods; D001769:Blood / Q000382:microbiology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D015203:Reproducibility of Results; D012606:Scotland; D012680:Sensitivity and Specificity; D018805:Sepsis / Q000175:diagnosis* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology*; D014481:United States