Bacteria eaters: the forgotten treatment for antibiotic resistance
Bacteriophages are viruses that infect only bacteria, and there are roughly ten of them for every bacterium in your gut. Professor Martha Clokie explains why a diverse phage population tracks with a healthier gut, and why these forgotten 1920s medicines are being revisited as antibiotic resistance already claims over a million lives a year.
Overview
Most of us grew up thinking every virus is an enemy. This conversation with Professor Martha Clokie of the University of Leicester, alongside Tim Spector, turns that idea inside out. Bacteriophages are the most numerous biological entities on the planet, and they are exquisitely specific: a phage that infects one bacterial species cannot infect another, and it cannot touch a human cell.
In the gut they act as gamekeepers, pruning back bacteria that grow too abundant, releasing nutrients for others, and sitting in the mucus lining like a first line of defence against invaders such as salmonella. The immune system learns from infancy to treat them as friends rather than foes. Early research suggests phage diversity rises through childhood, stabilises, and declines with age, and that a healthy gut carries a richer phage population than an unhealthy one.
Clokie also traces a striking piece of forgotten medical history: phages were isolated in 1915 and used to treat people through the 1920s, 30s and 40s, sold in British high street chemists until the 1960s, then abandoned almost everywhere except Georgia when antibiotics arrived. With more than a million deaths a year already attributed to untreatable bacterial infections, and a projected ten million if nothing changes, that abandoned science is being rebuilt. The episode closes on where phages might go next, from steering the microbiome to delivering drugs directly to cancer cells.
Key quotes
5Phage just means eat. It's Greek, from the Greek to eat. So bacteriophage is just a bacteria eater.
If there's too many deer in a forest, you introduce wolves, and that keeps them down so that they're actually healthy, and then that whole environment is much healthier.
It seems to be the more different ones you've got, the healthier you are overall.
It's estimated that if we don't do anything, we'll perhaps have 10 million people dying every year. So it'll exceed the number of people that are dying from cancers.
It used to be possible to buy bacteriophages in Boots the Chemist in the UK until about the 1960s.
Key ideas
9A virus has no metabolism of its own
The defining difference between a virus and a bacterium is that a virus cannot function alone. It is essentially a genome in a protein or lipid coat, and only comes alive when it enters a host cell.
The most numerous entities on Earth
For every bacterium there are thought to be at least ten bacteriophages, adding up to roughly 10 to the power of 31. Lined up end to end they would stretch a path 200 million light years long.
Specificity is why they are safe for us
A phage that infects one bacterial species usually cannot infect another, let alone a human cell. The surface of a human cell is built from entirely different material, and even inside, a phage has no machinery it can exploit.
Inside a bacterium, a phage becomes a factory
A lytic phage hijacks the bacterium's genetic machinery and redirects it to build copies of itself. In a precisely timed burst, a hundred or more new phages are released.
Some phages pay rent instead of killing
Other phages slip inside and simply stay, and while they lodge there they can make the bacterium hardier, better at surviving low-oxygen conditions, or able to produce useful compounds. It is a partnership, not just predation.
Phages as gamekeepers of the gut
When a bacterial population grows too abundant it becomes an easier target, so phages prune it back. That culling releases nutrients, opens space for other species, and keeps the whole ecosystem in balance.
Diversity tracks with health
Twin studies suggest phage diversity correlates with bacterial diversity, which itself correlates with health. In Crohn's disease, an inflammatory gut condition, both the amount and the range of phages appear to fall.
A shield in the mucus lining
Phages carry antibody-like domains that let them sit in the mucus layer of the gut. When an invading bacterium arrives, they intercept it, which is one reason healthy animals carry phages that kill salmonella while sick ones do not.
Largely uncharted territory
For every gram of gut material holding a billion bacteria there may be ten billion phages, and roughly 80% of them encode functions nobody has identified. As a field it sits about 25 years behind microbiome science.
Practical takeaways
7- 1
Feed the whole ecosystem, not just the bacteria 24:00
The same diverse, plant-rich eating pattern that supports bacterial diversity appears to support phage diversity too. There is no separate phage diet to follow.
- 2
Choose produce that still carries its microbes 53:40
Vegetables grown in gardens or small market gardens carried far more beneficial bacteria and phages than bagged salad packed in artificial atmospheres. Loose, less processed produce is the simpler choice.
- 3
Less spraying means more phages 54:10
Pesticides and herbicides reduce the bacteria on plants, and the phage diversity that travels with them falls in step. Where it is practical, lower-spray produce carries a richer microbial load.
- 4
Coffee drinkers carry a distinct phage signature 54:40
Regular coffee drinkers were found to be particularly high in one set of gut phages. It is a correlation rather than a proven cause, but it fits the wider picture of coffee as a friend to the gut.
- 5
Treat antibiotics as a finite resource 42:00
Antibiotic resistance is driven by overuse in people and, on a far larger scale, in agriculture, where around 70% of antibiotics are used. Every course avoided helps preserve the ones that still work.
- 6
Phage therapy is real, but still a last resort 50:00
Georgia treats thousands of patients a year, a Belgian military hospital published results from 100 cases, and Tom Patterson recovered from an untreatable infection. Elsewhere it is reserved for cases where nothing else has worked.
- 7
Watch this space rather than chase it 55:00
There are no phage products to buy for gut health, and the science is early. The sensible move is to keep building diversity through food while the research matures.
Topics & chapters
15Ten million deaths a year
The scale of antibiotic resistance and the rapid-fire questions that set up the episode. Martha Clokie's headline myth: that all viruses are bad.
What actually is a virus?
Why a virus differs from a bacterium, and how bacteria have viruses of their own. The ultimate parasite, alive only inside a host.
Ten to the power of thirty-one
Phages outnumber the stars in the visible universe, and a teaspoon of seawater holds a million bacteria and ten million phages. Where Clokie's twenty-year journey with phages began.
Why they cannot harm you
Phages are locked to specific bacterial surfaces and cannot enter or exploit human cells. The VHS analogy: even inside, they would have the wrong equipment.
The phage factory
How a phage hijacks a bacterium and turns its machinery into a production line for a hundred new viruses. The zombie analogy that unsettles the studio.
The phages that move in and stay
Some phages do not kill but lodge inside, earning their keep by making the bacterium tougher or more useful. A dance of co-evolution running for billions of years.
Gamekeepers, wolves and deer
Phages control which bacteria dominate the gut, pruning back overgrowth and releasing nutrients for others. Ecology, not warfare.
Diversity, disease and twins
What early studies show about phage diversity in healthy versus inflamed guts. The pattern mirrors what we already know about gut bacteria.
A defence system in the mucus
Phages sit in the gut lining and intercept invading bacteria, and the immune system is trained from infancy to leave them alone. Why healthy chickens and pigs carry salmonella-killing phages.
The phageome across a lifetime
Diversity builds after birth, stabilises around age two, rises again in adolescence and declines with age. Eighty percent of gut phages remain functionally unknown.
The healing waters of the Ganges
The first observation of phage activity was made in the Ganges in the late 19th century. Clokie's collaborators in Varanasi now purify Ganges phages to treat drug-resistant infections.
Antibiotic resistance now, not later
Over a million deaths a year already, with a projected ten million if nothing changes. Around 70% of antibiotics go into poultry, swine and fish farming.
The medicine we forgot
Phages were isolated in 1915 by Frederick Twort and used therapeutically by Félix d'Hérelle from the 1920s. Antibiotics were simpler and broader, so the field was abandoned everywhere except Georgia.
Tom Patterson and phage therapy today
Thousands treated annually in Georgia, 100 documented cases from a Belgian military hospital, and one man saved from a multi-drug-resistant infection. Phages spare the rest of the microbiome.
Cancer, coffee and the road ahead
Engineered phages could recognise a cancer cell and deliver a payload directly to it. Plus what diet, stevia and coffee appear to do to the phages we already carry.