FIG 1.

Schematic representation of the animal trials used to monitor the ESBL-producing E. coli transmission rate. (A) Representation of one round of trials with animal pairs. Each pen consisted of 4 pairs of I chicks and S chicks and 2 pairs of sentinel (Se) chicks, for a total of 6 cages per pen. (B) Representation of one round of group trials. Five challenged (I) chicks were housed together with 5 susceptible (S) chicks inside a cage in each pen; each group (treated and control groups) was housed in separate pens. Red, challenged (I) chicks; gray, susceptible or sentinel chicks. The schematic representation is not to scale. For details on cage size, distances, and ventilation, refer to “Chickens and housing conditions” in Materials and Methods.