Occurrence of Escherichia coli O157:H7 in diverse farm environments

In the United States, foodborne outbreaks of Escherichia coli O157:H7 illness have often been linked to the consumption of contaminated, undercooked ground beef. However, the occurrence of E. coli O157:H7 has also been reported in other farm animals. The objective of this study was to evaluate the occurrence of E. coli O157:H7 on diverse farm types and from a variety of farm samples. Rectal swabs (n=1686) and environmental samples (n=576) were collected from 16 farms in five states over 24 months and analyzed for the presence of E. coli O157:H7. Overall, E. coli O157:H7 was found in 3.6% of beef cattle, 3.4% of dairy cattle, 0.9% of chicken, 7.5% of turkey, and 8.9% of swine samples. The pathogen was isolated sporadically from each of the environmental sample types. Of particular concern was the isolation of E. coli O157:H7 from fresh feed samples, indicating a potential vector for transmission. The data from this study indicate a high occurrence of E. coli O157:H7 on swine and turkey farms. This unexpected result suggests that more research on the occurrence of E. coli O157:H7 on these types of farms is required in order to better understand potential reservoirs of pathogenic E. coli.