Researchers compared 20 years of antibiotic use on E. coli in the UK and Norway

Researchers from the Wellcome Sanger Institute, the University of Oslo, the University of Cambridge and collaborators have, for the first time, discovered that antibiotic use is not the only driver of superbugs.

In the UK and Norway, researchers compared the impact of antibiotic use on the treatment-resistant bacteria Escherichia coli (E. coli) over the last two decades.

Antibiotic resistance occurs when strains of bacteria evolve and develop resistance to many different types of antibiotics and can cause infections.

As the most common cause of bloodstream infections globally, 40% of E. coli bloodstream infections are resistant to a key antibiotic used in UK hospitals to treat serious infections.

The study conducted a high-resolution genetic comparison of bacteria to understand what influences the spread of E. coli, using over 700 new blood samples and nearly 5,000 previously sequenced bacterial examples.

Results showed that the increase in treatment-resistant bacteria varied depending on the type of broad-spectrum antibiotic used. Specifically, the rate of resistance to a commonly used antibiotic to treat urinary tract infections caused by E. coli ranged from 8.4% to 92.9%, depending on the country.

Furthermore, country-wide antibiotic usage levels also influenced the rate of resistance. In the UK, non-penicillin beta-lactams were used three to five times more on average per person compared to Norway, leading to a higher incidence of multi-drug resistant infections by a certain E. coli strain.

With multi-resistant bacterias, survival depended on which strains of E. coli were in the surrounding environment, making it impossible to determine whether one type of antibiotic would have the same effect on antibiotic-resistant bacteria spread in different countries.

“Continuing to use genomics to gain a detailed understanding of the underlying drivers of bacterial success is crucial if we are to control the spread of superbugs,” explained professor Jukka Corander, senior author, Wellcome Sanger Institute and University of Oslo.