Are E. coli Really Becoming More Heat Resistant?

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the December 2020 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

The past few columns have talked about how antibiotic use contributes to antibiotic resistant bacteria. The same survival-of-the-fittest principle applies to environmental stresses like heat.

Shiga-toxin-producing E. coli (STEC, including E. coli O157:H7) are the main food safety concern in Canadian beef processing facilities. High temperatures kill E. coli, so for many years large beef processing facilities have used hot water and steam to sanitize knives, equipment, carcasses and meat, and refrigeration to inhibit subsequent microbial re-growth. But if packing plants routinely use heat-based treatments to combat microbial contamination, will STEC and other E. coli eventually become heat-resistant and pose a risk to food safety? Continue reading

Do Cattle Bacteria Contribute to Antibiotic Resistance in Human Medicine?

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2020 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

E. coli live in the digestive tracts of warm-blooded animals and birds. Most are harmless, some are beneficial, and some (like E. coli O157:H7) can be very dangerous. E. coli are also involved in antibiotic resistance.

“Extended-spectrum beta-lactamase producing” (or ESBL) E. coli are a major concern in human medicine. These bacteria are resistant to many antibiotics used in both human and veterinary medicine. Ordinary E. coli can cause urinary tract or bloodstream infections in people. They’re usually quite easy to treat with antibiotics. But if ESBL E. coli are responsible, the infection can’t be easily treated with antibiotics, and the illness can be much worse or even fatal.

E. coli rarely causes disease in feedlot cattle. But ESBL E. coli are still a concern, because antibiotic resistance genes are often located on “mobile genetic elements” that bacteria can trade with each other, even with completely unrelated bacteria. So antibiotic resistant BRD bacteria like Mannheimia, Pasteurella or Histophilus can spread their antibiotic resistance genes to each other, or possibly to E. coli. That’s like a border collie developing horns after a day of herding Herefords. Continue reading

Your Burgers Are Still Done at 71

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2018 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

Maintaining consumer confidence is crucial to our industry. Consumer confidence in the safety of Canadian beef was briefly shaken by the 2012 XL Foods E. coli outbreak that infected at least 18 people, and resulted in the recall of 1,800 tonnes of beef, a $4 million legal settlement and the sale of the packing plant to JBS Canada. That event also led to a resurgence in media interest in E. coli research. Articles in both Meatingplace.com and the National Post featured interviews with researchers who expressed concern that Health Canada’s recommendation to cook hamburger patties to an internal temperature of 71oC may not be adequate to kill some strains of E. coli. These concerns stemmed from papers published in 2011, 2015 and 2016 that studied the genetics of heat resistant E. coli strains that had survived carcass washing interventions in a commercial beef processing facility in 2001 and 2002.

These concerns deserved serious investigation. In response, Continue reading

Developing Faster, Less Expensive Diagnostic Tests

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the October 1, 2018 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.



Last month’s column discussed how antibiotics are used in Western Canadian cow-calf operations. Respiratory diseases are a common reason for antibiotic treatment in cows, bulls, and calves and diarrhea is a common reason for antibiotic treatment in young calves. Because both respiratory and intestinal infections can involve many different microbes, having a better understanding of what microbes may be causing a particular animal to be sick could allow more appropriate treatment decisions. For example, antibiotics don’t kill viruses, so using antibiotics won’t help an outbreak of scours that is primarily viral in nature. Similarly, some antibiotics are more effective against some bacteria than others, so being able to select the antibiotic that is most appropriate for the bacteria that are involved would be helpful.

Continue reading

Non-O157 STEC

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the November 2016 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.


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There are between 50,000 and 100,000 different serotypes (strains) of E. coli. Most are harmless, some may be beneficial, but some produce a very dangerous Shiga toxin. Shiga toxigenic E. coli (STEC) can cause vomiting, diarrhea and abdominal pain in people. E. coli O157:H7 is the most well-known STEC, but it is not the only one.

All STEC’s carry at least one stx gene coding for the Shiga toxin, an eae gene coding for a protein that helps E. coli attach to the intestinal surface, and a wzx gene that codes for an “O” antigen. All three of those genes must be present in the E. coli cell for it to be a STEC.

Food safety risks due to E. coli O157:H7 are well known, and the beef industry has made great progress in controlling it. Non-O157 STEC infections are rarer, but in 2011 Continue reading

Dry Chilling (and two other things)

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the April 2016 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.


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The muscle tissues of healthy animals are essentially free of bacteria until carcasses are skinned. At that point, it is impossible to eliminate the transfer of bacteria from the hide and the environment to the meat.
Many of those bacteria are harmless, but some can cause meat to spoil faster. Others, like verotoxigenic E. coli (e.g. E. coli O157:H7 and others) can pose a very serious risk to human health. Well-managed packing plants can minimize the transfer of bacteria from the animal to the carcass, but they can’t eliminate it completely. Many food safety interventions such as Continue reading

Consumer MisReports

Consumer Reports Food Safety and Sustainability Center released its “Beef Report” on August 25. A number of questions, concerns and criticisms have been raised by the North American Meat Institute, the International Food Information Council, Business Insider, and others. Rather than answer the specific questions raised, Consumer Reports has encouraged people to read the report more closely.


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Unfortunately, reading the report more closely simply raises more questions about the expertise and/or integrity of Consumer Reports and its “policy and action arm,” Consumers Union.

Here’s one example.

The Danger of Superbugs” heads a section on Page 10 and 11 detailing the health hazards posed by Shiga-toxin producing E. coli (STECs, like E. coli O157). This directly implies that antimicrobial resistance will make STEC infections more difficult to treat. This is not true.

Antibiotics are not used to treat STEC infections in people. Instead, Continue reading

Hot Water Treatment of Beef Trim

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the March 2015 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.


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Combating bacteria would be simple if they stayed on the surface of beef. In that case, nearly any spray or wash could contact and kill the bacteria or wash them off. But beef isn’t smooth. Shallow cuts and cracks crisscrossing the meat surface can hide and protect bacteria. Killing these hidden bacteria is not simple. Irradiation would work, but isn’t approved for use in Canada yet. Organic acid washes and sprays may not reach the bacteria hidden in these cracks, or the acids may be neutralized by the meat proteins before bacteria can be killed. To kill these bacteria, food safety interventions need to penetrate a short distance into the meat surface. This is particularly important for beef trim (the small pieces of fat and meat that are removed as the carcass is processed into smaller cuts) that is used for hamburger. The late Dr. Colin Gill of AAFC Lacombe showed that exposing beef trim to extremely hot water essentially “cooks” the top few millimeters, and kills up to 90% of bacteria.

This raises an interesting dilemma. Consumers want safe beef, but they also Continue reading

Practical and effective food safety procedures for beef packing plants



Recent work has shown that E. coli can essentially be eliminated from dressed carcasses in commercial packing plants. Carcass chilling processes can be operated to supplement or largely substitute for decontaminating treatments. Machinery and personal equipment can be cleaned and used in ways that prevent such equipment from contaminating meat during carcass breaking. As a result, food safety issues with beef may arise if known best practices and treatments and practices necessary to produce cuts and trimmings free of pathogenic E. coli and Salmonella are incompletely or inappropriately implemented.

Research currently underway and funded by the National Check-off and Canada’s Beef Science Cluster is working to identify which Continue reading

Flipping for Mechanically Tenderized Beef

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the October 2014 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.


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All food surfaces carry bacteria, including steaks and roasts. Because beef cooks from the outside in, the outer surface is exposed to higher temperatures for a longer time than the inside of the beef. The heat of cooking will inactivate bacteria as long as they remain on the outside of cuts, and the surface is cooked thoroughly. That’s why steaks and roasts can be eaten rare. In ground beef, microbes from the surface get mixed throughout the beef, so consumers are encouraged to cook ground beef to an internal temperature of 71oC.

Mechanical tenderization pierces beef with small blades or fine needles. This cuts the connective tissue and makes the beef more tender. This improves the eating quality of lower cost, tougher beef cuts. Price and tenderness are two of the major drivers of consumer buying behavior and eating satisfaction, so mechanical tenderization has proven quite useful. Approximately 20% of Canadian beef is mechanically tenderized.

But if there are Continue reading