Viruses, fungi, bacteria and even parasites can attack the human brain and cause dangerous damage. Now a new procedure will make diagnosis easier and particularly useful in mysterious cases, which are also on the rise in Germany.
A newly developed genetic test can check brain fluid for almost all known pathogens: viruses, bacteria, fungi and parasites. In this way, the cause of brain infections can be determined relatively reliably and appropriate therapy can be initiated, writes an American research team after a seven-year study with samples.
According to the team published in the journal Nature Medicine, central nervous system (CNS) infections such as meningitis, encephalitis and myelitis can be life-threatening. explained. Rapid diagnosis and treatment are often essential to avoid serious consequences. Currently, several test procedures are often combined to clarify, but in half of the cases, for example, the cause of meningoencephalitis cannot be clarified.
“This topic is extremely important,” confirmed neurologist Helge Roland Topka, head physician at the Bogenhausen clinic in Munich, who was not involved in the study. The spokesperson of the Commission for Neurological Emergency Medicine of the German Neurological Society (DGN) spoke of a “fascinating technology”: “This system is able to find pathogens that you wouldn’t expect.”
The fully automated process that Chiu helped develop, called next-generation metagenomic sequencing (mNGS), analyzes brain fluid samples for different types of pathogens. The genetic material circulating in the brain fluid is isolated and sequenced. These sequences are then compared with databases and assigned to different organisms.
In the current one Study the team presents the results of tests of samples sent to the laboratory and examined there from 2016 to 2023. The evaluation detected an infection in one in seven (697 samples; 14.4%) of the 4828 total samples. The team detected DNA viruses in
The team also tested various diagnostic procedures on approximately 1,160 samples from San Francisco University Hospital: in 22% of the samples, only the new procedure identified the responsible pathogen.
With a rate of 99.6% for the so-called specificity, false positives were extremely rare. The so-called sensitivity, however, was weaker, around 63%. In just under two-thirds of patients with brain infection, a pathogen was actually identified. But this is still significantly better than antibody tests, whose sensitivity reaches only 29%, and direct testing methods for some pathogens, which would reach 46%.
However, the group writes: “With an overall sensitivity of 63.1%, the mNGS method is not sufficient to replace conventional microbiological tests.” to a pathogen for a short time such as West Nile virus. Or infections in which the triggers colonize only parts of the brain tissue and do not appear in the cerebrospinal fluid.
According to Munich-based DGN expert Topka, the biggest weakness of the procedure for use in emergency neurology is the analysis time, which currently takes a good 3.5 days. “We often only have an extremely short period of time to start therapy. In case of bacterial meningitis the prognosis worsens by 30% every hour.” You have to react immediately, often in cases of suspicion.
Pathogens that you wouldn’t suspect
For clarification and subsequent optimized therapy, a rapid multiplex PCR test is currently used, which analyzes the brain fluid in just over an hour, but only for around a dozen of the most common pathogens.
In contrast, the method presented by Chiu is capable of “finding pathogens that you are not specifically looking for.” This is extremely important, especially in mysterious cases without strong time pressure.
Chiu’s group also highlights the benefits of this approach. This applies especially to those pathogens that cannot be cultured in the laboratory, such as the Lyme disease bacterium Borrelia burgdorferi and Bartonella henselae, the cause of cat scratch disease, to diagnose viral infections and to clarify rare but extremely dangerous causes , such as amoebic encephalitis or amoebosis of swimming pools, as well as in investigations in case of epidemics.
After an outbreak of fungal meningitis in Mexico in 2023, the method identified the pathogen Fusarium solani in the first US patient and thus alerted US health authorities to the problem.
Infections with rare pathogens are also increasing in Germany, Topka said, mainly due to long-distance travel and global trade. The new approach is certainly useful for clarifying mysterious brain infections. “If the process were a little faster, this would be the solution to many infection problems,” Topka says.
The research group estimates that the cost of the test is around 3,000 dollars (just under 2,800 euros). This means that initially the procedure is only suitable for rich countries. However, costs may decrease in the future.
In the specialized magazine “Nature Communications” provides Chiu and another team are introducing a similar mNGS procedure: this can determine the viral causes of respiratory infections within a day. In this case the reliability of the results compared to the PCR standard is almost 94%.
dpa/sk
