NEW YORK (GenomeWeb) – Espoo, Finland-based molecular diagnostics firm Orion Diagnostica has launched a Clostridium difficile assay on its CE-marked Orion GenRead platform.
The bench-top assay works direct from stool on up to 12 samples at a time and can detect strongly-positive infections in 15 minutes using a patented isothermal amplification technology, a company representative told GenomeWeb in an email.
The Orion GenRead platform received CE marking in January, and the C. diff assay is the first test kit for the system. The test menu pipeline also includes assays for Salmonella and Campylobacter as well as other gastrointestinal and respiratory pathogens, the representative said.
In Europe, where the new test is currently available, the incidence of C. diff is expected to double in the next four decades and the direct cost of healthcare-associated C. diff infections is estimated to be €3 billion ($3.4 billion). In the US there were an estimated quarter of a million infections and 29,000 deaths in 2011, according to a recent New England Journal of Medicine study, although there also appears to be a relationship between adoption of highly sensitive molecular testing and higher observed infection rates, as previously reported.
The workflow for the Orion C. diff test takes about one hour, but results can be obtained up to four times as fast if the patient sample has a high concentration of bacterial DNA, the representative said.
The test kit is a "complete solution," according to the firm, and includes easy-to-use sample preparation without the need for separate nucleic acid purification, pre-calibrated freeze-dried reagents, and an internal control. The system is also "affordable," the representative said, noting that it is priced similarly to other commercial nucleic acid amplification-based molecular diagnostic tests.
The self-contained GenRead platform weighs less than eight pounds, and is about six inches tall, with a footprint comparable to an iPad. The color touch-screen display is programmed for 23 different languages and the unit has the option of being battery operated. It is comparable in size to the Alere i, Roche Liat, and Solana platform from Quidel — and all of these systems also have C. diff tests in their pipelines.
The isothermal amplification technique used in the GenRead system is a patented method called strand invasion based amplification, or SIBA. It was described in detail late last year in a proof-of-principle PLoS One article demonstrating its use for detecting Salmonella.
In the SIBA method, recombinase is used to amplify double-stranded DNA without prior denaturation by using a "non-extendable strand invasion oligonucleotide that is a substrate for recombinase," the Orion Diagnostica representative said.
Recombination reveals single-stranded DNA, enabling adjacent amplification primers to bind and be extended by a polymerase, but these primers are too short to be a substrate for recombinase.
The method differs from other isothermal nucleic acid amplification methods, like RPA, LAMP, or HDA, the representative explained. SIBA strand separation and amplification are "two separate events which have to work in concert," enhancing specificity and sensitivity. Furthermore, template DNA does not need to be denatured, and the method can be adapted for SYBR green or probe detection, or melting curve analysis.
Orion Diagnostica presented a multi-center evaluation of the C. diff assay at the fifth annual International Clostridium difficile Symposium recently, and was also among the co-sponsors of that event.
In that evaluation, three sites in Northern Europe used the Orion test on 1,160 stool samples suspected of containing C. diff, comparing the test to the Illumigene C. diff from Meridian Bioscience, the IMDX C. diff from Abbott Laboratories, and the Xpert C. diff from Cepheid, as well as to an immunoassay. The Orion test showed between 97 and 99 percent agreement with the established nucleic acid amplification-based methods, and there was 99.8 percent agreement among the three labs.
The firm also presented at the European Congress of Clinical Microbiology and Infectious Diseases in April 2014, demonstrating that the assay gave correct results for all 37 C. difficile toxinotypes tested and performed accurately compared to other assays on a set of 125 patient samples.
The launch of the CE-marked GenRead system and the Orion GenRead C. difficile test has now begun in Europe, and the firm is planning to eventually enter other markets including the US, the representative said.
Orion Diagnostica is also interested in discussing licensing opportunities for human in vitro diagnostics applications and non-human uses — such as food, feed, or water testing — with potential partners.