Comparison of the next-generation Xpert MRSA/SA BC assay and the GeneOhm StaphSR assay to routine culture for identification of Staphylococcus aureus and methicillin-resistant S. aureus in positive-blood-culture broths

Blake W. Buchan, Stephen Allen, Carey Ann D Burnham, Erin Mcelvania Tekippe, Thomas Davis, Michael H. Levi, Donna Mayne, Preeti Pancholi, Ryan F. Relich, Richard Thomson, Nathan A. Ledeboera

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

A bloodstream infection with Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), is a serious condition that carries a high mortality rate and is also associated with significant hospital costs. The rapid and accurate identification and differentiation of methicillin-susceptible S. aureus (MSSA) and MRSA directly from positive blood cultures has demonstrated benefits in both patient outcome and cost-of-care metrics. We compare the next-generation Xpert MRSA/SA BC (Xpert) assay to the GeneOhm StaphSR (GeneOhm) assay for the identification and detection of S. aureus and methicillin resistance in prospectively collected blood culture broths containing Gram-positive cocci. All results were compared to routine bacterial culture as the gold standard. Across 8 collection and test sites, the Xpert assay demonstrated a sensitivity of 99.6% (range, 96.4% to 100%) and a specificity of 99.5% (range, 98.0% to 100%) for identifying S. aureus, as well as a sensitivity of 98.1% (range, 87.5% to 100%) and a specificity of 99.6% (range, 98.3% to 100%) for identifying MRSA. In comparison, the GeneOhm assay demonstrated a sensitivity of 99.2% (range, 95.2% to 100%) and a specificity of 96.5% (range, 89.2% to 100%) for identifying S. aureus, as well as a sensitivity of 94.3% (range, 87.5% to 100%) and a specificity of 97.8% (range, 96.1% to 100%) for identifying MRSA. Five of six cultures falsely reported as negative for MRSA by the GeneOhm assay were correctly identified as positive by the Xpert assay, while one culture falsely reported as negative for MRSA by the Xpert assay was correctly reported as positive by the GeneOhm assay.

Original languageEnglish (US)
Pages (from-to)804-809
Number of pages6
JournalJournal of Clinical Microbiology
Volume53
Issue number3
DOIs
StatePublished - Mar 1 2015

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Methicillin-Resistant Staphylococcus aureus
Staphylococcus aureus
Gram-Positive Cocci
Methicillin Resistance
Methicillin
Hospital Costs
Blood Culture
Costs and Cost Analysis
Mortality
Infection

ASJC Scopus subject areas

  • Microbiology (medical)

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Comparison of the next-generation Xpert MRSA/SA BC assay and the GeneOhm StaphSR assay to routine culture for identification of Staphylococcus aureus and methicillin-resistant S. aureus in positive-blood-culture broths. / Buchan, Blake W.; Allen, Stephen; Burnham, Carey Ann D; Tekippe, Erin Mcelvania; Davis, Thomas; Levi, Michael H.; Mayne, Donna; Pancholi, Preeti; Relich, Ryan F.; Thomson, Richard; Ledeboera, Nathan A.

In: Journal of Clinical Microbiology, Vol. 53, No. 3, 01.03.2015, p. 804-809.

Research output: Contribution to journalArticle

Buchan, Blake W. ; Allen, Stephen ; Burnham, Carey Ann D ; Tekippe, Erin Mcelvania ; Davis, Thomas ; Levi, Michael H. ; Mayne, Donna ; Pancholi, Preeti ; Relich, Ryan F. ; Thomson, Richard ; Ledeboera, Nathan A. / Comparison of the next-generation Xpert MRSA/SA BC assay and the GeneOhm StaphSR assay to routine culture for identification of Staphylococcus aureus and methicillin-resistant S. aureus in positive-blood-culture broths. In: Journal of Clinical Microbiology. 2015 ; Vol. 53, No. 3. pp. 804-809.
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abstract = "A bloodstream infection with Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), is a serious condition that carries a high mortality rate and is also associated with significant hospital costs. The rapid and accurate identification and differentiation of methicillin-susceptible S. aureus (MSSA) and MRSA directly from positive blood cultures has demonstrated benefits in both patient outcome and cost-of-care metrics. We compare the next-generation Xpert MRSA/SA BC (Xpert) assay to the GeneOhm StaphSR (GeneOhm) assay for the identification and detection of S. aureus and methicillin resistance in prospectively collected blood culture broths containing Gram-positive cocci. All results were compared to routine bacterial culture as the gold standard. Across 8 collection and test sites, the Xpert assay demonstrated a sensitivity of 99.6{\%} (range, 96.4{\%} to 100{\%}) and a specificity of 99.5{\%} (range, 98.0{\%} to 100{\%}) for identifying S. aureus, as well as a sensitivity of 98.1{\%} (range, 87.5{\%} to 100{\%}) and a specificity of 99.6{\%} (range, 98.3{\%} to 100{\%}) for identifying MRSA. In comparison, the GeneOhm assay demonstrated a sensitivity of 99.2{\%} (range, 95.2{\%} to 100{\%}) and a specificity of 96.5{\%} (range, 89.2{\%} to 100{\%}) for identifying S. aureus, as well as a sensitivity of 94.3{\%} (range, 87.5{\%} to 100{\%}) and a specificity of 97.8{\%} (range, 96.1{\%} to 100{\%}) for identifying MRSA. Five of six cultures falsely reported as negative for MRSA by the GeneOhm assay were correctly identified as positive by the Xpert assay, while one culture falsely reported as negative for MRSA by the Xpert assay was correctly reported as positive by the GeneOhm assay.",
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AU - Levi, Michael H.

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