A global DNA deep dive shows why E. coli infections in diabetic foot wounds can be so stubborn, dangerous, and hard to treat.
A new study led by King’s College London, working with the University of Westminster, offers a clearer picture of the E. coli bacteria involved in diabetic foot infections. The research explores how varied these bacteria are and why certain infections become especially dangerous.
Published today (January 13) in Microbiology Spectrum, the study presents the first large-scale genomic analysis of E. coli taken directly from diabetic foot ulcers across several continents. By examining the bacteria at the DNA level, researchers aimed to understand why some infections are hard to treat and why they sometimes lead to severe or life-threatening complications.
A Major Cause of Amputation Worldwide
Diabetic foot infections are among the most serious complications linked to diabetes and remain a leading cause of lower-limb amputations around the world. While doctors know these infections are often complex, there has been limited information about the specific bacteria involved. This is especially true for E. coli, even though it frequently appears in samples taken from infected wounds.
A Global DNA Analysis of E. coli
To close this knowledge gap, scientists analyzed the complete genomes of 42 E. coli strains collected from infected diabetic foot ulcers. The samples came from patients in Nigeria, the UK, Ghana, Sweden, Malaysia, China, South Korea, Brazil, India and the USA. Sequencing the full DNA of each strain allowed the team to study global trends in how E. coli behaves in diabetic foot disease.
This detailed approach made it possible to compare genetic differences between strains, detect genes linked to antibiotic resistance, and identify traits connected to more severe infections.
No Single Culprit Behind These Infections
The results showed striking diversity among the E. coli strains. The bacteria belonged to many different genetic groups and carried a wide range of genes related to both disease and resistance to antibiotics. This means there is no single type of E. coli responsible for diabetic foot infections. Instead, multiple unrelated strains have independently adapted to survive in the diabetic foot environment.
By examining how these strains are related and which resistance mechanisms and virulence traits (the features or tools that make a microbe more harmful) they possess, the study helps explain why some infections worsen quickly or respond poorly to treatment.
Rising Concerns About Drug Resistance
One concerning finding was that about 8 percent of the strains were classified as multidrug-resistant or extensively drug-resistant. These bacteria can withstand multiple antibiotics or nearly all available treatment options, making infections much harder to control.
Dr. Vincenzo Torraca, Lecturer in Infectious Disease at King’s College London and senior author of the study, said: “Understanding these bacteria at a genomic level is a crucial step towards improving diagnosis and enabling more targeted treatments for people with diabetes. By identifying which E. coli strains are most common and which antibiotics they are likely to resist, clinicians can choose therapies that are more likely to work, helping to reduce prolonged infection, hospitalization, and the risk of amputation.”
Why the Findings Matter Globally
Victor Ajumobi, a second-year PhD student at King’s College London and the University of Westminster, and the study’s first author, highlighted the global importance of the work. “This information will be particularly valuable in low-resource settings, where E. coli infections of diabetic foot ulcers are more common and where rapid diagnostic tools for antimicrobial resistance are not always readily available,” he said.
Next Steps for Future Treatments
The researchers plan to build on these findings by studying how specific virulence factors influence disease progression. Many of the bacterial samples carried genes that help E. coli attach to human tissue or avoid the immune system. Understanding how these traits function inside diabetic foot wounds could point to new treatment targets and support the development of more effective therapies.
Reference: “Population structure, antimicrobial resistance, and virulence factors of diabetic foot-associated Escherichia coli” by Victor Ajumobi, Zaid Tahir, Polly Hayes, Adele McCormick and Vincenzo Torraca, 13 January 2026, Microbiology Spectrum.
DOI: 10.1128/spectrum.02837-25
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