the first stage of the study, a subset of 365 clinical samples was also plated in
parallel onto MacConkey agar in order to qualitatively assess the commensal
flora as well as the selectivity of the two selective media (ESBL-Bx and MCKC).
The chromogenic ESBL-Bx was obtained from the manufacturer as a prepared
plate medium, and MCKC was prepared from a dehydrated medium according
to the manufacturer’s instructions. All media were incubated in air at 37°C for 18
to 24 h. For a subset of 279 specimens, the incubation of cultures was prolonged
for 48 h