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E. coli strain spreads as fast as swine flu, surprising new research reveals

By isabelle // 2025-11-05

• A common gut bacterium can spread as fast as the swine flu virus.
• Scientists calculated a transmission rate for E. coli for the first time.
• A specific multi-drug resistant strain is the most transmissible.
• This rapid spread occurs via the fecal-oral route in communities.
• The findings demand a reevaluation of infection control strategies.

New research has uncovered that certain strains of the common gut bacterium E. coli can transmit between people as rapidly as some of the most infectious viral outbreaks, like swine flu, raising urgent new concerns about antibiotic-resistant infections. Researchers from the Wellcome Sanger Institute, the University of Oslo, and collaborating universities made this startling discovery. Their study, published in Nature Communications, marks the first time scientists have successfully calculated the basic reproduction number, or R0, for gut bacteria, a metric previously reserved mainly for viruses.

Tracking invisible spread

The study focused on three key E. coli strains circulating in the UK and Norway. Two of these strains are resistant to multiple classes of antibiotics and are a frequent cause of serious urinary tract and bloodstream infections. The researchers built a new model to estimate how efficiently one person can pass these gut bacteria to others. The results were alarming. One particular strain, known as ST131-A, was found to spread between people as rapidly as the H1N1 swine flu virus. This is particularly striking because E. coli is not airborne like the flu. It uses a longer transmission route, typically spreading via the fecal-oral route through contaminated hands, surfaces, food, or drink.

A new lens on bacterial threat

Professor Jukka Corander, senior author at the Wellcome Sanger Institute and the University of Oslo, explained the significance. "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," he said. The two other strains studied, ST131-C1 and ST131-C2, are multi-drug resistant but spread much more slowly among healthy people. However, the researchers noted a different danger with these strains. They are more likely to transmit in hospitals and care homes where vulnerable patients reside. In these settings, the consequences are dire, as several classes of antibiotics are no longer effective against them. Fanni Ojala, M.Sc., co-first author at Aalto University in Finland, highlighted the methodological breakthrough. "By having a large amount of systematically collected data, it was possible to build a simulation model to predict R0 for E. coli," Ojala said. "To our knowledge, this was not just a first for E. coli, but a first for any bacteria that live in our gut microbiome." The ability to assign an R0 value to bacteria opens the door to a clearer understanding of how bacterial infections spread. It helps identify which strains pose the greatest threat and could inform public health strategies to better protect people with compromised immune systems. This research provides a critical new tool for public health officials. Understanding the genetics of specific, highly transmissible strains could lead to new ways to diagnose and treat these infections in healthcare settings. This is especially important for bacteria that are already resistant to multiple types of antibiotics. The discovery that a common bacterium can spread with viral speed is a sobering reminder of the dynamic and persistent threat posed by antimicrobial resistance. It underscores that our defenses must evolve as quickly as the pathogens we seek to control. This new understanding of bacterial transmission dynamics forces a reevaluation of infection control, not just in hospitals but in everyday community life. Simple hygiene practices remain one of the most effective shields against an adversary that moves as fast as the flu. Sources for this article include: ScienceDaily.com News-Medical.net Nature.com

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