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Published: 08/06/22 11:10 Categories: Microbiology
Commemorations are being held in June for World Food Safety Day. This action is celebrated every year to draw attention and mobilize action to prevent, detect and manage foodborne risks and improve human health, which affect one in ten people around the world.
Foodborne pathogens and diseases
The most commonly found microorganisms mainly responsible for infectious outbreaks include Salmonella, Campylobacter, Listeria, Yersinia and Shiga toxin‐producing E. coli (STEC). The latter is positioned as the fourth most reported zoonotic disease in the EU in 2020 according to EFSA, whose data were impacted by two major causes: the UK's withdrawal from the EU and the COVID-19 pandemic.
Reported numbers of cases and notification rates of confirmed human zoonoses in the EU, 2020. EFSA and ECDC, 2021. The European Union One Health 2020 Zoonoses Report.
Escherichia coli, as is well known, is a gram-negative bacterium of the Enterobacteriaceae family and is considered to be part of the gut microbiota present in the vast majority of animals and human beings.
Specifically referring to STEC, also known as VTEC or EHEC, it is one of the main pathotypes of this bacterium that is unique due to its expression of Shiga toxins, very similar to Shigella dysenteriae toxins.
Within STEC, the most common serotype, due to its historical predominance in outbreaks and sporadic cases, is O157. However, this picture would seem to be changing, due to the emergence of other STEC serotypes over recent years, such as O26, O103, O104 and O145. It is important to point out that not all serotypes need to be reported.
Is STEC relevant to food safety?
The dangers of STEC lie in its transmission, which occurs primarily via contaminated foods and is therefore one of the most frequent causes of gastroenteritis. The most serious risk, however, is the chance of contracting Hemolytic Uremic Syndrome (HUS) which is characterized by acute kidney failure, and can even affect other organs such as the lungs, pancreas and heart and even cause death, in which the population most at risk are infants and the elderly.
Even though annual cases are not as high as Campylobacter or Salmonella cases, it is important to continue with the control and monitoring of STEC in food in order to avoid outbreaks such as the cases of contaminated seeds in Germany in 2011 (serotype O104). Last December saw an outbreak of contaminated chives (serotype O157) in Denmark, which resulted in one death, while the most recent outbreak came this March, in which the driver of infection was apparently a frozen product's dough (serotype O26) which sadly resulted in the death of two children.
The ISO 16654 standard indicates the method for the detection of STEC in food samples:
- Enrichment of the sample with TSB Broth Modified with novobiocin
- Selective isolation in CT-SMAC Agar and CondaChrome®E. coli O157:H7
And for rapid detection due to the presence of glucuronidase specific for E. coli, Condalab has available TBX Chromogenic Agar in accordance with the ISO 16649 standard.
For further information, sign up to watch the recording of our CondalabTalk 'STEC and its impact on food safety'. And if you need further information about our products or methods, do not hesitate to contact us.