The importance of commensal bacteria as mediators in the transmission and spread of resistance genes has been widely reported in the literature (6, 19) and both the correlation between the use of antibiotics in animals and increased numbers of resistance genes in the human microbiota (14) and the function of these bacteria as a reservoir of resistance genes that spread through the various ecosystems (15) have been demonstrated. Animals and animal products thus constitute a ‘stockpile’ from which resistant bacteria can be transferred to