Texas Tech University graduate students recently went shopping in 32 cities in 28 states for the kind of non-O157 toxin-producing escherichia coli now killing people in Europe.
While they did not find the rare serotype wreaking havoc in northern Europe, what they did find should be enough to concern Americans.
TTU graduate student Jessie L. Vipham and her colleagues collected samples from ground beef and whole-muscle beef cuts to test for the prevalence of non-O157 Shiga toxin-producing E. coli (STEC), Campylobacter and Salmonella.
All totaled, the TTU shoppers collected enough beef between February and May 2011 for 2,915 samples.
Non-O157 STEC antigens, like the deadly O104:H4 pathogen associated with the outbreak in northern Europe, were found in 5.9 percent of the beef samples.
“Whole muscle cuts had a prevalence of 4.11 percent and ground beef samples prevalence was 6.99 percent,” Vipham wrote for her master’s thesis in Animal Science.
The non-O157 serotypes found in the beef were some of the better known ones in the United States, including O26, O145, O103, and O111. While fairly common, these E. coli strains are not defined as “adulterants” by USDA’s Food Safety and Inspection Service (FSIS) and therefore are allowed in meat.
Among all E. coli strains, only O157:H7 is legally considered an adulterant — a poison — in meat and therefore not tolerated by FSIS inspectors.
The TTU study, which will be presented at the International Association for Food Protection’s (IFP’s) annual conference later this summer in Milwaukee, also found Campylobacter in 9.3 percent of the samples, with 17.24 percent in whole muscle cuts and 7.35 percent in ground beef.
Salmonella was present in 0.65 percent, with 1.02 percent found in whole cuts and 0.54 percent in ground beef.
Since October 2009, FSIS has been sitting on a petition filed on behalf of victims of non-O157 Shiga Toxin-producing E. coli to declare six more strains as adulterants. In addition to the four strains found in beef by TTU, the petition requests that 0121 and 045 be kept out of meat.
“Creating pathogen baselines in U.S. retail beef is imperative for targeting interventions for pathogen control,” Vipham wrote.
Since 2000, the federal Centers for Diseases Control and Prevention in Atlanta have required reporting of infections by non-O157 STECs, and concluded they “pose a significant health threat.” The CDC estimates that the six E. coli strains petitioners want declared adulterants cause an estimated 36,700 illnesses, 1,100 hospitalizations, and 30 deaths annually.
E. coli has been associated with human illnesses only since 1982, although there is debate over whether these are new pathogens or whether they have just been recently identified. The TTU study says there are more than 200 serotypes of STEC, but only those with “key virulence factors” cause human illness.
“In the past, most research has focused on E. coli O157:H7 because it was declared an adulterant for ground beef products in 1994,” Vipham wrote. “However, non O157 STEC have recently implicated in recalls and outbreaks, which may lead to the potential identification of non-O157 STECs to be labeled by the Food Safety and Inspection Service (FSIS) as adulterants.”
Vipham says non-O157 STEC accounted for 80 percent of diarrheal illnesses in Germany even before the current deadly O104:H4 outbreak.
In the U.S., Vipham found that in New Mexico recent annual totals of laboratory-confirmed, sporadic STEC infections were dominated (64 percent) by non-O157 STEC cases over STEC O157 cases (36 percent).
“Very little is currently known about non-O157:H7 STEC and their impact on food safety,”Vipham adds. “However, as explained above there is significant evidence to support a connection between the presence of these pathogens and foodborne illnesess.”
The TTU study says there were at lease 23 outbreaks of non-O157 STEC illnesses between 1990 and 2007 involving contaminated salads, berries, milk, cider, and punch being among the transmission sources.
Noting that Sen. Kirsten Gillibrand, D-NY, has proposed legislation to add the six non-O157 STEC strains to the Federal Meat Inspection Act (FMIA) adulterant list, the TTU study opined that “this type of legislation could be damaging to the beef industry, given that STEC are naturally occurring in the intestines of most farm animals.”
The study said worldwide prevalence for non-O157 STEC range from 4.6 to 55.9 percent in feedlot cattle; 4.7 to 44.8 percent in grazing cattle; and in cattle at harvest from 2.1 to 70.1 percent.
The Center for Science in the Public Interest is petitioning FSIS to declare four strains of antibiotic-resistant Salmonella — Salmonella Heidelberg, Newport, Hadar, and Typhimuriumin — as adulterants in ground meat and poultry because of the health threat they pose.