Norway tests fermented sausages for E. coli

An analysis of fermented sausages in Norway has found only one sample was positive for E. coli.

The Norwegian Veterinary Institute examined domestically produced fermented sausages for Shiga toxin-producing E. coli (STEC). There was one positive but the E. coli type usually does not cause serious human infection.

A total of 137 samples of fermented sausage were collected in 2020 and analyzed in 2021 on behalf of the Norwegian Food Safety Authority (Mattilsynet).

Enriched samples were tested for the presence of the genetic markers Shiga toxin (stx)1, stx2 and the intimin (eae) gene. Attempts at isolation were carried out from samples that were positive for one or more of the virulence markers. Isolates identified as STEC were further characterized using whole genome sequencing.

Shiga toxin-producing E. coli was isolated from only one sample, and it was STEC O76:H19 harboring stx1c, but not eae. STECs that carry stx1c are also often eae negative and are not commonly associated with serious illness, according to the report.

Good results in first analysis
In the primary screening of enriched samples, only a few were positive for the virulence markers. Results indicate that the occurrence of STEC in Norwegian fermented sausages is low, despite the small number of samples tested.

Such products had not been analyzed previously so the survey provides knowledge for the industry, authorities and research institutions. It is important to carry out similar work regularly to get updated Norwegian data, according to the report.

There has been an increase in human STEC cases in Norway in recent years with 511 in 2019 and 331 in 2020. The decrease from 2019 to 2020 is mainly due to fewer people infected abroad. In 2020, the most common serogroups were O103 and O26 with 22 and 20 cases each in Norway.

Only one sample in the survey contained stx and eae genes, and this was also positive for both stx1 and stx2. Two samples were positive for stx genes. Six were positive for eae.

“The study showed that there is a low incidence of dangerous E. coli bacteria in fermented sausages. Previous studies of cattle, sheep and ground (minced) meat also indicate a low incidence of selected types of E. coli. Although the sample selection was not large, these are good results for the meat industry,” said Catherine Svindland, from Mattilsynet.

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