FIGURE 5.

Animal and human commensal microbiota illustrating the passage of resistance genes from animals to humans. The acquisition in healthy subjects, either of resistance genes or resistant bacteria from food-producing animals, involves the pivotal role of the human commensal GIT microbiota. This can be regarded as a sieving filter, able first to retain and then amplify genes of resistance derived from the food chain or the environment. These persisting genes may subsequently be transmitted, possibly after a long delay, to specific human pathogens.