A rapid, sensitive method for testing the activity of Escherichia coli 0157:H7 secreted cytotoxins against epithelial cells from the jejunum and descending colon of cattle

Abstract

Current methods for assessing Escherichia coli O157:H7 secreted cytotoxin activity are based on exposing human cell lines for 12 to 72 h and monitoring changes in cell morphology, adherence or enzyme release. These methods, although sensitive, use non-ruminant cell lines that may not represent cattle responses to E. coli O157:H7 secreted cytotoxins. The modified lawn assay used in this study was found to be a simple, fast and sensitive method for assessing cattle epithelial cell susceptibility to E. coli O157:H 7 secreted cytotoxins within 4 to 6 h. Key words: Escherichia coli O157:H7, cattle, intestine, cytotoxins, cytotoxicity