A Silent Threat: Immune-Resistant Bacteria Spreading Like Swine Flu
It's a chilling thought: a common gut bacteria, Escherichia coli (E. coli), could be spreading as rapidly as the swine flu. New research has unveiled this startling possibility, highlighting the urgent need for better tracking and control of these potentially dangerous strains.
For the first time, scientists from the Wellcome Sanger Institute, the University of Oslo, the University of Helsinki, Aalto University in Finland, and their collaborators have developed a method to predict how quickly E. coli bacteria can transmit from one person to another. Previously, this kind of calculation was primarily used for viruses. The study, published in Nature Communications, focused on three major E. coli strains found in the UK and Norway. Notably, two of these strains are resistant to multiple classes of antibiotics, a growing concern in modern healthcare. These resistant strains are among the most common causes of urinary tract infections and bloodstream infections in both the UK and Norway. The ability to effectively track these bacteria could significantly improve public health measures, helping to prevent outbreaks of treatment-resistant infections.
But here's where it gets controversial: understanding the genetic mechanisms that allow certain E. coli strains to spread could lead to targeted treatments. This approach could reduce our reliance on broad-spectrum antibiotics, which often contribute to the problem of antibiotic resistance. The research team's method could also be adapted to study other bacterial pathogens, enhancing our ability to understand and control various invasive infections.
E. coli is a leading cause of infections worldwide. While most strains are harmless and reside in our gut, some can cause serious illness. These bacteria enter our bodies through direct contact, such as kissing, or indirect contact, such as sharing households, objects, or food. However, when E. coli enters the urinary tract or bloodstream, it can lead to life-threatening sepsis, particularly in individuals with weakened immune systems.
And this is the part most people miss: antibiotic resistance is becoming increasingly common in E. coli infections. The rates of antibiotic resistance vary globally. In the UK, over 40% of E. coli bloodstream infections are resistant to a key antibiotic. This is a critical issue for healthcare providers.
The study's breakthrough lies in using the basic reproduction number, or R0, a metric that describes how many new infections are directly caused by one infected person. While R0 is commonly used for viruses, it hasn't been applied to gut bacteria like E. coli because they don't always cause infections. The researchers analyzed E. coli colonization rates using data from the UK Baby Biome Study and combined it with genomic E. coli bloodstream infection surveillance data from the UK and Norway.
They used a software platform called ELFI (Engine for Likelihood-Free Inference) to create a new model that can predict the R0 for three major E. coli strains in the UK and Norway. The results showed that one strain, ST131-A, spreads as quickly as viruses that have caused major outbreaks, such as swine flu (H1N1), despite E. coli not being transmitted through airborne droplets. The other two strains, ST131-C1 and ST131-C2, which are resistant to several antibiotics, don't spread as rapidly between healthy individuals. However, they likely have a much higher transmissibility in hospitals and healthcare facilities.
Having an R0 for E. coli allows experts to better understand the factors influencing transmission, identify the riskiest strains, and inform public health measures to protect vulnerable populations. As Fanni Ojala, co-first author at Aalto University in Finland, noted, "By having a large amount of systematically collected data, it was possible to build a simulation model to predict R0 for E. coli. To our knowledge, this was not just a first for E. coli, but a first for any bacteria that live in our gut microbiome. Now that we have this model, it could be possible to apply it to other bacterial strains in the future, allowing us to understand, track, and hopefully prevent the spread of antibiotic-resistant infections.”
Dr. Trevor Lawley, Group Leader at the Wellcome Sanger Institute, who co-led the UK Baby Biome Study, added, “E. coli is one of the first bacteria that can be found in a baby’s gut, and in order to understand how our bacteria shape our health, we need to know where we start – which is why the UK Baby Biome study is so important. It is great to see that our UK Baby Biome study data are being used by others to uncover new insights and methods that will hopefully benefit us all.”
Professor Jukka Corander, senior author at the Wellcome Sanger Institute and the University of Oslo, concluded, “Having the R0 for E. coli allows us to see the spread of bacteria through the population in much clearer detail, and compare this to other infections. Now that we can see how rapidly some of these bacterial strains spread, it is necessary to understand their genetic drivers. Understanding the genetics of specific strains could lead to new ways to diagnose and treat these in healthcare settings, which is especially important for bacteria that are already resistant to multiple types of antibiotics.”
What are your thoughts on the implications of these findings? Do you think public health measures are adequately addressing the threat of antibiotic-resistant bacteria? Share your opinions in the comments below!
Reference: Ojala F, Pesonen H, Gladstone RA, et al. Basic reproduction number varies markedly between closely related pandemic Escherichia coli clones. Nat Commun. 2025;16(1):9490. doi:10.1038/s41467-025-65301-1 (https://doi.org/10.1038/s41467-025-65301-1)
