Antimicrobial resistance is rising among human infections caused by Shiga toxin-producing Escherichia coli (STEC), according to a study of nearly 2,000 U.S. cases between 2010 and 2021. Researchers from the University of Illinois Urbana-Champaign found that while overall resistance remains low, it is steadily increasing, particularly for common antibiotics like tetracycline and sulfisoxazole.
Why are E. coli infections becoming resistant to antibiotics?
The emergence of resistant E. coli is likely linked to environmental exposure, according to Csaba Varga, a professor of pathobiology at the University of Illinois Urbana-Champaign. Even though physicians typically do not prescribe antibiotics for STEC infections, the bacteria are developing resistance, suggesting they encounter these drugs elsewhere before infecting humans.
“Resistance doesn’t stay in one place; it moves through people, animals and the environment,” Varga explained. The study, which utilized data from the U.S. Centers for Disease Control and Prevention, tracked 1,995 samples of the O157 strain, which is responsible for most severe STEC illnesses in the country.
Antibiotics are often avoided for Shiga toxin-producing E. coli because the treatment can kill the bacteria but trigger the release of more toxin, potentially worsening the illness and increasing the risk of kidney failure.
How does geography and age affect infection risk?
Resistance patterns are not uniform across the United States. The research revealed that antimicrobial resistance varies significantly by geographical region and age group. Notably, younger adults in their 20s and 30s are currently the most likely demographic to carry infections resistant to certain antibiotics.
This long-term analysis provides a clearer picture than previous snapshots, which often failed to show how resistance shifts year by year. By focusing on 1,995 samples collected over an 11-year period, Varga and graduate student Tarjani Bhatt were able to map where and in whom resistance is emerging.
What is the “One Health” approach to food safety?
The rise in resistance highlights a critical need for improved antibiotic stewardship across the food production chain. Because STEC is a foodborne illness, experts argue for a “One Health” strategy—an integrated approach that monitors the intersection of human health, animal health, and environmental safety.
“Better antibiotic stewardship in agriculture, along with food safety and environmental controls, will be key to slowing this trend,” Varga said. “What happens on farms, in food production and in the environment can directly impact human health. Prevention has to happen from farm to fork.”
Frequently Asked Questions
- Who is at the highest risk for severe STEC complications? Children under five years of age are the biggest concern, as they are more likely to develop serious complications such as kidney failure, according to Varga.
- How many people get sick from this strain annually? Approximately 100,000 people in the United States contract Shiga toxin-producing E. coli each year, with many requiring hospitalization.
- Why is it difficult to treat these infections? Because standard antibiotic treatment can exacerbate the release of Shiga toxins, doctors typically avoid using them unless a patient is battling a secondary severe infection simultaneously.
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