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FDA Clears Roche’s PCR-Based MRSA Nasal Test

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By Ben Butkus

The US Food and Drug Administration has cleared Roche Molecular System's LightCycler MRSA Advanced Test for detecting methicillin-resistant Staphylococcus aureus for clinical use in the US, Roche said this week.

Roche's test becomes the third PCR-based MRSA test approved for clinical use in the US, joining Cepheid's Xpert MRSA/SA nasal assay for its GeneXpert PCR platform; and Becton Dickinson's GeneOhm MRSA assay, which runs on Cepheid's SmartCycler platform.

The clearance also comes on the heels of troublesome news surrounding one of Cepheid's amplification-based MRSA tests, the Xpert MRSA/SA blood culture assay, which the company voluntarily recalled last week due to reports of false negatives.

The recall has not affected the marketing status of Cepheid's nasal MRSA assay, which competes directly with the new Roche assay.

Roche Molecular Diagnostics President and CEO Paul Brown told PCR Insider this week that the timing of the launch of the LightCycler MRSA test was "purely coincidental" in relation to the Cepheid recall.

"We've had the filing with the FDA with some time now," Brown said. "I'm glad we could get our test out there and available to physicians. It gives the medical community another option, which is needed considering that the high rates of infection and mortality in [hospital-acquired infections] are an increasing concern."

S. aureus is one of the most frequently isolated bacteria from patients with HAIs. The US Centers for Disease Control estimate that 90,000 deaths are attributable to HAIs each year and that between 5 and 10 percent of US hospital inpatients acquire an HAI annually.

In 2007, the CDC estimated that HAIs were responsible for $4.5 billion to $5.7 billion in added healthcare costs annually. Meantime, Roche said that it estimates the market for molecular-based MRSA screening to be worth about $125 million this year and growing by 20 percent yearly.

"This is becoming an increasing problem for many healthcare systems around the world, including the US," Brown said.

The recall of the Cepheid test, which is suspected to have resulted from the emergence of novel strain types, may also give room for pause when considering the results of other amplification-based tests for MRSA — although last week an FDA spokesperson said that the recall doesn't suggest "any common ongoing problem for nucleic acid tests for organisms such as MRSA." (PCR Insider, 7/6/2010).

When asked whether he believed the recall would spur any additional scrutiny of the Roche LightCycler MRSA test by the FDA or internally, Brown said that "the agency has done a thorough review of our file over the last month, and I'm confident that the FDA has given a great deal of thought and scrutiny to our test."

The LightCycler MRSA test is a qualitative in vitro diagnostic test to directly detect nasal colonization with MRSA, and is designed to aid in the prevention and control of MRSA infections in healthcare settings, Roche said. It is performed on Roche's LightCycler 2.0 instrument with nasal swab specimens from patients suspected of MRSA colonization.

The test delivers results in less than two hours, and "appears to have better sensitivity compared to direct culture-based methods," Roche said, without elaborating.

"PCR-based diagnostics are very powerful, and in comparison to culture-based methods the rapid turnaround time of these PCR-based technologies is attractive," Roche Molecular Diagnostics President and CEO Paul Brown told PCR Insider. "It is fast and reliable when compared to culture-based screening."

In a statement, Lance Peterson, an epidemiologist and founder of the MRSA screening program at Northshore University HealthSystem in Evanston, Ill., said that the new test "showed good sensitivity with minimal hands-on time;" and that it gives technicians "the ability to have flexible batch sizes, which could make it the cost-effective choice for many hospital laboratories."

The approval of the Roche LightCycler MRSA test is the latest news in what has been a busy few weeks for nucleic acid-based MRSA testing.

Besides its recall, Cepheid also faces a potential legal battle over patents related to its MRSA blood culture test, as Abaxis has sued the company claiming sales of the test infringe upon some of its sample prep patents. Cepheid has denied the claims and filed a countersuit seeking the court to invalidate the patents (related story, this issue).

Also, late last month, Wayne, Pa.-based Molecular Detection said that it planned to launch its qualitative real-time PCR-based MRSA detection assay in the US in the first half of 2011.

Molecular Detection disclosed its plans to PCR Insider sister publication The Sample following news that it had raised $1.4 million as a follow-on to a $3.3 million Series C financing round announced in late 2009 (PCR Insider, 6/23/10).

The test is already currently available in Germany, the UK, Ireland, Switzerland, and Austria; and Molecular Detection also said this week that it has signed on Palex Medical to distribute the test in Spain.