title: An 11,000-isolate same plate/same day comparison of the 3 most widely used platforms for analyzing multidrug-resistant clinical pathogens.
abstract: Stewardship of the dwindling number of effective antibiotics relies on accurate phenotyping. We sought to conduct the first large-scale, same plate and day comparison of the 3 most widely used bacterial analyzers. A total of 11,020 multidrug-resistant clinical isolates corresponding to more than 485,000 data points were used to compare the 3 major identification and antibiotic susceptibility testing (AST) platforms. Bacterial suspensions, prepared from a single plate, were simultaneously tested on all platforms in the same laboratory. Discrepancies were derived from MIC values using 2014 interpretive guidelines. Molecular methods and manual microbroth dilution were reference standards. Most discrepancies were due to drug-organism-AST platform combination instead of individual factors. MicroScan misidentified Acinetobacter baumannii (P<0.001) and underestimated carbapenem susceptibility in Klebsiella pneumoniae. Vitek-2 and Phoenix had higher discrepancies for blaKPC-containing Enterobacteriaceae (P<0.05) and reported false susceptibilities more often. While all platforms performed according to standards, each had strengths and weaknesses for organism identification, assaying specific drug-organism combinations and inferring carbapenemase production.
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA; Uniformed Services University, Bethesda, MD USA. Electronic address: Lindsey.e.nielsen2.mil@mail.mil.
authors.forename: L E
authors.initials: LE
authors.lastname: Nielsen
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Clifford
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kwak
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: L
authors.initials: L
authors.lastname: Preston
authors.affiliation: Department of Biological Sciences, Boston College, Chestnut Hill MA 02467.
authors.forename: C
authors.initials: C
authors.lastname: Argyros
authors.affiliation: R. Adams Cowley Shock Trauma Center, Program in Trauma Infectious Diseases, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: R
authors.initials: R
authors.lastname: Rabinowitz
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA; Uniformed Services University, Bethesda, MD USA.
authors.forename: P
authors.initials: P
authors.lastname: Waterman
authors.affiliation: Multidrug-Resistant organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, USA; Uniformed Services University, Bethesda, MD USA; R. Adams Cowley Shock Trauma Center, Program in Trauma Infectious Diseases, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: E
authors.initials: E
authors.lastname: Lesho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification* / Q000187:drug effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000187:drug effects*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotics; Carbapenemase; MicroScan; Phoenix; Vitek-2