Veterinary medicine advisory committee

НазваниеVeterinary medicine advisory committee
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Dr. James S. Cullor

DR. CULLOR: I appreciate being here. My travel expenses are being paid by the Animal Health Institute. I am the director of the VMTRC. From time to time our faculty and our Center, through the contract and grant process, receives money from private industry including my laboratory, although it is mainly vaccines and not pharmaceuticals.


I am here today to talk about the framework document as a representative of and the director of the Dairy Food Safety Laboratory.


What we are being asked by all these discussion we have talked here today is really how do we do daily management of the production unit for animal health and well being, public health, environmental health, and medical ecology, and still manage the financial well being of the dairy. That, in fact, is what we are doing at the VMTRC with our students through programs like Dr. [Sisco's], TQM, breakthrough management, and infectious disease control, and so on, and so forth.


We have had several reviews today, and this one I think we need to go back and look at. The probability of disease transmission from animals to man is really influenced by the length of incubation period in the animal, the length of time the animal is infective, the pathogen load contained in the animal product or placed into the environment, the stability of the agent in the environment, the population density of animals and man, animal husbandry practices, maintenance, production, and control of wild rodents and insects, virulence of the microbe, and the route of transmission.


In all of this, the compounds we are talking about, these anti infective or antimicrobial agents, really have a positive impact in two main areas. By shortening the length of time the animal is infective and reducing the pathogen load contained in the animal product, or placed into the environment.

At the American Academy of Veterinary Pharmacologists and Toxicologists last year, we presented a model where we looked at, on one end of the spectrum, absolute, unrestricted use of all antibiotics where you could violate any orifice you wanted to, with any antibiotic you wanted to, and given enough time you would get enough drug resistance that the pathogens would overwhelm the pasteurization and our meat processing, and we would have an increased risk to the human population.

That same model shows, on the other end of the spectrum, if you completely remove antibiotics from the food animal production system, the pathogen loads again will reach critical mass where they will get past all of the pasteurization and other types of procedures, and again present a problem to the human population.

In that model, then, the middle ground is where you combine management practices, antimicrobial therapy, good methods of animal husbandry, and so on, and so forth. That is where the human population is at the least risk of being infected by these pathogens.

I submit to you that if you go to Vietnam today, you can see one end of that spectrum. You can go see the result of the human population for the lack of antibiotics, and the model accurately predicts what happens.

I am afraid that if we continue this framework as it is, that we will have that type of an environment and really a problem for our food animal production industry.

We have talked about and heard a lot about Salmonella, E. coli, and Campy, but I submit that the list will grow and grow each year until we get these plus Yersinia and others, and so that   


We get often as veterinarians, we get the comment, "Well, why don't you just go clean up the dairy" or "Why don't you just go clean up the farm, and we wouldn't have all this trouble."

I submit to you that every day in the hospitals around this country, they have problems with cleaning them up, and when we work in an environment where these are the criteria for eradicating a pathogen, it has to be a single host species with no external reservoir species. That is not the case with Salmonella, E. coli, or any of the others.

In order to eradicate a pathogen, it has to be identified to be present in only a small percent of the farms, ranches, dairies, or feed lots, and we know that it can be worldwide, not just in the U.S.

The pathogen of interest serves as a disease marker for detecting endemic herds, and we know that organisms like 0157 is not a marker for the endemic disease.

Appropriate assays are validated and can correctly identify the carrier animals. In fact, they do not exist, and not have been validated for such a purpose.

Effective means of intervening in the chain of infection after the carrier animals have been removed from the herd must be established, and that is where antimicrobials and vaccines and management practices can play a part.

We have to have substantial financing, many billions of dollars to do this, and we don't see that anywhere either in private industry or from the government, and a long term resolve by everybody involved to implement all of the necessary measures for eradication, and we very seldom see that long term resolve exist.


I know this is a little difficult to see and almost impossible, but what I wanted to show is that we took    one of the issues is the surveillance system, how can we track antimicrobial resistance and what is going to happen.

What we used was the USDA panel of organisms, and what we did then is we took that panel and we looked at heifers    we call them springer heifers. They have been on the dairy. This is a closed herd that milks about 5,000 cows a year. They have five dairies. They feed their babies hospital milk, mastitis milk. It has been pasteurized. It has antibiotics in it. They were raised on that for at least 60 days in their early life.

Then, they are raised in the environment all the way through out of the dairy until they are pregnant and ready to calf. We go in and test those animals just before they calf, and these are Staph aureus isolates.

What we saw was that on this dairy    we did it for 1995, 1996, and 1997, the same dairy where we know all the antibiotics used    and what this assay showed was that in '95, 4 percent of the Staph aureus isolates were resistant to chloramphenicol, in '96, 12 percent, and in '97, zero percent.

We looked again at another one, streptomycin; in '95, 4 percent were resistant; '96, 4 percent resistant, in '97, none, and so on, and so forth. We had four different antibiotics out of that panel that showed this resistance, where, in fact, these animals weren't exposed to these antibiotics any other way than at birth or in the environment around.

We used this data as an early indicator. We are going to do the 1998 data now. This surveillance system can't be looked at, at any one year. It has to be looked at over a period of time, and you have heard that several times already today. Probably a minimum of three years is going to be needed to take a look at some of this information.

So, now we have been asked several times to comment on the framework and what we might do.

Part 1, the categorization. It makes sense, but it really needs to be better simplified, and you have heard over and over again if you get in number 1 category, you can't get out of there under this system.

So, I think we can reduce it maybe to three categories, and then be objective and really make this setting transparent; that an expert panel get together with CDC and CVM and really relook at these categories and see if we can't help them out a little bit.

Monitoring thresholds. It is a good idea, but we really don't know where to set them, and you have heard that over and over today.

For veterinary therapeutics, we have breakpoints established for maybe three or four drugs, but none are set for enterics, and we have got to look at that. Therefore, it is not going to be very easy for these products and for these zoonotics to be put together especially under a direct regulatory action.

So, let's set some targets and then use them for further study, let the NCCLS group sit in on this, and let them be responsible for setting these targets and then reviewing them, and not a government agency.

For therapeutic use in animals. Again, a full risk assessment needs to be done, and we have heard that over and over today, and we have heard it challenged over and over, but I think we have heard from our colleague from Canada of the fact this can be done, and if we don't know how to do it, let's take him out to dinner tonight and get some ideas.

We do support judicious use and education about use of antibiotics, and we should continue to do that, and this framework should reflect that position.

We need R & D on better slaughter, processing, storage, and preparation of our food products, cold sterilization with pulsed ultraviolet light, things like that can be done, and we have seen over and over that the HACCP program that is being implemented has been severely underestimated by this document and by some of the early speakers.

This is working. The statistics show it, and the prevalence data shows it, and we need to keep supporting it, and then build upon that. Resistance thresholds, really, this is more appropriate as a research study, not that I am from an academic environment or anything, but I think rather than a regulatory document, we need to support more research into this area, and really work from there and then set the thresholds.

Regarding the pre approval and post approval studies, basically, I support a good body of studies on the pre approval side, including the Salmonella shedding studies and modifications that were proposed by Dr. Miller this morning.

We should support other good descriptive studies of treatment resistance, transfer of mechanisms, and so on, and so forth. We should support and enhance slaughterhouse under NARMS surveillance system. It is in its infancy right now, we have heard that, and it has its strengths and weaknesses and I think, as a group, we can together and really pull it together and make it a better system, and just like it was intended to be, and mature it as we go along.

Really, I support research and not regulatory studies for understanding on farm animal epidemiology through a competitive grant system. We have a wealth of good university personnel, a lot of good scientists, a lot of good veterinary students and animal science students, and so on, and so forth, that can do a lot to improve this.

I think these suggestions represent really a simple, solvable proactive way that is science driven, and it does support public health. Remember, you are asking us to, on a daily basis, manage these dairies for animal health, public health, environmental health, medical ecology, and the financial well being.

This framework document, although a good start, does not help us to do that, and we need to work on it, and I support the idea that we can modify this and make it a better document than it stands today.

Thank you.

DR. STERNER: Thank you, Dr. Cullor.

Questions of panel members of Dr. Cullor?

[No response.]

DR. STERNER: We are at that stage, and I know you have all been anxiously awaiting with relief to your posterior, and that is our final speaker of the night.

Dr. Barbara Glenn, is that correct? I have no affiliation for you, but I assume again that you will explain that to us, and you have the final 10 minute period of the night.

Dr. Barbara Glenn

DR. GLENN: Mr. Chairman, it is my pleasure to be the last speaker this evening. My name is Barbara Glenn, and I am executive vice president for Scientific Liaison for the Federation of Animal Science Societies.

I have not received any financial support regarding my statement, and my expenses are paid by my employer.

FASS, or the Federation of Animal Science Societies, is a federation of three professional societies, and has a membership of about 11,000 scientists who are in academia, government, and industry. Our members do research, teaching, and information exchange to students, producers, consumers, and other members of the public.

Our three member societies are sponsors of three major scientific journals that are respected around the world in the animal, dairy, and poultry scientific community.

We are familiar with the proposed framework that you have released for review and comment. In general, we request that you allow the science and the facts to guide your deliberation and actions.

Some of the issues are old and have been raised for 20 or more years. With new antibiotics and possible new emerging strains of pathogens, some questions are new. We should learn from past experiences and carefully look at new situations while research should be directed to fill in the information gaps that exist, so as to factualize the decisionmaking process.

This is a topic of very serious concern and should not be taken lightly. To not act if some of the concerns turn out to be real is not ethical. Likewise, to take actions that are not warranted also can be inappropriately costly to both livestock producers and consumers.

Specifically, we believe the issue of implementing a valid monitoring process to assess the development of resistance in microbes to be much more complicated than might be thought. There are a number of questions that seem to be pertinent, and for which the answers are not obvious from your framework.

Some of these that come to mind are the following. First, how many samples are needed to provide assurance of real changes due to antibiotics versus random changes that occur over time? Are present baselines defined?

Secondly, what is the definition of resistance? Is it just any increase in dose required to inhibit organisms, or is it the total resistance to a previously effective antibiotic?

Many new antibiotics have required an increased dose after initial introduction, but remain effective at the slightly higher dose levels on an indefinite basis. Would such be considered evidence sufficient to remove an antibiotic? If required dose increases, what level is considered resistance, 2X, 100X, et cetera?

Thirdly, where would microbes be sampled? Is it feasible to do adequate sampling on the farm? Who would do this, and what level of funding would be needed to have government employees doing this sampling? What does the farm information do if it does not relate to the level on the food? What are levels on farm or at the processing level more important to human health considerations?

We hope that the VMAC and your professional staff will discuss these and other related scientific issues, and provide us with answers prior to taking any actions that have a major impact on the health and well being of animals.

Further, we would hope that your deliberations would identify areas of critical information that are really needed to shore up the basis for such decisions.

In addition, we would hope to have your support for research funding to provide enough information to make all of us more comfortable with the important questions that are being raised.

Thank you very much.

DR. STERNER: Thank you, Dr. Glenn.

Questions from panel members?

[No response.]

DR. STERNER: You really drew the short straw when it comes to how much we could stand.

I want to personally thank you all for your kind indulgence. I think we might have set an all time record for a continuous meeting. That is not my intent, but I think you all see the importance of this issue and the deliberations that will go on subsequent to our tomorrow morning's two scheduled speakers.

With that, we stand adjourned until tomorrow morning's reconvention.

[Whereupon, at 7:45 p.m., the proceedings were recessed, to be resumed at 8:30 a.m., Tuesday, January 26, 1999.]


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