TESTING OF BOB CALF FECAL SWABS FOR THE PRESENCE OF ESCHERICHIA-COLI O157-H7

Rectal swabs were collected from 304 Bob calves (calves under 10 d old ) brought to slaughter in the states of Washington (77 swabs), Califor nia (127 swabs), and Wisconsin (100 swabs). The swab samples were test ed for the presence of Escherichia coli 0157:H7 by the use of a direct smear method, enrichment method, and the use of the Petrifilm(TM) Tes t Kit-HEC-for hemorrhagic E. coli 0157:H7 (3M Company, St. Paul, MN). The organism was not isolated from any of the samples by any method, t hough the 3M test kit did give 21 positive signals. Of these positive signals, three were shown to be caused by sorbitol-positive, O157-posi tive, H7-negative E. coli. The cause of the other 18 signals was not d etermined.