Nanosphere, Inc., a leader in the development and commercialization of advanced molecular diagnostics systems, has received the US Food and Drug Administration (FDA) approval to market Gram-Positive Blood Culture Nucleic Acid Test (BC-GP) on the automated sample-to-result Verigene System.

The BC-GP test notably expands Nanosphere’s infectious disease test capabilities to include fast detection of bacteria that can cause deadly bloodstream infections, an increasingly recognized health threat.

With a single automated test, the Verigene BC-GP test provides fast genus and species level detection for a broad panel of clinically significant gram-positive bacteria.  The BC-GP test also detects several crucial markers for antimicrobial resistance, including the mecA, vanA, and vanB genes, which confer resistance to the antibiotics methicillin/oxacillin and vancomycin.  Rapid detection of these antimicrobial resistance markers provides vital information for clinicians to determine the best treatment for bloodstream infections.

“With the BC-GP test, patients suspected of deadly infections can now get a first-ever diagnostic tool for detecting disease-causing bacteria while simultaneously determining antibiotic resistance within the critical timeframe for making and adjusting initial treatment," said William Moffitt, Nanosphere’s chief executive officer.

The BC-GP test provides identification of bacteria and antimicrobial resistance genes from gram-positive blood culture bottles within two and a half hours, as compared with current microbiological methods, which can take up to two to three days.

Rapid and accurate identification of bacteria and resistance markers is critical in guiding appropriate antibiotic treatment. Studies show delayed administration of appropriate antibiotics is associated with a 7.6 per cent decrease in survival rate for each hour therapy is delayed. Rapid molecular testing of blood cultures reduces this time, with associated hospital cost savings of up to $21,000 per patient.

The sample-to-result BC-GP test automates the steps of bacterial DNA extraction and target detection on the Verigene System.

The ease-of-use and fast turnaround time of the BC-GP test allow hospitals of any size to benefit from the speed and accuracy of automated molecular testing. In addition to its gram-positive blood culture test, Nanosphere is currently developing a test for gram-negative blood cultures that will provide genus, species, and resistance detection on the same automated platform. These tests are part of a comprehensive infectious disease test menu, including the multiplexed Verigene RV+ respiratory virus test cleared by the FDA in 2011, as well as tests for C. difficile and a panel of enteric bacterial and viral pathogens that Nanosphere plans to submit for FDA clearance in 2012.

Septicemia is associated with more than 1.6 million hospitalizations per year in the United States and is the most expensive cause of hospitalization totaling $15.4 billion in aggregate hospital costs.3 Septicemia occurs when a pathogenic microorganism, usually a bacterium or a fungus, enters the bloodstream and causes an inflammatory immune response.  Because bloodstream infections and septicemia are pervasive problems associated with high mortality rates, timely delivery of appropriate treatment is essential.

Bloodstream infections with gram-positive bacteria are often complicated by antimicrobial resistance.  The inability to rapidly identify resistant strains of pathogenic bacteria has led to antimicrobial use that is often ineffectual, wasteful, or bears risk of proliferating resistant strains. Rapid identification of both organism and resistance is essential to implementing efficient and appropriate therapy.

Gram-positive bacteria are also a common source of contamination during blood draws.  Contaminant species are frequently responsible for false-positive blood cultures that lead to inappropriate antimicrobial use.  Patients with contaminated blood culture bottles are often presumptively treated for bloodstream infections for several days until the organism can be identified as a contaminant using conventional biochemical methods.  Patients with false-positive blood culture results triggered by contaminants have hospitalization costs more than $8,000 higher than patients with true negative blood culture results.  Due to the large burden of infections and contaminants due to gram-positive bacteria, rapid identification of bacteria isolated from blood cultures is a primary healthcare concern.