economics Nature Is Weird

Older people and women take more antibiotics but have lower rates of drug-resistant infections.

March 31, 2026

Original Paper

Age and Sex: Associations with Antimicrobial Resistance in Community-Onset Escherichia coli Bloodstream Infections

Peter Collignon, John Beggs, Jan Maree Bell, Denise Daley, Elizabeth Roughead, Australian Group on Antimicrobial Resistance

SSRN · 6437138

The Takeaway

A study of 44,000 infections found a 'paradox' where the demographics that consume the most antimicrobials actually show the least resistance. This flips the standard public health assumption that higher community usage directly correlates with higher resistance rates at the individual demographic level.

From the abstract

Background: Globally, females and older people often use more antimicrobials than males and younger people. However, little is known about whether these differences in antimicrobial use are associated with higher rates of antimicrobial resistance.<br><br>Methods: The Australian Group on Antimicrobial Resistance monitors antimicrobial resistance in bloodstream infections in adults and children using commercial automated susceptibility methods. Community-onset E. coli episodes, with matching demog