Category Archives: E.coli O157:H7

Research – Prevalence of Shiga‐like toxin producing Escherichia coli strain (E. coli O157) in freshly consumed vegetables and its characterization

Wiley Online Library


Escherichia coli is a vast genus with various beneficial to harmful species. O157:H7 is a shiga‐like toxin (stx) producing E. coli that cause’s major health threats in humans, through oral route. However, the presence of E. coli O157:H7 in vegetables is not yet reported in India. Hence, we surveyed the vegetables markets and enumerated the presence of E. coli O157 in freshly consumed vegetables namely, cucumber, radish, lettuce, cabbage, and menthos. Three consecutive surveys from three different market areas were done with 1 month interval. A total of 603 E. coli colonies were isolated. Presence of shiga toxin genes (Stx) were confirmed by colony polymerase chain reaction (PCR) using Stx1 and Stx2 markers that showed 25 and 12 positive colonies, respectively. Among the five vegetables, cabbage had the highest Stx positive colonies (16%). Compared to supermarkets, vegetables from the farmers market did not have much load of E. coli O157. Further, characterization of isolated E. coli colonies were performed using PCR techniques with gene specific markers namely, E. coli uidA, E. coli O157 specific uidA and intimin gene markers. Our analysis showed 6% of E. coli O157 population in the freshly consumed vegetables much above than 2% threshold level, thus providing a warning foresight related to disease outbreak.

Practical applications

Molecular survey using a number of Escherichia coli O157 specific genes through PCR is an easy, rapid, and a reliable method for pathogenic bacteria identification and characterization amidst other indigenous microbial load. Additionally, polymerase chain reaction (PCR)‐based enumeration of E. coli O157 in vegetables assist us in determining the threshold level for forewarning of pathogenic disease outbreaks. Further, the severity of outbreak could be predicted using E. coli O157 specific shiga toxin (stx) and receptor genes (intimin). The presence of E. coli O157 specific shiga toxins and intimins in a pathogen signifies severity and virulence of strains in causing potential outbreaks. PCR‐based studies enables rapid identification of inoculums source (E. coli O157 spread) from farmers field/cattle shed. Thus, it could be reliably used to stop the further spread of disease from the source inoculums during the outbreaks.

USA – FDA Report on E. Coli O157 Outbreak in Romaine Lettuce Points to “Significant” Finding of Strain in Sediment of Water Reservoir

Food Safety Tech 

The November 2018 outbreak of E.coli O157:H7 infections linked to romaine lettuce caused 62 illnesses across 16 states. The FDA zeroed in on the Central Coast growing regions of northern and Central California as being responsible for the contamination. The outbreak was declared over on January 9 and yesterday FDA released the report, “Factors Potentially Contributing to the Contamination of Romaine Lettuce Implicated in the Fall 2018 Multi-State Outbreak of E.Coli O157:H7”, which provides an overview of the investigation.

The report states that a sediment sample coming from an on-farm water reservoir in Santa Maria (Santa Barbara County, California) tested positive for the outbreak strain of E. coli O157:H7. Although this particular farm was identified in several legs of the Fall 2018 traceback investigations that occurred in the United States and Canada, as well as being a possible supplier of romaine lettuce in the 2017 traceback investigations, the FDA said that the farm is not the single source of the outbreak, as there is “insufficient evidence”. The traceback suggests that the contaminated lettuce could have come from several farms, because not all tracebacks led to the farm on which the contaminated sediment was found.


Research – Season and Species: Two Possible Hurdles for Reducing the Food Safety Risk of Escherichia coli O157 Contamination of Leafy Vegetables

Food Protection Eurofins Food Testing UK

The food safety risk of Shiga toxin–producing Escherichia coli (STEC) infection per serving of leafy vegetables was investigated using a quantitative microbial risk assessment (QMRA) approach. The estimated level of E. coli O157 contamination was based on observed numbers of Enterobacteriaceae and E. coli on leafy vegetables grown and processed in southern Sweden from 2014 to 2016. Samples were collected before harvest, after washing, and at the end of shelf life. The observed counts were combined with data on the ratio of E. coli to E. coli O157 taken from earlier studies to estimate the probability of illness. The risks of STEC infection associated with species, either spinach (Spinacia oleracea) or rocket (Diplotaxis tenuifolia), growing season (spring or autumn), and washing (washed or not washed) were then evaluated. The results indicated that leafy vegetable species and growing season could be possible hurdles for reducing the food safety risk of STEC infection. At harvest, the probability of infection was 87% lower when consuming rocket compared with spinach and 90% lower when consuming leafy vegetables grown in spring compared with autumn. These relative risk reductions remained consistent even with other serving sizes and dose-response models. The lowest risk of STEC infection was associated with leafy vegetables early in the production chain, i.e., before harvest, while the risk increased during storage and processing. Consequently, the highest risk was observed when leafy vegetables were consumed at the end of shelf life. Washing had no effect on the food safety risk of STEC infection in this study. To improve the quality of QMRA, there is a need for additional data on the relationship between indicator organisms that can be easily enumerated (e.g., E. coli and Enterobacteriaceae) and E. coli strains that can cause STEC infection (e.g., E. coli O157) but are difficult to identify in food samples such as leafy vegetables.

UK- Scotland – Guidance for Scottish local authority officers on the production of cheese from unpasteurised milk


The Scottish Food Enforcement Liaison Committee (SFELC) has endorsed guidance produced by their Joint Specialist Cheese and Risky Foods Short-Life Working Group on the production of cheese from unpasteurised milk.

The guidance aims to control the microbiological risks in the production of artisan cheeses made from unpasteurised milk, specifically Shiga toxin-producing Escherichia coli(STEC). The guidance applies to all establishments producing cheese made from unpasteurised milk from cows, goats, sheep and buffalo.

Cheese made from unpasteurised milk has been linked to outbreaks of human illness and in particular, illness caused by STEC organisms including E. coli O157. The guidance has been developed in relation to the control of STEC and is intended for use during the inspection and enforcement of food safety controls applied by cheesemakers producing cheese made from unpasteurised milk.

The guidance reflects current scientific knowledge and understanding in relation to STEC and the production of cheese from unpasteurised milk. As scientific information and evidence on STEC evolves, the guidance will be reviewed. In addition, the guidance will complete a pilot implementation phase before a scheduled review.

The guidance is available to view at:

Details of a recent report on pathogen risks in unpasteurised cheese in Scotland can be viewed on the HPS weekly report, current note 52/5006:

Research – University of Cincinnati professor studies hamburger E. coli (O157) with NIAID grant


kswfoodworld E.coli O157

Image CDC


Alison Weiss, PhD, professor in the Department of Molecular Genetics, Biochemistry and Microbiology in UC College of Medicine, has been awarded a four-year grant of $1.6 million from the National Institute of Allergy and Infectious Diseases (NIAID) to study Shiga toxin producing Escherichia coli 0157:H7, also sometimes referred to as Hamburger E. coli.

Hamburger E. coli is the cause of foodborne illness and is an infection that often leads to bloody diarrhea and can result in kidney failure. It is mostly associated with eating undercooked, contaminated ground beef, and can be spread by person-to-person contact. In severe cases it can be fatal.

The infection was first discovered in hamburger meat, but it is carried asymptotically by many creatures so anything that has fecal matter from cattle can contaminate food, says Weiss. Vegetables and fruits can also carry E. coli if contaminated with animal fecal matter during field irrigation or as a result of harvesting or preparation of produce. Human hygiene practices can also spread E. coli.

Shiga toxin producing E. coli (STEC), including 0157:H7, are an important cause of diarrheal disease, causing about 265,000 illnesses in the United States annually.

USA – CDC Reports Romaine Lettuce Outbreak Over – E.coli

Food Safety Tech Eurofins Food Testing UK

Although FDA is continuing its investigation into the source of the E.coli outbreak involving romaine lettuce grown in California, the CDC has declared the outbreak over. Contaminated romaine that caused illnesses should no longer be available, FDA stated in an outbreak update. Consumers will not need to avoid romaine lettuce, and retailers and restaurants do not need to avoid selling or serving the product, according to the agency. Suppliers and distributors need not avoid shipping or selling any romaine that is on the market either.

UK – UK family still waiting for answers one year after E. coli poisoning

Barf Blog

The Yorkshire Post reports parents of two boys who be­came se­ri­ously ill af­ter con­tract­ing E.coli 0157 sus­pected to be from beef burg­ers are still wait­ing for an­swers from su­per­mar­ket gi­ant Sains­bury’s more than a year later.

Al­fie and Oliver Maude, then seven and three, from Rich­mond, North York­shire, came down with up­set stom­achs two days af­ter eat­ing the Taste the Dif­fer­ence Aberdeen An­gus burg­ers in Oc­to­ber 2017. Al­fie was ad­mit­ted to Dar­ling­ton hos­pi­tal two days later with ex­cru­ci­at­ing stom­ach pain and se­vere de­hy­dra­tion.