Category Archives: E.coli O157:H7

Research – Response to Questions Posed by the Food and Drug Administration Regarding Virulence Factors and Attributes that Define Foodborne Shiga Toxin–Producing Escherichia coli (STEC) as Severe Human Pathogens

Journal of Food Protection


The National Advisory Committee on Microbiological Criteria for Foods (NACMCF or Committee) was asked to report on (i) what is currently known about virulence and pathogenicity of Shiga toxin–producing Escherichia coli (STEC) and how they cause illness in humans; (ii) what methods are available to detect STEC and their specific virulence factors; and most importantly (iii) how to rapidly identify foodborne STEC that are most likely to cause serious human disease. Individual working groups were developed to address the charge questions, as well as to identify gaps and give recommendations for additional data or research needs. A complete list of Committee recommendations is in Chapter 4.

STEC infections cause illnesses that range in severity from diarrhea to diarrhea with grossly bloody stools, called hemorrhagic colitis (HC), to the life-threatening sequela of infection, the hemolytic uremic syndrome (HUS). STEC are ingested in contaminated food or water or through direct contact with infected animals or people. Of all STEC that cause disease in the United States, E. coli O157:H7 (O157) causes the most outbreaks and the largest number of cases of serious illness (as assessed by the number of patients hospitalized or with HUS). The infectious dose 50% (ID50) of O157 is low (estimated to be 10 to 100 bacteria). As determined in animal models, these bacteria bind to enterocytes in the large intestine through the intimin outer membrane protein (the gene for intimin is eae), attach and efface the mucosa, and elaborate Shiga toxin (Stx) that passes from the intestine through the bloodstream to sites in the kidney. Certain Stx subtypes are more commonly associated with severe STEC human illness, e.g., Stx2a, Stx2c, and Stx2d. The serogroups (O antigen type only) linked to most cases of illness in the United States are O157, O26, O103, O111, O121, O45, and O145 in order of decreasing incidence. STEC disease is linked most often to foods of bovine origin and fresh produce; disease burden attributed to beef and dairy products is broadly similar in numbers to that attributed to fresh produce.

Stx production, a phage-encoded trait, and intimin, but not the O antigen type, are major drivers of pathogenicity. Thus, predictions of the pathogenic potential of STEC can be made based on Stx subtype and the potential of the bacteria to attach in the intestine. The combination of virulence genes in E. coli that has led to the most severe disease is stx2a with aggR (a genetic marker for enteroaggregative E. coli [EAEC]). The second-highest risk group are those O157 STEC that have stx2a and eae, followed by that same combination in O26, O103, O111, O121, O45, or O145. The combinations of stx1a and stx2a, or stx2a and stx2c, or stx2d with eaeare also of particular concern. The lack of eae suggests a reduced potential for human disease except when aggR or stx2d is present. There have been a few exceptions to this hierarchy, such as O103 that produce only Stx1 and O113 that is eae negative.

The protocols currently used by the U.S. Food and Drug Administration (FDA), U.S. Department of Agriculture–Food Safety and Inspection Service (USDA-FSIS), clinical laboratories and public health laboratories (PHLs), and the food industry include enrichment, culture, multiplex real-time PCR (RT-PCR), toxin immunoassays, biochemical characterization, DNA-based serotyping, DNA microarray, and whole genome sequencing (WGS). The advantages and limitations of each method are summarized in this report. New and developing high-throughput methods are discussed and include metagenomics, digital PCR, biosensors, and microarray.

STEC disease prevention has been and will continue to be driven by improvement in outbreak detection, investigation, and food industry practices. Highlights of Committee recommendations include the following:

  • Develop a new universal enrichment culture medium that can be broadly used for all STEC in any food.

  • Explore high-throughput methods that can detect STEC virulence factor genes directly from enrichment medium and develop and/or improve methods that can ascertain that all critical STEC markers found in the enrichment broth are within the same cell to eliminate the need to isolate the organism.

  • Expand systematic sampling of food, animals, and water for STEC.

  • Explore ways for industry to share test data anonymously.

  • Fund academic research on (i) the regulation of toxin expression and the phages that encode toxin; (ii) mechanisms of attachment by eae-negative STEC; (iii) oral-infection animal models or cell culture models that are more reflective of human disease; and (iv) human host factors that influence the outcome of STEC infection.

  • Link standardized epidemiological, clinical, and STEC WGS data to monitor trends in recognized and emerging virulence attributes such as Stx type and phage profiles.

  • Further develop WGS methods to (i) predict toxin levels produced by an STEC and (ii) generate a classification scheme based on genomic clusters.

The Committee agrees that a combination of genetic characteristics (attributes) exist that signal potentially high-risk STEC and that these STEC will eventually be identifiable using high-throughput techniques that analyze gene profiles. Thus, to rapidly identify foodborne STEC that are most likely to cause serious human disease, the Committee recommends that STEC analyses move toward using virulence markers rather than serogroup or serotype to identify pathogens. The Committee concurs that as ease of use increases and costs decrease, culture-independent diagnostic tests (CIDTs) based on genomic clusters or lineages will be more broadly used to predict whether an STEC isolate is likely to cause serious human disease.

Executive summary of the charge.

STEC are a large, diverse group of bacteria that are characterized by the production of Stx. There are two main Stx types, designated Stx1 and Stx2, and within each are many subtypes. Currently, there are three known Stx1 (Stx1a, Stx1c, and Stx1d) and seven known Stx2 (Stx2a, Stx2b, Stx2c, Stx2d, Stx2e, Stx2f, and Stx2g) subtypes, but some of these are produced mostly by environmental- or animal-associated strains. Thus far, Stx1a, Stx2a, Stx2c, and Stx2d are the subtypes most frequently implicated in human illness. There are estimated to be >400 known STEC serotypes that can produce any of the Stx types, subtypes, or combination of subtypes. However, only a subset of these STEC serotypes have been associated with human illness. Furthermore, the production of Stx alone without other virulence factors, such as intimin, has been deemed to be insufficient to cause severe human illness.

Research – Shiga toxin/verocytotoxin-producing Escherichia coli (STEC/VTEC) infection – Annual Epidemiological Report for 2017


In 2017, 6 457 confirmed cases of infections with Shiga toxin/verocytotoxin-producing Escherichia coli (STEC/VTEC) were reported in the EU/EEA.

Research -Inhibition of bacterial human pathogens on tomato skin surfaces using eugenol‐loaded surfactant micelles during refrigerated and abuse storage

Wiley Online


The plant‐derived essential oil component eugenol (1.0% wt/vol), free or loaded into surfactant micelles constructed of sodium dodecyl sulfate (SDS; 1.0% wt/vol), 200 ppm free chlorine (hypochlorous acid [HOCl]; pH 7.0), and sterile distilled water were evaluated for their ability to reduce Salmonella Saintpaul and Escherichia coli O157:H7 on skin surface samples of Roma tomatoes. Samples were treated and then stored aerobically for up to 10 days. All samples were initially stored at 5 °C; one set of samples was shifted to 15 °C after 5 days of storage to simulate temperature abuse during postharvest handling. Encapsulated and free eugenol, HOCl, and empty SDS micelles reduced pathogens to nondetectable counts (detection limit: 0.5 log10 cfu/cm2) during refrigerated storage (p ≥ .05). Conversely, during temperature abuse storage (15 °C), only free and micelle‐loaded eugenol consistently reduced pathogens to nondetection. Eugenol‐loaded micelles can be used to decontaminate harvested tomatoes from enteric bacterial pathogens.

Practical applications

Tomatoes may be consumed raw and have been repeatedly implicated in the occurrence of human foodborne disease. Washing of tomatoes with novel antimicrobial interventions that increase the dispersion of antimicrobials over the surface of the tomato should result in greater reduction of microbial foodborne pathogens through enhanced contact of antimicrobial with pathogen. Application of surfactant micelle‐entrapped eugenol onto tomato surfaces reduced Salmonella Saintpaul and Escherichia coli O157:H7 to nondetection during refrigerated (5 °C) and temperature abuse (15 °C) storage. Micelle‐loaded eugenol reduced numbers of aerobic bacteria, Enterobacteriaceae, and fungi to nondetection during temperature abuse storage.

Research – An approach to improve the safety and quality of ready‐to‐eat blueberries

Wiley Online


Bioactive edible coatings were developed and applied to blueberries as a natural treatment. E. coli O157:H7, L. innocuaS. aureus, and P. aeruginosa were subjected to four bioactive compounds and to three film‐forming solutions (FFS). Vanillin and geraniol at low concentrations (1.2–1.8 mg/mL and 0.4–1 μL/mL) demonstrated significant inhibitory effects on all pathogens counts. Chitosan (Ch) showed a high antimicrobial activity (final counts below 2 log CFU/mL). The effectiveness of Ch plus vanillin (Ch‐Va) and geraniol (Ch‐Ge) in improving the safety were tested against pathogens inoculated on blueberries. Ch, Ch‐Va, and Ch‐Ge coatings exerted a bactericidal effect on all pathogens (from 1.24 to more than 2 log reductions). Significant reduction in yeast and mold counts was achieved with Ch (1.09 log) and Ch + Va (1.74 log). Sensory attributes of blueberries remained acceptable. Ch‐Va and Ch‐Ge were an alternative to improve the quality and safety and could be effective in extending the shelf life of ready‐to‐eat blueberries.

Practical applications

The present study proposes the use of natural coatings enriched with biopreservatives as a technological alternative to enhance the quality and safety of minimally processed fruits. According to the results obtained, the application of chitosan plus vanillin/geraniol coatings on fresh blueberries would allow to offer a safe product and respond the growing demand of consumers for fresh, environmentally friendly and chemical preservatives‐free foods. These findings and those obtained by the sensory evaluation support the practical application of this alternative in the minimally processed fruit industry.

USA – Aurora Packing Recalls Beef Products For Possible E. coli 0157

Food Poisoning Bulletin

kswfoodworld E.coli O157

Image CDC


Aurora Packing Company of Illinois is recalling about 4,838 pounds of beef heel and chuck tender products because they may be contaminated with E. coli O157:H7 bacteria. No confirmed reports of illness have been received in association with this recall.

The products were produced and packed on February 27, 2019. These are the recalled products:

  • Varying catch weight cardboard box case packages containing bulk pieces of “AURORA ANGUS BEEF BONELESS BEEF – CHUCK TENDER” and case code 61150 marked on the label.
  • Varying catch weight cardboard box case packages containing bulk pieces of “BONELESS BEEF – HEEL MEAT” and case code 29970 on the label.
  • Varying catch weight cardboard box case packages containing bulk pieces of “BONELESS BEEF – HEEL MEAT” and case code 49970 stamped on the label.

These products have the establishment number “EST. 788” inside the USDA mark of inspection. They were shipped for institutional use in Illinois, Iowa, and Wisconsin. The problem was discovered during FSIS traceback activities after routine testing.

USA – Beef heel and chuck tender recalled over E. coli O157:H7 fears

Food Safety News

Aurora Packing Company, Inc.,  located in North Aurora, IL  is recalling approximately 4,838 pounds of beef heel and chuck tender products that may be contaminated with E. coli O157: H7, according to the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS).

The bulk beef products were produced and packed on Feb. 27, 2019. The following products are subject to recall:

  • Varying catch weight cardboard box case packages containing bulk pieces of “AURORA ANGUS BEEF BONELESS BEEF – CHUCK TENDER” and case code 61150 represented on the label.
  • Varying catch weight cardboard box case packages containing bulk pieces of “BONELESS BEEF – HEEL MEAT” and case code 29970 represented on the label.
  • Varying catch weight cardboard box case packages containing bulk pieces of “BONELESS BEEF – HEEL MEAT” and case code 49970 represented on the label.

The products subject to recall bear establishment number “EST. 788” inside the USDA mark of inspection. These items were shipped for institutional use in Illinois, Iowa, and Wisconsin.

The problem was discovered during traceback activities following routine FSIS testing. There have been no confirmed reports of adverse reactions due to consumption of these products.

Research – Estimate of the annual burden of foodborne illness in nondeployed active duty US Army Service Members: five major pathogens, 2010–2015

In this study, we estimate the burden of foodborne illness (FBI) caused by five major pathogens among nondeployed US Army service members. The US Army is a unique population that is globally distributed, has its own food procurement system and a food protection system dedicated to the prevention of both unintentional and intentional contamination of food. To our knowledge, the burden of FBI caused by specific pathogens among the US Army population has not been determined. We used data from a 2015 US Army population survey, a 2015 US Army laboratory survey and data from FoodNet to create inputs for two model structures. Model type 1 scaled up case counts of Campylobacter jejuniShigella spp., Salmonella enterica non-typhoidal and STEC non-O157 ascertained from the Disease Reporting System internet database from 2010 to 2015. Model type 2 scaled down cases of self-reported acute gastrointestinal illness (AGI) to estimate the annual burden of Norovirus illness. We estimate that these five pathogens caused 45 600 (5%–95% range, 30 300–64 000) annual illnesses among nondeployed active duty US Army Service members. Of these pathogens, Norovirus, Campylobacter jejuni and Salmonella enterica non-typhoidal were responsible for the most illness. There is a tremendous burden of AGI and FBI caused by five major pathogens among US Army Soldiers, which can have a tremendous impact on readiness of the force. The US Army has a robust food protection program in place, but without a specific active FBI surveillance system across the Department of Defence, we will never have the ability to measure the effectiveness of modern, targeted, interventions aimed at the reduction of specific foodborne pathogens.