This story is part of a partnership between MedPage Today and VICE News.
Antibiotics have saved countless lives in the 88 years since penicillin was discovered, but the antibiotics we have aren't working as well as they once did — and if we don't act, the results could be disastrous, infectious disease experts say.
Early antibiotics were so good that doctors simply thought they'd "conquered germs," and never considered the germs could evolve, said Dr. Frank Esper, an infectious disease specialist at UH Case Medical Center in Cleveland, Ohio. But then antibiotics started failing, and doctors realized the bacteria were adapting.
Although "superbug" isn't a medical term, it's often used to describe a bacteria that's resistant to antibiotics, such as Staphylococcus aureus, E. coli, and tuberculosis. And it's a big deal.
"We can't treat infections," said Dr. Barbara Murray, past president of the Infectious Diseases Society of America and co-director of the Center for the Study of Emerging and Re-Emerging Pathogens at UTHealth in Houston. "There are now infections that I see in the hospital that I can't treat because the bacteria is resistant to everything I have available. The patient dies."
According to the Centers for Disease Control and Prevention, 2 million people a year in the US develop antibiotic-resistant infections, and 23,000 of them die of those infections.
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When bacteria become resistant to antibiotics, it means those antibiotics are no longer able to kill the bacteria when given in a concentration that's safe to administer to humans. (Like all drugs, at certain levels, even antibiotics can be toxic, so there are limits to how much a patient can take.)
Resistance happens naturally when the bacteria mutate at random, but it's spurred by repeated exposure to antibiotics, "teaching" the bacteria to evolve. It can also happen when whole genes — developed over hundreds of thousands of years and designed to resist threats to the bacteria — are passed from bacteria to bacteria.
The evolutionary process is sped up by improper use of antibiotics, for instance when patients don't take their full course of antibiotics because they stop when they start to feel better. That leaves a few of the strongest bacteria behind — the ones that didn't die because of some mutation — which can then reproduce and spread. This can also happen when a drug contains too little of the antibiotic concentration needed to kill the bacteria. Or it can happen in agricultural settings, in which livestock animals are fed low levels of antibiotics, allowing them to become petri dishes for bacterial mutations.
It can also happen just through normal use of antibiotics. If you take an antibiotic for an ear infection, it goes into your blood, which hits all the bacteria living in your gut, Esper said. It may not be enough to kill them, but it's enough to put "pressure" on them to evolve.
"When you're dealing with bacteria, you're not just dealing with one little bacterium sitting around being killed by one particular antibiotic," Esper said, explaining that these are mutations occurring in populations of billions of bacteria. When a handful don't respond to a drug by random luck, that creates a problem.
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In the United States, antibiotic-resistant infections mostly spread in hospitals, where patients are already vulnerable and have additional opportunities to acquire new bugs via catheters and intravenous lines and other "breaches," Murray said.
"A lot of things done to the patient to keep them alive predispose them to breaches of normal barriers to infection," she said. "An IV line through the skin is not normal. It's not supposed to be there… it's a hole in the skin."
When one antibiotic doesn't work, doctors can usually switch to another one to knock out the bacteria, and using multiple antibiotics is a good way to prevent resistance from developing. But we're running out of available antibiotics, and finding new antibiotics is a challenge.
"It's expensive and there's very little return on the dollar," Murray said. "Pharmaceutical companies, who do they answer to? Stockholders."
She explained that although the government offers tax breaks and other incentives for these companies to develop new antibiotics, it's still much more attractive to them to make a drug that treats a chronic condition, like hypertension, that patients will need to take the rest of their lives, than to make something that cures them in five days. The Infectious Diseases Society of America is pushing for 10 new antibiotics by 2020, but experts have said there aren't enough prospective antibiotics in the drug development pipeline to meet that goal.
But resistance isn't going to stop.
"Can we stop it? My feeling from an evolutionary standpoint is the answer is no — you don't stop evolution," Esper said. "Bacteria are doing their God-given right to evolve under selective pressure."
However, he said we can minimize that pressure and slow it down by being careful not to overuse or misuse antibiotics.
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Follow Sydney Lupkin on Twitter: @slupkin