A handful of promising, real-life studies have been conducted with humans and other animals, though most of the research in that realm thus far has been conducted in the lab. More controlled trials will be required before some of these applications will be available to the public, but meanwhile, scientists have turned up exciting results in another area of use: countering the growing antibiotic-resistance crisis. “The loss of antibiotics due to antimicrobial resistance is potentially one of the most important challenges the medical and animal-health communities will face in the 21st century,” says Dr. Cyril Gay, the senior national program leader at the United States Department of Agriculture’s (USDA) Agricultural Research Service.
As Cari Romm previously reported in The Atlantic, livestock consume up to 80 percent of the antibiotics used in the U.S., and the amount actually jumped by 16 percent between 2009 and 2012, according to a recent FDA report. This rampant use of the drugs has led to “superbugs” that are becoming increasingly resistant to the antibiotics that are used to treat not just farm animals, but humans as well. In fact, almost 70 percent of the antibiotics given to these animals are classified as “medically important” for humans. According to Romm, “In the U.S., antibiotic resistance caused more than two million illnesses in 2013, according to a report by the Centers for Disease Control and Prevention, and an estimated 23,000 deaths,” and they’ve also amounted to an extra $20 billion in healthcare costs. And it’s only poised to get worse: a recent report commissioned by the U.K. government estimates that drug-resistant microbes could cause more than 10 million deaths and cost the global economy $100 trillion by the year 2050.
While the drugs are, of course, sometimes necessary to treat infections in livestock, the real reasons they’re overused are to speed up growth and to compensate for the cramped, unsanitary living conditions the animals endure. Dr. Stuart B. Levy, a man of many titles—hematologist and professor at Tufts University; director of the Center for Adaptation, Genetics, and Drug Resistance; president of the Alliance for the Prudent Use of Antibiotics; and author of the book The Antibiotic Paradox: How the Misuse of Antibiotics Destroys Their Curative Powers—says he and his colleagues consider the misuse of antibiotics on farms to be the biggest influence on antibiotic resistance, which has been declared “an increasingly serious threat to global public health that requires action across all government sectors and society” by the World Health Organization. Levy has been warning about this impending disaster for nearly 40 years, a couple of decades after farmers discovered that putting small amounts of antibiotics in the animals’ feed resulted in increased growth. Even back then, a study led by Levy found that chickens developed resistance to the antibiotic tetracycline at a rapid pace–within a week, the animals had resistant bacteria in their gut. Months later, the stubborn bugs had spread to untreated chickens and even the farmers. And it didn’t stop there: Those resistant bacteria also became resistant to other antibiotics that the chickens hadn’t even consumed. “Antibiotics used anywhere creates antibiotic resistance, and that resistance doesn’t stay in that environment,” Levy says. “And resistance is transferrable among bacteria of different types.”
Whether farmers choose to use it or not, there is a strong alternative on the horizon. Numerous recent studies—including several done by the USDA—have shown great promise in using essential oils as an alternative to antibiotics in livestock. One of their studies, published in October 2014 in the journal Poultry Science, found that chickens who consumed feed with added oregano oil had a 59 percent lower mortality rate due to ascites, a common infection in poultry, than untreated chickens. Other research, from a 2011 issue of BMC Proceedings, showed that adding a combination of plant extracts—from oregano, cinnamon, and chili peppers—actually changed the gene expression of treated chickens, resulting in weight gain as well as protection against an injected intestinal infection. A 2010 study from Poultry Science produced similar findings with the use of extracts from turmeric, chili pepper, and shiitake mushrooms. A multi-year study is currently underway at the USDA that includes investigations into the use of citrus peels and essential oils as drug alternatives.
Of course, there is also a dire need for alternatives to antibiotics for the direct treatment of infections in humans and animals, not only for illness prevention and growth-boosting in livestock. Research investigating the use of essential oils in humans has produced encouraging results, but such studies have been small and surprisingly rare, especially given the demonstrated success of their use in livestock. An Italian study found that a combination of thyme and clove essential oils was just as effective in treating bacterial vaginosis as the usual antibiotic treatment, and results of a study by U.S. researchers show that staph-infected wounds healed faster when they were treated with vapors of tea-tree oil than with conventional methods. Research published in December 2013 reported that a hand gel made with lemongrass oil was effective in reducing MRSA on the skin of human volunteers, and previous research has shown that a cleanser made with tea-tree oil clears MRSA from the skin as effectively as the standard treatments to which bacteria appear to be developing resistance. This type of simple, inexpensive fix—an essential-oil-based hand sanitizer—could be a major boost to hospitals, in particular, since MRSA infections are so common in healthcare settings.
In the lab, scientists have been testing all kinds of combinations of essential oils and antibiotics, and they’re repeatedly finding that the oils—used on their own and in combination with some common antibiotics—can fight numerous pathogens, including antibiotic-resistant strains of E. coli, Staphylococcus aureus(which causes staph infection), and other common types of bacteria. Results consistently show that combining essential oils and antibiotics significantly lowers the amount of antibiotic required to do the job. For example, two recent studies showed that lavender and cinnamon essential oils killed E. coli, and when combined with the antibiotic piperacillin, the oils reversed the resistance of the E. coli bacteria to the antibiotic. Another recent study found that basil oil and rosemary oil were both effective in inhibiting the growth of 60 strains of E. coliretrieved from hospital patients. Other research has produced similar results for many other essential oils, both alone and in combination with antibiotics. Researchers believe that one mechanism by which the oils work is by weakening the cell wall of resistant bacteria, thereby damaging or killing the cells while also allowing the antibiotic in.
Further investigation is clearly needed to advance this promising area of research, but that would require time and money. “Such investment is not likely to come from the mainstream pharmaceutical industry, which has not placed much emphasis on antibiotic development for a number of reasons, including the excessive cost in bringing a single drug to market without a commensurate return,” says Dr. Nicole M. Parrish, associate professor of pathology at the Johns Hopkins University School of Medicine and associate director of medical mycobacteriology at The Johns Hopkins Hospital, who co-authored a recent review on the potential use of essential oils as alternatives or supplements to antibiotics.
It took Sechler nearly 10 years just to get the people he works with to believe in his method, including farmers, workers at the feed mills, and his own employees, of which there are now around 1,200. He has met his share of skepticism from colleagues, too. For someone who notes that he lacks a formal education, Sechler is at the forefront of some cutting-edge methods (for one, he counts Temple Grandin, the famous animal-science expert, as a friend who helped him implement a humane slaughter system). He has been on the antibiotic-free kick for about 30 years, and he describes his current method in terms of its effects on gut bacteria—another hot topic right now. “We started with a breed of chicken that wasn’t raised to be stressed and overfed and to live in sanitary conditions,” he says. They also feed the chickens high-quality grains enhanced with essential oils, and they avoid the use of toxic chemicals like hexane, which is commonly used by other farmers in processing their feed. “With our chicken breed, housing environment, and feeding program, we’re able to promote healthy gut bacteria—we use oregano oil to kill the bad bacteria and cinnamon oil to support the good bacteria.”
Adopting healthier practices may cost a penny or nickel more per pound, which could affect stock prices of the big poultry producers. Sechler, whose company is not publicly traded, says he has been fortunate to have a loyal and ever-growing customer base that is willing to pay a bit more for better quality. Sechler says if the public starts asking for antibiotic-free meat en masse, more producers will comply, and change should come from other key players, too. “Essential-oil use by the food industry should be a hundred times bigger than it is,” he says. “Universities need to be able to speak up to some in the industry without getting their heads chopped off,” instead of tiptoeing around them because they provide research funding. He also believes the USDA and the FDA should create standards limiting antibiotic use and require everyone in the industry to comply by a certain date, similar to the way fuel efficiency standards for cars have been introduced and enforced.
“Unfortunately in this industry, you have to force people. Unless everyone has to do it, many won’t,” Sechler says. Despite encouraging study results and Sechler’s proven success, the lack of regulation and record-keeping is a potential problem with the use of essential oils, too: “These products are being used every day, but I really can’t tell you how many chickens or turkeys are being given these products because I don’t think there is anyone keeping track of this across the country,” Hofacre says, and Gay notes that the feed additives are not regulated either. “However, they are being used very successfully and I think as we learn more about the various essential oils and other plant extracts we will find more effective combinations,” Hofacre says.
Levy thinks the investigations into plant extracts as alternatives to antibiotics is “wonderful,” but he cautions that for any alternative, “it should be demonstrated that this practice is really useful, and alternatives should be given the same scrutiny” that antibiotics haven’t been.