For years, the global health community has raised concern about growing resistance of microorganisms to antibiotics.
Now, a new study shows it may be linked to the bacteria that exists in poop.
Bacteria growing resistance to antibiotics is the result of different causes: it could the result of antibiotic residues in the environment promoting the evolution of new forms of resistance.
On the other hand, it could be simply the result of contamination by bacteria that exist in faeces. They tend to be more resistant.
A study published in Nature Communications shows that “crAssphage”, a virus specific to bacteria in human faeces, is highly correlated to the abundance of antibiotic resistance genes in environmental samples.
This could mean faecal pollution is the reason behind increasing resistant bacteria often found in environments impacted by humans.
A clear exception is in environments polluted with high levels of antibiotics from manufacturing—where genes linked with resistance are common without the presence of crAssphage.
Joakim Larsson, a professor in environmental pharmacology at Sahlgrenska Academy, University of Gothenburg, and one of the co-authors of the study, says, “These finding are important as they can inform management of human health risks associated with antibiotic resistant bacteria in the environment. While antibiotic residues is clearly the cause for the exceptionally high levels of resistance found near some manufacturing sites, faecal pollution is probably the explanation in most other places.”
Does that mean we don’t need to worry about the low levels of antibiotics released from places like sewage treatment plants?
Says Larsson: “The study indicates the importance of taking into account the level of faecal pollution when interpreting findings of antibiotic resistance in the environment. It implicates that one often do not need to explain such findings by on-site selection from residual antibiotics. But it does not exclude that there still is selection by low levels of antibiotics in the environment going in in parallel. Other findings still suggest that low, environmental levels of certain antibiotics could select for resistance. This needs further research.”