Billions of Enemy Soldiers

A science reporter’s second task—after, you know, conveying facts—is trying to keep the public at the appropriate state of alarm. It’s a delicate task. The Ebola outbreak, for example, has been a roller coaster ride of “you’re panicking unnecessarily” and “you should be totally freaking out.”

Here’s another example: Two patients at Ronald Reagan UCLA Medical Center died last week from antibiotic-resistant bacteria. The first news stories warned us of the dangers of “nightmare superbugs,” while the second media wave insisted that it’s “not as scary as it seems.” That’s nice to hear, because “nightmare superbug” seems kinda scary.

The thing is, both angles are correct. You should be very, very concerned about certain elements of the UCLA story but not so worried about others. Allow me to elaborate.

Be very worried about drug abuse.

The nonchalance with which we misuse and overuse antibiotics is astonishing, given their importance. In 1900, the three leading causes of death in the United States were all infectious diseases (pneumonia, tuberculosis, and diarrhea/enteritis). They accounted for one of every three deaths. Today, only one infectious disease (the flu) is in the top 10 causes of mortality, and U.S. life expectancy has increased by a wonderful 30 years since 1900. Not all that improvement comes down to better drugs—hygiene, nutrition, sanitation, and hospital practices also played a role—but it’s hard to overstate the importance of antibiotics.

In a sense, antibiotics have been too successful. Parents, farmers, and even some doctors now think they can cure just about anything with them. Our foolish mismanagement of one of the greatest innovations in human history, however, will eventually render these medicines almost completely useless.

When parents take their sniffly children to the doctor, they routinely demand antibiotics. Pediatricians know that most such infections are viral—not bacterial and therefore immune to antibiotics—but many cave to parental expectations anyway. A 2001 study showed that demanding parents take home antibiotic prescriptions nine times as often as those who don’t pressure their doctors.

Taking a full course of antibiotics for a viral infection is bad, but taking half a course is even worse—and that’s what too many patients do. Three or four days after seeing the doctor, their immune system fights off their illness. Since they no longer have symptoms, they stop taking the pills. This shortening of a course of antibiotics, however, exposes bacteria to the drug without killing them—in other words, it gives them a really good chance of developing resistance mechanisms. It’s like showing the enemy your secret weapon but not using it.

The problem of priming bacteria for drug resistance is even worse in places where patients don’t need a prescription to get antibiotics. In India, Greece, Syria, and dozens of other countries, there’s nothing to stop you from buying a handful of antibiotics whenever you feel a little stuffy.

But in terms of sheer volume, none of the above abuses comes close to what is happening on American farms.

Approximately 80 percent of antibiotics sold in the United States are fed to cows, pigs, chicken, and other livestock. Most of those animals aren’t even sick—farmers drug them to make them grow plumper faster. The agricultural industry has, in essence, turned livestock into proving grounds for antibiotic resistance, where bacteria can test their resistance strategies against drugs that are the same as or similar to those administered to people. Scientists have already traced human outbreaks of antibiotic resistance to animals, and we will certainly see more such cases in the future.

Be less worried about the CRE outbreak at UCLA.

Carbapenem-resistant enterobacteriaceae, or CRE, were responsible for last week’s deaths at UCLA. CRE are extremely nasty bacteria—much more virulent than MRSA and other well-known antibiotic-resistant pathogens. These bacteria, however, are selective killers. They typically only infect and kill people with chronic illnesses like inflammatory bowel disease or cancer. Here’s why.

CRE live in the human gastrointestinal system and usually spread through fecal-oral transmission—that’s a nice way of describing getting someone else’s poop in your mouth. This is a special problem in hospital rooms, where, despite our best sanitation efforts, just about everything is covered in what epidemiologists evocatively call a “fecal patina.”

The fecal patina isn’t a huge problem for people who are otherwise healthy, because CRE are thick, gooey, and slow. When dropped into a healthy human GI tract, native bacteria typically overwhelm them. In other words, CRE can colonize within a healthy patient but typically fail to produce a true infection.

The bottom line: CRE is a major worry for hospital epidemiologists and people with certain chronic conditions. If you’re not one of those people, this specific outbreak is less of a concern.

But…CRE may hint at what’s in store for us.

Don’t get too comfortable. Like Jacob Marley on Christmas Eve, CRE outbreaks offer a glimpse into a potentially dismal future.

When a patient falls ill with CRE, doctors prescribe a class of antibiotics called polymixins. They were developed in the 1950s but soon abandoned because polymixins are toxic to human kidneys. Since the drug has basically been sitting on a shelf gathering dust for decades, we also lack adequate data on its safety and dosage. It is, in short, an unlikely savior, but it’s the only drug that CRE hasn’t been exposed to—and therefore hasn’t conquered.

Treating CRE with polymixins is an incredibly delicate balancing act between fighting off an infection and overdosing the patient’s kidneys. It’s not always possible to walk that tightrope. The mortality rate for some forms of CRE is close to 50 percent among the ill patients it attacks. If the pathogen finds a better transmission and infection strategy, it could be very dangerous for healthy people, too.

“These infections can start with chronically ill people but can eventually spread to others,” says Carmen Cordova, sustainable livestock science fellow with NRDC (disclosure). “The best thing we can do is to minimize the misuse and overuse of all classes of antibiotics.”

This future is near. Many farm animals carry bacteria that produce an enzyme to chew up penicillin, cephalosporins, and other classes of antibiotics. Epidemiologists in India have discovered CRE in the water supply and in sewage. These bacteria are closing in on us, and we have thrown away our weapons.

So go ahead—start freaking out about antibiotic resistance. I won’t tell you to calm down.