RESEARCH:

The potential for the control of Escherichia coli O157 in farm animals - Duncan SH, Booth IR, Flint HJ, Stewart CS. Division of Gut Microbiology and Immunology, Rowett Research Institute, Aberdeen, UK. J Appl Microbiol 2000;88 Suppl:157S-165S.
The presence of Escherichia coli O157 in the faeces of farm animals appears to provide a primary route for human infection, either through physical contact or by contamination of the food chain. Controlling the survival and proliferation of this pathogen in the ruminant gut could offer a measure of protection in the short term, and ultimately complement alternative biotechnological based solutions. Normally, E. coli is greatly outnumbered in the ruminant gut by anaerobic bacteria, producers of weak acids inhibitory to the growth of this species. Withdrawal of feed prior to animal slaughter reduces the concentration of these acids in the gut and may be accompanied by the proliferation of E. coli. There are conflicting reports concerning the effects of changes in the ruminant diet upon faecal shedding of E. coli O157. It is contended that it is important to identify animal husbandry methods or feed additives that may be accompanied by an increased risk of proliferation of this pathogen. Greater understanding of the mechanisms involved in bacterial survival in the presence of weak acids, in the interactions between E. coli and other gut bacteria, and of the effects of some antibacterial plant secondary plant compounds on E. coli, could lead to the development of novel control methods.


Probiotics: "living drugs" - GW Elmer, Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle. Am J Health Syst Pharm 2001 Jun 15; 58(12):1101-9.
The uses, mechanisms of action, and safety of probiotics are discussed. Probiotics are live microorganisms or microbial mixtures administered to improve the patient's microbial balance, particularly the environment of the gastrointestinal tract and the vagina. The yeast Saccharomyces boulardii and the bacterium Lactobacillus rhamnosus, strain GG, have shown efficacy in clinical trials for the prevention of antimicrobial-associated diarrhea. Other probiotics that have demonstrated at least some promise as prophylaxis for this type of diarrhea are Lactobacillus acidophilus, Bifidobacterium longum, and Enterococcus faecium. The use of S. boulardii as an adjunctive treatment to therapy with metronidazole or vancomycin has been found in controlled studies to decrease further recurrences of Clostridium difficile-associated disease. Other gastrointestinal disorders for which probiotics have been studied include traveler's diarrhea, acute infantile diarrhea, and acute diarrhea in adults. Several Lactobacillus species given in yogurt or in tablet or suppository form have shown clinical efficacy as a treatment for vaginal infections. Lactobacillus strains have also been examined as a treatment for urinary-tract infections. Putative mechanisms of action of probiotics include production of pathogen-inhibitory substances, inhibition of pathogen attachment, inhibition of the action of microbial toxins, stimulation of immunoglobulin A, and trophic effects on intestinal mucosa. The available probiotics are considered nonpathogenic, but even benign microorganisms can be infective when a patient is severely debilitated or immunosuppressed. Probiotics have demonstrated an ability to prevent and treat some infections. Effective use of probiotics could decrease patients' exposure to antimicrobials. Additional controlled studies are needed to clearly define the safety and efficacy of these agents.

PRACTICAL APPLICATIONS:

Botanicals as part of an integrated value-added pork production system - Palmer Holden, Animal Science, Dr. James McKean, Veterinary Medicine, Iowa State University. Leopold Center Progress Reports Volume 10 (2001).
Some herbs are known to exhibit natural antimicrobial activity and other characteristics that could be useful in value-added animal production. Four botanical products were tested for possible inclusion in swine feeds as alternatives to synthetic chemotherapeutic and antimicrobial agents.
http://www.ag.iastate.edu/centers/leopold/pubinfo/2001cpr/00-37.pdf

Alternatives to Antibiotic Use for Growth Promotion in Animal Husbandry - M. Ellin Doyle, Ph.D., Food Research Institute, University of Wisconsin–Madison.
Since the discovery and development of the first antibiotics prior to the Second World War, these drugs have played an important role in curing disease in humans and animals. In 1946 experiments showed that low, subtherapeutic levels of antibiotics could increase feed efficiency and growth in food animals, and the addition of various antibiotics to feed for livestock was initiated. Because prevention of disease transmission and enhancement of growth and feed efficiency are critical in modern animal husbandry, there has been widespread incorporation of antibiotics into animal feeds in many countries.
Swine feeds in the U.S. often contain antibiotics for purposes of disease prevention and growth promotion. According to data from USDA and Animal Health Institute, antibiotics are currently used in 90% of starter, 75% of grower and more than 50% of finisher feeds for pigs. Antibiotics have also been widely used in animal feed in many other countries although a number of individual countries and the European Union have recently restricted the subtherapeutic use of some antibiotics. Precise figures on the relative amounts of antibiotics used in humans and in animal agriculture are impossible to obtain. Various estimates have been calculated by the Institute of Medicine, the Animal Health Institute, a trade organization, and the Union of Concerned Scientists. Human use of antibiotics has been estimated at 1.36–14.64 million kg/yr while estimated antibiotic use in animal agriculture is 7.36–11.18 million kg/yr. Although estimates from different sources are not directly comparable, it is clear that there is significant use of antimicrobial agents both in human medicine and in agriculture. Currently, the potential for agricultural antibiotics to contribute to the development of antibiotic-resistant bacteria of human concern is the subject of intense debate and research.
http://www.wisc.edu/fri/briefs/antibiot.pdf


ALTERNATIVES TO ANTIBIOTIC FEED ADDITIVES FOR PIGS
Why are we becoming concerned over feeding antibiotics to farm animals?
From the outset, there were worries that through over-use, the effectiveness of feed antibiotics might diminish and that strains of bacteria would arise which were resistant to their effect. Of greatest concern was the possibility that resistance generated on the farm could lead to a loss of effectiveness of key antibiotics in human medicine.
Recently the European Community reviewed the technical information and changing social attitudes to the use of additives in animal feed. As a result the EU has introduced legislation, which effectively bans most feed antibiotics from August 1999.
http://www.bsas.org.uk/socinfo/isspaps/isspap06.htm

Do they take sugar? Part I: new alternatives in pig nutrition –
New thinking, inevitably presents commercial opportunities directed with enthusiasm to a
beleaguered pig industry already punch drunk from 'flavour of the month' products, many of which disappear without trace within months of their launch. Products pioneered at some obscure university, allegedly achieving excellent results when fed to pigs in distant lands, tend to be associated with a lack of credible data, and an excess of marketing hype. Nevertheless, enlightened farmers and their veterinary surgeons are extending the range of products used to fight disease and are increasingly using these to complement new management strategies.
http://www.scientecmatrix.com/seghers/tecma/matrix.nsf/fnl1?openform&link=http://www.scientecmatrix.com/tecma/matrix.nsf/WELCOME1_IE?OpenFrameset

Antimicrobials in Food Production: Resistance and Alternatives: Many Attractive Alternatives to Antibiotics Despite Challenges Bringing Them into Wide Use –
Information describing exactly how much antimicrobials go into animal feed for growth promotant uses and how much are being used to treat diseases in animals is hard to come by. One reason is that manufacturers have not been forthcoming about such figures. One common estimate is that about half of the antimicrobials used in agriculture goes to growth promotion. A 1978 estimate from the FDA is that 50% of all antibiotics made in the United States ends up in animal feeds.
http://www.asmusa.org/memonly/asmnews/apr01/feature2.html

The Search for Alternative Feed Additives - Janice Murphy, OMAFRA Swine Nutritionist.
At the Agriculture's Role in Managing Antimicrobial Resistance Conference, Will Nap, the chair of Ontario Pork, discussed building a strategy to address antimicrobial resistance for the swine industry. In reference to antimicrobial use he commented, "we must assume that an outcry against their use in production practices will require some form of abatement in Canada." As consumer acceptance shifts away from antimicrobial use in livestock production, alternatives are being explored and minds are opening up to new, and even some old, possibilities.
http://www.gov.on.ca/OMAFRA/english/livestock/swine/facts/info_n_alternativefeed.htm

Agricultural antibiotics and resistance in human pathogens: Villain or scapegoat? - Allison J. McGeer, MSc, MD. CMAJ 1998;159:1119-20.
As described in this issue by Dr. George Khachatourians, the use of antimicrobial drugs in agriculture also has a significant impact on resistance in human pathogens. Nearly half of all antimicrobial use in North America is in agriculture, and the great majority of such use is for promotion of growth in farm animals, rather than for crop treatments or therapy. The volumes used, and the fact that the low doses of antibiotics used for growth promotion may be more effective in inducing resistance than the higher doses used for therapy, mean that this use of antibiotics contributes significantly toward selection for antimicrobial resistance in human pathogens.
http://www.cma.ca/cmaj/vol-159/issue-9/1119.htm

Producing Pigs without Antibiotic Growth Promoters - William H. Close
Close Consultancy, 129 Barkham Rd. Wokingham, RG41 2RS UK. Advances in Pork Production (2000) Volume 11, pg. 47.
This paper considers the consequences of the removal of antibiotic growth enhancers in pig diets and examines alternative strategies that are available as replacement products.
http://www.afns.ualberta.ca/bps/bps2000/PDFs/Chap06%20-%20Close.pdf