Presence of any Shiga toxin-producing E. coli (STEC) in ready-to-eat food is a potential risk to health, regardless of strain or genetic fingerprint, according to Food Standards Scotland (FSS).

The agency says it wants to make clear its position that such foods should not contain STEC. Presence of STEC in food not cooked prior to consumption has the potential to cause food poisoning. Agency officials said the advice is for local authorities, industry and consumers to ensure there is no misunderstanding.

STEC is defined as an E. coli bacterial cell that contains a Shiga toxin producing gene, also known as stx. The ability of STEC to cause illness involves a number of factors and is not fully understood, according to FSS. While other genes in addition to stx have been linked to serious infections, it is not possible to guarantee a STEC lacking these other genes will not cause illness.

The most common type of STEC infection in Scotland is the potentially deadly E. coli O157, however it is not the only one associated with human illness. Up to 30 percent of STEC isolated from patients in the country are non-O157 strains. About a third of those strains lack other genes that reports say are necessary to cause infection.

The FSS consulted with the Food Standards Agency, Health Protection Scotland, Public Health England, The Moredun Research Institute, Royal Environmental Health Institute of Scotland, Chartered Institute for Environmental Health, the Scottish E. coli O157/STEC Reference Laboratory, Association of Public Analysts Scotland, the Directors of Public Health in Scotland, the Faculty of Public Health UK and the chief medical officer, Scotland in drafting the statement.

Professor Norval Strachan, independent chief scientific adviser for FSS, said the statement clarifies the position with regard to STEC in ready-to-eat food in Scotland.

“Illness caused by STEC can be very serious for young children and older people in particular, and can cause severe disease, and even death,” Strachan said. “As few as 10 – 100 cells of STEC can cause infection. This remains Food Standards Scotland’s paramount concern. Our decisions are always evidence-based and taken in the best interests of consumers.”

The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) released a report on STEC last year.

STEC infection typically causes abdominal pain and diarrhea which is often bloody. Impact of infection can vary, but it is particularly dangerous for vulnerable groups, especially children under five years old and the elderly. Some people may develop serious complications such as hemolytic uremic syndrome (HUS), a cause of kidney failure and infection may prove fatal. HUS is more often associated with strains that produce Stx2a than the stx 1a gene.

Meanwhile, the Public Health Agency of Sweden (Folkhälsomyndigheten) has published a report summarizing a survey in April 2018 on how STEC diagnostics are conducted at Sweden’s clinical microbiological laboratories. It found E. coli diagnostics show large variations between the different labs in the country with varying isolation rates.

Three out of seven labs had a direct multiplex PCR and in this panel STEC was included. The others analyzed the samples for STEC according to specific criteria and/or indications. In line with a previous survey in 2015, the criteria for examining samples for STEC varied greatly as well as the methodology used from detection to isolation.

In Sweden, more than 500 enterohemorrhagic (EHEC) cases are reported per year in humans, of which 50 percent to 60 percent are domestically infected. The highest incidence is seen in those aged 1 to 4 years old.

(To sign up for a free subscription to Food Safety News, click here.)