Finnish study estimates STEC cases linked to medium-cooked beef patties

Authorities in Finland have assessed the food poisoning risk associated with medium-cooked ground beef patties made from Finnish meat and served in food service outlets.

Medium-rare or medium-done ground (minced) beef patties are associated with the potential for microbiological contamination, especially from Shiga toxin-producing E. coli (STEC). In recent years, illnesses caused by STEC have increased to just under 300 in 2022.

The Finnish Food Authority (Ruokavirasto) found that the proportion of ground beef patties served medium and how hot they were heated greatly influenced the risk of people getting sick. The agency recommends that such patties be served fully cooked in restaurants but also has advice if an outlet wants to sell them medium-cooked.

Modeling risk of illness
If 12 percent of patties were cooked medium to an internal temperature of 55 degrees C (131 degrees F), there would be 100 illnesses per 100,000 residents in Finland per year. If all ground beef patties were served fully cooked, only 3 per 100,000 people would get sick per year. These cases would be caused by cross-contamination in the kitchen.

If all ground beef patties are cooked to perfection, it was predicted that 178 people would fall ill annually. If patties are medium-cooked at 55 degrees C for six minutes, there would be about 30 times the number of sick people. If the internal temperature of medium-ground beef steaks were 60 or 65 degrees C (140 to 149 degrees F), the amount of sick people would be significantly lower.

Data for the risk assessment came from the Finnish Food Authority’s registers and a survey of food establishments with 27 responses. Serving medium-cooked ground steaks appeared to be relatively common. Outlets were either unfamiliar with recommendations on preparing ground beef steaks or did not follow them for various reasons.

Many parts of the model are based on past results published in the literature. As there was no recent research, the STEC prevalence in beef was assumed to be the same as in beef carcasses, which is likely to be overestimated. Scientists said the lack of information causes uncertainty in the results.

A study also looked at how STEC is transferred from the surface of artificially contaminated roast beef to the inner parts of the meat when surfaces are removed. Surface removal only worked when the level of contamination was low. Even then, some tested roasts were still positive.

The environmental department of the Oulu region recently revealed that risk management plans for ground beef steaks served medium in restaurants needed improvement.

Findings showed that customers received information about the doneness of the steak but were not told about the E. coli risk. The microbiological quality of raw meat was good, but STEC was found in two of the 12 samples. Restaurants must put risk management methods in writing. Inspections found that only one of 12 sites had described such written measures as part of self-monitoring.

Sushi control findings
In a separate control operation, officials from Helsinki, Porvoo, Espoo, and Keski-Uusimaa have looked at sushi quality.

177 samples were taken in 2023 from 59 restaurants and 30 stores where sushi was prepared for the public. Regarding microbiological quality, 142 samples were good, 22 were described as avoidable, and 13 were bad. The avoidable samples are still safe to eat. Thirteen repeat samples were taken due to poor initial results. More samples were taken from restaurants, but the quality of sushi made in stores was slightly better. Temperature control, sushi pH, and shelf life were also assessed.

Bacillus cereus was the cause of one poor sample result. Listeria monocytogenes was detected thrice but at levels below 100 colony-forming units per gram (CFU/g). Officials urged the Finnish Food Authority to translate sushi preparation guidelines into different languages to help with instructions and advice given to operators.

“A lot of unheated ingredients are used in sushi, which may partly be the reason for poor sample results. Hygienic handling and storing raw materials and using fresh ingredients are important in ensuring sushi quality,” said the control report.

A similar survey was done in Lappeenranta and Imatra in the summer of 2023. From 23 samples, ten were rated as good, nine as avoidable, and four as bad.

Bacillus cereus was found twice, and Coagulase-positive staphylococci was found thrice. Low levels of Listeria monocytogenes were detected in one sample. Deficiencies were found in sushi temperature control, the surfaces’ cleanliness, and the raw materials’ cooling and freshness.

Operators were given written instructions and asked to consider sample results as part of self-monitoring. All detected issues were corrected.

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