Category Archives: E.coli O157:H7

Research – Detection of Escherichia coli O157:H7 in imported meat products from Saudi Arabian ports in 2017

Escherichia coli O157:H7 is a foodborne pathogen, which causes various health conditions in humans, including fatigue, nausea, bloody diarrhoea and in some cases, even death. In 2017, 15.71% of the total imported food products in Saudi Arabia (SA) were meat-based. India and Brazil are two of the top five countries from where SA imports meat. According to the Saudi Food and Drug Authority, in 2017, at least 562, 280, and 50 samples of imported beef, chicken and sheep meat, respectively, were tested for the presence of E. coli O157:H7. Amongst these, E. coli O157:H7 was detected in respectively 6.80% and 2.20% of the tested beef meat samples imported from India and Brazil as well as in respectively 6.96% and 3.57% of the tested chicken samples imported from Brazil and Ukraine. Moreover, the pathogen was detected in 2.13% of the tested sheep meat samples imported from India. The present report provides evidence that imported meat can serve as the carrier of E. coli O157:H7, which may lead to epidemics within the Kingdom of Saudi Arabia.

USA – USDA Starts Testing Ground Beef For Big Six E. coli Strains, O157

Food Poisoning Bulletin

The USDA’s Food Safety and Inspection Service (FSIS) has started testing ground beef, bench trim, and other raw ground beef components for Shiga toxin-producing E. coli strains (STEC) that are adulterants. They include the “Big Six” O26, O45, O103, O111, O121, and O145 as well as O157. The testing started on February 1, 2023. This new program was announced in the Federal Register on June 4, 2020.

USA – Persistent Strain of E. coli O157:H7 (REPEXH01) Linked to Multiple Sources



REPEXH01 is a persistent strain of Shiga toxin-producing E. coli O157:H7 bacteria that has caused illnesses and outbreaks in the United States.

Illness caused by this strain was first reported to PulseNet in 2017. Illnesses caused by this strain occur year-round but are less common in winter.

In the past, the REPEXH01 strain has spread to people through contaminated food and contaminated recreational water.

This strain is relatively diverse genetically. Bacteria in this strain are within 21 allele differences of one another by whole genome sequencing, which is more diverse than typical multistate foodborne outbreaks where bacteria generally fall within 10 allele differences of one another.

Identified outbreak sources*

*Confirmed sources were implicated by epidemiologic
plus traceback or laboratory data. Suspected sources
were implicated by epidemiologic data only. More info

  • Recreational water (confirmed): 1 outbreak
  • Romaine lettuce (confirmed): 1 outbreak
  • Leafy greens (suspected): 1 outbreak
  • Ground beef (suspected): 2 outbreaks

UK – APHA part of 5 UK E. coli outbreaks in 2022

Food Safety News

The Animal and Plant Health Agency (APHA) was involved in another two E. coli outbreaks in the United Kingdom in the final quarter of 2022.

In the first, APHA helped Public Health Wales investigate two human cases of Shiga toxin-producing E. coli (STEC) O145 linked to a private collection of animals on a smallholding. Multiple species were onsite including cattle, goats, deer, and pigs. Some food consumed by people was grown in the garden where cattle manure was used. Thirty environmental fecal samples were collected but a match to the outbreak strain was not found.

In the second, APHA visited an open farm at the request of an incident management team following an outbreak of E. coli O157 in people. The outbreak strain was detected in one environmental sample from a pig enclosure. The incident is ongoing so it is unclear how many people are sick. The advice was provided to reduce the risk to the public by making improvements to the supervision of animal contact, enhancing handwashing facilities, and improving some animal exhibits.

In all of 2022, APHA was part of five E. coli investigations. The agency helped the UK Health Security Agency (UKHSA) investigate E. coli O103, O145, and O26 outbreaks between July and September.

The E. coli O26 outbreak also involved cryptosporidium. There were 11 cases of cryptosporidium and two people had confirmed E. coli O26. Cryptosporidium patients had visited an open farm attraction during the incubation period of illness. The E. coli patients had links to the same premises.

The E. coli O103 outbreak with 11 cases was associated with soft, raw milk cheese from a dairy farm in the East of England. Pasteurization was put in place for the production of the soft cheese, HACCP processes were reviewed, and enhanced control measures were taken.

The E. coli O145 outbreak with 10 patients was traced to the consumption of milk products from a dairy farm in North West England, with illness onset from mid-July. Investigations identified an issue with pasteurization and problems with the cleaning and storage of milk crates.

Research – Microbial Dynamics in Mixed-Culture Biofilms of Salmonella Typhimurium and Escherichia coli O157:H7 and Bacteria Surviving Sanitation of Conveyor Belts of Meat Processing Plants



Biofilm formation can lead to the persistence of Salmonella Typhimurium (ST) and E. coli O157:H7 (O157). This study investigated the impact of meat processing surface bacteria (MPB) on biofilm formation by O157 (non-biofilm former; NF) and ST (strong biofilm former; BF). MPB were recovered from the contacting surfaces (CS), non-contacting surfaces (NCS), and roller surfaces (RS) of a beef plant conveyor belt after sanitation. O157 and ST were co-inoculated with MPB (CO), or after a delay of 48 h (IS), into biofilm reactors containing stainless steel coupons and incubated at 15 °C for up to 144 h. Coupons were withdrawn at various intervals and analyzed by conventional plating and 16S rRNA gene amplicon sequencing. The total bacterial counts in biofilms reached approximately 6.5 log CFU/cm2, regardless of MPB type or development mode. The mean counts for O157 and ST under equivalent conditions mostly did not differ (p > 0.05), except for the IS set at 50 h, where no O157 was recovered. O157 and ST were 1.6 ± 2.1% and 4.7 ± 5.0% (CO) and 1.1 ± 2.2% and 2.0 ± 2.8% (IS) of the final population. Pseudomonas dominated the MPB inocula and biofilms, regardless of MPB type or development mode. Whether or not a pathogen is deemed BF or NF in monoculture, its successful integration into complex multi-species biofilms ultimately depends on the presence of certain other residents within the biofilm.

Research – The Effect of High-Pressure Processing on the Survival of Non-O157 Shiga Toxin-Producing Escherichia coli in Steak Tartare: The Good- or Best-Case Scenario?



Samples of steak tartare were artificially contaminated with a cocktail of Shiga toxin-producing Escherichia coli (STEC) O91, O146, O153, and O156 to the level of 3 log and 6 log CFU/g. Immediately after vacuum packing, high-pressure processing (HPP) was performed at 400 or 600 MPa/5 min. Some of the samples not treated with HPP were cooked under conditions of 55 °C for 1, 3, or 6 h. HPP of 400 MPa/5 min resulted in a 1–2 log reduction in the STEC count. In contrast, HPP of 600 MPa/5 min led to the elimination of STEC even when inoculated to 6 log CFU/g. Nevertheless, sub-lethally damaged cells were resuscitated after enrichment, and STEC was observed in all samples regardless of the pressure used. STEC was not detected in the samples cooked in a 55 °C water bath for 6 h, even after enrichment. Unfortunately, the temperature of 55 °C negatively affected the texture of the steak tartare. Further experiments are necessary to find an optimal treatment for steak tartare to assure its food safety while preserving the character and quality of this attractive product.

USDA Methods Update – Detection, Isolation, and Identification of Top Seven Shiga Toxin-Producing Escherichia coli (STEC) from Meat Products, Carcass, and Environmental Sponges


This method describes the laboratory procedure for analysis of raw and ready-to-eat meat products, and laboratory environmental sponge samples for the seven targeted STEC serogroups (O157, O26, O45, O103, O111, O121 and O145).

Research – Quantifying risk associated with changes in EHEC physiology during post-harvest pre-processing stages of leafy green production



The goal of this project is to determine if the time between harvest and end use of romaine lettuce impacts E. coli O157:H7 pathogenicity and detectability resulting in increased health risk. Laboratory scale experiments with inoculated lettuce undergoing simulated harvest and cooling will be used to measure changes in E. coli O157:H7 stress tolerance and virulence. Input from industry partners including temperature data from commercial romaine harvesting and cooling, and details on supply chain logistics, will be combined with the laboratory scale experimental data and used to model risk associated with specific harvest and handling practices. The resulting quantitative tool will be publicly available and allow for growers and producers to determine any practices that should be implemented to reduce the potential for O157 transmission on romaine lettuce.

Research – Spraying an army of bacteria-eating viruses can save us from food poisoning

Interesting Engineering

Every year more than 40 million people in the U.S. suffer from foodborne illnesses caused by bacteria, viruses, and various other types of pathogens. Food contamination is often underestimated, but it is responsible for 420,000 deaths annually. This number represents more people than the entire population of Iceland.

After being produced on a farm, food passes through a lot of channels before it makes it to our platter. Preventing it from contamination is almost impossible. However, a team of researchers from McMaster University in Ontario has figured out a way to free food from disease-causing bacteria before it goes into your stomach, according to a press release.

They have developed a food decontamination spray that employs food-safe microscopic beads containing bacteriophages (viruses that kill bacteria). The researchers claim, during the study, they were able to free lettuce and meat from E. coli 0157, a common food-borne pathogen that infects the human intestine and causes health issues such as diarrhea. 

USA – Morasch Meats Inc. Recalls Raw Frozen Diced Beef Products Due to Possible E. Coli O157:H7 Contamination


WASHINGTON, Dec. 22, 2022 – Morasch Meats Inc., a Portland, Ore. establishment, is recalling approximately 3,930 pounds of raw frozen diced beef products that may be contaminated with E. coli O157:H7, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) announced today.

The raw frozen diced beef items were produced on August 24, 2022. The following products are subject to recall [view labels]:

  • 30-lb. box packages containing “BEEF DICED 3/10# BAGS,” with case code FM010152, LOT#: 082422 and a date of 8/24/2022 on the case label. Each case contains three 10 lb. vacuum-sealed, clear plastic bags of the diced beef products.

The products subject to recall bear establishment number “EST. 4102” inside the USDA mark of inspection. These items were shipped to distributor locations in Oregon for further distribution to restaurants and other institutional users.

The problem was discovered by FSIS during review of testing results, which showed the product tested positive for E. coli O157:H7.

FSIS is concerned that some product may be in institutional or restaurant freezers. Restaurants and institutions are urged not to serve these products. These products should be thrown away or returned to the place of purchase.

Click to access recall-labels-045-2022_0.pdf