SENSITIVITY OF ESCHERICHIA-COLI O157-H7 STRAIN-932 TO SELECTED ANTICOCCIDIAL DRUGS IN BROILER CHICKS

The ability of selected anticoccidial drugs to inhibit the colonizatio n of day-old male broiler chicks (Comish Rocks) by Escherichia coli 01 57:H7, strain 932 was examined. Chicks were challenged with 1.8 x 10(9 ) E. coli 0157:H7 on Day 1, and fed diets supplemented with three sele cted anticoccidial drugs; monensin, nicarbazin, or robenidine. The cec al and colon fecal contents of the chicks were removed on Day 7, 14, a nd 21 postinoculation and examined for the concentration of E. coli 01 57:H7 per gram of contents. Monensin effectively reduced cecal and col on colonization of the chicks by E. coli 0157:H7. By Day 7, there were significant reductions in the bacterial population of the cecal conte nts of chicks receiving the monensin-medicated feed, and by Day 21 no E. coli 0157:H7 was recovered from the cecal and colon contents. The b acterial counts in the colon contents of the nicarbazin- and robenidin e-medicated and unmedicated chicks were significantly higher than the monensin-treated chicks. Bacterial populations in the colon contents w ere high only when there were high bacterial concentrations in the cec al contents.