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It's time to Speak Out Recently I was invited to speak to a cattlemen's association on the antibiotics issue. As with many cattle producers, most of this group were quite willing to give up low-level antibiotics, thinking that the swine and poultry industries would be more severely impacted.. Likewise, the feeling is that by voluntarily giving up low-level antibiotics, the image of beef would be enhanced. The problem is that while the image of our product is certainly important, it is not the real issue. The real issue is resistant bacteria - organisms that are resistant to every existing human antibiotic - bacteria that pose a risk to every human being, including you and I, and our families. The reality is that animal agriculture is being used as a scapegoat. While giving up antibiotics might give the beef industry some good P.R., it would do little if anything to eliminate the problem of resistant bacteria. For example, the low-level feeding of antibiotics was banned in Great Britain over 30 years ago. Yet on a per-capita basis, Great Britain has more cases of resistant bacteria than the U.S. or Canada. Why? A flawed theory For the last 50 years, medical schools have taught that the only responsible way to administer antibiotics is in large, therapeutic doses. The theory is that by giving massive doses of antibiotics you kill all the bacteria in an infection, thereby preventing resistance from occurring. Conversely, the wrong or irresponsible way to give antibiotics is in small, low-level doses. The low doses, which simply control bacterial populations rather than eliminate them, are deemed to be the source of resistant bacteria. That is, since the bacteria are not totally destroyed, over time they develop resistance. This is a very logical theory, and to this day is believed by most practicing physicians and veterinarians. Unfortunately, it is wrong. I say unfortunately, because it would be wonderful if it were true. We could simply be careful to always give large therapeutic doses, and resistant bacteria would not be a problem.
This is why resistance has occurred for every new human antibiotic put on the market. The plain truth is that resistance to human antibiotics has primarily occurred because of overuse of antibiotics in humans, not animals. Common sense You need not be a microbiologist or biogeneticist to come to this conclusion. According to the FDA, it has only been since about 1995 that the superbugs have emerged as a major problem. Yet the low-level antibiotics that we use in the cattle industry have been in use for a minimum of 20 years, some of the (the tetracyclines) for nearly 50 years. Likewise, if you look at where most of the infections occur, the inescapable conclusion is the problem is human antibiotics given at therapeutic doses. That is, the vast majority of resistant bacterial infections occur in hospitals - staphylococcus and streptococcus infections subsequent to surgery. Creating a vicious cycle, hospitals routinely give surgery patients large doses of antibiotics as a precaution, in essence perpetuating the problem. The reality is that new human antibiotics come out on the market, and for a while are effective. Indeed, it takes upwards of $100 million to bring a human antibiotic to market. Most of that cost is in safety testing. Before beginning safety testing, of course, pharmaceutical companies test for effectiveness against bacteria (which in comparison costs virtually nothing). If the drug is effective, then they invest in safety studies. The bottom line is that no pharmaceutical company is going to spend $100 million plus on a product that isn't effective. Once on the market, however, after a period of use, resistant organisms, appear. The bacteria and antibiotics we use in the cattle industry were around long before, but the resistance doesn't occur until after the human drug has been put in use. It doesn't take Sherlock Holmes to figure that one out. Salmonella The Center for Disease Control (CDC) maintains that the source for salmonella infections is food, and since we use antibiotics in food animals, therefore we are responsible for the emergence of resistant strains of salmonella. That is a serious charge that we should in fact take seriously. The problem is that a lot of people are confusing salmonella with the staph and streptococcus superbugs. The fact is that the "super" bacteria that have the medical community most concerned have nothing to do with salmonella or other bacteria associated with food animals. Salmonella from food animals are not exposed to human antibiotics and have never been found in the animal to have resistance to multiple human antibiotics. Commonly, salmonella are commonly found resistant to tetracycline, which is often used in animals. But "super" salmonella have never been found in the animal. That is, unlike the "super" staph and strep bacteria frequently encountered in hospitals, salmonella in animals do not show resistance to a broad battery of human antibiotics. Frequently, salmonella infections in humans are found to have resistance to human antibiotics, but in almost all cases, the resistance was derived from antibiotics taken by the patient. The most common scenario has been that the patient was taking antibiotics for some other reason when they acquired the salmonella infection (more later). Illegal use This does not mean thee have not been problems, because there have. In late 1970 and then again in the 1980's there were several cases in which salmonella infections were encountered which were resistant to chloramphenicol, the preferred drug fro treatment of severe cases of salmonella in humans. Chloramphenicol is a prohibited drug for use in food animals, but as it turned out, veterinarians had illegally supplied dairy fars with chloramphenicol for treating their calves. While this is a black mark against animal agriculture, it is important to realize it had nothing to do with the legal use of low-level antibiotics. It was therapeutic use of a prohibited drug. Banning the use of low-level antibiotics would not have impacted this situation in any way. Likewise, limiting all drug use in animals to prescription only would also have had no effect since chloramphenicol was already a prescription drug. Indeed, this has been the approach in Great Britain (low-level use is banned and all therapeutic use is by prescription), yet Britain has more cases of resistant salmonella than the U.S. or Canada. It is also important to realize these isolated incidences were the only scenario in which drug use in animals has ever impacted human health. Salmonella readily develop resistance, and will develop resistance to drugs, administered to human drugs (other than penicillin) has never been encountered in animals. The most at risk It should be realized it is you and I, not the public, who are most at risk to any potential resistant salmonella. That is, those of us who handle and work with animals and are in contact with manure on a daily basis have the most to fear from resistant animal bacteria than the public at large. Even though farm workers are exposed on daily basis to salmonella, it is relatively rare for an infection to occur in farm families. Why? Most occur from the consumption of unpasteurized milk or raw meat. Even without resistance, the types of bacterial infections that can be acquired by eating uncooked animal products are a very serious matter. Salmonella are readily destroyed by ordinary cooking temperatures and the public should be brought to the realization that anyone who tells them to eat raw animal products is not a nutritionist but someone with fraudulent credentials. Human to human transmission Compared to other diseases, salmonella infections usually require a relatively large number of organisms. As a result, the most serious cases of salmonella usually come from the consumption of raw foods, However, salmonella infections can be acquired by other means. Although easily killed at cooking temperatures, salmonella can grow and reproduce at food-warming temperatures, This makes contamination by infected food handlers a danger. Cafeterias, buffets and other food service operations that hold foods for a long periods are a particular threat. As we know, salmonella are able to develop resistance more rapidly than many other enteric bacteria. As mentioned, a common scenario is for humans to unkowningly acquire a subclinical salmonella infection. Later they begin taking antibiotics for an unrelated reason. This suppresses other enteric bacteria and suddenly salmonella populations expand to become a full-blown illness. When sampled, these salmonella will obviously have a resistance for whatever antibiotic was taken. While salmonella and other enteric bacteria transmitted by animal products will readily develop resistance to antibiotics, organisms with multiple resistances to human antibiotics have not been encountered in animals. Salmonella should not be confused with the superbugs. Reasonable regulation In some cases, antibiotics used in humans are also used in animals. There is a theory that bacteria common to animals might be able to pass resistance developed in the animal on to a different species of bacteria (not found in animals). This is called plasmid transfer, and credible microbiologists agree it may be possible. Based on this, plus the fact that bacteria such as salmonella camphylobacter, etc., would develop resistance, it is reasonable to reserve the use of the newer and more powerful human antibiotics for human use only. Most of our harshest critics have to admit that there is no scientific evidence that low-level antibiotc use in animals has harmed human health. As a means of justifying a bon on all antibiotic use, however, a new theory has been put forth. Some in the medical community believe it is possible for bacteria resistant to animal antibiotics to somehow develop a cross-resistance to human antibiotics. This is a theory that defies all the evidence that has occurred throughout the history of antibiotic use. That is in the 50 years antibiotics have been used in animals, this has not occurred. As discussed previously, if this were true, when new human antibiotics come on the market, bacteria would not be susceptible, but they are. The reality is that it is only after a period of use that resistance develops. The harsh reality is that resistance to human antibiotics occurs because of over-use in humans. Why is there over-use of human antibiotics? As discussed previously, while the therapeutic-only theory of antibiotics is not correct, another adage taught in medical schools is. Specifically, physicians are told they must not prescribe antibiotics unless they are ablolutely necessary. By limiting the use you limit the potential for resistance. Unfortunately, when medical students get out into practice, they find their lofty ideals of prescription dreailed by dictates of the non-medical world. To a certain extent, their patients demand antibiotics. For colds, or flu, which are viral diseases unaffected by antibiotics, their patients don't want to be told there are no medications that will help. They want the doctor to give them a prescription. If their doctor sends them away empty-handed, they won't come back. The solution is found in a study in Finland in which antibiotic use in humans was restricted and bacterial resistance declined in an equivalent manner.
If we do nothing In 1955, 1966, 1967, 1970, 1977, 1984, 1987 and 1989, there were attempts to ban the low-level feeding of antibiotics. However, in each case, after review by the FDA, the National Institute of Health or the National Academy of Science in the U.S., no action was taken. The reason, of course, is that no definitive reason to ban low-level feeding could be found. Unfortunately, this latest campaign against antibiotics is different that all the rest, Always before, science was the basis for decision-making. This time, we're told science is not good enough. The FDA says they must now base their decisions on the "perceptions" of the medical profession. What is most disturbing is this "perception" that resistance to animal antibiotics can be transferred to human antibiotics. In Denmark, for example, Avoparcin, an ionophore, has been banned due to a perceived (but unproved) theory that resistance can be passed to Vancomycin, a very important human antibiotic. Most of us have felt we might lose Aureomycin, Terramycin, sulphmethazine, and/or Neomycin (1U); broad-spectrum antibiotics used in the feed (since these have long been the targets of attempts to ban low-level antibiotics). With what has occurred in Europe, however, there is no telling what we might lose. The unthinkable is that we might lose ionophores over here, but that is within the realm of possibilities. Should ionophores be taken away, feedlots would have to feed higher levels of roughage to offset the control of lactic acid-producing bacteria. Over 10 years ago, entomologists, learned that it is best not to try and annihilate insect pests or those insects will develop resistance to the pesticides. Instead, they try to keep crop pests down to what is known as an economic threshold. They don't try to kill all the bugs, just keep their numbers down below a level that would cause economic damage to the crop. In time, medical practitioners will learn that the same relationship applies with bacteria. However, unless we move to educate the public, it will happen later rather than sooner. In the meantime, the cattle industry will be on a politically expendable hit list for drugs. Management of cattle will be more difficult, cost of production will be increased, but the development of resistant bacteria that threaten us as human beings will not be curtailed. --written by David Price This article was taken under permission from the
David Price is a consulting nutritionist based in Las
Cruces, New Mexico. Copyright © 1999 , Canadian Cattlemen.
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