There's a new challenger to Methicillin-resistant Staphyloccus MRSA in the category of most prevalent healthcare associated infection in the U.S. C. difficile, a spore forming bacteria, taxes American healthcare institutions up to $51.5 million a day and is demanding a much more efficient means of detection.

Cepheid (Sunnyvale, California) reported it has received clearance from the FDA to market its Xpert C. difficile test, an on-demand molecular diagnostic test designed for 45-minute detection of the bacterium that causes Clostridium difficile infection (CDI). The Xpert C. difficile test is the first test for CDI to deliver both rapid turnaround and what the company describes as a high degree of accuracy.

The test specifically targets the Toxin B gene, which was discovered in 1978 to be the cause of antibiotic-associated diarrhea and colitis. The Toxin B (tcdB) gene is the critical component of all toxigenic Clostridium difficile strains — including the epidemic 027/NAP1/BI strain. Cepheid will also continue to work closely with the FDA to deliver an additional product featuring simultaneous differentiation of the 027/NAP1/BI epidemic strain.

"Cepheid is the only company that has dared to use toxicology cultures as a rate of comparison," David Persing Executive VP chief medical and technology officer at Cepheid told Medical Device Daily. "We made the decision early on to find out if we were going to use the toxicology cultures as our standard. The subject of a standard of comparison for these kinds of test has been in discussion for years now."

A toxigenic culture is a fecal culture followed, in the case of positivity, by a direct immunoassay on colonies to detect toxin. Most tests don't use this method because it's too labor intensive.

The Xpert C. difficile test is Cepheid's seventh test to receive FDA clearance, and fourth in its expanding menu of on-demand HAI products. The test, which runs on Cepheid's GeneXpert System, will be available for shipment next week.

The GeneXpert System is a closed, self-contained, fully-integrated and automated platform that represents a paradigm shift in the automation of molecular analysis, producing accurate results in a timely manner with minimal risk of contamination.

The system also combines on-board sample preparation with real-time PCR (polymerase chain reaction) amplification and detection functions for fully integrated and automated nucleic acid analysis.

The system is designed to purify, concentrate, detect and identify targeted nucleic acid sequences thereby delivering answers directly from unprocessed samples. Modular in design, the GeneXpert System has a variety of configurations to meet the broad range of testing demands of any clinical environment.

As CDI rates continue to rise throughout the world, a more virulent epidemic strain, known as 027/NAP1/BI, has now been detected in at least 48 states, Canada, and throughout Europe.

In major EU countries CDI incidence is reported at 11 per 10,000 admissions. Highly virulent (027-NAP1-BI) strains have caused outbreaks of severe disease in Europe and North America — with mortality rates above 50%. The number of reported deaths are rising and, in the case of England and Wales, increasing by 72% between 2005 and 2006.

"As the leader in molecular HAI testing, it is incumbent for Cepheid to provide healthcare institutions access to the most comprehensive suite of rapid and accurate HAI tests on the market. The Xpert C. difficile test establishes new levels of speed, accuracy, and ease-of-use for CDI testing," said John Bishop, Cepheid's CEO.

"As Cepheid continues the development of innovative new diagnostic solutions, we will strive to measure our product design against a solid understanding of healthcare's current, and future, needs for rapid and accurate diagnostic tests. Our novel approach for the Xpert C. difficile test, as measured against the true gold standard of toxigenic culture, delivered on that vision."

The news gave a boost to the company's shares last week. At one point shares rose as much 39 cents, or 4.6%, to $8.86 in afternoon trading. The stock has traded between $4.93 and $30 over the last 52 weeks, and is off 18% since the start of the year. By Friday afternoon stocks were trading at $9.81.