How Common are Drug-Resistant Diseases?

Federal authorities have spent much of this week looking for people who might have come into contact with a man who has a drug-resistant form of tuberculosis.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, talks to NPR's Steve Inskeep about drug-resistant disease strains and how difficult they are to treat.

Are there other diseases out there that you would describe as being drug resistant?

Oh, plenty. Drug-resistant TB is one of many, many examples of microbes that develop a resistance to the standard antimicrobials that are generally used successfully against them. In fact, it has really put a damper on the extraordinary advances that have been made over decades and decades of antimicrobial agents, antibiotics, antivirals — because, sooner or later, microbes have the capability of being able to evolve toward protecting themselves from what we do to blunt them.

What are some other diseases that people didn't worry much about 10 or 20 years ago that now have strains that can kill you?

Staphylococcus is the prime example of that — typical staph infections. Some of them are more severe than others. Within a few years of the introduction of the penicillins, back in the 1950s, these staphylococci developed resistance. Then a new generation of drugs, methicillin, was developed, and they were very well treated with methicillin. Then, very soon thereafter, methicillin-resistant staphylococcus came in. Over a period of time, when you use antibiotics, you can actually make the resistance phenomenon come in sooner rather than later.

How does that happen? You kill off the weak ones and the strong ones survive?

Microbes, as they replicate, are continually able to mutate and divert themselves around. If you go with an antibiotic that's successfully treating a microbe, there will always be a small fraction of the microbe that, under most circumstances, wouldn't be a problem. But when you get rid of all of the sensitive microbes with the antibiotic, then those other strains that were generally minor strains start to take over. The problem is, they're resistant to the antibiotic, and then they become predominant microbes in a particular infection.

Are we accelerating this process by the way we use antibiotics?

Unfortunately, yes. There is a considerable amount of what we call inappropriate use of antibiotics. People come into a doctor's office. They don't have a bacterial infection. They have a viral infection, but they want an antibiotic, thinking it's going to make them better more quickly. If you inappropriately treat somebody with antibiotics, you will select for the less benign component of that.

You will get rid of the ones you don't have to worry about, and the ones you do have to worry about will have room to grow?

Exactly. Precisely.

Is the pharmaceutical industry coming up with new antibiotics as rapidly as the old ones become less useful?

Unfortunately, the answer to that is no. There is not that much of an incentive for pharmaceutical companies to make new antibiotics because, first of all, antibiotics generally are not used on a daily basis, year-round. Pharmaceutical companies like to get a new blockbuster drug that you and I will use every day: lipid-lowering agents, blood-pressure agents, new types of Viagra — the things that people use over a long period of time. Antibiotics are effective, but they are not a long-term, major investment usually. Occasionally, you get a brand new blockbuster antibiotic, but that is more unlikely than it is likely.

Can you anticipate a time when we might have to accept much higher rates of infectious diseases and death, perhaps like we had a century ago?

No. ... It's a threat. I will not submit that we have to accept that one day that's going to happen. I have confidence that the research community will keep up, but it's not going to happen automatically. It's going to be kind of an agreement between the fundamental research community and the developmental community and the pharmaceutical organizations. If we get asleep at the switch, then it's going to happen. But we should not allow that to happen.

This story contains only a portion of the conversation, and excerpts have been edited for clarity. To hear the entire conversation, click the "Listen" button at the top of the page.

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