Researchers map potentially harmful bugs found cities around the world

Researchers analysed the genetic sequences of microorganisms found in train stations, benches and other public areas in the mass-transit systems in 60 cities across the world, including Offa, Nigeria. They found many similar types, and many that are linked to diseases. Such a detailed map, or atlas, of potentially harmful microorganisms found in cities will help authorities identify health risks.

Many people around the world live in cities, and these high numbers also attract different microorganisms in those cities, some which can cause diseases. Researchers are interested in knowing the different microorganisms in different cities so that they can predict disease burdens. 

In this study, the researchers explored the different microorganisms found in different cities and compiled a map.

They collected samples from 60 cities across the world over three years. They took samples from railway stations, benches in waiting rooms, and where people buy train/bus tickets. They then analysed the genetic sequences found in those samples so that they could identify the microorganisms. 

From this they were able to map a total of 4424 different microbial species according to where they were sampled from.

This “geospatial” atlas revealed 31 species, found in nearly all samples (97%), that were different from the commensal bacteria usually found in humans (commensal bacteria help provide nutrients and protection against infections).

Importantly, many of the genetic sequences they found in their samples are associated with antimicrobial resistance, which is the ability of microorganisms to survive drugs intended to kill them.

The researchers say they also found many unknown microorganisms in their samples. But overall, their atlas profiles many characteristics and novel genetic elements of all the known and unknown species they detected, including 10,928 viral, 1302 bacteria, and 2 archaea novel species.

Some of the species identified may cause disease, but more work is needed to confirm any health risks.

The researchers said this was the first study to map the spread of microorganisms in urban areas across the world.

They however cautioned that their analysis may have missed some viruses because the methods they used were not best suited for viral analysis. They also say more studies are needed to investigate how seasonal changes might affect urban microorganism populations.

This study was done by a group of researchers from many countries around the world, including Kenya.

Abstract

We have created a global atlas of 4,728 metagenomic samples from mass-transit systems in 60 cities across 3 years. This is the first systematic, worldwide study cataloging the urban microbial ecosystem. We identify taxonomically-defined microorganisms collected across three years. This atlas provides an annotated, geospatial profile of microbial strains, functional characteristics AMR markers, and novel genetic elements, including 10,928 viral, 1302 bacteria, and 2 archaea novel species. We identify 4,424 species of urban microorganisms and a consistent “core” of 31 species found in nearly all samples that is largely distinct from any human commensal microbiome. Profiles of AMR genes show geographic variation in type and density. Together, these results constitute a high-resolution, global metagenomic atlas, which enables the discovery of new genetic components, highlights potential forensic applications, and provides an essential first draft of the global AMR burden of the world’s cities.

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