The role of meat in foodborne disease

Meat has featured prominently as a source of foodborne disease and a public health concern. For about the past 20 years the risk management paradigm has dominated international thinking about food safety. Control through the supply chain is supported by risk management concepts, as the public health risk at the point of consumption becomes the accepted outcome-based measure.

Foodborne pathogens can be detected at several points in the supply chain and determining the source of where these pathogens arise and how they behave throughout meat production and processing are important parts of risk-based approaches. Recent improvements in molecular and genetic based technologies and data analysis for investigating source attribution and pathogen behaviour have enabled greater insights into how foodborne outbreaks occur and where controls can be implemented. These new approaches will improve our understanding of the role of meat in foodborne disease and are expected to have a significant impact on our understanding in the next few years.

The role of meat in foodborne disease: Is there a coming revolution in risk assessment and management?

Meat Science

Narelle Fega, Ian Jenson

https://doi.org/10.1016/j.meatsci.2018.04.018

https://www.sciencedirect.com/science/article/pii/S0309174018300731

Nanobot viruses tag and round up bacteria in food and water

A PR which continues with the we’re-all-hosts-on-a-viral-planet themed, but gives some advice about how to work with nature to achieve goals.

Viruses engineered into “nanobots” can find and separate bacteria from food or water.

These viruses, called bacteriophages or just phages, naturally latch onto bacteria to infect them (SN: 7/12/03, p. 26). By tweaking the phages’ DNA and decking them out with magnetic nanoparticles, researchers created a tool that could both corral bacteria and force them to reveal themselves. These modifications can boost the sensitivity and speed of rooting out bacteria in tainted food or water, the researchers reported March 20 at the annual meeting of the American Chemical Society.

“You’re taking the power of what evolution has done … to bind bacteria, and then we’re just helping that out a little bit,” said Sam Nugen, a food and biosystems engineer who leads the team designing these phages at Cornell University.

Competing technologies for detecting bacteria use antibodies, the product of an immune response. But these are expensive to produce and work best in a narrow temperature and pH range. In contrast, phages “exist everywhere,” making them potentially more broadly useful as bacteria hunters, Nugen said. “They’ve had to evolve to bind well in much broader conditions than antibodies.”

Phages identify and grab bacteria using proteins on their leglike tail fibers, which form a strong bond with compounds on the bacterial cell surface. To infect the cell, the phage injects its genetic material. This hijacks the cell, forcing its machinery to produce phage clones.

Nugen and collaborators programmed phages to tag E. coli bacteria. The team’s engineered phages contained extra DNA that told the bacteria to make an easily detectable enzyme. When the infection caused the bacterial cells to rupture and release the new phages, a chemical reaction involving the enzyme produced a measurable signal: light, color or an electric current. For example, the phages exposed E. coli in milk and orange juice by turning the liquids red or pink.

The researchers also loaded the phages with nanoparticles with a magnetic iron and cobalt core. Once the phages latched onto the bacteria, researchers could use a magnet to round the bacteria up even before the bacteria ruptured and announced their presence. This allowed the researchers to detect low concentrations of bacteria: less than 10 E. coli cells in half a cup of water. Conventional methods grow the bacteria into colonies to find them, which can take up to two days. But using the phages, Nugen and his colleagues skipped this step and found the cells within a few hours.

Using phages for magnetic separation would be “really nice for food and environmental samples because they tend to be really dirty,” said Michael Wiederoder, a bioengineer at the U.S. Army Natick Soldier Research, Development and Engineering Center in Massachusetts, who was not involved in the research. The salt, sugar and fats in food can slow the reactions of antibody-based tests, he said.

Also, the phages infect only bacteria that can reproduce, allowing testers to tell the difference between live cells and those killed by antibiotics, heat or chlorine. With food, “whether the bacteria are alive or dead is the difference between you getting sick and not,” Wiederoder said.

The nanobots could also prove useful for blood or other human samples. There, phages would provide a way to find resistant bacteria left alive after a course of antibiotics.

The next challenge: tinkering with the phages to tune which bacteria they go after. In nature, phages prey on specific species. But in food, it may be helpful to detect several common offenders, like E. coli, Salmonella and Listeria, or, alternatively, to have greater discrimination to find only the pathogenic E. coli and leave the rest.

Risk is not low if cause is not known: 5, then 19, now 34 sick and 1 dead sick in E. coli outbreak linked to Edmonton restaurant

If the E. coli-romaine lettuce made it to an Alaskan prison, maybe it made it to an Edmonton restaurant.

Just asking.

According to the Toronto Star, one person has died and more than 30 people have fallen ill following an E. coli outbreak that Alberta Health Services has called “extremely complex” to investigate.

In a statement, AHS says it has expanded its investigation into the source of an outbreak of E. coli, beyond cases directly linked to an Edmonton restaurant late last month.

While 21 of these lab-confirmed cases are linked to Mama Nita’s Binalot restaurant in Edmonton, AHS no longer has public health concerns related to the restaurant.

The number of lab-confirmed cases of E. coli has increased to 34, including 11 patients who have needed hospital care, and one patient who has died likely due to E. coli infection.

“This outbreak is extremely complex, however AHS, in partnership with other provincial and federal agencies, is doing all we can to protect the health of Albertans,” said Dr. Chris Sikora, a medical officer of health in the Edmonton zone, in a statement. “The risk of illness remains very low.”

AHS has not yet identified the source of these cases, but believes they are linked to the initial outbreak.

The risk is not low if the cause is not known.

AHS has worked closely with the owners of Mama Nita’s Binalot since it was identified that a cluster of people with lab-confirmed E. coli ate at the restaurant. AHS says the owners have taken significant steps to manage this issue, including voluntarily closing until AHS was confident the restaurant could reopen without presenting a risk to the public.

Canadian E. coli cases believed to have been caused by deer meat

Cured deer meat is believed to be behind a series of E. coli cases in Tavistock, Oxford County, in Ontario, Canada.

Public Health says they can’t confirm it yet, but they believe the illnesses were caused by the meat which was sourced and processed from two private hunt camps in December 2017.

The first case was reported by a Tavistock resident in mid-February with the second coming a month later in March and a third in the first week of April.

They say laboratory results, expected later this week, will confirm if E.coli is present in the deer meat.

Raw is risky: Fresh herbs can be contaminated

I’m not a fan of the guac, ever since a hungover former partner spewed vile smelling green stuff at the side of the road decades ago.

And I’m wary of fresh herbs, based on previous outbreaks.

So is the U.S. Food and Drug Administration which on Feb. 23, 2018, revealed details on just how many bacteria are hiding in fresh, store-bought herbsThe agency plans to continue testing herbs through 2019 to thoroughly assess their “rates of bacterial contamination.”

The plan is to test 1,600 samples of items “typically eaten without having undergone a ‘kill step,’ such as cooking, to reduce or eliminate bacteria.” These items include fresh cilantro, parsley, and basil.

This first round of results revealed that of the 139 fresh herb samples tested, four tested positive for salmonella and three contained E. coli bacteria.

The Packer noted the testing found  no pathogens in the U.S. herbs versus imported herbs.

In the same period, the FDA found that three of the 58 U.S.-processed avocado products that were tested had listeria, and one of the 49 imported samples had listeria.

From 1996 to 2015, the FDA linked 2,699 illnesses and 84 hospitalizations to fresh herbs.

The FDA also plans to sample processed avocado for similar reasons – from 2005 to 2015, 525 illnesses were linked to avocados in 12 separate outbreaks. Of 107 avocado and guacamole samples in the initial results, four contained listeria. Avocados, the FDA notes, “have a high moisture content and a non-acidic pH level, conditions that can support the growth of harmful bacteria.”

E. coli spread in cattle caused by water troughs

Krishna Ramanujan of the Cornell Chronicle reports:

A major study led by Cornell researchers reveals for the first time that water troughs on farms are a conduit for the spread of toxic E. coli in cattle, which can then spread the pathogen to people through bacteria in feces. The study was published Feb. 7 in the journal PLOS ONE.
“Water troughs appeared in our mathematical model as a place where water can get contaminated and a potential place where we could break the cycle,” said Renata Ivanek, associate professor of epidemiology in the College of Veterinary Medicine and the paper’s senior author. The hypothesis was then tested in the field – with surprising results.
People commonly acquire infections from shiga toxin-producing E. coli through cow feces-contaminated beef and salad greens. The main shiga toxin-producing strain, E. coli 0157:H7, causes more than 63,000 illnesses per year and about 20 deaths, according to the Centers for Disease Control. Though cows carry and spread E. coli 0157:H7 when they defecate, the bacteria do not make them sick.
“Farmers do not see a problem because there are no clinical signs in cows; it is totally invisible,” Ivanek said.
A vaccine to reduce bacterial shedding in cows exists, but the beef industry has little incentive to use it, partly due to cost, and the industry does not benefit from labeling beef as “E. coli safe,” Ivanek said. So Ivanek and a research team of 20 co-authors conducted a study to identify other ways to reduce the bacteria’s prevalence in cattle, which can vary over the year from zero to 100 percent of cows in a feedlot carrying the bacteria, with rates generally rising in the summer.
The researchers ran mathematical modeling studies to see if they could pinpoint areas in the farm where infections might spread between cattle. They found that water in a trough, especially in summer months, could heat and promote pathogen replication, causing more cows to acquire the bacteria when they drink. The researchers hypothesized that frequently changing the water in the summer could keep the water colder, limiting bacterial growth.
On most farms, water troughs automatically refill when they get low enough, and farmers can adjust the water levels so they refill more often. This tact saves water and keeps it fresher while ensuring cows still have enough to drink.
The group ran control trials in a feedlot over two summers. This involved reducing the water volume in troughs in randomly selected treatment pens and leaving the volume unchanged in control pens. They expected that reducing the water levels in troughs would prevent the spread of E. coli. Instead they found that it increased spread; in the treatment pens, the odds of finding shiga toxin-producing E. coli in cows was about 30 percent higher than in the control pens.
“Our modeling studies did pick up the right parts of the system,” Ivanek said, “but the mechanism that we postulated is the opposite from what we thought.”
More study is needed to determine why more water in troughs reduced E. coli in cows, but Ivanek questions whether the lower volume made it easier for cows to swallow debris at the bottom of tanks, or whether a fuller tank reduced E. coli concentrations.
The study will trigger more research on environmental sources of E. coli spread in cattle, Ivanek said.
Next steps include repeating the results in other feedlots, evaluating the effectiveness and cost benefit of using more water to reduce E. coli, investigating how seasons and temperatures play a role in prevalence of E. coli, and understanding the actual mechanisms that led to the results.
Wendy Beauvais, a postdoctoral researcher in Ivanek’s lab, is the paper’s first author. Co-authors included researchers from Texas A&M University, West Texas A&M University and Texas Tech University.
The study was funded by the U.S. Department of Agriculture, the National Institutes of Health and the Texas Veterinary Medical Foundation.

 

New class of antibiotics may be capable of killing superbugs

When I was younger my mother got me a job in a hospital as a nurse’s aide while I finished my studies at university. As part of my duties I had to ensure patients that had methicillin-resistant Staphylococcus aureus (MRSA) were well taken care of. I was in my second year of University at that time and was vaguely familiar with this bug. Then came vancomycin resistant Enterococcus (VRE).
I left.

Anne Stych of Biz Women reports

Scientists studying microorganisms living in soil have discovered a new class of antibiotics that could kill deadly superbugs without triggering resistance.
The discovery leads researchers to believe there’s “a reservoir of antibiotics in the environment we haven’t accessed yet,” said Sean Brady, an associate professor at Rockefeller University in New York, who led the study.
The research, published in the journal Nature Microbiology, said the newly-discovered antibiotics kill superbugs including methicillin-resistant Staphylococcus aureus (MRSA), a potentially deadly infection that is resistant to several antibiotics.
A team led by Brady discovered the new class of antibiotics, called malacidins, while cloning and sequencing DNA from microorganisms in soil samples contributed by people across the United States, The Washington Post reported.
They were looking for microorganisms with a known gene that acts as an “on/off” switch and makes it more difficult for microbes to develop antibiotic resistance, per the Post.
The World Health Organization (WHO) last month called antibiotic resistance a “serious situation” worldwide in both low-income and high-income countries.
The organization’s research showed that resistance to commonly-used antibiotics varied widely among the 22 reporting countries, with resistance to penicillin in bacterial pneumonia cases ranging from zero to 51 percent, while E coli bacteria antibiotic resistance levels ranged from 8 percent to 65.
According to the U.S. Centers for Disease Control and Prevention, each year at least 2 million people in the United States become infected with bacteria that are resistant to antibiotics. At least 23,000 people die as a direct result, while many more die of conditions that were complicated by an antibiotic-resistant infection.
Worldwide, deaths from antibiotic-resistant infections are predicted to reach10 million a year by 2050, per the Post.
“Some of the world’s most common — and potentially most dangerous — infections are proving drug-resistant,“ said Dr . Marc Sprenger, director of the WHO Antimicrobial Resistance Secretariat. “And most worrying of all, pathogens don’t respect national borders. That’s why WHO is encouraging all countries to set up good surveillance systems for detecting drug resistance that can provide data to this global system.”
Researchers said although the discovery is promising and reveals the untapped biodiversity of our ecosystem, it will take years for the new class of antibiotics to be developed for practical use.

 

Yup, they get into produce seeds, especially sprouts: Salmonella and E. coli internalization

Vegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior of Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC) cells artificially internalized into vegetable seeds during the germination process.

Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains of Salmonella or EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization of Salmonella and EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after post-internalization seed surface decontamination.

Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive for Salmonella and EHEC, respectively. The average Salmonella populations were significantly larger (P < 0.05) than the EHEC populations. Significantly larger Salmonella populations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pre-germinated seeds. Three Salmonella and two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.

Salmonella and EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.

Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli cells artificially internalized into vegetable seeds during germination

Appl. Environ. Microbiol. January 2018 84:e01888-17; Accepted manuscript posted online 27 October 2017, doi:10.1128/AEM.01888-17

Da Liu, Yue Cui, Ronald Walcott and Jinru Chen

http://aem.asm.org/content/84/1/e01888-17.abstract?etoc

 

 

California sisters fighting to recover from E. coli

The Public Health Agency of Canada may think Shiga-toxin producing E. coli is no biggie, but tell that to the Niles sisters of southern California, who were both hospitalized with hemolytic uremic syndrome (HUS).

ABC 30 reports that Mariska and Willow were active and healthy kids with no medical history. Their parents thought it was a terrible case of the flu. Originally their pediatrician thought it was norovirus. But after days of worsening symptoms, they were admitted to Valley Children’s Hospital with E. coli.

13-year-old Mariska Niles is finally starting to improve after 16 days in the hospital. She’s had more blood transfusions than she can count along with excruciating stomach pain and she was hallucinating.

The sisters were diagnosed with E. coli HUS or typical hemolytic uremic syndrome but the girls had unique cases.

Dr. Molly Dorfman said, “There’s was pretty atypical. Particularly the severity of Willow’s case was very very severe.”

This form of bacteria usually originates from contaminated food or water products. Pinpointing the exact source has been difficult. They haven’t traveled anywhere recently. The family hadn’t eaten out lately. It’s likely other family members also ate what the girls did but did not become violently ill. Even more puzzling, Mariska and Willow rarely eat the same things.

9-year-old Willow’s kidney’s still are not working. She has been debilitated by toxins from the infection, and at one point couldn’t wake up. Both sisters have had blood transfusion and dialysis.

Steam with your melons? If it makes produce safer, why not

Abstract

The purpose of this study was evaluation of the effectiveness of superheated steam (SHS) on inactivation of foodborne pathogens on cantaloupes and watermelons.

Saturated steam (SS) treatment was performed at 100 °C and that of SHS at 150 and 200 °C. Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes-inoculated cantaloupes and watermelons were exposed for a maximum of 30 s and 10 s, respectively. Populations of the three pathogens on cantaloupes and watermelons were reduced by more than 5 log after 200 °C steam treatment for 30 s and 10 s, respectively. After SHS treatment of cantaloupes and watermelons for each maximum treatment time, color and maximum load values were not significantly different from those of untreated controls. By using a noncontact 3D surface profiler, we found that surface characteristics, especially surface roughness, is the main reason for differences in microbial inactivation between cantaloupes and watermelons. The results of this study suggest that SHS treatment can be used as an antimicrobial intervention for cantaloupes and watermelons without inducing quality deterioration.

Comparison of the effect of saturated and superheated steam on the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes on cantaloupe and watermelon surfaces, Korea, April 2017 to October 2017, Food Microbiology, Volume 72

Sun-Ah Kwon, Won-Jae Song, Dong-Hyun Kang

http://www.sciencedirect.com/science/article/pii/S0740002017303805?_rdoc=1&_fmt=high&_origin=gateway&_docanchor=&md5=b8429449ccfc9c30159a5f9aeaa92ffb&ccp=y