Skip to main content

The antibiotics that could kill you

By Martin J. Blaser
updated 3:58 PM EDT, Tue April 22, 2014
STORY HIGHLIGHTS
  • Martin Blaser: Overprescription of antibiotics put Americans at risk for disease
  • He says we wipe out good, protective germs, bringing danger of "antibiotic winter"
  • With lower resistance, plague inevitable in interconnected world, he says
  • Blaser: Targeted antibiotics, less interference in natural process are key to cutting vulnerability

Editor's note: Dr. Martin J. Blaser is the Singer Professor of Medicine and director of the Human Microbiome Program at New York University. He was previously the president of the Infectious Diseases Society of America and is the author of a new book, "Missing Microbes: How the Overuse of Antibiotics is Fueling Our Modern Plagues" (Henry Holt). The opinions expressed in this commentary are solely those of the author.

(CNN) -- In 2010, Americans were prescribed 258 million courses of antibiotics, a rate of 833 per thousand people. Such massive usage, billions of doses, has been going on year after year.

We have few clues about the consequences of our cumulative exposures. We do know that widespread antibiotic treatments make us more susceptible to invaders by selecting for resistant bacteria.

These risks are now well-known, but I want to lay out a new concern: that antibiotic use over the years has been depleting the pool of our friendly bacteria -- in each of us -- and this is lowering our resistance to infections. In today's hyperconnected globe, that means that we are at high risk of future plagues that could spread without natural boundaries from person to person and that we could not stop. I call this "antibiotic winter."

Martin Blaser
Martin Blaser

To explain: In the early 1950's, scientists conducted experiments to determine whether our resident microbes -- the huge number of bacteria that live in and on our bodies, now called our "microbiome" -- help in fending off invading bacteria. They fed mice a species of a typical invader, disease-causing salmonella. It took about 100,000 organisms to infect half of the normal mice. But when they first gave mice an antibiotic, which kills both good and bad bacteria, and then several days later gave them salmonella, it took only three organisms to infect them. This isn't a 10 or 20% difference; it's a 30,000-fold difference.

That was in mice, but what about humans? In 1985, Chicago faced a massive outbreak of salmonella. At least 160,000 people became ill and several died from drinking contaminated milk. The health department asked victims of the outbreak and unaffected persons, "Have you received antibiotics in the month prior to becoming ill?" People who said yes were five times more likely to become ill than those who drank the milk but hadn't recently received antibiotics.

People carry a small number of highly abundant bacterial species and a large number of much less common ones. For example, you may carry trillions of Bacteroides thetaiotaomicron in your colon and only a thousand cells, or fewer, belonging to many other species. We are not sure how many rare species any of us has. If you had only 50 cells of a particular type, it would be difficult to detect them against the background of trillions of others.

When you take a broad-spectrum antibiotic, which is the kind most commonly prescribed, it may be that rare microbes occasionally get wiped out entirely. And once the population hits zero, there is no bouncing back. For your body, that species is now extinct. My worry is that some of these critical residential organisms -- what I consider "contingency" species -- may disappear altogether.

Why might it matter? Those puny species may not be so inconsequential. Microbes multiply. Any small population of, say, 50 cells can explode into a billion or more in one week. The trigger for their massive bloom could be a food you've eaten for the first time, which only they have the enzymes to digest. In the presence of this food, the rare microbe goes into overdrive, doubling every 12 or 20 minutes, multiplying by a million percent or more.

Consumers demanding drug-free meat
Study: Sinus infection? Skip antibiotics
Is it safe to eat chicken?

This could be good for you because some of the energy captured by these digesting microbes might end up in your bloodstream. When food is in short supply, as has been the case for most of human existence, and people need to eat unfamiliar plants or animals, it is useful to have a repertoire of enzymes that help us process a wide variety of nutrients. The genes of our flexible partners, our resident microbes, provide those enzymes.

Now consider the consequences if one of your rare microbes -- an ancient one that has been dwelling in Homo sapiens for 200,000 years -- went extinct. One possibility is that it doesn't matter. Perhaps that microbe was a marginal player -- good riddance. Another possibility: It's a "contingency" organism, useful -- crucial -- when we need it for protection.

When a new influenza epidemic arose in Mexico in 2009, people in California and Texas soon fell ill, and then flu appeared in New York a few days later. After a few weeks, this flu spread throughout the world. Considering the numbers of people infected, we were lucky that it was not a highly lethal strain. Yet thousands of people all over the world did die. Even when a strain is not that virulent, when hundreds of millions of people are infected, deaths add up. And when the strain is worse, the deaths climb into the millions.

Our world has gotten smaller. We have much greater global access to one another -- at the very moment in our history when our ancient microbial defenses are degrading. This makes us vulnerable to microbial invaders and provides fuel for disease conflagrations, with consequences scarcely imaginable.

Plagues are inevitable wherever people congregate. With a global population of 7 billion, rising by 80 million annually, the question is not whether another big plague will come, but when it will happen, what will cause it, and who will be affected. In 1918-19, influenza killed tens of millions, in an era without airplanes and with much less mass transit to spread it. With a huge world population that is essentially contiguous, and with so many people with weakened defenses, we are vulnerable as never before.

I see many parallels between our changing climate and our changing microbiome. The modern epidemics -- asthma and allergic disorders, obesity, and metabolic disorders -- are not only diseases, they are external signs of change within. But they also indicate a deeper imbalance, the loss of our reserves.

Our diverse microbes, with their millions of genes helping us resist disease, are the guerrilla warriors defending the home domain -- as long as we protect them. But recent studies suggest that otherwise normal people already have lost 15% to 40% of their microbial diversity and the genes that accompany it.

This is the greatest danger before us -- invaders causing an epidemic against which we are helpless. Unless we change our ways, we do indeed face an "antibiotic winter."

We must end the assault on our microbes, by cutting antibiotic use and also such elective practices as unnecessary cesarean sections that bypass the natural order of mothers passing on their bacteria to their babies. There are times when both of these are needed urgently, but we already know that we are overusing them.

Technology already provides important tools to improve doctors' judgments about when antibiotics are needed, but we must get them into the clinic. We also must develop new tools, like "narrow-spectrum" antibiotics that target only the invader and minimize collateral effects.

We must understand that every antibiotic course has a biological cost, and more precisely align possible benefit with the full costs. I predict that in the future we will routinely be giving children back their lost microbes, in early life to restore their patrimony and after the antibiotic courses that are truly necessary.

Just as we have abused marvelous inventions like freon and the internal combustion engine, so too we have abused our "wonder drugs." But the possible costs of these practices are our worst nightmare; we need to prepare, starting now.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

ADVERTISEMENT
Part of complete coverage on
updated 4:06 PM EDT, Tue October 21, 2014
Timothy Stanley says Lewinsky is shamelessly playing the victim in her affair with Bill Clinton, humiliating Hillary Clinton again and aiding her critics
updated 9:02 PM EDT, Mon October 20, 2014
Imagine being rescued from modern slavery, only to be charged with a crime, writes John Sutter
updated 12:00 PM EDT, Tue October 21, 2014
Tidal flooding used to be a relatively rare occurrence along the East Coast. Not anymore, write Melanie Fitzpatrick and Erika Spanger-Siegfried.
updated 7:35 AM EDT, Tue October 21, 2014
Carol Costello says activists, writers, politicians have begun discussing their abortions. But will that new approach make a difference on an old battleground?
updated 9:12 AM EDT, Tue October 21, 2014
Sigrid Fry-Revere says the National Organ Transplant Act has caused more Americans to die waiting for an organ than died in both World Wars, Korea, Vietnam, Afghanistan and Iraq
updated 2:51 PM EDT, Tue October 21, 2014
Crystal Wright says racist remarks like those made by black Republican actress Stacey Dash do nothing to get blacks to join the GOP
updated 6:07 PM EDT, Tue October 21, 2014
Mel Robbins says by telling her story, Monica Lewinsky offers a lesson in confronting humiliating mistakes while keeping her head held high
updated 9:29 AM EDT, Mon October 20, 2014
Cornell Belcher says the story of the "tea party wave" in 2010 was bogus; it was an election determined by ebbing Democratic turnout
updated 4:12 PM EDT, Mon October 20, 2014
Les Abend says pilots want protocols, preparation and checklists for all contingencies; at the moment, controlling a deadly disease is out of their comfort zone
updated 11:36 PM EDT, Sun October 19, 2014
David Weinberger says an online controversy that snowballed from a misogynist attack by gamers into a culture war is a preview of the way news is handled in a world of hashtag-fueled scandal
updated 8:23 AM EDT, Mon October 20, 2014
Julian Zelizer says Paul Krugman makes some good points in his defense of President Obama but is premature in calling him one of the most successful presidents.
updated 10:21 PM EDT, Sun October 19, 2014
Conservatives can't bash and slash government and then suddenly act surprised if government isn't there when we need it, writes Sally Kohn
updated 8:05 AM EDT, Wed October 22, 2014
ISIS is looking to take over a good chunk of the Middle East -- if not the entire Muslim world, write Peter Bergen and Emily Schneider.
updated 9:00 AM EDT, Mon October 20, 2014
The world's response to Ebola is its own sort of tragedy, writes John Sutter
updated 4:33 PM EDT, Fri October 17, 2014
Hidden away in Russian orphanages are thousands of children with disabilities who aren't orphans, whose harmful treatment has long been hidden from public view, writes Andrea Mazzarino
updated 1:22 PM EDT, Sat October 18, 2014
When you hear "trick or treat" this year, think "nudge," writes John Bare
updated 12:42 AM EDT, Sat October 18, 2014
The more than 200 kidnapped Nigerian schoolgirls have become pawns in a larger drama, writes Richard Joseph.
updated 9:45 AM EDT, Fri October 17, 2014
Peggy Drexler said Amal Alamuddin was accused of buying into the patriarchy when she changed her name to Clooney. But that was her choice.
updated 4:43 PM EDT, Thu October 16, 2014
Ford Vox says the CDC's Thomas Frieden is a good man with a stellar resume who has shown he lacks the unique talents and vision needed to confront the Ebola crisis
updated 4:58 AM EDT, Sat October 18, 2014
How can such a numerically small force as ISIS take control of vast swathes of Syria and Iraq?
updated 9:42 AM EDT, Fri October 17, 2014
How big a threat do foreign fighters in Syria and Iraq pose to the West? It's a question that has been much on the mind of policymakers and commentators.
updated 8:21 AM EDT, Fri October 17, 2014
More than a quarter-million American women served honorably in the Iraq and Afghanistan wars. Now they are home, we have an obligation to help them transition back to civilian life.
updated 4:27 PM EDT, Thu October 16, 2014
Paul Begala says Rick Scott's deeply weird refusal to begin a debate because rival Charlie Crist had a fan under his podium spells disaster for the Florida governor--delighting Crist
updated 12:07 AM EDT, Thu October 16, 2014
The longer we wait to engage on Ebola, the more limited our options will become, says Marco Rubio.
updated 7:53 AM EDT, Wed October 15, 2014
Democratic candidates who run from President Obama in red states where he is unpopular are making a big mistake, says Donna Brazile
updated 12:29 AM EDT, Thu October 16, 2014
At some 7 billion people, the world can sometimes seem like a crowded place. But if the latest estimates are to be believed, then in less than a century it is going to feel even more so -- about 50% more crowded, says Evan Fraser
updated 12:53 PM EDT, Mon October 20, 2014
Paul Callan says the Ebola situation is pointing up the need for better leadership
updated 6:45 PM EDT, Wed October 15, 2014
Nurses are the unsung heroes of the Ebola outbreak. Yet, there are troubling signs we're failing them, says John Sutter
updated 1:00 PM EDT, Wed October 15, 2014
Dean Obeidallah says it's a mistake to give up a business name you've invested energy in, just because of a new terrorist group
updated 7:01 PM EDT, Wed October 15, 2014
Fear of Ebola is contagious, writes Mel Robbins; but it's time to put the disease in perspective
updated 1:44 PM EDT, Tue October 14, 2014
Oliver Kershaw says that if Big Tobacco is given monopoly of e-cigarette products, public health will suffer.
updated 9:35 AM EDT, Sat October 18, 2014
Stop thinking your job will make you happy.
updated 10:08 PM EDT, Tue October 14, 2014
Ruben Navarrette says it's time to deal with another scandal involving the Secret Service — one that leads directly into the White House.
updated 7:25 AM EDT, Tue October 14, 2014
Americans who choose to fight for militant groups or support them are young and likely to be active in jihadist social media, says Peter Bergen
updated 9:03 AM EDT, Mon October 13, 2014
Stephanie Coontz says 11 years ago only one state allowed same sex marriage. Soon, some 60% of Americans will live where gays can marry. How did attitudes change so quickly?
updated 4:04 PM EDT, Tue October 14, 2014
Legalizing assisted suicide seems acceptable when focusing on individuals. But such laws would put many at risk of immense harm, writes Marilyn Golden.
updated 9:07 AM EDT, Mon October 13, 2014
Julian Zelizer says the issues are huge, but both parties are wrestling with problems that alienate voters
updated 6:50 PM EDT, Mon October 13, 2014
Mel Robbins says the town's school chief was right to cancel the season, but that's just the beginning of what needs to be done
updated 11:43 AM EDT, Sat October 11, 2014
He didn't discover that the world was round, David Perry writes. So what did he do?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT