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ISU Associate Professor and Former USDA Deputy Undersecretary Food Safety Responds to CBS News Segments on Antibiotics - Feb. 9 and 10

Date: 
February 10, 2010
Contacts: 

Dr. H. Scott Hurd, Veterinary Diagnostic and Production Animal Medicine, (515) 294-7905
Ms. Tracy Ann Raef, Veterinary Communications, (515) 294-4602


Key Facts Disagree with CBS Evening News Segment on Antibiotics Aired on February 9, 2010

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. 

Prepared by
H. Scott Hurd DVM, PhD

Former Deputy Undersecretary Food Safety, USDA

 

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 on 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.
 
Key Facts Disagree with CBS Evening News Segment on Antibiotics Aired on February 10, 2010
 
CBS: Antibiotics in Denmark are used sparingly and only when animals are sick.

HURD:That is true. So sparingly in fact that farmers and veterinarians are not even allowed to use antibiotics to prevent common illnesses they know are coming. They must wait until pigs suffer and die. According to the World Health Organization (WHO), the Danish Pilot Program resulted in an increase in diarrhea in pigs and a 25 percent increase in deaths. In fact, many small farmers were driven out of business due to this ban. The number of farms went from 25,000 in 1995 to less than 10,000 in 2005. What appeared to be a ban on antibiotic use in healthy pigs actually pointed out the benefits of its use in helping pigs grow healthy.

Ironically, once a pig does become visibly sick, the government allows farmers to use antibiotics that are similar to those used in humans. In fact, uses of these antibiotics have risen dramatically since the ban. One of these, tetracycline, is what American teenagers with acne often take for up to six months to treat their condition.

 

 

CBS: The experiment to stop widespread use of antibiotics was launched 12 years ago, when European studies showed a link between animals that were consuming antibiotic feed everyday and people developing antibiotic-resistant infections from handling or eating that meat.

HURD: No studies ever showed such a linkage. The government records clearly show it was a precautionary action due to the possibility of risk.

It should be noted that Denmark is a very small country (about one-third the size of Iowa), which produces fewer pigs than the state of Iowa. So clearly, their “experiment” was not on a national (U.S.) scale in terms of size.

Interestingly, farmers in Denmark are using zinc to prevent post-weaning diarrhea, which again was documented by the WHO. Recent data published by Danish scientists show that the use of zinc may actually be selecting for MRSA, which would be another unintended consequence of the ban on antimicrobial growth promoters

CBS: Since the ban, the Danish pork industry has grown by 43 percent – making it one of the top exporters of pork in the world. All of Europe followed suit in 2006. But the American Pork Industry doesn't want to.

HURD: In 1997, the Danish pork production was 21,180,000 head. In 2008, the industry had grown to 27,078,000, but about 5 million pigs were exported to other European countries to be fed for market. That means that net growth in the industry was approximately 5 percent, not the 43 percent reported by CBS.

DANMAP 2008 – the Danish Government’s own report – states that since 1998, the first year of the ban, active kilograms of antimicrobials used to treat animals increased 110 percent while animal production has only increased 5 percent.

Because Denmark exports more than 85 percent of the pork it produces, it may be important for the government and producers to position the ban as a success, regardless of the apparent negative consequences.

CBS: Without growth-promoting antibiotics, it only costs $5 more for every 100 pounds of pork brought to market in this country.

HURD: According to a recent analysis by Iowa State University, a U.S. ban would increase costs by approximately $6 per animal in the first year. The total cost of a ban to all U.S. pork producers, spread across a ten-year period, could be in excess of $1.1 billion and lead to a 2 percent hike in consumer pork prices.

Even though the ban raised pork prices and put small producers out of business, cost is not really the issue. The focus should be on public health. Did the ban in Denmark improve public health? Neither the World Health Organization nor I find any evidence that it did.

CBS: Dr. Ellen Silbergeld said, "I think the Danish and European experience indicate that there will be real and measurable public health benefits," she said. "There'll be improvements in food safety and actually in the prevalence of drug resistant infections in people."

HURD: The World Health Organization (WHO) has stated there was no evidence of improved public health (WHO, 2002, pp. 27-29). In fact, resistant rates in human Salmonella cases have increased, and Denmark is currently experiencing their largest outbreak of methicillin-resistant Staph Aureus (MRSA) in its history. Denmark has seen a largest increase in human MRSA cases since it banned antibiotic growth promotion in animal agriculture.

CBS: According to one study, when different countries introduced certain antibiotics on farms, a surge occurred in people contracting antibiotic resistant intestinal infections one to two years later. One infection, Campylobacter, increased 20 percent in Denmark and 70 percent in Spain.

HURD: The example of resistant Campylobacter does not relate to the use of antibiotics for growth promotion or even of any antibiotics in feed. The type of antibiotic, fluoroquinolones, was used to treat sick animals, and in the United States required a veterinary prescription. In pigs, they were delivered by giving the animals a shot.

The antibiotics that have been used in feed in the U.S. are old— most have been used for more than 40 years. In addition, risk assessments have shown that they do not pose a risk to human health. In fact, FDA surveillance shows that resistance to these antibiotics in pork products is steady to declining. (NARMS)

CBS: After the ban, a Danish study confirmed that removing antibiotics from farms drastically reduced antibiotic-resistant bacteria in animals and food.

HURD: The only resistance that decreased was in Entercoccus spp., which is not a food-borne pathogen (DANMAP 2008).

The total tonnage of antibiotic used in Denmark decreased after the ban. However, please note that the amount of product used to TREAT SICK pigs increased 100 percent. It doubled. Why? Because the prior usage, that was labeled “growth promotion,” was actually preventing illness. It was doing some good. Therefore, it cannot be termed “non-therapeutic.”

Now, the key point is that the type of drug used to TREAT sick pigs was different than what had been preventing disease. These treatment drugs are very similar to those used to treat human illness. So, just what did the World Health Organization say about these events and data?

“It is probable, however, that termination of antimicrobial growth promoters had an indirect effect on resistance to tetracycline resistance among Salmonella Typhimurium because of an increase in therapeutic tetracycline use in food animals.”

“Increased tetracycline resistance among Salmonella may result in additional human Salmonella infections… since persons who take tetracycline for other reasons are at increased risk of becoming infected with tetracycline-resistant Salmonella.”

So, based on this, there might be MORE risk now than before the ban because of an increase in treatments. Also, resistance in human food-borne pathogens, such as Salmonella and Campylobacter has not decreased at all.

CBS: Danish scientists believe if the U.S. doesn't stop pumping its farm animals with antibiotics, drug-resistant diseases in people will only spread. "It's not going to be a time bomb that goes off like this," said Dr. Frank Aarestrup, of the Danish Food Institute at the University of Denmark. "It's something that's slowly getting more and more complicated, more difficult for us to actually treat infections.”

HURD: That’s simply not an accurate description of what America’s pork producers do at all. This is evidenced by the grassroots initiative of Pork Quality Assurance Plus®. The program helps guide farmers through the proper and judicious way to handle and use antibiotics responsibly. It’s a program that’s been in place for more than 20 years.

Also, as one of the primary government officials responsible for promoting the idea of a ban on antibiotic growth promoters, Dr. Aarestrup’s professional credibility depends on positioning the ban as a success.

Drug resistance in food-borne disease is not the major concern with human-resistance issues. Less than 1 percent of food-borne illnesses require antibiotic therapy. The human-health crisis with resistance is focused on pathogens that are often hospital-acquired. Thus, bans, such as what Denmark implemented, will not address those issues.

CBS: It costs very little to convert a farm to antibiotic-free. And it doesn't cost consumers much more either. The example was given showing that antibiotic-free pork production would only cost farmers $5 more per hundredweight or 5 cents per pound, so why not just do it to improve human health?

HURD: U.S. economists have shown that if those same antibiotic bans occurred in California, it would add $5 to the cost of every pig. Because I spent three months working in Denmark, I can assure you these effects are real and still present. For this reason, I hope U.S. decision makers will balance this information with the goal of “protecting finite resources while feeding a growing population.”

Antibiotics that prevent animal illness are good for us all. A recent study by Dr. Randy Singer at the University of Minnesota has shown that the consumption of subclinically ill poultry could increase the total number of human illness days.

Any attempt to ban antibiotic use in livestock won’t improve human health, and indeed may result in an increase of food-borne disease. One published risk assessment (Cox, et al.) concluded that there would be 4,500 more cases of food-borne illness if one antibiotic were banned for each one person that may have an extended illness due to use of that antibiotic.

CBS: The FDA has for the first time come out against using certain antibiotics to promote growth in livestock.

HURD: The U.S. Food and Drug Administration (FDA) may be attempting to exercise the European form of the precautionary principle—an overarching view that says, if it looks bad, don’t do it. However, current FDA regulations state that each bug-drug combination (bacteria-antibiotic) must be evaluated on a case-by-case basis (Guidance 152). This approach is consistent with a scientific approach to decision making.

 

For more information about Dr. Hurd's Lab, visit:

http://vetmed.iastate.edu/research/labs/food-risk-modeling-and-policy-lab