London, Nov 09: Researchers have, for the first time, estimated how quickly E. Coli bacteria can spread between people, and one strain moves as fast as swine flu.

Using genomic data from the UK and Norway, scientists modelled bacterial transmission rates and discovered key differences between strains.

Their work offers a new way to monitor and control antibiotic-resistant bacteria in both communities and hospitals.

New research has revealed that Escherichia coli (E. coli), a bacterium that normally lives in the human gut, can spread through populations at a rate comparable to the swine flu.

The researchers from the Wellcome Sanger Institute, the University of Oslo, the University of Helsinki, Aalto University in Finland, and their collaborators have been able to estimate how efficiently one person can pass gut bacteria to others.

The study, published on November 4 in Nature Communications, examined three key E. coli strains circulating in the UK and Norway.

Two of these strains were resistant to several common classes of antibiotics. They were also the most frequent causes of urinary tract and bloodstream infections in both countries.

The researchers suggested that better monitoring of these strains could guide public health responses and help prevent outbreaks of infections that are difficult to treat.

In the long term, gaining insight into the genetic factors that help E. coli spread could lead to more targeted therapies and reduce reliance on broad-spectrum antibiotics.

The approach developed in this study could also be adapted to investigate other bacterial pathogens and improve strategies for managing invasive infections.

According to the study, E. coli is one of the leading causes of infections around the world. While most strains are harmless and normally inhabit the gut, the bacteria can enter the body through direct contact, such as kissing or indirect means like shared surfaces, food, or living spaces.

When E. coli moves into areas such as the urinary tract, it can cause serious illness, including sepsis, especially in people with weakened immune systems.

Scientists often describe how infectious a pathogen is using the basic reproduction number, known as R0.

This number estimates how many new cases a single infected person might cause. It is typically applied to viruses and helps predict whether an outbreak will expand or decline.

Until now, researchers have been unable to assign an R0 value to bacteria that normally colonise the gut, since they often live in the body without triggering illness.

To overcome this, the team combined data from the UK Baby Biome Study with genomic information from E. coli bloodstream infection surveillance programs in the UK and Norway, previously compiled by the Wellcome Sanger Institute.

Using a software platform called ELFI3 (Engine for Likelihood-Free Inference), the researchers built a new model capable of estimating R0 for the three major E. coli strains studied.

Their results showed that one particular strain, known as ST131-A, can spread between people as rapidly as some viruses that have caused global outbreaks, including the swine flu (H1N1). This is particularly striking because E. coli is not spread through airborne droplets like flu viruses are.
The two other strains studied, ST131-C1 and ST131-C2, are resistant to multiple antibiotic classes but spread much more slowly among healthy individuals. However, in hospitals and other healthcare environments, where patients are more vulnerable and contact is frequent, these resistant strains could move through populations much faster.

Understanding R0 for Bacteria:

Assigning an R0 value to bacteria opens the door to a clearer understanding of how bacterial infections spread.

It also helps identify which strains pose the greatest threat and could inform public health strategies to better protect people with compromised immune systems.

Fanni Ojala, M.Sc., co-first author at Aalto University in Finland, explained: “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 and co-lead of the UK Baby Biome Study, who was not involved in this research, noted: “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.”

The success of this study relied on extensive genomic data from the UK and Norway, all sequenced at the Wellcome Sanger Institute. This large-scale data made it possible to identify transmission patterns in detail.

The datasets originated from earlier studies published in The Lancet Microbe,4,5 which laid the foundation for the modeling breakthrough achieved in this new research.