A bulletin for the Australian Food Industry September 2001
Contents: Chloropropanols in food | Irradiation of herbs, spices and certain nuts in Australia | Surface decontamination of melons | Antibiotic use in food producing animals | 75 years of CSIRO Research
Antibiotic use in food producing animals
The use of antibiotics in animals has been a contentious public health issue for many decades. Antibiotic resistance in foodborne pathogens is a growing problem in both developed and developing countries although the underlying causes of the two scenarios are probably different.
- Obligatory prescriptions for all antimicrobials used for disease control in food animals.
- Termination or rapid phasing-out of the use of antimicrobials for growth promotion if they are also used for treatment of humans in the absence of a public health safety evaluation.
- Creation of national systems to monitor antimicrobial usage in food animals.
- Pre-licensing safety evaluation of antimicrobials with consideration of potential resistance to human drugs.
- Monitoring of resistance to identify emerging health problems and timely corrective actions to protect human health.
- Guidelines for veterinarians to reduce overuse and misuse of antimicrobials in food animals.
The over-riding concern is that addressed in the second principle, the use of antibiotics for growth promotion in food animals if those same antibiotics are used for the treatment of human disease.
The same position as that taken by the WHO consultancy had previously been strongly stated by the Joint Export Advisory Committee on Antibiotic Resistance (JETACAR) in Australia. JETACAR was established in 1998 by the Commonwealth Department of Health and Aged Care and the Commonwealth Department of Agriculture, Fisheries and Forestry - Australia. In handing down in 1999 a report titled, The use of antibiotics in food producing animals: antibiotic-resistant bacteria in animals and humans , JETACAR presented 22 recommendations to the Health and Agriculture Ministers.
Foremost among these was the recommendation that Australia adopt a conservative approach to minimise the use of antibiotics in humans and animals.
- are of demonstrable efficacy in livestock production under Australian farming conditions; and
- are rarely or never used as systemic therapeutic agents in humans or animals, or are not considered critical therapy for human use; and
- are not likely to impair the efficacy of any other prescribed therapeutic antibiotic or antibiotics for animal or human infections through the development of resistant strains of organisms.
This is the background to the decision in July 2001 of the Australia New Zealand Food Standards Council (ANZFSC) not to accept, without a further review, a recommendation of the Australia New Zealand Food Authority (ANZFA) to allow low level residues of cephalosporin antibiotics in beef sold for human consumption. The cephalosporin family of antibiotics is an important treatment of many human infections because it remains relatively free of the resistance problems that have diminished the effectiveness of some other antibiotics.
The proposal from ANZFA has been referred back to JETACAR which was established to assess the whole issue of antibiotic resistance in the Australian context. The ANZFA position, based on advice from JETACAR, is that antibiotic residues in Australian foods are already very low and permitted residue limits are set so low they are unlikely to play a role in the development of resistance by foodborne bacteria. This tends to be confirmed by the results of the 1999/2000 National Residue Survey which found that in 5000 samples of beef, sheep meat, pork, chicken and game, fewer than 3 per cent contained antibiotic residues and fewer than 0.3 per cent contained residues above the maximum permitted limit.
However the action taken by ANZFSC is a result of concern all round the world. In a review of the spread of antibiotic resistance in foodborne bacteria, workers at the Laboratory of Enteric Pathogens, Central Public Health Laboratory, London (International Journal of Food Microbiology 6 2000 1) state that drug resistance in foodborne bacterial enteric pathogens is an almost inevitable consequence of the use of these antimicrobials in food producing animals. The drugs may be used either therapeutically or prophylactically or for growth promotion (as feed additives).
These authors believe that the acquisition of antibiotic resistance in certain strains of Salmonella typhimurium followed the introduction in calf husbandry of antimicrobials, or of veterinary analogues with cross resistance to antibiotics, used in human medicine. For Campylobacter spp., resistance in the UK and the USA to certain classes of antibiotic used in chickens has also increased although the authors note that, in this case, the way these antibiotics have been used in human medicine is also an important factor.
In another review published before the ANZFSC decision, an Australian worker cautioned that countries such as Australia that have not licensed fluoroquinolones for use in food-producing animals and have restricted the use of third generation cephalosporins should maintain that stance (Nutrition Research Reviews 13 2000 279).
The question of antibiotic resistance in foodborne bacteria has now been taken up by the Codex Alimentarius Commission's Committee on Food Hygiene. A discussion paper recommending that the Committee commission risk assessments for specific bacterium / antimicrobial / food combinations has been prepared and it calls for priority proposals from member countries. The Codex Committee on Residues of Veterinary Drugs in Foods is also to consider a discussion paper on the use of antimicrobials in animal production at its meeting in December 2001.
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