Background on antibiotic resistance
Antibiotics, since their discovery 70 years ago, have saved millions of lives, Zurek said.
“Unfortunately, because of the intensive use of antibiotics in human medicine, we pose high pressure on bacteria, and they respond by developing resistance,” he said. “The resistant strains then survive and are selected by antibiotic treatments. Currently, we have situations where people get infections they die from because the antibiotics are not effective anymore. The bacteria that caused the infections are multi-drug resistant.”
According to a 2013 report by the Centers for Disease Control and Prevention, at least 2 million people become infected with antibiotic-resistant bacteria, and at least 23,000 people die each year as a direct result of these infections in the United States.
Currently, two places where antibiotics are most widely used are hospitals and food animal production facilities, Zurek said. Antibiotics in food animal production are not only used to treat infections in animals but also in helping animals grow.
“Antibiotics in low doses are added as feed additives, primarily in poultry and swine diets,” he said. “The outcome is that the animals grow faster. At the same time, if you use low doses of antibiotics extensively, that poses selective pressure on bacteria in the digestive tract of these animals and results in antibiotic resistance.”
Humans experiencing more problems with antibiotic resistance could be due to many potential reasons, Zurek said, including overuse of antibiotics in human medicine and human connection to antibiotic use in food animals. There are likely many other potential environmental connections as well, so it’s hard to pinpoint specific infections and where the antibiotic resistance originated.
In addition to the insects, Zurek and his research team have also showed that wild birds, such as ravens and crows, carry multi-drug antibiotic-resistant bacteria.
“Wild birds can pick up the antibiotic resistant bacteria from fields where animal manure was used as a fertilizer,” he said. “We still don’t know how significant these birds are as carriers. We just know there are multiple venues where wildlife can acquire resistant strains and move them around in the environment.”
Making strides on the issue
To help eliminate the potential connection to food animal production, the U.S. Food and Drug Administration last December released its first request to antibiotic manufacturers to voluntarily remove antibiotics from the list for animal growth promoters. The plan is to phase out antibiotics as a feed additive for growth promotion in United States in the next three years.