Study taps genes in sewage to track drug resistance

Slum housing by dirty waterway in the city, with a water pipe in the foreground
Copyright: Mark Henley/Panos

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  • Researchers used genes recovered in sewage to estimate antimicrobial resistance
  • They found Africa, Asia and South America to have highest levels compared with other regions
  • Countries should improve their sanitation to curb antimicrobial resistance, experts say

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[DAR ES SALAAM] Studying genetic materials recovered from untreated sewerage can help identify and curb antimicrobial resistance in human populations worldwide, a study suggests.
The study identifies Africa, Asia and South America as the regions with high levels of antimicrobials whereas North America and Western Europe have low levels.

Antimicrobial resistance, a global health problem characterised by the ability of microbes such as bacteria and viruses to counter the effects of medicines, endangers achievement of the Sustainable Development Goals, according to the WHO.

Researchers who conducted the study say that it is challenging to obtain representative data on antimicrobial resistance for healthy human populations so they were motivated to test the use of untreated sewage samples to generate evidence.

“It would be important for countries to invest in good infrastructure, sanitation and their general health system.”

Frank M. Aarestrup, Technical University of Denmark

“Our findings suggest that global antimicrobial resistance gene diversity and abundance vary by region, and that improving sanitation and health could potentially limit the global burden of antimicrobial resistance,” says the study published in the journal Nature Communications this month (8 March)

“It would be important for countries to invest in good infrastructure, sanitation and their general health system,” according to Frank M. Aarestrup, a co-author of the study and head of the research group for genomic epidemiology at the Technical University of Denmark.

Aarestrup tells SciDev.Net that his team has been working on how antimicrobial resistance spreads but for more than 20 years having reliable data has been difficult until they began to explore untreated sewage.

By studying genetic materials of untreated sewerage in 74 cities across 60 countries, and analysing the data with advanced statistical methods, the researchers were able to estimate patterns of resistant bacteria across different regions.

The researchers also used their data to estimate antimicrobial resistance levels for 259 countries and territories, and generate global maps of antimicrobial resistance in healthy humans.

Global predictions of antimicrobial resistance abundance in all countries and territories in the world.
Global predictions of antimicrobial resistance abundance in all countries and territories in the world.
Light blue means low antimicrobial resistance
Dark blue means high antimicrobial resistance
Source: Rene S. Hendriksen and others

“The countries standing out as having the most divergent distribution of antimicrobial resistance genes were Brazil, India and Vietnam, suggesting that these countries could be hot spots for emergence of novel antimicrobial resistance mechanisms,” the researchers explain.

Lowest levels were found in the Netherlands, New Zealand and Sweden whereas highest antimicrobial resistance levels were found in Nigeria, Tanzania and Vietnam.

“The study is important for African countries where there is still lack of adequate sewage systems to deal with animal and human's waste,” says Erick Venant, the CEO of Tanzania-based non-governmental organisation known as Roll Back Antimicrobial Resistance Initiative.

“Countries should improve the sewage systems as this study has revealed the role of the environment in the emergence of antimicrobials resistance,” Venant tells SciDev.Net.

This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.


Rene S. Hendriksen and others Global monitoring of antimicrobial resistance based on metagenomics analyses of urban sewage (Nature Communications, 8 March 2019)