Posted in | Nanomedicine | Microscopy

Nanosphere’s Verigene Gram-Positive Blood Culture Test Illustrates High Diagnostic Accuracy

Nanosphere, Inc., a leader in the development and commercialization of advanced molecular diagnostics systems, today announced publication of a prospective, multicenter study that illustrates the high diagnostic accuracy and potential clinical impact of the company's FDA-cleared Verigene® Gram-Positive Blood Culture (BC-GP) Test in the peer-reviewed, open-access journal PLOS Medicine, published by the Public Library of Science.

The results reported in this manuscript, authored by leading experts in microbiology and molecular diagnostics, demonstrate the performance of the Verigene BC-GP Test in simultaneously detecting and identifying Staphylococcus aureus and 11 other gram-positive bacterial gene targets known to cause bloodstream infections and three genetic resistance determinants (the mecA, vanA, and vanB genes), directly from positive blood culture media. In addition, a retrospective analysis of turn-around time found that the Verigene BC-GP Test identified methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) species -- two especially deadly causes of bloodstream infection -- an average of 42 hours faster than reference methods.

"The study concluded that the Verigene BC-GP Test is capable of detecting the leading causes of gram-positive bacterial bloodstream infections as well as genetic markers for methicillin resistance in Staphylococcus aureus and vancomycin resistant Enterococcus directly from positive blood cultures, and has the potential to markedly reduce turn-around time for reporting," said Dr. Nathan A. Ledeboer, Associate Professor of Pathology at the Medical College of Wisconsin.

"We are very pleased these study results have been published in PLOS Medicine, an evidence-based journal that focuses on diseases that cause the greatest healthcare and economic burden worldwide," said Michael McGarrity, Nanosphere's president and chief executive officer. "These results are significant as they further validate the compelling value of the Verigene BC-GP Test in enabling rapid analysis and reporting of this time-critical, clinically actionable information to physicians. Our tests have been designed based on comprehensive market feedback to work hand-in-hand with laboratory best practices to provide physicians with the optimal set of results for clinical decision making. Furthermore, we believe the Verigene System's ability to directly detect a comprehensive panel of bacterial DNA targets without the use of PCR is ideally and uniquely suited to the challenge of accurately identifying organisms in blood culture media."

The manuscript, published under the title "Multiplex Identification of Gram-positive Bacteria and Resistance Determinants Directly from Positive Blood Culture Broths: Evaluation of an Automated Microarray-Based Nucleic Acid Test," was composed by Blake W. Buchan1, Christine C. Ginocchio2,3, Ryhana Manji2, Robert Cavagnolo4, Preeti Pancholi5, Lettie Swyers5, Richard B. Thomson Jr.6, Christopher Anderson6, Karen Kaul6, and Nathan A. Ledeboer1.

With an impact factor of 16, PLOS Medicine is the leading open-access medical journal, providing an influential venue for outstanding research and commentary on the major challenges to human health worldwide.

About Verigene® Gram-Positive Blood Culture Nucleic Acid Test

The Verigene® Gram-Positive Blood Culture Nucleic Acid (BC-GP) Test performed using the sample-to-result Verigene System is a qualitative, multiplexed in vitro diagnostic test for the simultaneous detection and identification of potentially pathogenic gram-positive bacteria which may cause bloodstream infection. These include the following organisms and antibiotic resistance markers:

Staphylococcus spp.
Streptococcus spp.
Listeria spp.
Enterococcus faecalis
Enterococcus faecium
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus lugdunensis
Streptococcus pneumoniae
Streptococcus anginosus group
Streptococcus agalactiae
Streptococcus pyogenes


mecA gene, conferring methicillin resistance
vanA and vanB genes, conferring vancomycin resistance

The Verigene BC-GP Test is performed directly on blood culture bottles identified as positive by a continuous monitoring blood culture system and which contain gram-positive bacteria. The Verigene BC-GP Test is indicated for use in conjunction with other clinical and laboratory findings to aid in the diagnosis of bacterial bloodstream infections; however, it is not to be used to monitor these infections. Sub-culturing of positive blood cultures is necessary to recover organisms for susceptibility testing, identify organisms not detected by the Verigene BC-GP Test, differentiate mixed growth, associate antimicrobial resistance marker genes to a specific organism, or for epidemiological typing.


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