Speeding Up the Diagnosis of Meningitis

Cepheid based out of Sunnydale, CA has just received FDA approval for the Xpert EV ™ test, which will help speed the diagnosis of viral meningitis. The product has been available for about a year in Europe, and should now help improve patient outcomes in the US.

The Xpert EV ™ test, a new test available for Cepheid's GeneXpert system, helps to distinguish between viral and bacterial meningitis. Meningitis is an inflammation of the cerebrospinal fluid that surrounds the brain and spinal cord. Normally this fluid is sterile, meaning there are no bacteria or viruses found there. A bacterial infection of this fluid can be fatal in as little as 2 days, while a viral infection will make you very sick but resolves itself usually in 7-14 days. Looking at the symptoms you have it can be nearly impossible to determine which type of meningitis you have. Typically it can take over a week for physicians to receive back the test results they need to determine which type of meningitis you may have, so during that time they must assume you have the worst case of bacterial meningitis. This can mean you are on high doses of powerful antibiotics while they wait for bacterial growth in the samples of spinal fluid they obtain. This causes a lot of worry and anxiety for you and your family, is expensive, contributes to bacterial resistance to antibiotics, and can even have unwanted side effects.

The Xpert EV ™ test looks for proteins produced by Enteroviruses, which cause about 90% of the cases of viral meningitis. Enteroviruses have a specific RNA (or riboxynucleic acid) protein sequence. This test uses reverse-transcription real-time polymerase chain reaction (RT-PCR) to rapidly increase the RNA protein levels to a detectable amount. The test is a self-enclosed cartridge system that only requires the addition of the sample cerebrospinal fluid- it is much simpler than current tests available for this. If they are not present nothing happens, but if they are there then in about 2.5 hours time the levels are great enough to show up as a positive result. Presumably, if you are positive for this virus then you do not have the bacterial infection, and your treatment can be modified.

The accuracy of the Xpert EV test was confirmed in a large study at six different hospitals. A total of 255 patient samples were tested and demonstrated that 96 percent of patients who tested positive did indeed have viral meningitis, and that 97 percent of patients who tested negative did not have viral meningitis.

If you or someone you love experiences symptoms such as fever and chills, severe headache, nausea and vomiting, stiff neck, sensitivity to light (photophobia), and/or behavior changes, please head immediately to an emergency department. There they can take a sample of your cerebrospinal fluid through a spinal tap, and get you on the road to recovery a little faster thanks to this new test.