BACK IN 1974, on a private farm in Sherborn about 25 miles outside Boston, researchers from Tufts University conducted a prophetic experiment. The scientists, led by Dr. Stuart B. Levy, fed 325 freshly hatched Leghorn chickens in two groups mash that either contained or was free of a common antibiotic called tetracycline, a drug given at low doses to prevent infections in livestock. Within just two weeks, nearly all of the chickens that had received tetracycline had bacteria resistant to the drug in their feces. Even more alarming, within several months, the farmers and their family members were colonized through the air by tetracycline-resistant bacteria. And within that year, the animals and humans on the farm were infected by E. coli bacteria resistant not only to tetracycline but also to penicillin, sulfa drugs, and streptomycin — medicines often used to treat common infections in humans. The everyday farming practices mimicked in the study had created a superbug.
Today, this four-decade-old landmark study is more relevant than ever. Last month brought the dire news of another superbug. A 49-year-old Pennsylvania woman was infected by a strain of E. coli resistant to colistin, an antibiotic of last resort. The discovery of the superbug, wrote scientists reporting the case, “heralds the emergence of a truly pan-drug resistant bacteria.’’
This specific bacteria isn’t likely to cause a pandemic anytime soon. Its resistance to colistin classifies it as a superbug, but it was treatable with varying doses of other available antibiotics. Yet the Pennsylvania discovery highlights the enduring predicament that led researchers to conduct the study on a farm 40 years ago: Doctors are continually seeing patients with bacterial infections that resist our first-line antibiotics — so much so that the World Health Organization has called antibiotic resistance a global health crisis.
Massachusetts is not in any way immune to this worldwide problem. Almost every day I’m in the hospital, I meet a patient with a bacterial infection — a rash, urinary tract infection, pneumonia — that doesn’t respond to the usual antibiotics such as ciprofloxacin. Patients like these usually end up staying in our hospitals longer, have a greater risk of complications, and cost the US health care system nearly $60 billion a year. And while doctors can usually find something on the pharmacy shelf to eradicate the infection, that happy outcome is no longer a given. Of the nearly 2 million Americans infected with antibiotic-resistant bacteria each year, 23,000 people die — that’s more deaths than by homicide.
Our industrial agricultural practices are partly at fault — after all, nearly 80 percent of antibiotics consumed in this country are used on farms, not in clinics. For decades, farmers have been feeding antibiotics to chickens and cattle because these medicines help animals grow faster and can treat infections that break out in crowded factory farms. But as the Sherborn experiment and numerous corroborating studies have suggested, the inappropriate use of antibiotics in farm animals quickly contributes to the spread of drug-resistant bacteria to humans.
Consequently, in December 2013, the US Food and Drug Administration finalized voluntary guidelines asking drug companies to remove growth promotion claims from the labels of antibiotics given to animals. Some big companies like Subway, Chick-fil-A, and McDonald’s have promised to stop serving chicken raised with antibiotics in coming years — though McDonald’s made a similar promise a decade ago and didn’t follow through — and Perdue says two-thirds of its chicken products are now antibiotic-free. But many factory farms continue to use these drugs via the loopholes in the watered-down FDA guidance.
Meanwhile, in countries like Denmark (one of the world’s largest exporters of pork), stricter antibiotics bans and the resultant changes in farming conditions have led to reductions in antibiotics resistance in humans with no negative effects on pork production. Trying to echo such successes, many farms in Massachusetts have worked hard to become less reliant on antibiotics. “All of our animals are free range,” says Kim Denney, co-owner of Chestnut Farms in Hardwick. “If we manage them in a healthy and sustainable way, it actually ends up being cheaper and we don’t need to use interventions like antibiotics.”
Reducing agricultural consumption of antibiotics depends on what customers like us are willing to pay for. If we continue to buy meat from factory farms where unhealthy practices abound, the problem of antibiotic resistance will persist. Buying locally produced and antibiotic-free chicken, for instance, can cost $2 or more per pound at the supermarket — but it is the socially responsible alternative. “It all comes down to willingness to pay for food. Eat less but better quality meat,” Denney says. “Otherwise there are more superbugs coming.”
Farms, of course, aren’t the only place we have to look to overcome the problem of drug-resistant bugs. We use antibiotics in clinical medicine as if they were water, and for a long time, that made sense. Since penicillin was discovered nearly a century ago, antibiotics have proved a miracle drug that catapulted us out of the dark era when 5 out of every 1,000 mothers died in childbirth and when pneumonia was the leading cause of death in the United States, killing 3 out of every 10 people who contracted it. The drugs have given us the ability to perform complex surgeries without fear of infection. They help cancer patients tolerate high doses of chemotherapy without worry that microbes will overwhelm their suppressed immune systems. Antibiotics are among the only tools in medicine today with the potential to cure completely, but their power has given us a false confidence that they only benefit and never harm.
Now our blind reliance on them has become dangerous. A recent study found that nearly 1 in 3 outpatient antibiotic prescriptions were not needed — that’s around 47 million unnecessary prescriptions a year in the United States alone. Many doctors hand out the drugs even when they suspect the infection is a virus that wouldn’t even respond to traditional antibiotics. When patients with colds or other respiratory tract infections visit their doctors, more than 70 percent leave with antibiotics that provide little to no benefit.
This is frequently a problem of expectation, and I’ve experienced its pressures myself. Half of patients who go to their doctor with an acute respiratory tract infection expect to get antibiotics. And research shows doctors who simply think their patients want the drugs are more likely to write a script, even if it won’t help. As much as physicians try to be critical thinkers, we like to please our patients, even if that means giving an azithromycin course against our better judgment. It’s bad medicine — but it’s what happens in the real world. To guard against this often unspoken interchange, patients should ask their doctors if they actually need the antibiotics they’re being prescribed.
Antibiotics serve us well when used appropriately — but the resistance we increasingly see every day is a symptom of their wild overuse. A bill pending in the Massachusetts Legislature seeks to improve living conditions for farm animals in the state and could theoretically reduce the situations that encourage farmers to rely on antibiotics. Even though policy like this might help, consumers — of food and of medical services — have power to force change right now. Buying from antibiotics-free farms exerts pressure on big agribusiness to follow suit. Doctors must reexamine their habits and have frank conversations with patients to reduce the frequency of unnecessary prescriptions.
Too many of us have forgotten that we once lived in a frightening world with no defense against bacteria. Every time we take an unnecessary antibiotic today is another opportunity for bacteria to evolve and escape the drug’s intended effect. We are fighting a battle against superbugs. If we want to keep fighting, we had better evolve, too.