FDA approves rapid tests for MRSA, influenza

Infection detection in real time

In what could be a boon for infection surveillance and treatment programs, the Food and Drug Administration has approved a new rapid test for methicillin-resistant Staphylococcus aureus (MRSA) that can identify the bug in two hours. In a separate ruling, the FDA gave the green light to a new rapid test that detects influenza and several other respiratory viruses.

The FDA has cleared for marketing the first rapid blood test for MRSA, the BD GeneOhm StaphSR Assay (Becton Dickinson Inc.; Franklin Lakes, NJ). The test uses molecular methods to identify whether a blood sample contains genetic material from the MRSA bacterium or from the drug-susceptible staph. "The BD GeneOhm test is good news for the public health community. Rather than waiting more than two days for test results, health care personnel will be able to identify the source of a staph infection in only two hours, allowing for more effective diagnosis and treatment," Daniel G. Schultz, MD, director of the FDA Center for Devices and Radiological Health, said in a statement. FDA cleared the BD GeneOhm StaphSR assay based on the results of a clinical trial at five locations. The new assay identified 100% of the MRSA-positive specimens and more than 98% of the more common, less dangerous staph specimens.

In order to preserve the integrity of positive test results, the test should be used only in patients suspected of a staph infection, the FDA stated. The test should not be used to monitor treatment for staph infections because it cannot quantify a patient's response to treatment. Test results should not be used as the sole basis for diagnosis as they may reflect the bacteria's presence in patients who have been successfully treated for staph infections. Also, the test will not rule out other complicating conditions or infections, the FDA noted.

The other recently approved rapid test is the ProFlu+ test (Prodesse Inc., Milwaukee), which can provide results in as few as three hours. The real-time test employs a multiplex platform that allows several tests to be processed using the same sample to detect influenza A virus, influenza B virus, and respiratory syncytial virus A and B (RSV). "Antiviral drugs are most effective when initiated within the first two days of symptoms," Schultz said. "This new test, which is part of the new era of molecular medicine, can help the medical community quickly determine whether a respiratory illness is caused by one of these four viruses and initiate the appropriate treatment."

ProFlu+ uses a molecular biology process to isolate and amplify viral genetic material present in secretions taken from the back of the throat in patients. While ProFlu+ is faster than conventional tests, it is specific to the four viruses, and is more accurate when used with other diagnostics, such as patient data, bacterial, or viral cultures, and X-rays, in diagnosing a patient. Positive results do not rule out other infection or coinfection and the virus detected may not be the specific cause of the disease or patient symptoms, the FDA added.