Swedish scientists have developed an innovative tool that tracks a person's last visited locations. It uses the microbial fingerprint of each location. The working principle of the system resembles satellite navigation, but instead of GPS it identifies the geographical origin of microorganisms. By analyzing the bacteria, it is possible to determine exactly where a person has been. Unique bacterial communities live in different places, and when we come into contact with surfaces, such as handrails in public transportation, we transfer the microbes characteristic of that location to ourselves. This makes it possible to establish a link between a person and the location of their recent stay. The researchers created the Microbiome Geographic Population Structure (mGPS) algorithm, which uses artificial intelligence to localize samples across different bodies of water, countries, and cities. The team analyzed extensive microbiome datasets from urban environments, soil, and marine ecosystems, training the model to identify unique proportions of microbial “footprints” and associate them with geographic coordinates. The study involved 4,135 samples from public transportation in 53 cities, 237 soil samples from 18 countries, and 131 seawater samples from 9 bodies of water. As a result, scientists were able to pinpoint the source for 92% of the city samples. For example, in Hong Kong mGPS with 82% accuracy pointed to the subway station from where the material was taken, and in New York the system was able to distinguish the microbiome of a kiosk from the handrail just 1 meter away. The authors of the project believe that this technology opens new horizons in medicine, epidemiology and forensics. In addition, the migration pathways of microorganisms will help to study the spread of diseases, identify potential foci of infection and localize the emergence of antibiotic resistance