A variety of antimicrobial types are used in livestock production. Their use inevitably leads to the selection of resistant forms of bacteria in the ecosystem of use. This selection will occur with all uses in livestock production including treatment, prophylaxis and growth promotion.
Priority medical problems arising from the use of antimicrobials in livestock production have been summarized1 recently. Use of quinolones2 in livestock has been identified as a particular area of concern because of the significance of this group of antimicrobials for the treatment of a broad range of infections in humans including gastrointestinal infections caused by zoonotic bacteria transmitted to humans via the food chain.