| dc.description.abstract | Escherichia coli O157:H7 and the big six non-O157 E. coli serogroups (O26, O45, O103, O111, O121, and O145) have been declared adulterants in meat. Cattle and other ruminants are common reservoirs of these shigatoxigenic E. coli (STEC). However, little is known about the prevalence of STEC in beef cattle, especially on cow-calf operations. Foodborne outbreaks involving STEC have been repeatedly traced back to farms, indicating the need to understand the prevalence of these microorganisms at the pre-harvest level. In this study, fecal, water, sediment, and equipment swab samples were collected from several cow-calf operations in Oklahoma and Louisiana to determine the occurrence of E. coli O157:H7 and the big six non-O157 E. coli as well as identify potential on-farm contamination sources. Positive samples were screened for the presence of stx and eae genes for confirmation as STEC. Results from the study indicate a 4.4% and 21.4% positive occurrence of E. coli O157:H7 in Oklahoma and Louisiana, respectively and a 14% occurrence of non-O157 STEC in both states. The serogroups O26, O45, and O103 were the most prevalent in both states. In Louisiana, the use of municipal water significantly increased prevalence of non-O157 in comparison to the use of well water as a water source (P<0.05). A combination of water sources, predominantly streams and runoff, were used on the Oklahoma farms, which significantly increased (P<0.05) the prevalence of E. coli O157:H7 and non-O157 serogroups. Additionally, results indicate that other factors such as type of feed, animal density, and the frequency of cleaning particular common cattle contact areas like trailers, chutes, and alleyways, may serve as potential contamination sources in the farm environment. | |
