Antibiotics drive the evolution of resistance

Antimicrobial resistance happens when bacteria, viruses, fungi and parasites change over time and no longer respond to the medicines designed to kill them. For bacteria, resistance arises through random mutations or by acquiring resistance genes from other microbes.

When an antibiotic is used, it kills the susceptible bacteria but leaves any resistant ones behind. Those survivors multiply, and a population dominated by resistant germs takes over — natural selection in fast-forward. Worse, resistant bacteria can share their resistance genes with others that were never even exposed to the drug.

This is a natural process, but human behaviour speeds it up: the misuse and overuse of antimicrobials in people, animals and crops is the main driver. The stakes are high — bacterial resistance was directly responsible for an estimated 1.27 million deaths worldwide in 2019, and it makes routine surgery and cancer treatment far riskier.