Spread of plasmid-mediated nourseothricin resistance due to antibiotic use in animal husbandry.

After using of the streptothricin antibiotic nourseothricin in animal husbandry for growth promotion, plasmid-borne resistance to streptothricin could be observed in E. coli from nourseothricin fed pigs, from employees in pig farms and from their family members. Moreover, streptothricin resistance plasmids also occurred in E. coli of man without any contact to pig farms (gut flora and even urinary tract infections). However, these individuals live in villages and towns of the territory where nourseothricin was applied to pigs. Similar streptothricin resistance plasmids belonging to different incompatibility groups were found in both E. coli from pigs and E. coli from human beings. As no coselection of resistance to drugs indispensable for therapeutic use in man was observed, the application of nourseothricin in animal husbandry has not clinical implication for human medicine yet. Nevertheless, this problem remains under further investigation.