Antibiotic resistance has been called one of the greatest threats to global health, food security, and development. The World Health Organization warns that without urgent action, we may be heading toward a post-antibiotic era where common infections once again become deadly. Each year, drug-resistant infections already kill over a million people worldwide — more than HIV/AIDS or malaria — and that number is projected to rise dramatically.
How Does Antibiotic Resistance Develop?
Antibiotic resistance is a natural evolutionary process. Bacteria reproduce rapidly — some species can divide every 20 minutes — and random mutations occasionally produce individuals that can survive antibiotic exposure. When antibiotics kill susceptible bacteria, resistant ones survive and multiply, eventually dominating the population. This is natural selection operating in real time, demonstrating the same evolutionary principles described in our guide to biodiversity and evolution.
Human activities have dramatically accelerated this process. The overuse and misuse of antibiotics in human medicine — prescribing them for viral infections where they are ineffective, patients not completing prescribed courses, and over-the-counter availability in many countries — creates intense selection pressure favoring resistant bacteria. Agricultural use of antibiotics, which accounts for roughly 70 percent of global antibiotic consumption in some estimates, further compounds the problem.
Bacteria can share resistance genes with each other through horizontal gene transfer, spreading resistance even between different species. A resistance gene that evolves in a harmless soil bacterium can transfer to a deadly pathogen. This means that antibiotic use anywhere — in hospitals, farms, or the environment — can contribute to resistance everywhere.
Which Infections Are Becoming Untreatable?
Several bacterial infections are becoming increasingly difficult or impossible to treat with existing antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) causes skin infections, pneumonia, and bloodstream infections that resist many common antibiotics. Carbapenem-resistant Enterobacteriaceae (CRE) have been called nightmare bacteria because carbapenems are often the last-resort treatment for serious infections.
Drug-resistant tuberculosis kills hundreds of thousands of people annually, with extensively drug-resistant strains requiring treatment regimens lasting up to two years with drugs that are more toxic and less effective. Resistant gonorrhea, once easily curable, is running out of treatment options. Resistant urinary tract infections, once a minor nuisance, are becoming serious medical challenges.
What Solutions Are Being Developed?
New approaches to fighting bacterial infections are urgently needed. Phage therapy — using viruses that specifically infect and kill bacteria — is experiencing a renaissance after decades of neglect in Western medicine. Unlike antibiotics, phages evolve alongside their bacterial hosts, potentially overcoming resistance. Clinical trials for phage therapy are underway in several countries.
Antimicrobial peptides, CRISPR-based antibacterials that target specific resistance genes, and anti-virulence drugs that disarm bacteria without killing them are all in development. Artificial intelligence is accelerating drug discovery by screening millions of potential compounds and predicting which molecules will be effective against resistant bacteria.
Stewardship programs that promote appropriate antibiotic use, rapid diagnostic tests that distinguish bacterial from viral infections, and improved infection prevention through better sanitation, vaccination, and hospital practices are essential components of the response. Canada’s Pan-Canadian Action Plan on Antimicrobial Resistance coordinates efforts across human health, animal health, and agriculture.
The development of new antibiotics faces economic challenges — because new antibiotics should be used sparingly to preserve their effectiveness, the market incentive to develop them is weak. Novel funding models, including subscription-based payment systems and public-private partnerships, are being explored to address this market failure.
