Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped. Credit: USDA
Key points:
- Researchers determined that increased antibiotic use over the last 20 years in the UK and Norway is not the only driver of the spread of treatment-resistant bacteria.
- Bacteria survival depends on the genetic makeup of the strains in the environment, meaning that the effects of antibiotic use cannot be generalized across countries.
- These findings have the potential to inform new public health interventions to stop the spread of harmful infections.
A new study, published in Lancet Microbe, reveals the impact of antibiotic use on the rise of treatment-resistant bacteria over the last 20 years in the UK and Norway. This is the first study to directly compare the success of different strains of Escherichia. coli (E. coli) between two countries and examine differences linked to country-wide antibiotic usage.
Researchers conducted a high-resolution genetic comparison of nearly 5,000 bacteria samples from over 700 blood samples to determine which factors underlie the spread of antibiotic-resistant E. coli.
They found that increased antibiotic use has amplified the spread of treatment-resistant bacteria, but it is not the only driver. More specifically, the increase in treatment-resistant E. coli varies based on the type of broad-spectrum antibiotic used and the genetic makeup of the bacteria carrying antibiotic resistance genes.
One class of antibiotics, non-penicillin beta-lactams, was used three to five times more on average per person in the UK compared to Norway. This use pattern resulted in a higher incidence of infections by a certain multi-drug resistant (MDR) E. coli strain. The UK also used the antibiotic trimethoprim more often, but this was unrelated to resistance levels.
Looking closely at MDR bacteria, the researchers found that their survival depended on what E. coli strains were in the environment. Pairing this result with their other findings, the team determined that the effect of antibiotic use cannot be generalized across countries.
The team hopes to conduct future research that uncovers the combined impact of antibiotics, travel, and food production systems on country-wide drug resistance levels. This knowledge could inform new public health interventions and provide innovative strategies to stop the spread of harmful infections.
“Our study suggests that antibiotics are modulating factors in the success of antibiotic-resistant E. coli, instead of the only cause,” explained study co-author Julian Parkhill, professor at the University of Cambridge. “Our comprehensive genetic analysis shows that it is not always possible to predict how the use of antibiotics will impact an area without knowing the genetic makeup of the bacterial strains in that environment.”