[Read Part II]

Key Facts Disagree with CBS Evening News Segment on Antibiotics Aired on Feb. 9

The following facts provide the best available knowledge and information regarding the use of antibiotics in livestock and how they may affect the health of animals, people and food safety. This text can also be found here.

Prepared by
H. Scott Hurd DVM, PhD
Former Deputy Undersecretary Food Safety, USDA
Director WHO Collaborating Center for Risk Assessment
and Hazard Identification in Foods of Animal Origin,
College of Veterinary Medicine
Iowa State University
Ames, Iowa

CBS: A University of Iowa study last year found a new strain of Methicillin-Resistant Staph Aureus (MRSA) — in nearly three-quarters of hogs (70 percent), and nearly two-thirds of the workers (64 percent) — on several farms in Iowa and western Illinois. All of them use antibiotics, routinely. On antibiotic-free farms no MRSA was found.

HURD: First, this was a very small pilot study, which sampled fewer than 300 pigs. In it, only six farms used antibiotic-free production methods. The implication that this type of production is always free of MRSA is not true as there have been organic farms in other countries that have been found to be 100 percent positive for MRSA. On the other hand, in this Iowa study, some of the conventional farms that did use antibiotics were 100 percent free of MRSA. Secondly, there were two studies by the University of Iowa on MRSA in swine. The study that went unreported by CBS found conventional farms with MRSA rates in pigs of 23 percent, not 70 percent.  In personnel, the rate was 58 percent, not “nearly two-thirds.”

What also was not communicated is that there are at least three general categories of  MRSA. 1) Virulent forms of MRSA are a serious human health problem. These forms are most commonly found in healthcare settings such as hospitals, dialysis centers and long-term care facilities and are often referred to as healthcare- or hospital-acquired. They can cause serious, invasive illness and even death, particularly in people with weakened immune systems. 2) There are less virulent forms of MRSA commonly found throughout the general population (25-50 percent of people) that are also found in cats, dogs,  horses and other animals. These are typically referred to as community-acquired forms and are often linked to shared areas, such as locker rooms. 3) A third form that is less  invasive than the healthcare-associated form has been recently identified in European, Asian and North American swine farms. This livestock form (strain 398) does not transmit as easily between people as the other types. It has been found in some people who have close contact with livestock (pigs, calves, and poultry), although there is no data to indicate that these people have a higher-than-normal illness rate.

The type of MRSA that has been associated with livestock is unique (known as strain 398). This strain has not been found in human disease surveillance for MRSA conducted by either the U.S. Centers for Disease Control and Prevention (CDC) or the University of Iowa hospitals. It is very unlikely that the people interviewed for the CBS story had  livestock-associated MRSA. However, it’s much more likely these people had the very common community-acquired strain of MRSA from being in close contact with infected people – not animals.

The types of antibiotics used in modern pork production are not associated with the development of MRSA. Methicillin has never been used in animals in the United States.

Countries that have banned growth promotion uses of antibiotics, such as Denmark, have similar levels of MRSA in their livestock herds. Additionally, Denmark has been struggling with a major outbreak of human MRSA.

CBS: Health officials are concerned if workers who handle animals are getting sick – what about the rest of us? Drug resistant infections have sky-rocketed over the past two decades, killing an estimated 70,000 Americans last year alone.

HURD: The drug-resistant infections referred to here have little, to no, relationship to any antibiotic use in animal agriculture. The types of drug-resistant infections that are lethal are often associated with hospital-acquired infections – and the antibiotic used in those facilities.

According to the FDA, resistance in food-borne illness is stable to declining over the last several years. Scientific risk assessments conducted by myself and others have shown a person is more likely to die from a bee sting than have a few extra days of diarrhea due to a resistant  infection acquired from on-farm antibiotic use.

CBS: Antibiotic resistance is an emerging health crisis that scientists say is caused not only by  the overuse of antibiotics in humans, but in livestock as well. Antibiotics fed to healthy animals to promote growth and prevent disease.

HURD: Strategic use of antibiotics in animal agriculture prevents disease and produces safer food. A side benefit of this use is faster growth.

Since antibiotics have been used in humans for more than 60 years and in livestock for about 50 years, if there was going to be an epidemic of resistance related to antibiotic use in agriculture it would have occurred by now. The fact that it has not means that  antibiotic use in animals is not a major risk to human health.

CBS: "My fear is that one of these days we are going to have an organism that's resistant to everything that we know, and we'll be left powerless," said Thomas Cummins, Batesville's chief medical officer. "There are a lot of concerns about antibiotics being added to animal feeds that may be contributing to MRSA as well as other antibiotic resistance. Certainly the more bacteria are exposed to antibiotics in any shape or form, the more tendency there is for resistance."

HURD: While the types of antibiotics used in animal feeds do not contribute to the development of MRSA, the concern over the development of antibiotic resistance is why veterinarians and farmers have spent more than 20 years continually improving their antibiotic use. The results of these improvements are evident in FDA-monitoring studies that show that resistance in target pathogens is stable to declining.

Since antibiotics have been used in humans for more than 60 years and in livestock for about 50 years, if there was going to be an epidemic of resistance related to antibiotic use in agriculture it would have occurred by now. The fact that it has not means that  antibiotic use in animals is not a major risk to human health.

CBS: There are different types of drug-resistant bacteria. Some, like E. coli and salmonella, can be passed on to people by consuming undercooked meat and poultry. Now, scientists are worried that Americans may be acquiring drug-resistant MRSA – not from eating, but from handling tainted meat from animals that were given antibiotics.

HURD: Research demonstrates that when MRSA has been found in meat, it is present in extremely low levels. Because of this, the United States Centers for Disease Control and Prevention (CDC) and the European Food Safety Authority both conclude that the likelihood of MRSA being spread by handling or eating meat is very low.

As always, when meat is handled and cooked properly, there is virtually no risk of becoming sick from a food-borne pathogen.

CBS: Evidence of MRSA has been found in the nation's meat supply. But it's unclear how widespread it may be, because only a small fraction is tested for MRSA.

HURD: MRSA is not a food-borne illness, thus testing meat is unnecessary. The CDC and the European Food Safety Authority agree that the risk of MRSA from handling or eating meat is very low.

CBS: "If the bacteria becomes resistant to antibiotics, it can actually spread in many ways," Hearne said. "It could be in the food supply, but it also can be in waters that runoff in a farm. It could be in the air. It can happen very quickly in many different ways. It's why it's a practice that has to stop on the farms."

HURD: There is no evidence to support that these routes contribute to the human health concerns around antimicrobial resistance. Food-borne illness rates are declining, and resistance in those pathogens is stable to declining. Environmental spread of these pathogens is largely theoretical.

CBS: Using antibiotics to help animals absorb and process food so they grow bigger, faster is a selling point pushed by the pharmaceutical industry. Because animals are packed into confinement pens, antibiotics are also used to keep disease from spreading like wildfire.

HURD: Antibiotic use is one very important tool to maintain animal health in farms of all sizes and structures. Other tools used include hygiene, proper diet and nutrition, providing the proper environment and vaccination. Antibiotics help the animals grow healthier, improve animal well-being and help provide safe food.

CBS: But the bottom line on antibiotic use is this: no one is really monitoring it.

HURD: The U.S. Food and Drug Administration (FDA) regulates antibiotic use in both humans and animals. The FDA inspects the feed mills that would produce medicated feed. The agency also evaluates the safety of antibiotics used in animals for human safety. And, the FDA works with the USDA to conduct tests in processing facilities to make sure those regulations for antibiotic use are followed. So, it’s clearly a highly regulated practice – one the pork industry has shown a long history of commitment to by demonstrating its ongoing compliance with those regulations that help ensure safe food.