Concept preview

What you will be able to do

1. 01Give examples of helpful and harmful bacteria.
2. 02Explain how pathogenic bacteria cause disease.
3. 03Explain how antibiotics work and why they do not affect viruses.
4. 04Explain how antibiotic resistance evolves and how to slow it.

It is tempting to think of bacteria as germs to be wiped out, but that view is badly wrong. The overwhelming majority of bacteria are harmless or helpful, and life as we know it could not exist without them. Only a small minority are pathogens — disease-causers. Our real relationship with bacteria is a partnership far more than a war, and getting the balance right, in medicine and in ecosystems, is one of the central challenges of modern biology. This topic weighs both sides, then turns to the growing crisis of antibiotic resistance.