Category Archives: E.coli O157:H7

Research – A Novel Selective Medium for Simultaneous Enrichment of Shiga Toxin–Producing Escherichia coli and Salmonella in Ground Beef

Journal of Food Protection 


Microbiological analysis of ground beef for contamination by both Salmonella and Shiga toxin–producing Escherichia coli (STEC) is performed by the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS), as part of its Performance Standards Verification Testing program. FSIS has established a zero tolerance for STEC serotype O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 because they are regarded as adulterants. The detection and isolation of these specific serogroups presents a technical challenge necessitating time-consuming and costly laboratory procedures that often exceed the technical capabilities of many small internal and reference laboratories. We describe here a method using a novel STEC and Salmonella selective (SSS) broth that allows for simultaneous selective enrichment of STEC and Salmonella sp., providing isolation and detection from the same broth. The method only involves direct plating from beef enrichments to detect suspect isolates that can be easily confirmed by using immunoassays or PCR, rendering the isolation simpler and less costly than the current described methods. In a side-by-side comparison with modified tryptic soy broth (mTSB), the use of SSS broth resulted in primarily isolating STEC and Salmonella sp., while substantially suppressing the growth of other gram-negative Enterobacteriacae by 90%. Significantly more (χ2 < 3.84) samples containing E. coli O157:H7 and STEC O26, O111, O121, and O145 and a nondifferent (χ2 > 3.84) number of samples containing STEC O103 and O45 were identified when enriching in SSS broth. Coenrichment using six different Salmonella serovars showed numerically greater but not significant (χ2 < 3.84) positive samples by using SSS broth compared with mTSB for a majority of serotypes.

USA – Two E. coli Outbreaks in Tennessee Sicken 15

Food Poison Journal

The Knox County Health Department (KCHD) is concluding its investigation into a cluster of Escherichia coli (E. coli) O157 infections. Fifteen confirmed cases of E. coli O157 were reported to KCHD recently. All cases were among children, nine were hospitalized and seven developed a complication of the infection called Hemolytic Uremic Syndrome (HUS). Of the children who were hospitalized, one remains in fair condition at East Tennessee Children’s Hospital. Lab results from the Tennessee Department of Health have confirmed two different strains of E. coli O157 caused the children to become ill.


Research – Inactivation of Escherichia coli O157:H7 and Salmonella and Native Microbiota on Fresh Strawberries by Antimicrobial Washing and Coating

Journal of Food Protection Hepatitis A kswfoodworld

Antimicrobial washing (AW), antimicrobial coating (AC), and a combination of washing followed by coating (AW+AC) were evaluated for their ability to inactivate artificially inoculated foodborne pathogens and native microbiota on strawberries stored at 4°C. Strawberries were inoculated with a six-strain composite of Escherichia coli O157:H7 and Salmonella; treated by AW, AC, or AW+AC; and stored at 4°C for 3 weeks. The washing solution contained 90 ppm of peracetic acid, and the coating solution consisted of chitosan (1%, w/v), allyl isothiocyanate (1%, v/v), and corn-bio fiber gum (5%, w/v). The effectiveness of the antimicrobial treatments against E. coli O157:H7 and Salmonella pathogens and native microflora on strawberries and their impact on fruit quality (appearance, weight loss, color, and firmness) were determined. By the end of storage, pathogen populations on strawberries were 2.5 (AW+AC), 2.9 (AC), 3.8 (AW), and 4.2 log CFU for the positive (untreated) control. AW+AC treatments also inactivated the greatest population of native microflora, followed by the AC treatment alone. AW+AC treatments showed additional antimicrobial effectiveness against these two pathogens and native microflora. Both AW+AC and AC treatments preserved the color, texture, and appearance of strawberries throughout storage. The coating treatments (AW+AC and AC alone) further reduced the loss of moisture throughout storage. The AW treatment was the least effective in reducing populations of pathogens and native microflora and in maintaining the quality of strawberries throughout storage. This study demonstrates a method to improve the microbiological safety, shelf life, and quality of strawberries.

Research – Petting zoos as sources of Shiga toxin-producing Escherichia coli (STEC) infections


Despite their general low incidence, Shiga toxin-producing Escherichia (E.) coli (STEC) infections are considered an important public health issue due to the severity of illness that can develop, particularly in young children. We report on two Austrian petting zoos, one in Tyrol (2015) and one in Vorarlberg (2016), which were identified as highly likely infection sources of STEC infections. The petting zoo related cases involved a case of hemolytic uremic syndrome (HUS) due to STEC O157:HNM in 2015 and an outbreak of STEC O157:H7 infections affecting five young children and two adults in 2016. The HUS case accounted for 2.8% of the 36 STEC O157:HNM/H7 infections notified in Austria in 2015 (5,9% of 17 HUS cases). The seven cases described for 2016 accounted for 4.0% of the 177 human STEC infections documented for Austria in 2016, and for 19% of the 36 STEC O157:HNM/H7 infections notified that year. The evaluation of the STEC infections described here clearly underlines the potential of sequence-based typing methods to offer suitable resolutions for public health applications. Furthermore, we give a state-of-the-art mini-review on the risks of petting zoos concerning exposure to the zoonotic hazard STEC and on proper measures of risk-prevention.

A table of petting zoo outbreaks is available at

Canada – Food Recall Warning – Certain extra lean ground beef products recalled due to E. coli O157


Recall details

Ottawa, June 29, 2018 – The Butcher’s Blend is recalling certain extra lean ground beef products from the marketplace due to possible E. coli O157 contamination. Consumers should not consume the recalled products described below.

Recalled products

Brand Name Common Name Size Code(s) on Product UPC
None Extra Lean Ground Beef Approx. 1 lb None – Sold by The Butcher’s Blend at the Western Fair District Farmer’s Market on June 16, 2018 None
Mitchell’s Butcher’s Blend / Old East Village Grocer Extra Lean Ground Beef Approx. 1 lb Best Before JUN 23/18 Starts with 0 200150
Mitchell’s Butcher’s Blend / Old East Village Grocer Extra Lean Ground Beef Approx. ½ lb Best Before JUN 23/18 Starts with 0 200150

USA – Canal water likely source of E. coli in romaine-related outbreak

Food Safety News 


Federal officials say contaminated canal water near romaine lettuce growing fields is the likely source of the unusually virulent strain of E. coli that has sickened people across 36 states, killing five.

The outbreak is over, according to an update this afternoon from the Centers for Disease Control and Prevention. The agency has confirmed 210 people with infections. Twenty-seven of the victims have developed kidney failure. The most recent victim became sick on June 6.

“Samples have been collected from environmental sources in the region, including water, soil, and cow manure. Evaluation of these samples is ongoing,” according to an update this afternoon from the Food and Drug Administration investigators.

“To date, CDC analysis of samples taken from canal water in the region has identified the presence of E. coli O157: H7 with the same genetic fingerprint as the outbreak strain. We have identified additional strains of Shiga-toxin producing E. coli in water and soil samples, but at this time, the samples from the canal water are the only matches to the outbreak strain.”

USA – Family of East Tennessee boy with E. coli asks for breast milk donations


KNOXVILLE, Tenn. (WATE) – UPDATE: The family says they have found a source for breast milk, but would let people know if they need more.

The parents of a 2-year-old in Children’s Hospital due to complications from E. coli are asking for donations of breast milk for his feeding tube.

James and Genevieve Zenker posted to Facebook their 27-month-old son William has hemolytic uremic syndrome. They say he is suffering from kidney failure and colitis, as well as brain insult.