Ecological impact of antibiotic use in animals on different complex microflora: environment

Different means of interaction between microecological systems in different animal hosts (including humans) and the environment may occur during the t ransfer of resistant bacteria and their resistance genes. Spread of resista nce takes place in different ways with respect to clonal spread of resistan ce strains by the spread of wide host range plasmids and translocatable ele ments. Commensals in ecosystems have a special significance and a pronounce d capacity for acquisition and transfer of resistance genes as with Enteroc occus faecium and Escherichia coli in the gut flora or Pseudomonas spp. in aquatic environments. The route of transmission from animals to humans by m eat products is well established. Other routes via water and food plants (v egetables) have been investigated less, although resistance genes transfer in aquatic environments as evidenced from sequence comparison of such genes (e.g. tetR,floR in Salmonella typhimurium DT104). Whether this is due to r are but important transfer events or whether there is a more frequent excha nge in aquatic or terrestrial environments needs further elucidation. (C) 2 000 Elsevier Science B.V and International Society of Chemotherapy. All rig hts reserved.