Volume 1

Resistance to antibiotics and other antimicrobial agents / Select Committee on Science and Technology.

  • Great Britain. Parliament. House of Lords. Science and Technology Committee.
Date:
1998
Catalogue details

Licence: Open Government Licence

Credit: Resistance to antibiotics and other antimicrobial agents / Select Committee on Science and Technology. Source: Wellcome Collection.

    30/112 (page 28)
    3.6 Though applied in sub-therapeutic doses, growth promoters also appear to have the effect of suppressing disease (Q 418). While antibiotics for therapeutic use are available on a prescription- only basis (POMs), growth promoters are generally available to livestock producers from food manufacturers (“Pharmacy and Merchant’s List”—PML), without veterinary prescription.” Human health concerns ~ 3.7. The widespread use of antimicrobial agents as growth promoters, and the public health implications of their use, precipitated the appointment of a Committee on the Use of Antibiotics in Animal Husbandry and Veterinary Medicine (the Swann Committee: see Box 6) which in 1969 recommended banning the use of human therapeutic antibiotics as growth promoters for animals. This led to legislation. However no restriction was placed on the use of such antibiotics for therapy or prophylaxis in animal use. In 1992, the Expert Group on Animal Feedingstuffs (the Lamming Committee) recommended that prophylactic use should be “reconsidered”; the Veterinary Products Committee accordingly reconsidered it, and decided to “discourage” it, while continuing to consider each case on its merits. 3.8 Despite the Swann Report, the use of antimicrobial agents as growth promoters continues to generate criticism that they are used for purely economic reasons and as substitutes for good husbandry and hygiene, and that because of the risk to human health they should be banned (e.g. SKB p 475, Soil Association p 505), or at any rate restricted (e.g. Simmons Q 451). According to the BPMEF (p 388), “The only antibacterials authorised as digestive enhancers are ones that are not used, or related to those used, in human medicine. Antibacterials which are known or suspected of causing resistance in human bacteria are not used”. However avoparcin and virginiamycin would appear to be important exceptions: see below, Enterococci. Moreover, an agent reserved for animals today may be discovered tomorrow to have clinical applications in man; and resistance by the particular mechanism of efflux can act on highly diverse molecular classes, so that treatment with an animal agent might well give rise to cross-resistance to an unrelated agent used in man (SKB p 475). 3.9 Inthe course of our inquiry, the WHO convened a major multidisciplinary meeting on this subject.” Its report concluded, “Antimicrobial use leads to the selection of resistant forms of bacteria in the ecosystem of use. This will occur with all uses including treatment, prophylaxis and growth promotion...Low-level, long-term exposure to antimicrobials may have a greater selective potential than short-term full-dose therapeutic use”. The meeting recommended prohibition of growth promoters which are “used in human therapeutics, or known to select for cross-resistance to antimicrobials used in human medicine”; and “a systematic approach towards replacing growth- promoting antimicrobials with safer non-antimicrobial alternatives”. The Chief Medical Officer acknowledged the importance of the WHO meeting, and said, “The area is one of significant concern” (Q 769). Dr Robin Bywater of Pfizer, who attended the WHO meeting, told us that the industry would be “fully supportive” of reduced reliance on antimicrobial growth promoters, “if such products can be replaced by effective alternatives” such as probiotics” (Q 395). 3.10 The animal health and welfare and environmental benefits of growth promoters have been clearly delineated by NOAH (QQ 406-421), the BPMF (p 388) and UKASTA (p 533), and are illustrated by the experience of Sweden in trying to do without them (see below). Antimicrobial resistance in diseases affecting the animals themselves is of welfare and economic concern in animal production, but NOAH does not see it as a major problem in that context (p 212). What matters for our purposes is the potential of animal-derived resistant organisms and their genes The regulatory regime for animal feed is described in the evidence of the Veterinary Medicines Directorate (p 565) and the UK Agricultural Supply Trade Association (UKASTA, p 529). Medical Impact of the Use of Antimicrobials in Food Animals, Berlin, 13-17 October 1997. Probiotics work on the principle that harmful micro-organisms in the alimentary tract may be kept at low levels by displacing them with benign or beneficial organisms, as opposed to destroying them with antibiotics.