Antibiotics are one of the greatest breakthroughs of modern medicine, giving us a crucial weapon in the fight against infectious bacteria, but recently we've seen the rise of antibiotic-resistant bacteria. Now it seems this is a surprisingly ancient phenomenon.
There are a number of entirely human reasons why antibiotic resistance is on the rise. The most commonly cited reason is that people do not finish their entire course of prescribed antibiotics, and instead opt to stop taking the drug as soon as they feel better. That doesn't kill off all the harmful bacteria, and those that survive are more likely to be resistant to future antibiotic treatments. Over multiple generations, we're essentially weeding out the weaker bacteria, leaving only the strongest and most dangerous strains. It doesn't help that antibiotics are often thought of as a bit of a "wonder drug" that can cure anything, leading to widespread overuse that dilutes their impact and helps create resistant strains.
As such, it's easy to think that antibiotic resistance is a modern problem, a byproduct of human mismanagement of the drugs. And while it's certainly true that the levels of resistance have greatly increased in recent years, these bacteria did not gain the ability to fight off antibiotics from out of nowhere. There's a genetic basis for this resistance, and researchers at McMaster University have discovered that basis buried deep within Arctic permafrost dating back 30,000 years.
The researchers determined that bacteria from that time period carried antibiotic resistant genes, and there could be no doubt of their age: these scraps of bacterial DNA were found alongside DNA evidence of Pleistocene creatures like mammoths and ancient horses.
The researchers zeroed in on a particular stretch of DNA that, in modern bacteria, has allowed them to become largely resistant to the drug vancomycin. Resistance to this particular antibiotic first emerged in the 1980s and has remained a tragic hallmark of infectious outbreaks in hospitals around the world. Researcher Gerry Wright explains what they discovered in these ancient genes:
"We identified that these genes were present in the permafrost at depths consistent with the age of the other DNAs, such as the mammoth. Brian Golding of McMaster's Department of Biology showed that these were not contemporary, but formed part of the same family tree. We then recreated the gene product in the lab, purified its protein and showed that it had the same activity and structure then as it does now."
So then, the basic mechanisms of antibiotic resistance are at least 30,000 years older than the first antibiotic drugs, and that might be a massive underestimate. The researchers will be jumping up a couple orders of magnitude with their next research, which will look at permafrost that is over a million years old. There's a pretty decent chance that any bacterial DNA they can find in that ancient snow will show similar resistance.
As Wright explains, this finding is a reminder that we can work with the natural world, but it's a folly to think we can hope to control it:
"Antibiotics are part of the natural ecology of the planet so when we think that we have developed some drug that won't be susceptible to resistance or some new thing to use in medicine, we are completely kidding ourselves. These things are part of our natural world and therefore we need to be incredibly careful in how we use them. Microorganisms have figured out a way of how to get around them well before we even figured out how to use them."