Concepts explained
The Contaminated Dish — Bacteria Learn Faster Than We Do
A dish left over a holiday grew a mould, and around the mould the bacteria were gone. That is how our first antibiotic began — and the man who found it warned in his Nobel speech that careless use would teach the bacteria. He was exactly right.
Borrowing the mould's weapon
Piece 5 said antibiotics wipe out half the gut neighbours. But we did not invent this drug. Moulds and bacteria have fought over the same food for hundreds of millions of years, and moulds make substances that drive bacteria off. We only borrowed the weapon.
The clear ring Fleming saw was where that weapon had spread. He named the mould's substance . It is the blue mould from the face gallery — the one with brush-tipped spores.
Why it took ten years
The discovery was 1928; the medicine came in the 1940s. In between the paper lay buried. Fleming could not purify penicillin, and what he extracted lost its strength quickly. A discovery and a medicine are different things.
Florey and Chain at Oxford managed the purification, and America worked out mass production. Wounded soldiers of the Second World War lived because of it. Until then, an infection left nothing to do but wait and hope the body won. Dying of a small cut was not strange.
How does it kill only bacteria?
Piece 3 said antibiotics break the bacterial wall. More precisely: bacteria have something our cells do not — a rigid outer wall. Penicillin stops them laying the bricks when they build a new one. A growing bacterium without a wall bursts itself.
Our cells have no such wall, so nothing happens to us. Aim at what the enemy has and you do not — that is the mark of a good drug. It is also why fungal infections are hard to treat, as piece 3 said: fungi resemble us, so there is little to aim at.
The bacteria learn
When penicillin arrived, people thought the war with bacteria was over. It was not.
Bacteria split in two every twenty minutes. Each time they copy the blueprint, and now and then they copy it wrong. If one such mistake happens to shrug off the drug, that one survives — and by morning there are billions. The drug did not create the tough one. The drug cleared away everyone else.
Stranger still: bacteria can hand that ability to the neighbours, even across species. As if shaking hands with someone passed their talent to you.
Proof that this was possible arrived the same year as penicillin. In 1928 Griffith mixed dead bacteria with living harmless ones and watched the harmless turn deadly. Something had crossed over from the dead. That something was shown to be sixteen years later.
Why they say finish the course
Doctors say to finish the antibiotics even when you feel better. This is why. Stop after three days and the weak ones die while the tougher ones remain. When those multiply, the drug will not work next time.
Piece 3 said antibiotics do nothing for a cold. It is worse than nothing: you kill the neighbours while giving the surviving bacteria a practice session.
stopping early leaves the tough ones alive
useless against viruses, deadly to neighbours
it trains the wrong germs
you'll take them on a guess next time
A little further in
The biggest user is not the hospital
A large share of the world's antibiotics is eaten not by people but by farm animals — not only to cure disease but fed steadily in small doses to prevent illness in crowded pens and to add weight. That is a daily practice session for the bacteria. Europe has banned that use and other countries are cutting back.
Bacteria that shrug off several antibiotics already circulate in hospitals. New antibiotics are scarce: a company can hardly develop a drug that stops working in a few years. So research has revived on the lunar lander from the face gallery — the phage, the virus that eats only bacteria. Bringing in bacteria's oldest enemy.
Antibiotics touch only bacteria. So how do we hold off viruses? By rehearsing the body before the disease arrives. The story starts on the hands of women who milked cows. Next piece.
The question that remainsIf using a drug breeds the germs it cannot kill — can we ever win this fight, or only keep drawing?