FDA approves two diagnostic assays for dengue virus, C. difficile

The FDA announced recently the availability of two new tests to aid in the diagnosis of two infectious diseases.

The newly available tests include the DENV Detect IgM Capture ELISA (Inbios Inc), which detects antibodies to dengue virus in blood samples from patients with signs and symptoms of dengue fever or dengue hemorrhagic fever, and the Cepheid Xpert (Cepheid), which detects the toxin B gene associated with Clostridium difficile infection.

Dengue fever assay

The DENV Detect IgM Capture ELISA detects antibodies to dengue virus in blood samples from patients who have signs and symptoms of dengue fever or dengue hemorrhagic fever. The test will be available for use in clinical laboratories and will assist in the diagnosis of dengue, which can improve patient care and management. This is the first FDA approved test for direct detection of dengue virus.

The FDA advises that this test not be used in people who do not show signs or symptoms of dengue. Diagnostic testing for dengue is complicated by the fact that an IgM antibody response to the dengue virus infection is not detectable until 3 to 5 days after the onset of fever, which can produce a negative test result even though a person has dengue.

According to the FDA, this dengue test shows cross-reaction with other closely related viruses such as those that cause West Nile disease. However, in most patient testing situations found in the United States, a positive test result in a patient with signs or symptoms consistent with dengue should be considered presumptive evidence of dengue.

C. difficile assay

The Cepheid Xpert C. difficile/Epi assay is automated and works on the Cepheid GeneXpert Dx System to detect toxin gene sequences associated with toxigenic C. difficile. The Cepheid 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 determines if C. difficile is in a patient’s stool and also detects if 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 during the past decade, according to the FDA release.

“Health care 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,” 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 in a press release.

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