Occurrence of Escherichia coli O157:H7 in Diverse Farm Environments

Abstract

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.

Escherichia coliO157:H7: Animal Reservoir and Sources of Human Infection

“…None of the 23 STEC strains and 76 isolates from swine=pork samples (meat, feces, or carcasses) in Germany was associated with human disease (von Muffling et al, 2007). In contrast with the prevailing results, a 2-year U.S. study of four swine farms found EC O157:H7 in 8.9% of rectal swabs (Doane et al, 2007), but the study did not report any morbidity, and the bacteria could be nonvirulent. High prevalence of EC O157 in swine feces was noted in South Africa (9.5%, 23=76), but none of 20 isolates harbored stx genes and only 5=20 were eaeþ (Ateba and Bezuidenhout, 2008).…”

“…Fecal samples from seven species of domestic animals revealed no stx genes in chicken feces (Beutin et al, 1993), and surveys of farms with multiple animal types indicate that the prevalence of EC O157 in chickens is low, even if the bacteria are carried by the neighboring cattle. In the United States, EC O157:H7 was found in 3.6% of beef cattle and 7.5% of turkeys but only in 0.9% of chicken (Doane et al, 2007); 1%-6% of bovine fecal samples in each of 12 large cattle farms contained sorbitol-negative EC O157, but only 0.5% (1=200) of pooled samples from poultry was positive (Hancock et al, 1998). In Korea, up to 6.7% of cattle were positive for EC O157 but only one pig (0.3%) and no chickens were positive ( Jo et al, 2004).…”

Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

“…The prevalence of STEC O157:H7 in domestic chicken is relatively low, ranging from 0 to 1.5%, depending on the geographic location sampled (92,94,125,126). Interestingly, the prevalence in turkeys was higher than that in chickens, with up to 7.5% of fecal samples testing positive (92,126). Experimentally colonized chickens have been reported to harbor and shed STEC O157:H7 in their feces for periods in excess of 11 months (127).…”

Smarter inspection will improve food safety in Canada

“…In addition, it now seems that, because of contaminated feed, E.coli O157:H7 can be found in hogs and poultry, where its absence was previously conspicuous. 13 Because antibiotics are used in animal feed to promote growth, repeated exposure of recycled pathogens to antibiotics may increase the frequency of acquired antibiotic resistance by these organisms.…”