Medical genetic

The researches find that the meta genomic next-generation sequencing (mNGS), developed by UCSF scientists to diagnose patients with mysterious inflammatory neurological conditions, the technique was shown to identify infections better than any standard clinical method. “The infectious cause of half the cases of meningitis and encephalitis go undiagnosed in hospitals around the country; and these severely ill patients are in dire need of a better testing tool”; says Charles Chiu, MD, Ph.D., professor of laboratory medicine and medicine at UCSF and senior author of the new study.

Next-generation sequencing

Unlike conventional testing, which is often drive by doctors’ hunches, the mNGS test offers an unbiase approach that can detect nearly all possible pathogens bacteria, viruses; fungi and parasites present in patients’ spinal fluid, giving doctors clear direction for treatment. The study, publish June 13, 2019 in the New England Journal of Medicine; is set up to enroll only the most challenging cases.

To qualify, a patient had to be hospitalize with an acute neurological illness with no conclusive diagnosis. The study include 204 pediatric and adult patients; mostly from California, who had meningitis (inflammation of the lining surrounding the brain); encephalitis (inflammation of the brain itself) or myelitis (inflammation of the spinal cord).

The test find many of the same infections identify by conventional laboratory testing methods, which generally look for pathogens one at a time; and require that doctors know what they are looking for to be successful. But it also find 13 infections that are miss by all conventional tests, such as a case of infection by St. Louis encephalitis virus, which had not been see in California since 1986.

Acute neurological illness

And in more than half of those cases; the mNGS diagnosis is indispensable in guiding the treatment of these patients. In a case of hepatitis E virus infection that had been miss by conventional testing, the successful mNGS diagnosis likely spared the patient from having to undergo a liver transplant.

“The mNGS test is generally order as a test of last resort; and we end up enrolling the hardest patients to diagnose;” says Chiu; also director of the UCSF-Abbott Viral Diagnostics and Discovery Center. “All conventional microbiology tests combine yield diagnoses in less than 50% of these patients. They are not shows that a single test mNGS  make a significant dent in that number.”

In all, the test identified 32 infections of the nervous system in 31 patients. In addition to the 13 diagnoses made by mNGS only; the new technology confirm 19 infections that had also been diagnose by conventional tests. Fewer than half of meningitis and encephalitis cases are cause by infections. Most of the rest are the result of autoimmune reactions; in which the patient’s own body attacks the nervous system.

The autoimmune reactions

The two conditions require very different treatments; however suppressing immunity in a patient with an infection can be harmful, and giving antibiotics in a case of autoimmune disease is ineffective and may unnecessarily promote antimicrobial resistance so the first thing a doctor needs to know when treating such patients is which category of inflammatory disease they have.