#FEMSmicroBlog: Polymicrobial community members promoting the transfer of plasmids to uropathogenic Escherichia coli
In urinary tract infections, different bacteria can live as polymicrobial communities. As these bacteria interact with each other, they may exchange plasmids encoding important properties to ensure their survival. The study “Community context influences the conjugation efficiency of Escherichia coli” in FEMS Microbes investigates the microbial-ecological context for horizontal gene transfer between different urinary pathogens, as explained by Misshelle Bustamante and Marjon de Vos in this #FEMSmicroBlog. #FascinatingMicrobes
Can you summarise the significance of your paper for microbiologists outside from your field?
Bacteria can transfer plasmids from one bacterium to another via conjugative horizontal gene transfer. Some transferred plasmids encode important functions such as antimicrobial resistance. As genetic exchanges often take place in poly-microbial infections, they can drive the spread of drug resistances.
We focused on uropathogenic Escherichia coli and the pOXA-48 plasmid, which contains resistance genes to last resort antimicrobials. In our study, we found that the conjugation rate of this plasmid changed upon interactions with other bacterial species.
The presence of Gram-positive species, such as enterococci and Staphylococcus simulans, but sometimes also of Gram-negative bacteria increased the conjugation rate. This means that the microbial-ecological context is important for the level of horizontal gene transfer.
We also found that different uropathogenic Escherichia coli strains undergo horizontal gene transfer at different levels. Some strains are more efficient in receiving pOXA-48 plasmid than others and some strains did not take it up at all.
What can policymakers learn from your research results?
Within just 1 hour and even under poor nutrient conditions, a plasmid carrying last resort antimicrobial resistance genes can spread to several uropathogenic Escherichia coli strains via conjugative horizontal gene transfer. And we didn’t even use any antibiotic selection to maintain the plasmid. No wonder this plasmid has already been disseminated globally!
It’s important that policymakers understand that the spread of antibiotic resistance through plasmids in polymicrobial infections, such as urinary tract infections, depends on both the genetic background of the pathogens and their ecological context.
First, this means that prudent use of antibiotics is critical. Once bacteria have become resistant, they will be selected in the presence of antibiotics. Infections consisting of such antibiotic-resistant bacteria cannot, or only with difficulty, be cured. On top of that, these newly resistant bacteria can subsequently spread the antimicrobial resistance.
Currently, we mostly see the plasmids of the resistant bacteria as the threat because these encode the resistance genes. However, the genetic context of both bacteria and the microbial ecological community are important for the rate of resistance spread. Hence, we would argue that the community rather than only the resistant bacteria, or the plasmid itself, should be considered in the propagation process of antimicrobial resistance.
To disentangle the factors that contribute to the global threat of antimicrobial resistance we should focus on the factors that determine the rate of resistance spread.

Why are your results important for society or non-scientists?
The spread of antimicrobial resistance is a world-wide problem, especially with more pathogens taking up antimicrobial resistances. This can lead to infections that are increasingly difficult to cure.
Urinary tract infections are such tough infections, especially in older people and women. They are the ones mainly suffering from urinary tract infections. At least one in two women will have at least one urinary tract infection in their lifetime, in comparison to one in ten men.
It is therefore relevant and important to understand how uropathogens become easily resistant to antimicrobials via horizontal gene transfer and which factors are important in this process. Knowing that our study reveals a small part of how important the microbial-ecological context is for the spread of antimicrobial resistance, has been a big motivation. And microbes just always keep surprising us!
What was one of the main hurdles you encountered, and how did you solve it?
For me, MB, it was to start my PhD in the middle of the corona crisis, which delayed both the experiments and the social interactions. However, we had great scientific collaborators and patience, which I believe got us through.
In my case, MdV, ramping up a lab in the corona crisis, a concussion due to an accident, and the main care for a small kid, slowed down the pace of science. But as Misshelle mentioned, great scientific collaborations and patience were key and the only solution.
You decided to opt for the Transparent Peer Review route offered by FEMS Microbes. What motivated you to do so, and what are the benefits in your opinion?
We opted for the Transparent Peer Review because the exchange with the reviewers greatly improved our manuscript. It also provided us with new insights that we had not considered before our submission and that made it into the final version.
Since this greatly improved the manuscript, we thought the process should be made public. We believe in open science!
- Read the article “Community context influences the conjugation efficiency of Escherichia coli” by Bustamante et al. in FEMS Microbes (2024).
Misshelle Bustamante is an Ecuadorian biologist and a PhD student at GELIFES at the University of Groningen. She has been studying the role of ecological interactions on the spread of antimicrobial resistance by means of conjugative plasmids in pathogenic microbial communities. She is highly interested in the bridge between Science and Public Policy, which she aims to pursue after her PhD.
Marjon de Vos is an assistant professor at GELIFES at University of Groningen (The Netherlands) where she investigates the ecology and evolution of bacteria derived from polymicrobial infectious ecosystems, and antibiotic resistance. She is passionate about disentangling the ecological drivers of evolutionary processes within microbial populations.
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The section #FascinatingMicrobes for the #FEMSmicroBlog explains the science behind a paper and highlights the significance and broader context of a recent finding. One of the main goals is to share the fascinating spectrum of microbes across all fields of microbiology.
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