4.1 Development of resistance

It was in 2012, in a cave much deeper than I'm able to go, that Hazel's team made their breakthrough discovery.

So the kind of areas that we sample look quite a bit like this.

Hazel took a bunch of bacterial samples from the cave and sent them off to a lab for analysis. The results shocked everyone.

So I sent him just 100, and he started testing them. And he's like, you're not going to believe this, but they're resistant to everything. Everything that's used.

So these were bacteria you found on a wall in a cave.

Much, much more remote than this, much further way.

That had not seen humans for ...

We know humans had never been in there because we have the exploration records. So there was no impact on it. And they were resistant to practically every antibiotic that's used in the clinic.

That is both incredibly exciting and incredibly scary. Nobody had ever thought that you would find resistant bacteria down at the bottom of a bloody cave.

They’ve had no interaction with humans. But the bacteria Hazel found in the cave were resistant to a huge array of antibiotics we use in modern medicine. This resistance had clearly evolved over millions of years without us having anything to do with it. Why?

Well, it makes sense when you think of antibiotics not as man-made, but the byproduct of war between microbes. They make chemical weapons to destroy their enemies and steal their resources, weapons we have learned to exploit as antibiotics. The bacteria living deep in the cave have had millions of years to evolve weapons that can target and destroy even their toughest rivals. The battle for scarce resources, like nutrients and energy, is particularly brutal down here in the caves.

It's really starved down here. There's no resources. It's probably one of the most starved environments on Earth. Because if you think about it, any energy needs to come in through the rock. And so there's a big competition for nutrients.

The fewer the resources, the more intensely the microbes battle. And that creates resistance. Because the bacteria under attack don't just lie back and die. When billions of bacterial cells are bombarded, all it takes is for one cell to mutate its DNA in such a way that the antibiotic can no longer kill it. This ability to resist then spreads fast. So developing resistance to antibiotics is an entirely natural process which the bacteria of Carlsbad have taken to the extreme.