DEFRA Antimicrobial Resistance Coordination Group, Policy Division, Veterinary Medicines Directorate, Woodham Lane, New Haw, Surrey KT15 3LS, UK
Keywords: surveillance, antimicrobial, resistance, veterinary
Sir,
A recent issue of the Journal carried a meeting report by Hunter and Reeves1 on the current status of surveillance of resistance to antimicrobial agents. Members of the DEFRA Antimicrobial Resistance Co-ordination (DARC) Group thought an update of recent developments in the veterinary field in the UK might be of interest to readers.
The most recently available figures summarizing sales of antimicrobials for use in animals for 2000 in the UK were published in February 2002 by the Veterinary Medicines Directorate (VMD), DEFRA (www.vmd.gov.uk). Extrapolation of the figures produced by other countries, particularly those outside the European Union, to the UK situation may not be entirely appropriate, since in some other countries the recommendations of the Swann Committee (1969)2 have not been adopted and a range of antimicrobials is still available for use as growth promoters in animals.
A network of 14 regional veterinary laboratories in England and Wales belonging to the Veterinary Laboratories Agency (VLA) has contributed to a national veterinary antimicrobial susceptibility database since 1998. The results of this surveillance for antimicrobial resistance in veterinary pathogens and certain commensal bacteria of animals are available on the DEFRA website at www.defra.gov.uk/animalh/diseases/zoonoses/conference/index.htm. The Zoonoses Order of 1989 requires that the isolation of a salmonella in the UK from certain species of animals (including the common farmed domestic species) must be reported to the relevant authority (the VLA in England and Wales) and a culture provided, if required. In most cases, a culture is required, and the majority of these salmonella cultures are subjected to susceptibility testing. The results are summarized annually and are also available on the web at www.defra.gov.uk/animalh/diseases/zoonoses/conference/index.htm. In addition to the isolates from animals, salmonellas from imported birds, animal feeds and the imported raw constituents of animal feeds are also screened for resistance. Veterinary salmonellas have been screened in England and Wales for antimicrobial resistance since the early 1970s. The DARC Group is not aware of any herd health schemes that routinely look at the degree of resistance of bacteria carried by healthy animals, although this has been suggested as a distinguishing quality and safety mark.3
Studies on the prevalence of certain bacterial pathogens and their degree of antimicrobial resistance in healthy animals (sheep, cattle and pigs) at the point of slaughter have recently been completed by DEFRA. The results were announced at a public meeting on Surveillance for Antimicrobial Resistance in Domestic Livestock and the Risks to Public Health, held at the National Agricultural Centre, Stoneleigh on 12 February 2002 and are also available at the web address given above. These studies included zoonotic organisms (Salmonella spp. and Campylobacter spp.) as well as commensals such as Escherichia coli and Enterococcus faecium. Thus, there are two complementary approaches to surveillance occurring in the veterinary field. These provide both a targeted alert system to detect the emergence of new types of resistance in veterinary pathogens and certain zoonotic organisms such as Salmonella spp., and also surveillance of selected populations of particular relevance to public health (animals at the point of slaughter).
Although a number of studies have demonstrated transmission of resistant bacteria or bacterial resistance genes along the food chain from animals to man,4,5 the overall contribution of animals to the resistance problems in man has proved more difficult to assess. Clearly, some events, such as the evolution of multi-resistant tuberculosis and methicillin-resistant Staphylococcus aureus, have been linked to medical, and not veterinary, use of antimicrobials. An important factor aiding progress in this area is considered to be harmonization of the test methods used in medical and veterinary laboratories. Some advances have already been made in this direction; for example the susceptibility studies on campylobacter isolates from animals at slaughter were performed using a method identical in all respects to that in use at the PHLS Laboratory for Enteric Pathogens, Colindale. This ensured that the levels of resistance in human and animal isolates could be compared directly. A harmonization trial to standardize the susceptibility testing of salmonellas within the UK at the medical and veterinary reference laboratories is currently being considered.
A proposal for developing a strategy to strengthen veterinary surveillance for antimicrobial resistance has been published on the website of the VMD (www.vmd.gov.uk). The Draft Strategy for Surveillance of Antimicrobial Resistance in Animals: Action Plan for England and Wales completed a 12 week public consultation exercise earlier this year to seek the views of interested stakeholders. The comments received are now being considered by the DARC Group.
Acknowledgements
The DARC Group are particularly grateful to Mr Chris Teale (VLA) and Professor John Threlfall (PHLS) who collated the information for this manuscript on behalf of the DARC Group.
Footnotes
* *Tel: +44-1932-338409; Fax: +44-1932-336618; E-mail: k.goodyear{at}vmd.defra.gsi.gov.uk
References
1
.
Hunter, P. A. & Reeves, D. S. (2002). The current status of surveillance of resistance to antimicrobial agents: report on a meeting. Journal of Antimicrobial Chemotherapy 49, 1723.
2 . Swann Report. (1969). Joint Committee on the Use of Antibiotics in Animal Husbandry and Veterinary Medicine. Report. HMSO, London.
3 . Van den Bogaard, A. E. J. M. & Stobberingh, E. E. (1996). Is it time to ban all antibiotics as animal growth-promoting agents? Lancet 348, 14546.
4
.
Mølbak, K., Baggesen, D. L., Aarestrup, F., Ebbesen, J. M., Enberg, J., Freydenahl, K. et al. (1999). An outbreak of multidrug-resistant, quinolone-resistant Salmonella enterica serotype Typhimurium DT104. New England Journal of Medicine 341, 14205.
5 . Walker, R. A., Lawson, A. J., Lindsay, E. A., Ward, L. R., Wright, P. A., Bolton, F. J. et al. (2000). Decreased susceptibility to ciprofloxacin in outbreak-associated multiresistant Salmonella typhimurium DT104. Veterinary Record 147, 3956.[ISI][Medline]