Verotoxigenic Escherichia coli in Slaughter Cattle and Ground Beef in South Dakota

Abstract

Fecal swabs collected from 140 cattle at slaughter and 126 ground beef samples collected from all regions of South Dakota during the summer months of 1993 and 1994 were cultured for Escherichia coli O157:H7 with the U.S. Department of Agriculture methodology using the 3M E. coli Test Kit HEC (USDA Report, 1989). In addition to the screening for E. coli O157:H7, the Petrifilm plates were the source for isolated colonies (10 per enrichment for most samples) which were evaluated for shiga-like toxin (SLT) genes and ability to produce SLT I and/or II. The sampling protocol required that fecal swabs and ground beef be collected in four geographical quadrants of the state (Southeast, Northeast, Southwest and Northwest). The cattle management practices in the diverse areas of the state could be evaluated if patterns of infection or contamination were observed.