New research suggests that DNA molecules called plasmids, some of which protect bacteria from antibiotics, can spread rapidly through bacterial “communities” that are treated with antibiotics.
Plasmids are found in bacterial cells, sometimes slowing down the growth of bacteria, but they can carry genes that prevent the action of antibiotics (so-called antimicrobial resistance).
A new laboratory study conducted by the University of Exeter has shown that a plasmid that benefits one or more species spreads not only through these species but also among others in the community.
Bacterial communities exist both in the environment and in the “microbiome” of individual organisms, including humans.
“Very often, antimicrobial resistance is not related to the bacteria themselves – it is encoded in the plasmids they carry and can pass on,” said lead author Arthur Newbury of the Institute for Environment and Sustainability at the Penrine Campus in Exeter, Cornwall.
“Plasmids can jump between bacteria and, although most do not cause antimicrobial resistance, those that make a new host instantly resistant.
“These plasmids become useful when there are antibiotics nearby, which is one of the reasons why resistance can appear and spread very quickly in hospitals.”
When one or more species of bacteria benefit from the content of the plasmid, the plasmid reaches a “higher density” in the population, making it more likely to spread to other species.
In turn, this increases the likelihood that the plasmid will be transmitted to a pathogenic (pathogenic) species in the community – even if the species has not yet been exposed to antibiotics.
“Our results suggest that the effects of antibiotics on microbial communities – including human microbiomes – may contribute to the spread of other genes encoded by plasmids, including antimicrobial resistance genes,” said Dr. Dirk Sanders, also of ESI. .
The study used a networked approach – a very effective way to study complex situations, ranging from bacterial communities to pandemics.
The team is already expanding this study by testing with more plasmids and more complex bacterial communities (including tests on how plasmids can spread in wastewater).
“There is a huge potential for plasmid-induced antimicrobial resistance to spread to the environment,” Dr. Sanders explained.
The study is funded by the Environmental Research Council.
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