Effects of esculin and esculetin on the survival ofEscherichia coliO157 in human faecal slurries, continuous-flow simulations of the rumen and colon and in calves

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Abstract
The human pathogenEscherichia coliO157:H7 is thought to be spread by direct or indirect contact with infected animal or human faeces. The present study investigated the effects of the plant coumarin esculin and its aglycone esculetin on the survival of a strain ofE. coliO157 under gut conditions. The addition of these compounds to human faecal slurries andin vitrocontinuous-flow fermenter models simulating conditions in the human colon and rumen caused marked decreases in the survival of an introduced strain ofE. coliO157. When four calves were experimentally infected withE. coliO157 and fed esculin, the pathogen was detected in five of twenty-eight (18 %) of faecal samples examined post-inoculation, compared with thirteen of thirty-five (37 %) of faecal samples examined from five control calves not fed esculin. Coumarin compounds that occur naturally in dietary plants or when supplemented in the diet probably inhibit the survival ofE. coliO157 in the gut.