CDI Diagnostic Test Establishes New Benchmarks

An on-demand molecular diagnostic test was designed for 45-minute detection of Clostridium difficile infection (CDI).

CDI rates continue to rise throughout the world and a more virulent epidemic strain, known as 027/NAP1/BI, has been detected in at least 48 states (USA), Canada, and throughout Europe. A rapid, accurate CDI test eliminates repetitive testing and enables implementation of appropriate treatment.

The Xpert C. difficile test, a product of Cepheid (Sunnyvale, CA, USA), has been cleared for the direct detection of toxigenic C. difficile from stool specimens, by the U.S. Food and Drug Administration (FDA; Silver Springs, MD, USA). The test targets the toxin B (tcdB) gene, the cause of antibiotic-associated diarrhea and colitis. The gene is the critical component of all toxigenic C. 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.

The GeneXpert system delivers on-board sample preparation and real-time polymerase chain reaction (PCR) amplification, with fully integrated and automated nucleic acid analysis. The system purifies, concentrates, detects, and identifies targeted nucleic acid sequences, thereby delivering answers directly from unprocessed samples.

C. difficile, a spore-forming bacterium, is approaching methicillin-resistant Staphylococcus aureus (MRSA) as the most prevalent Healthcare Associated Infection (HAI) in the United States. On any given day, more than 7,000 patients in the U.S. are suffering from CDI, causing the deaths of approximately 300 patients. The disease can range in severity from mild to severe diarrhea, pseudomembranous colitis, toxic megacolon, sepsis, and death.

"The previous lack of an accurate and rapid diagnostic test for CDI has greatly impeded our ability to halt the increasing rate of CDI, which has taken a severe turn in the past several years. Patients can have their first diarrhea symptoms on a Monday and be dead by Thursday," said Dale Gerding, M.D., professor of medicine, division of infectious diseases, Loyola University Chicago-Stritch School of Medicine (Maywood, IL, USA). "Toxigenic culture offers high sensitivity, but laboratories find it burdensome and far too slow for practical diagnostic use. Instead, many use less labor-intensive toxin EIA (enzyme immunoassay) and GDH (glutamate dehydrogenase) tests, which fail to detect 20-50% of cases. From a practical standpoint, this means many patients are not subjected to proper isolation procedures that can curtail transmission of C. difficile."

Cepheid develops, manufactures, and markets fully integrated systems and tests for genetic analysis in the clinical, industrial, and biothreat markets.

Related Links:
Cepheid
U.S. Food and Drug Administration
Loyola University Chicago-Stritch School of Medicine