In 2022, about 10.6 million people worldwide contracted tuberculosis, including 1.3 million children. The diagnosis of tuberculosis in adults is usually made from sputum (sputum) in the microbiology laboratory. In children, however, the diagnosis is usually made clinically, as the disease often cannot be detected using standard laboratory tests.

As a rule, they do not produce sputum. It is estimated that about 60% of tuberculosis cases in children are not diagnosed. This has serious consequences, as 1 in 5 children under the age of 14 will die from tuberculosis if they are not treated. There is an urgent need for new diagnostic methods that are more sensitive, less invasive and easier to perform.

FFP2 masks filter the exhaled air and have already been used successfully in adults to detect the genetic material of tuberculosis bacteria (M. tuberculosis-DNA). Until now, there has been no corresponding study for children.

To close this gap, Lennard Meiwes, a medical student from Lübeck, developed a method at the Research Center Borstel to detect M. tuberculosis DNA from respiratory masks for children. Together with clinicians and scientists in Germany and the Republic of Moldova, he conducted an initial clinical study to demonstrate the feasibility of the method.

Children with pulmonary tuberculosis wore three modified FFP2 masks for half an hour at a time. The masks contained a strip of 3D-printed polyvinyl alcohol (Meiwes had purchased the printer for the research group on eBay), which can be used to obtain samples from breath.

The masks were then examined using manual and automated polymerase chain reaction (qPCR) and targeted molecular biological methods to identify changes in the genetic material of the bacteria that indicate antibiotic resistance (targeted next-generation sequencing).

Meiwes succeeded in making the method so sensitive that he was able to reduce the detection limit to less than four copies of the pathogen's genetic material. However, despite these promising results in the laboratory, M. tuberculosis DNA could not be detected in any of the 30 masks worn by children for 30 minutes.

"Although our method showed such a low detection limit, we were unable to detect the genetic material of the tuberculosis bacteria in clinical use in children. These results indicate that children with pulmonary tuberculosis probably do not form aerosols through which the bacteria are transmitted," explains Meiwes, whose work is now published in The Journal of Infectious Diseases.

Thanks to Meiwes's preparations, Dariusz Wölk, a medical student from the University of Hamburg in the Clinical Infectious Diseases group in Borstel, is now examining the results in adults in the Republic of Moldova. Like Meiwes, Wölk interrupted his medical studies for a year to do this. Initial results show that the method works in adults.