Cattle are considered to be an important reservoir for E. coli O157:H7 (7). E. coli O157:H7 resides in the intestine of cattle, which intermittently shed this pathogen in their feces (4). Fecal contamination of meats during processing of cattle causes significant economic losses to the cattle industry and accounts for numerous outbreaks of severe diarrheal illness in humans (9). Moreover, release of E. coli O157:H7-contaminated manure into the environment carries a potential risk for contaminating ground water, fruits and vegetables. Several disease outbreaks have resulted from consumption of vegetables (5), fruits/fruit juices (3), and drinking water (1) which presumably become contaminated with E. coli O157:H7- containing manure. Reducing valence and shedding of E. coli O157:H7 in cattle, therefore, may prove an effective pre-harvest strategy for reducing post-harvest contamination of meats and for protecting water and agricultural products from E. coli O157:H7 contamination.
The objectives of the study were to use a modified strain of E. coli O157:H7 as a vaccine against E. coli O157:H7.