Grass-Fed Cattle and E. coli O157:H7
Researchers have busted the food safety myth that grass-fed beef has less risk of E. coli O157:h7 than grain-fed beef. The study, to be published in Foodborne Pathogens and Disease, tested bacterial contamination rates in 50 beef products labled as “grass-fed” and 50 conventionally raised beef products. The percentages of Escherichia coli positive samples did not differ between the two groups (44% vs. 44%).
The researchers conclusion:
Taken together, these data indicate that there are no clear food safety advantages to grass-fed beef products over conventional beef products.
Source: Jiayi Zhang, Samantha K. Wall, Li Xu, Paul D. Ebner, “Contamination Rates and Antimicrobial Resistance in Bacteria Isolated from “Grass-Fed” Labeled Beef Products,” Foodborne Pathogens and Disease. -Not available-, ahead of print. doi:10.1089/fpd.2010.0562.
Cranberry Juice and the Mechanical Forces Involved in the Attachment of E. coli O157:H7
Researchers at Worcester Polytechnic Institute (WPI) in Massachusetts may have discovered why cranberry juice fights off E. coli O157:H7 infections. In a paper published this month by Molecular Nutrition and Food Research, “Direct adhesion force measurements between E. coli and human uroepithelial cells in cranberry juice cocktail“, Professor Terri Camesano and his team present the first specific measurements of the mechanical forces involved in the attachment of the virulent E. coli to human urinary tract cells.
The study also documents how the force of attachment is reduced in the presence of cranberry juice cocktail. “This is not a clinical study—it’s a mechanical study that shows us the direct forces that can lead to infection,” Camesano said.
E. coli O157:H7 is covered with small hair-like projections known as fimbriae which act like hooks and latch onto cells that line the urinary tract. When enough of the virulent E. coli adhere to cells in this way, they cause an infection. Previous work by Camesano has shown that exposure to cranberry juice causes the fimbriae on E. coli to curl up, reducing their ability to attach to urinary tract cells.
“We know, on average, how many fimbriae are on each E. coli cell. And the total force we measured correlates with that number. So the data lead us to believe that the fimbriae each bind to a specific receptor on the uroepithelial cells,” Camesano said.
The data showed that the attachment force of the virulent E. coli weakened as the amount of cranberry juice cocktail increased. The study also showed that a strain of E. coli without fimbriae did not bind well to the human urinary tract cells, regardless of the concentration of cranberry juice cocktail, providing further evidence that fimbriae are essential for infection.
Furthermore, Camesano’s team found that in the absence of cranberry juice, the strength of the virulent E. coli’s bond to the human cells was so strong that it could not be broken by the typical force of urine flowing through a person’s urinary tract. However, as the cranberry juice concentration increased, the bond weakened to the point where the E.coli could be stripped away by the force of flowing urine. “The shear force created by flowing urine is a defense mechanism against urinary tract infection,” Camesano said.
E. coli Found in Reusable Grocery Bags
Research out of the University of Arizona in Tucson and Loma Linda University in Loma Linda, California found Escherichia coli (E. coli) in 12 % of reusable grocery bags used for the study. Researchers collected shopping bags from consumers entering grocery stores in San Francisco, Los Angeles and Tucson. Owners of the bags were interviewed on bag usage, storage and cleaning.
Only 3% of the reusable grocery bag owners bothered to wash their bags, which was determined by the researchers to reduce the bacteria in bags by 99.9%. Also, people used the same bags to carry meat and produce, creating a situation ripe for cross contamination.
E. coli Raw Milk Minnesota Outbreak Investigation Grows
A Minnesota E. coli outbreak linked to raw milk has state health officials digging deeper into the investigation of how at least eight people became sick, and how to prevent the outbreak from growing, according to local news sources.
The E. coli raw milk outbreak has been linked to Hartmann Farm dairy in Gibbon, Minnesota and has sickened at least 8 people. At least one of the cases has developed into a serious complication called hemolytic uremic syndrome, or E. coli HUS. This occurs when the E. coli infection damages the blood cells, causing serious kidney problems and in some cases, death.
Since state health investigators from the Minnesota Department of Agriculture (MDA) and the Minnesota State Health Department (MDH) began investigating the farm on May 26, they have returned to confiscate records and collect samples from Hartmann Farm owner Michael Hartmann. At the beginning of the investigation, health officials stated the strain of E. coli found at the Hartmann farm matched the strain found in the outbreak victims. Later, according to news sources:
“State investigators went back to the Michael Hartmann farm in Gibbon a second time last Wednesday to collect more samples, confiscate financial records, and document what they allege are unsanitary conditions on the farm.”
Throughout the investigation, officials have pointed to a number of concerns about the farm and its production process, including unsanitary conditions due mostly to manure contamination, and milking facilities that investigators called “filthy.” Officials took photos and collected more testing samples on a June 16 search of the farm, and confiscated Hartmann’s financial and production records, which officials believe will show Hartmann was producing and selling foods like milk, cheese, yogurt, ice cream and meat all in violation of food safety laws.
E. coli Prevention Starting With Cattle: Research Report
Stopping E. coli at one of its most common sources–the digestive systems of cattle–is the subject of new E. coli prevention research from the University of Idaho.
The potentially life-threatening bacteria, E. coli O157:H7, colonize in cattle’s gastrointestinal tracts and can live there because the bacteria is harmful to humans but not cattle. Fecal matter from the environments in which the cattle are raised can spread and contaminate meat during the slaughtering process, and/or contaminate surrounding water supplies and groundwater that can lead to contamination of produce growing in the surrounding areas.
Researchers, however, are gaining insight into how E coli bacteria grow and survive inside cattle. The University of Idaho study shows that E. coli O157:H7 bacteria have chemical signals that allow it to sense their environment and activate certain genes in the cattle that help the bacteria colonize in cattle’s guts. And the ability to disrupt that signal could hold the key to preventing the life-threatening pathogen from growing inside the cattle, researchers say. This could potentially be done through feed additives that would block the transmission of that chemical signal.
E. coli Prevention: What you can do
Although research is an important component of E. coli poisoning prevention, the truth is that E. coli bacteria can still be found in foods, beverages and water sources. According to food safety attorney Fred Pritzker:
“Preventive measures by the meat industry may reduce the number of cattle that carry E. coli and the frequency of contamination of meat during processing. But since research into such prevention measures is just beginning, it is important that you understand the steps you can take to protect yourself and your family.”
E. coli Prevention
- Cook meat thoroughly
- Keep a clean kitchen
- Drink pasteurized beverages
- Wash fruits and vegetables thoroughly
- Wash your hands
USDA-FSIS Guidance for Reducing Escherichia coli O157:H7 Shedding in Cattle
USDA-FSIS has issued a guidance for reducing Escherichia coli O157:H7 (E. coli O157:H7). According to the guidance, pre-harvest cattle management controls and interventions are emerging as an option that offers great opportunity to improve food safety.
Consensus within the beef industry is that beef producers should follow basic recommended principles of cattle management. The following are the basic recommended principles of cattle management.
- Clean water;
- Clean feed;
- Clean environment that is appropriately drained;
- Separate housing of calves and heifer or reduced animal density; and
- Biosecurity—wildlife exclusion to the extent possible.
According to the FSIS, current research has not shown a reduction E. coli O157:H7 shedding in cattle when these basic principles are used. Nevertheless, FSIS supports the principles because of their foundation in animal health and welfare. They provide a foundation for the processing interventions and sanitary dressing procedures used to control E. coli O157:H7 contamination in raw beef.
