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In a groundbreaking analysis, researchers from the Wellcome Sanger Institute, the University of Oslo, and the University of Cambridge, along with collaborators, have explored the impact of antibiotic use on the rise of treatment-resistant bacteria over the last two decades in the UK and Norway. The study, published in Lancet Microbe, reveals that while increased antibiotic use has contributed to the spread of superbugs, it is not the sole trigger.
The researchers conducted a high-resolution genetic comparison of bacteria, examining over 700 new blood samples alongside nearly 5,000 previously sequenced bacterial samples. The goal was to understand the factors influencing the spread of antibiotic-resistant Escherichia coli (E. coli).
The findings indicate that greater antibiotic use does lead to an increase in treatment-resistant bacteria in certain instances. However, the impact varies depending on the type of broad-spectrum antibiotic employed. The study also underscores that the success of antibiotic-resistance genes hinges on the genetic makeup of the bacteria carrying them.
Dr. Anna Pontinen from the University of Oslo, a visiting scientist at the Wellcome Sanger Institute, noted that the study provides answers to longstanding questions about the causes of multidrug-resistant bacteria in populations.
For the first time, researchers were able to directly compare the success of different E. coli strains between two countries, Norway and the UK, and elucidate differences based on countrywide antibiotic usage levels.
Analysis spanning nearly two decades revealed that antibiotic use was linked to increased resistance in certain instances, dependent on the type of antibiotic. For instance, the UK showed higher incidence rates of infections by a specific multi-drug resistant E. coli strain, attributed to the three to five times higher usage of non-penicillin beta-lactams per person in the UK compared to Norway.
However, the study also found that while the UK more frequently used the antibiotic trimethoprim, there were no higher levels of resistance in the UK when comparing common E. coli strains found in both countries.
Survival of multidrug-resistant (MDR) bacteria was found to depend on the strains of E. coli in the surrounding environment, emphasizing that widespread use of one type of antibiotic may not have identical effects on antibiotic-resistant bacteria spread in different countries.
Professor Julian Parkhill, co-author from the University of Cambridge, concluded, “Our study suggests that antibiotics are modulating factors in the success of antibiotic-resistant E. coli, instead of the only cause.”
