Faculty members from the Kansas State University College of Veterinary Medicine have developed a faster, more efficient method of detecting “Shiga toxin-producing E. coli,” or STEC, in ground beef, which often causes recalls of ground beef and vegetables.
“The traditional gold standard STEC detection, which requires bacterial isolation and characterization, is not amenable to high-throughput settings and often requires a week to obtain a definitive result,” said Jianfa Bai, section head of molecular research and development in the Kansas State Veterinary Diagnostic Laboratory.
The new method developed by Bai and colleagues requires only a day to obtain confirmatory results using a Kansas State University-patented method with the partition-based multichannel digital polymerase chain reaction system.
“We believe the new digital polymerase chain reaction detection method developed in this study will be widely used in food safety and inspection services for the rapid detection and confirmation of STEC and other foodborne pathogens,” said Jamie Henningson, director of the Kansas State Veterinary Diagnostic Laboratory.
When ingested through foods such as ground beef and vegetables, STEC can cause illnesses with symptoms including abdominal pain and diarrhea. Some illnesses caused by STEC may lead to kidney failure and can be life-threatening.
“Some E. coli strains do not produce Shiga toxins and thus do not affect human health as much,” said Xuming Liu, research assistant professor. “Because cattle feces and ground beef can contain harmless or less pathogenic E. coli along with STEC, the most commonly used polymerase chain reaction cannot identify pathogenic E. coli strains in a complex sample matrix.”
The new digital polymerase chain reaction test was developed for research and food safety inspections that require shorter turnaround and high throughput, without sacrificing detection accuracy.
“While the current, commonly used testing method is considered to be the gold standard, it is tedious and requires many days to obtain results that adequately differentiate the bacteria,” said Gary Anderson, director of the International Animal Health and Food Safety Institute at the K-State Olathe campus.
The study, “Single cell-based digital PCR detection and association of Shiga toxin-producing E. coli serogroups and major virulence genes,” which describes the test design and results, was published in the Journal of Clinical Microbiology.
Bacterial persistence is a form of phenotypic heterogeneity in which a subpopulation, persisters, has high tolerance to antibiotics and other stresses. Persisters of enteric pathogens may represent the subpopulations capable of surviving harsh environments and causing human infections. Here we examined the persister populations of several shiga toxin-producing Escherichia coli (STEC) outbreak strains under conditions relevant to leafy greens production.
The persister fraction of STEC in exponential-phase of culture varied greatly among the strains examined, ranging from 0.00003% to 0.0002% for O157:H7 strains to 0.06% and 0.08% for STEC O104:H4 strains. A much larger persister fraction (0.1–11.2%) was observed in STEC stationary cells grown in rich medium, which was comparable to the persister fractions in stationary cells grown in spinach lysates (0.6–3.6%). The highest persister fraction was measured in populations of cells incubated in field water (9.9–23.2%), in which no growth was detected for any of the STEC strains examined. Considering the high tolerance of persister cells to antimicrobial treatments and their ability to revert to normal cells, the presence of STEC persister cells in leafy greens production environments may pose a significant challenge in the development of effective control strategies to ensure the microbial safety of fresh vegetables.
Enhanced formation of shiga toxin-producing Escherichia coli persister variants in environments relevant to leafy greens production
Several types of mettwurst, manufactured by a South Australian Company, have been recalled after it was discovered the products may be contaminated with harmful bacteria.
Wintulichs, based in Gawler, recalled their Metwurst Garlic 300g, 375g, 500g, 700g, Mettwurst Plain 700g and Mettwurst Pepperoni 375g products.
Food Standards Australia New Zealand say the products have been sold at Woolworths, IGA and independent stores across SA.
The recall is due to incorrect pH and water activity levels, which may lead to microbial contamination and could cause illness if consumed.
Customers should return the products to the place of purchase for a full refund.
In Australia and around the world, the incidence of reported foodborne illness is on the increase. Regularly cited estimates suggest that Australia is plagued with over two million cases of foodborne illness each year, costing the community in excess of $1 billion annually.
Based on the case studies cited here and a thorough examination of a variety of documents disseminated for public consumption, government and industry in Australia are well aware of the challenges posed by greater public awareness of foodborne illness. They are also well aware of risk communication basics and seem eager to enter the public fray on contentious issues. The primary challenge for government and industry will be to provide evidence that approaches to managing microbial foodborne risks are indeed mitigating and reducing levels of risk; that actions are matching words.
There is a further challenge in impressing upon all producers and processors the importance of food safety vigilance, as well as the need for a comprehensive crisis management plan for critical food safety issues.
On Feb. 1, 1995, the first report of a food poisoning outbreak in Australia involving the death of a child from hemolytic uremic syndrome (HUS) after eating contaminated mettwurst reached the national press. The next day, the causative organism was identified in news stories as E. coli 0111, a Shiga-toxin E. coli (STEC) which was previously thought to be destroyed by the acidity in fermented sausage products like mettwurst, an uncooked, semi-dry fermented sausage. By Feb. 3, 1995, the child was identified as a four-year-old girl and the number sickened in the outbreak was estimated at 21.
The manager of the company that allegedly produced the contaminated mettwurst had to hire security guards to protect his family home as threats continued to be made on his life, and the social actors began jockeying for position in the public discourse. The company, Garibaldi, blamed a slaughterhouse for providing the contaminated product, while the State’s chief meat hygiene officer insisted that meat inspections and slaughtering techniques in Australian abattoirs were “top class and only getting better.”
On Feb. 4, just three days after the initial, national report, the South Australian state government announced it was implementing new food regulations effective March 1, 1995. The federal government followed suit the next day, announcing intentions to bolster food processing standards and launching a full inquiry. Even the coroner investigating the death of the girl said on Feb. 9 that investigations relating to inquests usually took about three months to complete, but he would start the hearing the next day if possible.
By Feb. 6, 1995, Garibaldi Smallgoods declared bankruptcy. Sales of smallgoods like mettwurst were down anywhere from 50 to 100 per cent according to the National Smallgoods Council.
The outbreak of E. coli O111 and the reverberations fundamentally changed the public discussion of foodborne illness in Australia, much as similar outbreaks of STEC in Japan, the U.K. and the U.S. subsequently altered public perception, regulatory efforts and industry pronouncements in those countries. The pattern of public reporting and response followed a similar pattern of reporting on the medical implications of the illness, attempts to determine causation and finger pointing. Such patterns of reporting are valid; when people are sick and in some cases dying from the food they consume, people want to know why. The results altered both the scientific and public landscapes regarding microbial foodborne illness, and can inform future risk communication and management efforts.
In all, 173 people were stricken by foodborne illness linked to consumption of mettwurst manufactured by Garibaldi smallgoods. Twenty-three people, mainly children, developed HUS, and one died. Although sporadic cases of HUS had been previously reported, this was the first outbreak of this condition recognized in Australia.
Once public attention focused on Garibaldi as the source of the offending foodstuff, the company quickly deflected criticism, blaming an unnamed Victorian-based company of supplying contaminated raw meat, and citing historical precedent as proof of safety. Garibaldi’s administration manager Neville Mead was quoted as saying that he was confident hygiene and processing at the plant were up to standard, adding, “We stand by our processing. We’ve done this process now for 24 years and it’s proved successful.” Such blind faith in tradition, even in the face of changing science-based recommendations, even in the face of tragedy, is often a hallmark of outbreaks of foodborne illness, reflecting the deep cultural and social mythologies that are associated with food.
However, given the uncertainties at the time, a spokesman with the Australian Meat and Livestock Association appropriately rejected such allegations, saying, “I believe it is irresponsible of them (Garibaldi) to make that statement when there is absolutely no evidence of that at all.” Likewise, Victorian Meat Authority chairman John Watson said his officers were investigating Garibaldi’s claims, but that even if the raw meat had come from
Victoria, the supplier may not necessarily be the source of the disease, but rather it could be based in Garibaldi’s processing techniques.
Similarly, when Garibaldi accused the watchdog South Australian Health Commission of dragging its feet with investigations, Health Minister, Dr. Michael Armitage responded by publicly stating that, “They indicated to us that they wanted their lawyers first to be involved before they provided us with information (concerning the mettwurst). It was only (after) earlier this week, under the Food Act, we issued a demand for that information, that we got it. So indeed, I would put it to Garibaldi that the boot is completely on the other foot.”
Likewise, South Australia’s chief meat hygiene officer, Robin Van de Graaff rejected such claims, saying that, “These organisms are part of a large family of bugs that are normal inhabitants of the gut of farm animals … If a tragedy like this occurs it is usually because, and it no doubt is in this case, not because of a small amount of contamination at the point of slaughter but because of the method of handling and processing after that.” The statements of government regulators would be subsequently validated.
Wheat flour has recently been recognised as an exposure vehicle for the foodborne pathogen Shiga toxin-producing Escherichia coli (STEC). Wheat flour milled on two sequential production days in October 2016, and implicated in a Canada wide outbreak of STEC O121:H19, was analysed for the presence of STEC in November 2018.
Stored in sealed containers at ambient temperature, the water activity of individual flour samples was below 0.5 at 6 months post-milling and remained static or decreased slightly in individual samples during 18 months of additional storage. STEC O121 was isolated, with the same genotype (stx2a, eae, hlyA) and core genome multilocus sequence type as previous flour and clinical isolates associated with the outbreak. The result of this analysis demonstrates the potential for STEC to persist in wheat flour at levels associated with outbreak infections for periods of up to two years. This has implications for the potential for STEC to survive in other foods with low water activity.
Shiga toxin-producing Escherichia coli survives storage in wheat flour for two years
This study was conducted to validate a simulated commercial baking process for plain muffins against E. coli O121 (isolated from the recent illness outbreak associated with flour), and compare the thermal inactivation parameters (D- and z-values) of cocktails of four isolates of E. coli O121 and three serovars of Salmonella (Newport, Typhimurium, and Senftenberg) in muffin batter.
Flour samples were spray inoculated with the E. coli O121 or Salmonella cocktails, dried back to the pre-inoculation weight to achieve ~7 log10 CFU/g, and used to prepare muffin batter. For the muffin baking validation study using E.coli O121, muffin batter was baked at 375 °F (190.6 °C) oven temperature for 21 min followed by 30 min of ambient cooling. The E. coli O121 population decreased by >7 log10 CFU/g in muffins by 17 min of baking, and was completely eradicated after 21 min of baking and ambient cooling. The D-values of E. coli O121 and Salmonella cocktails in muffin batter at 60, 65 and 70 °C were 42.0 and 38.4, 7.5 and 7.2, and 0.4 and 0.5 min, respectively; whereas the z-values of E. coli O121 and Salmonella were 5.0 and 5.2 °C, respectively.
Comparison of survival and heat resistance of Escherichia coli O121 and salmonella in muffins
I have so many Larry stories that I’d probably get sued now that he’s a big shot.
But when I was teaching him and Kevin, about 1995 (I may have noticed Chapman joined my lab about 1999, it’s all a purple haze, but I got those 70 peer-reviewed papers out and made full-professor) so here’s Larry, now that he’s returned to Guelph (that’s in Ontario, Canada) and maybe you have a chat with Malcolm, see about getting my $750,000 returned and we can do some fun research.
Despite appearances, experts say a recent rise in major recalls is not a sign of food supply problems, but the result of a more active investigative body and better testing tools — though they add more can be done.
“This is proof that the system is working well,” said Lawrence Goodridge, a professor focusing on food safety at The University of Guelph, speaking about the recent meat recall.
Yet, he believes that “in Canada, we have to get to a place where we can actually stop the food from going to retail in the first place.”
Since Sept. 20, a investigation by the Canadian Food Inspection Agency into possible E. coli 0157:H7 contamination in some beef and veal products sold by Ryding-Regency Meat Packers Ltd. and St. Ann’s Foods Inc. has led to the recall of nearly 700 products.
The CFIA suspended the Canadian food safety license for St. Ann’s meat-processing plant, as well as Ryding-Regency’s slaughter and processing plant, both in Toronto, in late September.
No illnesses have been reported in association with the products, according to the CFIA, but symptoms of sickness can include nausea, vomiting, abdominal cramps.
Emma Broadhurst was six months pregnant when she flew out to Turkey with friends for a 7-night stay at the Crystal Sunset Luxury Resort and Spa, east of the city of Antayla, at the start of September.
But, according to Andy Rudd of The Mirror, within days of arriving she fell unwell suffering from chronic diarrhea and became dehydrated and lost weight.
Just over 24 hours later her best friend’s seven-year-old son, Kailan, also fell ill with diarrhea and on their return to the UK his mum, Emma McComb, fell ill and Kailan was left ‘screaming in agony’ and projectile vomiting.
All three, who shared a room while on holiday, were then diagnosed with salmonella poisoning after stool samples were sent for testing by their local GP, claims Emma.
The friends stayed in the same hotel where two-year-old Allie Birchall and her family holidayed before little Allie was taken ill before passing away having contracted E. coli.
All members of her family, from Wigan, Greater Manchester, suffered from gastric symptoms including stomach cramps and diarrhoea during their 10-day stay with Jet 2.
Allie’s condition became so severe she was rushed to hospital after the family returned to the UK.
Her parents had to make the heartbreaking decision to switch off her life support on August 3.
Dr. Janice Fitzgerald said some of the cases are connected to an advisory issued by Memorial University last week, saying Eastern Health was investigating reports of students experiencing gastrointestinal illness.
The university said Wednesday that test results indicated one student living in residence “may have contracted the E. coli bacteria” and 21 students had reported similar symptoms.
Fitzgerald said it’s too early in the investigation to determine a cause of the outbreak.
Two abstracts attempt to provide guidance to these important questions to reduce the toll of STEC.
FAO and WHO conclude shiga toxin-producing Escherichia coli (STEC) infections are a substantial public health issue worldwide, causing more than 1 million illnesses, 128 deaths and nearly 13 000 Disability-Adjusted Life Years (DALYs) annually.
To appropriately target interventions to prevent STEC infections transmitted through food, it is important to determine the specific types of foods leading to these illnesses.
An analysis of data from STEC foodborne outbreak investigations reported globally, and a systematic review and meta-analysis of case-control studies of sporadic STEC infections published for all dates and locations, were conducted. A total of 957 STEC outbreaks from 27 different countries were included in the analysis.
Overall, outbreak data identified that 16% (95% UI, 2-17%) of outbreaks were attributed to beef, 15% (95% UI, 2-15%) to produce (fruits and vegetables) and 6% (95% UI, 1-6%) to dairy products. The food sources involved in 57% of all outbreaks could not be identified. The attribution proportions were calculated by WHO region and the attribution of specific food commodities varied between geographic regions.
In the European and American sub-regions of the WHO, the primary sources of outbreaks were beef and produce (fruits and vegetables). In contrast, produce (fruits and vegetables) and dairy were identified as the primary sources of STEC outbreaks in the WHO Western Pacific sub-region.
The systematic search of the literature identified useable data from 21 publications of case-control studies of sporadic STEC infections. The results of the meta-analysis identified, overall, beef and meat-unspecified as significant risk factors for STEC infection. Geographic region contributed to significant sources of heterogeneity. Generally, empirical data were particularly sparse for certain regions.
Care must be taken in extrapolating data from these regions to other regions for which there are no data. Nevertheless, results from both approaches are complementary, and support the conclusion of beef products being an important source of STEC infections. Prioritizing interventions for control on beef supply chains may provide the largest return on investment when implementing strategies for STEC control.
Second up, in 2016, we reviewed preventive control measures for secondary transmission of Shiga-toxin producing Escherichia coli (STEC) in humans in European Union (EU)/European Free Trade Association (EEA) countries to inform the revision of the respective Norwegian guidelines which at that time did not accommodate for the varying pathogenic potential of STEC.
We interviewed public health experts from EU/EEA institutes, using a semi-structured questionnaire. We revised the Norwegian guidelines using a risk-based approach informed by the new scientific evidence on risk factors for HUS and the survey results.
All 13 (42%) participating countries tested STEC for Shiga toxin (stx) 1, stx2 and eae (encoding intimin). Five countries differentiated their control measures based on clinical and/or microbiological case characteristics, but only Denmark based their measures on routinely conducted stx subtyping. In all countries, but Norway, clearance was obtained with ⩽3 negative STEC specimens. After this review, Norway revised the STEC guidelines and recommended only follow-up of cases infected with high-virulent STEC (determined by microbiological and clinical information); clearance is obtained with three negative specimens.
Implementation of the revised Norwegian guidelines will lead to a decrease of STEC cases needing follow-up and clearance, and will reduce the burden of unnecessary public health measures and the socioeconomic impact on cases. This review of guidelines could assist other countries in adapting their STEC control measures.
Mapping of control measures to prevent secondary transmission of STEC infections in Europe during 2016 and revision of the national guidelines in Norway
Allie Birchall came down with the severe illness after returning to the UK following a stay at a luxury resort east of the coastal city of Antayla.
Her family were forced to turn off Allie’s life support machine just two weeks after their holiday because of complications caused by the illness.
The family had travelled to Turkey with tour operator Jet2 Holidays on 12 July and said they had concerns about the hygeine of the Turkish resort.
Katie Dawson, Allie’s mother, said her daughter did not start getting ill until five days after getting back to their home in Atherton, Greater Manchester.
According to Ms Dawson, Allie began suffering with stomach cramps, diarrhoea, loss of appetite and lethargy before being admitted to Royal Bolton Hospital on July 30.
The hospital confirmed Allie had contracted Shiga-Toxin producing E.Coli (STEC), which later led to her developing deadly Haemolytic Uraemic Syndrome (HUS) – a life-threatening complication related to the poisoning.
Allie was moved to the Manchester Royal Infirmary and put in an induced coma on August 1.
An MRI scan was carried out, which revealed that she had sustained severe brain trauma and damage. Katie had to make the difficult decision to terminate Allie’s life support following the advice from doctors.
“While nothing will bring her back, we need to know what caused her illness and if anything could have been done to prevent it.
The family have now instructed specialist international serious injury lawyers, Irwin Mitchell, to investigate what happened.
Public Health England is also currently investigating the matter, and an inquest has been opened to examine the circumstances surrounding Allie’s death.