Assay Detects Bacterial Toxin That Causes Diarrhea

An assay that can detect the toxin B gene associated with Clostridium difficile infection (CDI) in stool samples is now available.

The assay is fully automated and works on the GeneXpert Dx System to detect toxin gene sequences associated with toxigenic C. difficile. The GeneXpert Dx System consists of an instrument that houses single-use disposable cartridges, a personal computer, and software that allow a laboratory technician to run tests and view test results quickly.

The test, Xpert C. difficile/Epi assay determines if C. difficile is in a patient's stool and also detects if the C. difficile is the epidemic 027/NAP1/BI strain, which has been associated with a marked increase in the severity and incidence of CDI in North America and Europe over the past decade. The test utilizes automated real-time polymerase chain reaction (PCR) to detect C. difficile DNA. The test is intended for use as an aid in the diagnosis of CDI. The detection of the 027/NAP1/B1 strain is for epidemiological purposes only and should not be used to determine or monitor treatment. Health care facilities should monitor the number of C. difficile infections and, especially if rates at the facility increase, the severity of disease and patient outcomes.

Both the Xpert C. difficile/Epi assay and GeneXpert Dx System are manufactured by Cepheid, (Sunnyvale, CA, USA). The US Food and Drug Administration, (FDA; Silver Springs, MD, USA), have cleared the test for clinical laboratory use. Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostics Device Evaluation and Safety in the FDA's Center for Devices and Radiological Health, said, "Healthcare professionals in the infectious disease community who have seen various outbreaks of CDI associated with aggressive strains in recent years, now have a new testing tool to detect this disease."

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The US Food and Drug Administration