Antibiotics are drugs that can kill bacteria. But many germs have evolved genes that make them immune to one or more of these drugs. In some cases, only one lone drug remains that can kill them. If bacteria found a way to resist — ignore — that last drug too, these killer germs might be unstoppable. Infections that were once easy to treat would become incurable. And, new data show, bacteria are dangerously close to that scary future.

Scientists have just reported finding a bacterial gene that lets germs resist drugs that doctors use only as a last resort.

The bacteria, discovered in China, can resist the drug colistin. That’s an antibiotic that doctors reserve for the sickest patients, those sick from germs resistant to all other drugs. It’s not time to panic — yet. Instead, scientists say, it’s time to take a hard look at how doctors, and farmers, use antibiotics on a daily basis. That won’t get rid of the colistin-resistant bacteria. But it could help prevent other resistant germs from evolving.
Why colistin resistance is a big deal

Most bacteria die when hit with an antibiotic — a drug doctors use to target them. But a few germs may be lucky. They will have genes — sets of instructions inside them — that allow them to survive the antibiotic and to keep on making someone sick.

Even though bacteria may be resistant to the first drug a doctor tries, there are usually other drugs that can be substituted. But over time, germs can develop an ability to withstand them, too. Sometimes, all that is left are drugs that belong to a group known as polymyxins (PAH-lee-MIX-ins). These antibiotics are toxic in people. That’s why doctors use them only as a last resort. But they will kill off even the hardiest bacteria — allowing people to get well.