The year before USDA’s new groundbreaking non-O157 E. coli policy went into effect, the agency went back to America’s feedlots to find out just how prevalent six new strains were at the source. The 2011 study into the prevalence of Escherichia coli O-Types and Shiga-Toxin genes in fecal samples from feedlots is being published in the current issue of the pricey journal, Foodborne Pathogens and Disease. According to the abstract for that study, which is behind a $51.00 pay wall, the July to October 2011 investigation into 21 feedlots that volunteered for the study found one or more E. coli O-serogroups in 44.2 percent of the 1,145 fecal pools that were evaluated. 
The pool prevalence for E coli strains was:
- O157 – 19.7 percent
- O45 – 13.8percent
- O103 – 9.9 percent
- O121 – 9.3 percent
- O145 – 5.5 percent
- O36 – 1.1 percent
- O26 – 0.5 percent
“While efforts to control foodborne illness associated with Shiga toxin-producing Escherichia coli (E. coli) O157 through processes and procedures implemented at harvest facilities have been very successful, there is concern about the burden of illness associated with other Shiga toxin-producing E. coli,” the study says. The 2011 feedlot study was conducted at the behest of USDA’s Animal and Plant Health Inspection Service by the Centers for Epidemiology and Animal Health at Colorado State University and the Kansas State Veterinary Diagnostic Laboratory. “Little is known about the prevalence and distribution of these E. coli in the animal production environment,” the researchers said, referring to the six additional strains that were classified as adulterants and became subject to testing after June 4, 2012. The feedlot testing occurred almost a year earlier involved taking individual fecal swabs collected from cattle 60 days after they arrived in the feedlot and then pooling them for evaluation using polymerase chain reaction assay to identify the presence of all seven strains of E. coli that are now banned. E. coli O157:H7 was first recognized a foodborne pathogen associated with consumption of ground beef in 1982. It gained worldwide attention with the Jack-in-the-Box outbreak 20 years ago when nearly 700 illnesses and four deaths occurred. E coli O157:H7 has been banned from beef since 1994. “Nearly all pools were positive for ehxA (99.7 percent) or stx2 (98.6 percent), “ according to the study abstract. “The pool level prevalence for stx1 and eae was 65.5 percent and 69.3 percent, respectively. Pools that were positive for one or more of the other E. coli O-serogroups were 1.37 times more likely to be positive for E. coli O157. “Conversely, pools that were positive for E. coli O157 were 1.43 times more likely to be positive for at least one of the other E. coli O-serogroups evaluated. These data will be useful to understand the expected prevalence of potential Shiga toxin–producing E. coli in cattle feedlots.” The CSU/KSU feedlot study for the Animal and Plant Health Inspection Service marked the third time since 1999 that USDA went to where cattle are held to conduct research.