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Canadian Researchers Working on ‘Smart Labels’ to Detect Food Pathogens

The day may not be too far off when consumers and food manufacturers will be able to detect the presence of E. coli, Listeria or Salmonella by visual changes in a polymer-based “smart label” now being developed by engineering professors at the University of Alberta.

Members of the six-person research team still need to do more testing, get government approvals and move on from the lab to product manufacturing. However, the technology appears to hold promise for enhancing food safety both in the factory and in grocery stores.

“To the naked eye, it looks very much like a normal plastic material,” Dr. Dominic Sauvageau, a chemical engineer and researcher in biotechnology, recently told the Edmonton Journal. “The idea is to have a material that’s easy to make, that is cheap, that can give us a visual or measurable response when a pathogen is present.”

The “smart labels” turn from blue to white or become cloudy if E. coli, Listeria or Salmonella bacteria are present on the food product being checked.

Sauvageau and his team of researchers got $ 220,000 from the Alberta Livestock and Meat Agency, which is concerned about the safety of the province’s huge cattle industry. There’s still another year to go in the team’s three-year project.

Alberta has witnessed a rash of foodborne illness outbreaks and recalls in the recent past, with the latest being an E. coli one potentially related to recalled pork products, another E. coli outbreak in August linked to bean sprouts, and a Salmonella one in June linked to sprouted chia seeds.

And, in 2012, an E. coli outbreak linked to an Alberta beef processing plant resulted in sickening 18 people and prompting what became the largest beef recall in Canada’s history at 8 million pounds.

Food Safety News

‘Trojan Horse’ Antimicrobial Seeks to Kill Pathogens Through Direct Food Contact

A computerized illustration of SDC attacking a microorganism.

An antimicrobial product used to disinfect and sanitize food contact surfaces in the restaurant and manufacturing industries is now being tested directly on food and has shown a “materially significant reduction” in Salmonella contamination on poultry.

That’s according to Hank Lambert, CEO of PURE Bioscience Inc. of El Cajon, CA, the company that created and patented its silver dihydrogen citrate (SDC) product about a dozen years ago. SDC is a colorless, odorless and low-toxicity liquid containing silver ions, citric acid, water and other ingredients.

Bacteria respond to the citric acid as a food source, and the active ingredients in SDC then cause irreversible damage to the microorganism’s DNA, reproductive functions stop, and the organism dies. The company claims that its product has 30-second bacterial and viral kill times and 24-hour residual protection.

Salmonella is a serious problem in the poultry industry, and infection from the bacteria is a common source of foodborne illness. The U.S. Centers for Disease Control and Prevention estimates there are 1.2 million illnesses linked to Salmonella bacteria each year, with about 23,000 hospitalizations and 450 deaths.

PURE® Hard Surface is registered with the U.S. Environmental Protection Agency for food surface decontamination applications, and SDC has been determined Generally Recognized as Safe (GRAS) for use as a biocide on food processing equipment, machinery and utensils. Besides Salmonella, the company notes that the SDC formula in PURE® Hard Surface is also effective on hazardous food pathogens such as E. coli and Campylobacter, as well as on a several types of viruses and fungi.

PURE Bioscience’s new product, as yet unnamed, along with test results and other information, is about to be submitted to the U.S. Food and Drug Administration and the U.S. Department of Agriculture for potential regulatory approval for direct food contact as a processing aid for poultry.

Lambert told Food Safety News that Dr. James Marsden of Kansas State University’s Animal Science and Industry faculty has tested the SDC formula on poultry and is now embarking on additional tests of the product on produce (lettuce, cilantro and spinach) and meat (beef, pork, lamb and veal).

“The results showed that the combination of treatments has the potential to reduce Salmonella on raw poultry products to levels below the detection limit when SDC is included in the process,” notes a company statement.

Marsden will be preparing the submissions to USDA and FDA, which the company indicates would be made before the end of May.

“These are specific approvals for specific food groups,” Lambert explained. “We would have to go through the [Food Contact Notification] process for produce and for the other meats. We might use different applications and dilutions.”

PURE Bioscience has recently been repositioning itself to focus more on the food industry, said Lambert, who previously managed the food safety services business for Underwriters’ Laboratories (UL) and has also worked as a food industry and consumer products executive. He joined the company as CEO this past September in order to move the new agenda forward.

“I was instantly attracted and interested in a food safety solution to take antimicrobial applications in the food industry to the next level and provide an increased level of protection against the pathogens that are so persistent throughout the food industry,” he said.

Lambert said the next step would be arranging for pilot plant testing in USDA-inspected poultry processing plants. If everything goes well, he said that federal agency regulatory approvals could be in place by the end of the year.

Food Safety News

CFIA tests show no pathogens on 99.9 percent of leafy greens

With new federal produce safety standards coming soon, the leafy greens industry could use some good news and, last month, Canadian authorities reassured consumers that leafy greens are safe to eat after reporting over 99.9 percent of fresh leafy greens it tested had no detectable pathogens.

The Canadian Food Inspection Agency tested 4,250 samples of domestic and imported, whole and fresh-cut fresh leafy vegetables available at retail in Canada as part of a five-year project. Starting in 2008-09, CFIA has collected more than 10,000 samples, many of which are still being analyzed.

But so far, CFIA found that 99.9 percent of leafy greens had no detectable level of the following pathogens: Salmonella, E. coli O157:H7, E. coli O157:NM and generic E. coli, in addition to Listeria monocytogenes for fresh-cut samples.

Twelve samples were considered “unsatisfactory” during the 2009-10 study due to the presence of Salmonella, Listeria monocytogenes, and/or high levels of generic E. coli, CFIA reported. None of the samples were found to be positive for E. coli O157:H7 or E. coli O157:NM, however. Two products ended up being recalled and no illnesses were linked to the products.

“The overall finding of this survey suggests that the vast majority of leafy green vegetables in the Canadian market are produced and handled under good agricultural and manufacturing practices,” CFIA said. “However, vegetable contamination with E. coli, Listeria or Salmonella could sporadically occur.”

The Produce News | Today’s Headlines – The Produce News – Covering fresh produce around the globe since 1897.

CFIA tests show no pathogens on 99.9 percent of leafy greens

With new federal produce safety standards coming soon, the leafy greens industry could use some good news and, last month, Canadian authorities reassured consumers that leafy greens are safe to eat after reporting over 99.9 percent of fresh leafy greens it tested had no detectable pathogens.

The Canadian Food Inspection Agency tested 4,250 samples of domestic and imported, whole and fresh-cut fresh leafy vegetables available at retail in Canada as part of a five-year project. Starting in 2008-09, CFIA has collected more than 10,000 samples, many of which are still being analyzed.

But so far, CFIA found that 99.9 percent of leafy greens had no detectable level of the following pathogens: Salmonella, E. coli O157:H7, E. coli O157:NM and generic E. coli, in addition to Listeria monocytogenes for fresh-cut samples.

Twelve samples were considered “unsatisfactory” during the 2009-10 study due to the presence of Salmonella, Listeria monocytogenes, and/or high levels of generic E. coli, CFIA reported. None of the samples were found to be positive for E. coli O157:H7 or E. coli O157:NM, however. Two products ended up being recalled and no illnesses were linked to the products.

“The overall finding of this survey suggests that the vast majority of leafy green vegetables in the Canadian market are produced and handled under good agricultural and manufacturing practices,” CFIA said. “However, vegetable contamination with E. coli, Listeria or Salmonella could sporadically occur.”

The Produce News | Today’s Headlines – The Produce News – Covering fresh produce around the globe since 1897.

CFIA tests show no pathogens on 99.9 percent of leafy greens

With new federal produce safety standards coming soon, the leafy greens industry could use some good news and, last month, Canadian authorities reassured consumers that leafy greens are safe to eat after reporting over 99.9 percent of fresh leafy greens it tested had no detectable pathogens.

The Canadian Food Inspection Agency tested 4,250 samples of domestic and imported, whole and fresh-cut fresh leafy vegetables available at retail in Canada as part of a five-year project. Starting in 2008-09, CFIA has collected more than 10,000 samples, many of which are still being analyzed.

But so far, CFIA found that 99.9 percent of leafy greens had no detectable level of the following pathogens: Salmonella, E. coli O157:H7, E. coli O157:NM and generic E. coli, in addition to Listeria monocytogenes for fresh-cut samples.

Twelve samples were considered “unsatisfactory” during the 2009-10 study due to the presence of Salmonella, Listeria monocytogenes, and/or high levels of generic E. coli, CFIA reported. None of the samples were found to be positive for E. coli O157:H7 or E. coli O157:NM, however. Two products ended up being recalled and no illnesses were linked to the products.

“The overall finding of this survey suggests that the vast majority of leafy green vegetables in the Canadian market are produced and handled under good agricultural and manufacturing practices,” CFIA said. “However, vegetable contamination with E. coli, Listeria or Salmonella could sporadically occur.”

The Produce News | Today’s Headlines – The Produce News – Covering fresh produce around the globe since 1897.

CFIA tests show no pathogens on 99.9 percent of leafy greens

With new federal produce safety standards coming soon, the leafy greens industry could use some good news and, last month, Canadian authorities reassured consumers that leafy greens are safe to eat after reporting over 99.9 percent of fresh leafy greens it tested had no detectable pathogens.

The Canadian Food Inspection Agency tested 4,250 samples of domestic and imported, whole and fresh-cut fresh leafy vegetables available at retail in Canada as part of a five-year project. Starting in 2008-09, CFIA has collected more than 10,000 samples, many of which are still being analyzed.

But so far, CFIA found that 99.9 percent of leafy greens had no detectable level of the following pathogens: Salmonella, E. coli O157:H7, E. coli O157:NM and generic E. coli, in addition to Listeria monocytogenes for fresh-cut samples.

Twelve samples were considered “unsatisfactory” during the 2009-10 study due to the presence of Salmonella, Listeria monocytogenes, and/or high levels of generic E. coli, CFIA reported. None of the samples were found to be positive for E. coli O157:H7 or E. coli O157:NM, however. Two products ended up being recalled and no illnesses were linked to the products.

“The overall finding of this survey suggests that the vast majority of leafy green vegetables in the Canadian market are produced and handled under good agricultural and manufacturing practices,” CFIA said. “However, vegetable contamination with E. coli, Listeria or Salmonella could sporadically occur.”

The Produce News | Today’s Headlines – The Produce News – Covering fresh produce around the globe since 1897.

Eco-friendly ProduceShield extends shelf life, reduces pathogens

A new product rolled out in October has been shown to beat back spoilage organisms and extend shelf-life for fresh produce as well as offer a sustainable pathogen-fighting wash that outperforms chlorine or acid-based alternatives, according to developer CMS Technology.

The Danbury, CT-based firm developed ProduceShield after a team of scientists worked more than six years developing an environmentally friendly, FDA-certified as Generally Recognized as Safe product that can respond to the growing instances of foodborne outbreaks, Harley Langberg, operations director for CMS Technology, told The Produce News.

It relies on a positively charged, cationic carrier technology that remains stable in cold and hot temperatures and can be used in wide-ranging environments, said Langberg.

And unlike other washes, ProduceShield does not have to be rinsed after application, and companies tell CMS that they’re looking for alternatives to chlorine and acid-based products because there’s concern bacteria are becoming resistant to these technologies or can reappear after the product is rinsed off, according to Langberg.

Firms that have been using chlorine for more than 20 years are beginning to look for alternatives, especially as new federal food-safety regulations are coming down the pike from the U.S. Food & Drug Administration, said Langberg, adding that the product is an effective weapon against E. coli, Salmonella and Listeria.

“We’ve shown we’re better than anything out there,” said Langberg, pointing to the product’s success in killing off spoilage bacteria and extending shelf life for commodities like leafy greens, butternut squash and strawberries.

The firm is focusing marketing efforts on three links in the food supply chain: supermarkets, universities and schools, and farm and processors.

Langberg said ProduceShield can be used on the farm as part of its post-harvest spray before product is sent to processors or supermarkets. In supermarkets, it can be applied to protect against spoilage and bacteria from the handling of produce. Some supermarkets just use water or a citrus wash.

The new product also has tremendous benefit in schools and universities.

“They want something that protects against spoilage and protects the children,” Langberg said.

Georgia-based Kennesaw State University has successfully integrated ProduceShield into its food program that serves 7,000 meals a day. Known as a leader in food safety and sustainability efforts, the school was recognized last year by the National Restaurant Association with its Innovator of the Year Award.

The university found produce washed with ProduceShield lasts two to three weeks longer than if the fruits and vegetables were washed in water, which is a huge benefit for a school that manages its own farm, greenhouse and apple orchards.

“As food safety is at the forefront of our program, we appreciate not only the preservation qualities of your product but the eco-friendly component that ties in to our sustainability initiatives,” Gary Coltek, senior director of Kennesaw’s culinary and hospitality services, wrote in a testimonial about the product.

In the meantime, the company has contracted with a food-safety research institute to conduct further tests on its new technology, and it plans to ramp up marketing in the retail sector and extend the marketing reach to seafood, poultry and plastics.

For more information, log on to www.cmstechnology.com/produceshield.

The Produce News | Today’s Headlines – The Produce News – Covering fresh produce around the globe since 1897.

USDA Email Reveals Poultry Industry Plans to Monitor Pathogens

U.S. Department of Agriculture inspectors should not interfere with poultry industry efforts to collect chicken samples from processing facilities for a program intended to set pathogen reduction goals, according to an internal email from an administrator within the USDA’s Food Safety and Inspection Service (FSIS).

The email, which was sent internally on Friday and released to the public on Tuesday by Food & Water Watch, was the first known acknowledgement of such a program by USDA or the poultry industry.

The program, organized by the National Chicken Council, aims to collect samples of chicken parts from “most all poultry establishments” in order to develop voluntary pathogen reduction performance goals, said Dr. John Engeljohn, FSIS Assistant Administrator for the Office of Field Operations and author of the email.

“As a consequence, there is the potential that some in-plant inspectors and field supervisors may begin questioning this effort and take steps to force the establishments to turn over the results of the sampling,” Engeljohn wrote to more than a dozen FSIS personnel. “Please talk to your field staff to discourage them from interrupting an important industry effort.”

Because inspectors may mistakenly assume that the sampling could influence decision-making at individual poultry establishments, field inspection teams should be briefed to not interrupt this “important industry effort,” Engeljohn continued. As such, FSIS does not have authority to review the data being collected.

In fact, any interruption of the industry’s data collection would have a negative impact on public health, Engeljohn said.

In a press release Tuesday morning, the consumer group Food & Water Watch (FWW) said that this email is evidence that USDA would permit the poultry industry to self-regulate on pathogen levels in chicken parts.

The National Chicken Council answered back, telling Food Safety News that the plan was not to self-regulate or replace upcoming USDA standards. The industry is just trying to get ahead of upcoming performance standards expected to be set by FSIS, said Tom Super, vice president of communications at the National Chicken Council.

The poultry industry has the most responsibility to reduce pathogen loads on chicken parts, but USDA needs to answer questions about how those pathogen loads might be enforced, said Tony Corbo, senior lobbyist at FWW. According to a 2012 UDSA report, the estimated national prevalence of Salmonella on chicken parts was 24 percent, while Campylobacter was 21 percent.

One concern FWW expressed was that the industry might be allowed to set its own standards for chicken parts. FSIS is currently expected to release performance standards on chicken parts in this year, though it already has Salmonella standards of 7.5 percent on whole chicken carcasses and 49 percent on ground poultry.

Corbo said that while it’s mainly the poultry industry’s responsibility to curb contamination rates, FSIS cannot relax on releasing its own standards.

“I have no problem with the poultry industry collecting data, but I want to know if this is going to be a substitute for setting FSIS performance standards,” Corbo told Food Safety News. “That’s my gripe.”

The government is still scheduled to roll out its performance standards this year, unaffected by the industry’s research, according to Super at the National Chicken Council.

“Let me be clear: this is not self-regulation,” Super told Food Safety News. “Nor is the industry setting its own performance standards for pathogen reduction on chicken parts.”

The data being collected by the poultry industry will be used to take a hard look at the process of cutting chicken into parts, Super said. It’s a way for the industry to prepare to meet or exceed whatever performance standards FSIS plans to set, he added.

“We are collectively and non-competitively exploring all options to reduce contamination throughout the process in order to provide the safest product possible to our consumers,” he said.

Corbo said that the internal email raised questions about transparency at FSIS. Consumer advocacy groups, including FWW, held their monthly meeting with FSIS on Jan. 15, just two days prior to Engeljohn’s email. At that point, the poultry industry’s plan had never been discussed at a meeting and no one from the groups had heard of it, Corbo said.

Due to government closures from inclement weather, FSIS representatives could not be reached at their offices on Tuesday.

Food Safety News

Pasteurization: How Heat Keeps Pathogens at Bay

When Louis Pasteur developed and patented the process of pasteurization in the 1860s, it had nothing to do with milk. He was more concerned with keeping beer from spoiling.

But, by the turn of the century, this method of preservation had been adapted to address common water- and milk-borne diseases such as tuberculosis, diphtheria, severe streptococcal infections, typhoid fever and other foodborne illnesses.

Pasteurizing milk became routine in the U.S. starting in the 1920s. Today, a number of other products on grocery store shelves, including eggs and juices, are also pasteurized.

While pasteurization doesn’t kill all the microorganisms in our food, it does greatly reduce the number of pathogens so that they are unlikely to cause disease. And, like with Pasteur’s beer, it reduces spoilage organisms, extending our food’s “shelf life.”

The method of pasteurization simply involves heating food (usually a liquid) to a specific temperature for a certain length of time and then immediately cooling it. Manufacturers use various time-temperature combinations when treating their products.

“Vat pasteurization” means milk is heated to 63 degrees Celsius for 30 minutes, but “your normal pasteurization is probably going to be for 15 seconds at 72 degrees [Celsius],” says Michele Jay-Russell, a veterinarian and food safety specialist at the Western Institute for Food Safety and Security at University of California, Davis. This is called “high-temperature short-time” (HTST) processing, or flash pasteurization.

At the most extreme, there’s “ultra pasteurization,” which could involve heating to 138 degrees C for 2 seconds. This variation sterilizes food and allows for products to be on shelves instead of the refrigerated section of the grocery store (think boxed milk).

The specific temperatures allotted for pasteurization are based on the ability to kill the most heat-resistant of pathogens, Jay-Russell says. Campylobacter will die pretty quickly at 72 degrees C, she says, but processors need higher temperatures to kill Q fever.

“If you can kill that off, you’ve killed off everything else,” Jay-Russell adds.

Of course, pasteurization is in the news these days because of the debate about raw milk.

The market is growing of consumers seeking unprocessed foods or those wanting to support small farms. And advocates of raw milk defend it for a number of reasons, particularly arguing that pasteurization reduces the nutritional and health benefits of milk.

But, without pasteurization, E. coli, Campylobcater and Salmonella can be much more prevalent in the milk. According to the Centers for Disease Control and Prevention (CDC), there were 148 outbreaks due to consumption of raw milk or raw milk products reported between 1998 and 2011. Among the victims, there were 2,384 illnesses, 284 hospitalizations and two deaths.

Milk is a real breeding ground for pathogens, Jay-Russell says.

“If you get Salmonella or E. coli on a lettuce leaf, it’s not a happy environment for that bacteria. If you put just a couple of cells into raw milk, it’s like a culture medium,” she says.

Because raw milk can be particularly dangerous for young children whose immune systems are especially susceptible to infection, the American Academy of Pediatrics (AAP) issued a policy statement in December stating that pregnant women, infants and children should only consume pasteurized milk and milk products.

The health benefits that proponents say are removed by pasteurization “have not been clearly demonstrated in evidence-based studies and, therefore, do not outweigh the risks of raw milk consumption,” the AAP said. “Substantial data suggest that pasteurized milk confers equivalent health benefits compared with raw milk, without the additional risk of bacterial infections.”

“You have to take steps to keep the risk as minimal as possible,” Jay-Russell says.

Food Safety News

Ants protect acacia plants against pathogens

Jan. 15, 2014 — The biological term “symbiosis” refers to what economists and politicians usually call a win-win situation: a relationship between two partners which is beneficial to both. The mutualistic association between acacia plants and the ants that live on them is an excellent example: The plants provide food and accommodation in the form of food bodies and nectar as well as hollow thorns which can be used as nests. The ants return this favor by protecting the plants against herbivores. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now found that ants also keep harmful leaf pathogens in check. The presence of ants greatly reduces bacterial abundance on surfaces of leaves and has a visibly positive effect on plant health. Study results indicate that symbiotic bacteria colonizing the ants inhibit pathogen growth on the leaves.

Myrmecophytes are plants which live in a symbiotic relationship with ants. The acacia species Acacia hindsii, which is native to tropical dry forests in Central America, is such a myrmecophyte. Its inhabitants are ants of the genus Pseudomyrmex. The ants depend completely on their host plants for nectar and the food bodies rich in proteins and lipids which they require. The acacia also provides shelter, the so-called domatia, in the hollows of its swollen thorns. In return for room and board, mutualistic Pseudomyrmex ferrugineus ants become bodyguards, protecting their host against herbivores and competing plants. However, some ants also benefit from the plant’s services without giving anything in return, such as the parasitic ant species Pseudomyrmex gracilis.

Scientists at the Max Planck Institute for Chemical Ecology have now looked more deeply into the insect-plant interaction, asking whether the tiny bodyguards also provide protection against microbial pathogens. They compared the leaves of acacia plants which were inhabited by either mutualistic or parasitic ants to leaves from which ants had been removed. Intriguingly, the leaves of acacia colonized by parasitic ants showed more leaf damage from herbivores and microbial pathogens than did the leaves that had mutualistic ants. The presence of the right symbiotic partner seemed to have a positive effect on the plant’s health.

Analysis of the surfaces of the leaves revealed that the number of plant pathogens as well as of necrotic plant tissues increased considerably when mutualistic Pseudomyrmex ferrugineus ants were absent. These plants also showed strong immune responses in the form of an increased concentration of salicylic acid, a plant hormone which regulates defense against pathogens. Detailed analysis of the bacterial composition on the surfaces of the leaves suggested that the presence of mutualistic ants changed the bacterial populations and reduced harmful pathogens. Although far less pronounced, this effect could also be observed in parasitic ants.

How antimicrobial protection is transferred from ants to plant is still unclear. Chilean researcher Marcia González-Teuber, first author of the publication, suspected that microorganisms associated with the ants might play a role. Because acacia leaves are touched mainly by ants’ legs, she extracted the legs of mutualistic and parasitic ants and tested the effect of the extracts on the growth of bacterial pathogens in the lab. Plant pathogen Pseudomonas syringae was sensitive to the application of leg extracts of both ant species and its growth was inhibited. In the next step, the scientist isolated and identified bacteria from the legs of the ants. In lab tests, bacterial strains of the genera Bacillus, Lactococcus, Pantoea and Burkholderia effectively inhibited the growth of Pseudomonas bacteria isolated from infected acacia leaves. Interestingly, some of the bacterial genera associated with the ants are known to produce antibiotic substances.

The Jena researchers have thus added another level of interaction to the symbiosis between ants and their host plants. “Such mutualistic relationships are much more complex than previously thought. In the future, we will have to include bacteria and other microorganisms in our considerations,” says Wilhelm Boland, head of the Department of Bioorganic Chemistry at the Max Planck Institute. Studies on symbiotic relationships between ants and myrmecophytic plants should not overlook the role of bacterial partners that help the ants protect “their” plants.

ScienceDaily: Agriculture and Food News

Fresh-cut fruit: useful microorganisms against bacterial pathogens

Pseudomonas graminis is the best one
Fresh-cut fruit: useful microorganisms against bacterial pathogens

In the last few years, the increase of foodborne illness outbreaks associated to the fresh produce is related to the increase of fresh-cut fruit and vegetables consumed.

Scientists from Spain and The Netherlands have evaluated the native microorganisms from fresh and fresh-cut fruit that showed an inhibitory activity against the most important bacterial pathogens (Escherichia coli O157:H7, Salmonella, Listeria innocua) detected on the fresh produce up to the present.

The study was carried out on fresh-cut apples and peaches, 97 and 107 strains were isolated from apples and peaches, respectively. The best antagonist was tested for phytopathogenicity, antimicrobial substances production, and minimum inhibitory concentration.

Among isolated microorganisms, only 7 strains were selected for their strong antagonistic activity with more than 1-log unit reduction of bacterial pathogen load. However, the CPA-7 strain, identified as Pseudomonas graminis, resulted the best antagonist by reducing the bacterial pathogen load from 2.8 to 5.9-log units. Moreover, it resulted the only able to inhibit Escherichia coli O157:H7 at refrigeration temperatures on both fruits.

Tabels – Population of Escherichia coli O157:H7 on ‘Golden Delicious’ apple (left) and ‘Elegant Lady’ peach (right), plugs in the presence of different antagonists (concentration between 10 6 e 10 8 cfu/ml) and stored at 5 °C over 10 days. Plugs were inoculated with con E. coli O157:H7 at 10 7 cfu/ml. . Click here to enlarge the tables.

This study has showed that Pseudomonas graminis could be used as biological control against the potential bacterial pathogens of fresh-cut fruit. However, its antagonistic activity against pathogens is not instantaneous but it occurs gradually during shelf-life, thus the scientists suggest to use the antagonist only after other sanitation treatments.

Source: Alegre I., Viñas I., Usall J., Teixidó N., Figge M.J., Abadias M., “Control of foodborne pathogens on fresh-cut fruit by a novel strain of Pseudomonas graminis“, 2013, Food Microbiology, Vol. 34, pagg. 390-399. Further info: http://www.ncbi.nlm.nih.gov/pubmed/23541207

Publication date: 10/21/2013
Author: Emanuela Fontana
Copyright: www.freshplaza.com


FreshPlaza.com

Food Testing: Labs Test for Pathogens at Different Rates in the U.S. and Europe

Microbial testing can be a helpful way to identify pathogen risks for fresh produce, but it’s not a guarantee of safety. That’s why this one option in the toolbox is used differently by Americans and Europeans.

Testing in the U.S. varies somewhat from company to company, but it follows similar procedures that were standardized in 2007 with the Leafy Green Marketing Agreement, says Trevor Suslow, food-safety specialist at the University of California, Davis. It involves sampling from a field before or after harvest to assess the risk of a lot.

“It’s submitted to a lab, the lab takes a random sub-sample from that tissue … they subject it to different types of enrichment, and then you use one of the rapid real-time PCR-type of test to ask the question, ‘Do we have detectable levels of pathogens in the sample or not?’” Suslow says. The result can then qualify a field for harvest or perhaps prompt further evaluation. Some companies go further and even uniformly test finished processed goods.

But the situation is different in Europe. While European labs do test for pathogens, it’s not their main concern, says Keith Warriner, a professor of food science at the University of Guelph and program director of the school’s food safety and quality assurance program.

“We just look for E. coli and Salmonella, whereas the Europeans are a bit more risk-based,” he says.

Mieke Uyttendaele, director of Belgium’s University of Gent Laboratory for Food Microbiology and Food Preservation, believes that less pathogen testing is done in Europe than the U.S.

“End-product testing is not assumed to be very effective in safeguarding the fresh produce supply chain,” she says. “So there is more effort put into a preventive approach – from farm to fork – which is also the basis of the EU General Food Law and EU food safety legislation, putting stress on ‘good agricultural practices.’”

Europe’s system focuses more on Hazard Analysis Critical Control Point (HACCP) principles, taking into account chemical and physical hazards as well as microbial ones and bringing in controls to address those risks.

North America doesn’t really have fully HACCP-based systems for produce, Warriner says, because the existing systems mainly address just microbial contamination and traceability.

“They believe that those production practices provide a high degree of protection and therefore also limit the value of pathogen testing as a way to qualify or disqualify a product for safety,” Suslow says.

There’s a low level of confidence in the statistics of sampling to detect pathogens, so testing is often targeted at hygiene indicators such as generic E. coli rather than pathogens themselves, Uyttendaele says. If the E. coli numbers are unacceptable, it’s probably followed up with pathogen testing or auditing of the farmer’s operations.

“The objective of testing is not the key issue for ‘safety assessment’ or ‘batch release’ but rather to pick up major breakages in good agricultural or good manufacturing practices,” Uyttendaele says.

Suslow and Warriner both say it’s very difficult to judge whether one system is better than the other since, after all, they are based on very different structures.

Europe’s agricultural system consists of a lot of smaller farms and, Suslow says, “The smaller the company, the harder it is economically to factor in the cost of pathogen-testing materials into your program.”

But in North America’s favor is “a much better surveillance system,” Warriner says. “And so when outbreaks happen, we’re really on to it.”

Food Safety News

Emerging Pathogens: Listeria Threatens a Growing Senior Population

From August through October 2011, 147 people in 28 states were infected with Listeria monocytogenes after eating cantaloupe from Jensen Farms in Colorado. There were 33 deaths, and one pregnant women had a miscarriage as a result, making it one of the deadliest outbreak of foodborne illness in the U.S. in recent years.

Apart from some diarrhea or minor gastrointestinal problems, most people don’t get sick when they’re exposed to Listeria. But, if the pathogen gets into their bloodstream, it can cause listeriosis, a disease that kills one out of every five victims. Because of these odds, Listeria has the highest mortality rate of foodborne pathogens.

Groups most at risk for Listeria infections are older adults, pregnant women and people with an underlying medical conditions such as cancer liver or kidney disease, diabetes or HIV/AIDS.

People 65 and older are four times more likely to get sick from Listeria poisoning than the general population, and pregnant women – who may not develop listeriosis themselves but whose babies could be threatened – are 10 times more likely.

While it’s important to remember that there are only about 800 laboratory-confirmed cases of Listeria in the U.S. each year, more than half of them occur among older adults. In the 2011 cantaloupe-related outbreak, most of the cases involved people older than 60, and those who died were between the ages of 48 and 96.

“Typically, when the highly susceptible populations are infected, they’re the ones that experience the most severe symptoms and often the high mortality rates,” said Michael Doyle, director of the Center for Food Safety. “As we age, we need to be more careful about the types of foods we eat. That means making sure that foods that are likely to be contaminated with harmful microbes should be cooked or somehow processed or treated to ensure safety. We should not be taking the risks that maybe younger people would take – eating less well-cooked meat, for example.”

Foods that typically cause Listeria outbreaks are Mexican-style soft cheeses made with unpasteurized milk, deli meats, and hot dogs. Produce was not often identified as a source in the past, but sprouts caused an outbreak in 2009, and pre-cut celery caused an outbreak in 2010.

“There have been a lot of successes on the ready-to-eat meat front,” said Alicia Cronquist, an epidemiologist with the Colorado Department of Public Health and Environment who investigated the 2011 outbreak. “Manufacturers have put in enormous efforts, and we’ve seen a real decline in outbreaks due to those deli meats and poultry products.”

Doyle agrees and says this is why he’s not as concerned about lunch meats now as he is about fresh produce.

“I am very concerned about fruits and vegetables – not just because of Listeria, but because we’ve had hiccups with a lot of other pathogens with fresh fruits and vegetables,” he said.

“We frequently identify new vehicles when we do outbreak investigations, whether it’s Listeria, E. coli or Salmonella,” Cronquist said. “This outbreak was very unusual in that it was huge and had a terrible number of fatalities, but it was also notable in that [cantaloupe] was a novel Listeria vehicle.”

In addition to its high mortality rate, Listeria is an unusual foodborne pathogen because it can survive and multiply at refrigerator temperatures. In order to avoid Listeria, CDC recommends that high-risk consumers heat hot dogs, lunch meats and cold cuts to an internal temperature of 165 degrees F and avoid products with unpasteurized milk, refrigerated paté or meal spreads, and uncooked smoked seafood.

When it comes to melon safety, consumers and food preparers should wash their hands before and after handling a whole melon, scrub the outside of melons under running water and dry them with a clean cloth or paper towel before cutting, and then promptly consume or refrigerate cut melon and keep it for no more than a week.

FDA has also released “Food Safety for Older Adults” to address threats from all major pathogens and offer prevention tips for seniors. Because, as Doyle says, “It’s the elderly that are going to be more susceptible to all these different pathogens, not just Listeria. They’re the ones that are going to suffer the most severe consequences.”

Food Safety News

Emerging Pathogens: Vibrio Cases in Oysters Expected to Continue Increasing

With a nearly 50-percent mortality rate, Vibrio vulnificus is the most deadly foodborne pathogen in the world, according to University of North Carolina at Charlotte Biology Professor Jim Oliver. And instances of infection in the U.S., however rare, are rapidly rising.

Fifteen years ago, there were 21 confirmed cases of Vibrio vulnificus and parahaemolyticus infections in the U.S. Last year, there were 193.

While infections from either of the pathogens are still rare compared with, say, Salmonella and Campylobacter, the incidence rate grew faster than any of the other five microbes tracked in the Centers for Disease Control’s 2012 Food Safety Progress Report. The vulnificus strain is responsible for 95 percent of seafood-related illness fatalities in the U.S., according to a 2013 study by Oliver and Joanna Nowakowska. Another Vibrio strain, parahaemolyticus, is milder, causing diarrhea, nausea, fever and chills, according to CDC.

Several studies have linked Vibrio’s quick growth rate with rising ocean temperatures, a critical condition favorable to the saltwater-based bacterium. Instances of Vibrio have started showing up in colder places where they were largely unheard-of before.

“Most notably, they’ve been [seeing cases] in places like the Baltic and Germany,” Oliver said.

While those cases usually involved Vibrio entering humans through wounds while they were swimming, a 2009 article by Oliver and Melissa Jones shows that about 93 percent of Vibrio cases in the U.S. manifest themselves in people who have consumed raw or undercooked oysters. Vibrio can also come from other undercooked seafood.

Vibrio doesn’t harm the oysters in any way, according to Rohinee Paranjpye, a research microbiologist with the National Oceanic and Atmospheric Administration.

“It appears to be a symbiotic relationship,” Paranjpye said.

Several post-harvest processing methods exist, which have varying degrees of success at killing Vibrio, but they have several drawbacks, said Chris Nelson, a trustee of the Gulf & South Atlantic Fisheries Foundation. One of the largest barriers is cost.

“There’s a huge barrier in terms of capitalization,” Nelson said. “Let’s say you needed a million dollars — and some of the post-harvest processing pieces of equipment are upwards of a million dollars — you have to be a certain size operation.”

In addition to the costs of equipment, a 2011 report from the Interstate Shellfish Sanitation Conference found that processing methods incur staff time and transportation costs. Because such costs are passed on to the consumer, Nelson said the price of oysters can multiply.

“Probably for every dollar spent processing, it’s going to result in at least three more dollars on the dinner plate,” he said. “And probably even more than that because, if you make the additional investment, you’re going to want an additional profit.”

The least-expensive method, which involves freezing the oysters, is typically not used during the summer months when the water is warmer and Vibrio cases are more likely to rise, Nelson said. During the winter, when oysters are plumper, they can take the beating of post-harvest processing. But, when it gets warmer, the reproduction cycle takes much of the meat out of oysters, and processing can reduce the product’s quality, he said.

However, the costs of processing vary depending on several factors, including the method used, the market intended for the oysters, and whether the company in question is using its own material or paying somebody else to process their catch.

For instance, processing can actually reduce the price of shucked oysters, according to the ISSC’s report. Certain methods will help open oysters up, which almost cuts in half the amount of time it takes to shuck them. However, the report also showed that only 40 percent of oysters are sold to the shucked market, while 60 percent are sold to the half-shell market.

Nelson said some regulations exist for post-harvest processing, but they vary by location and time of year.

Cooking oysters can kill Vibrio as well. But, as long as ocean temperatures continue to rise, Oliver said Vibrio will continue to be a problem.

“Vibrio cases in general, I’m very confident will increase,” he said.

Food Safety News

Emerging Pathogens: Vibrio Cases in Oysters Expected to Continue Increasing

With a nearly 50-percent mortality rate, Vibrio vulnificus is the most deadly foodborne pathogen in the world, according to University of North Carolina at Charlotte Biology Professor Jim Oliver. And instances of infection in the U.S., however rare, are rapidly rising.

Fifteen years ago, there were 21 confirmed cases of Vibrio vulnificus and parahaemolyticus infections in the U.S. Last year, there were 193.

While infections from either of the pathogens are still rare compared with, say, Salmonella and Campylobacter, the incidence rate grew faster than any of the other five microbes tracked in the Centers for Disease Control’s 2012 Food Safety Progress Report. The vulnificus strain is responsible for 95 percent of seafood-related illness fatalities in the U.S., according to a 2013 study by Oliver and Joanna Nowakowska. Another Vibrio strain, parahaemolyticus, is milder, causing diarrhea, nausea, fever and chills, according to CDC.

Several studies have linked Vibrio’s quick growth rate with rising ocean temperatures, a critical condition favorable to the saltwater-based bacterium. Instances of Vibrio have started showing up in colder places where they were largely unheard-of before.

“Most notably, they’ve been [seeing cases] in places like the Baltic and Germany,” Oliver said.

While those cases usually involved Vibrio entering humans through wounds while they were swimming, a 2009 article by Oliver and Melissa Jones shows that about 93 percent of Vibrio cases in the U.S. manifest themselves in people who have consumed raw or undercooked oysters. Vibrio can also come from other undercooked seafood.

Vibrio doesn’t harm the oysters in any way, according to Rohinee Paranjpye, a research microbiologist with the National Oceanic and Atmospheric Administration.

“It appears to be a symbiotic relationship,” Paranjpye said.

Several post-harvest processing methods exist, which have varying degrees of success at killing Vibrio, but they have several drawbacks, said Chris Nelson, a trustee of the Gulf & South Atlantic Fisheries Foundation. One of the largest barriers is cost.

“There’s a huge barrier in terms of capitalization,” Nelson said. “Let’s say you needed a million dollars — and some of the post-harvest processing pieces of equipment are upwards of a million dollars — you have to be a certain size operation.”

In addition to the costs of equipment, a 2011 report from the Interstate Shellfish Sanitation Conference found that processing methods incur staff time and transportation costs. Because such costs are passed on to the consumer, Nelson said the price of oysters can multiply.

“Probably for every dollar spent processing, it’s going to result in at least three more dollars on the dinner plate,” he said. “And probably even more than that because, if you make the additional investment, you’re going to want an additional profit.”

The least-expensive method, which involves freezing the oysters, is typically not used during the summer months when the water is warmer and Vibrio cases are more likely to rise, Nelson said. During the winter, when oysters are plumper, they can take the beating of post-harvest processing. But, when it gets warmer, the reproduction cycle takes much of the meat out of oysters, and processing can reduce the product’s quality, he said.

However, the costs of processing vary depending on several factors, including the method used, the market intended for the oysters, and whether the company in question is using its own material or paying somebody else to process their catch.

For instance, processing can actually reduce the price of shucked oysters, according to the ISSC’s report. Certain methods will help open oysters up, which almost cuts in half the amount of time it takes to shuck them. However, the report also showed that only 40 percent of oysters are sold to the shucked market, while 60 percent are sold to the half-shell market.

Nelson said some regulations exist for post-harvest processing, but they vary by location and time of year.

Cooking oysters can kill Vibrio as well. But, as long as ocean temperatures continue to rise, Oliver said Vibrio will continue to be a problem.

“Vibrio cases in general, I’m very confident will increase,” he said.

Food Safety News

Emerging Pathogens: Antibiotic Resistance Slowly Growing in Salmonella

The number of antimicrobial-resistant Salmonella serotypes hasn’t increased drastically in recent years, but drug-resistant Salmonella continues to pose a public health threat in the United States, particularly as resistance spreads across classes of drugs, necessitates the use of more expensive drugs, makes treatment less effective, and, in worse-case scenarios, leaves infections untreatable.

A recent Centers for Disease Control and Prevention study identified increasing resistance to a class of drugs called Cephalosporins, which are commonly used to treat severe Salmonella infections in adults and are the main drug of choice when treating children, for whom the fluoroquinolone class of drugs is not recommended. Currently, about five percent of Salmonella strains are resistant to Cephalosporins, mostly in cases of Salmonella Heidelberg and Salmonella Newport.

Cephalosporin resistance is the biggest current issue in drug-resistant Salmonella, said Robert Tauxe, deputy director of the Division of Foodborne, Waterborne, and Environmental Diseases at the National Center for Emerging and Zoonotic Infectious Diseases at the CDC.

Bhushan Jayarao, director of the Animal Diagnostic Lab at Pennsylvania State University, echoed that sentiment, adding that Salmonella Typhimurium and Salmonella Heidelberg are at risk of acquiring CTX-M resistance to cephalosporins. CTX-M is one form of the beta-lactamase enzymes that breaks down cephalosporins (which are used to treat severe Salmonella infections in humans) and thereby confers resistance to the bacteria that produces this enzyme.

READY-TO-EAT MEAT
The CDC study found that the main mechanism of resistance to cephalosporins is the production of beta-lactamases, which are enzymes that manage to inactivate the antimicrobial agent. Of concern to the researchers is the fact that the genes related to antimicrobial resistance are often mobile, moving between bacteria and Salmonella serotypes, humans and animals.

“The same genes were seen in several different kinds of Salmonella and in Salmonella collected from meat, animal and human samples, which shows that this gene is now pretty widespread,” said Maria Karlsson, research microbiologist with the National Antimicrobial Resistance Surveillance team at CDC. “The Salmonella are sharing this gene.”

Assessing the genetic structure of resistance to provide evidence that the exact same genes are flowing from animal to food to humans and between types of Salmonella is an advanced method of public-health surveillance and is something the CDC hopes to do more of in the future, Tauxe said.

It is typically difficult to trace the transmission of Salmonella strains within and between animal and human populations because of the rapidly changing nature of resistance patterns in bacteria. However, researchers from Penn State recently developed a way to identify and track Salmonella Typhimurium as it evolves and spreads.

The research centers on virulence genes and regions of the bacteria’s DNA called CRISPRs, short for clustered regularly interspaced short palindromic repeats. CRISPRs are present in a large number of foodborne pathogens and can be used to identify antibiotic-resistance patterns within Salmonella Typhimurium.

The researchers chose to study resistance and spread within Salmonella Typhimurium because it is the most frequently isolated serotype in humans, food, animals and the environment. Information garnered from the study of Salmonella Typhimurium isolates is now being applied to other serotypes, including Kentucky, Heidelberg, Enteritidis and Infantis.

Additionally, Penn State researchers are engaged in studying antimicrobial resistance in pathogens other than Salmonella that are significant to animal and human health. The research includes looking at mechanisms associated with antimicrobial resistance and undertaking genome sequence analysis in order to determine which genetic determinants, aside from antibiotic0resistant genes, influence the emergence of antibiotic resistance.

“I am very certain that, in the next couple of years, we will be able to identify key global genetic determinants in bacteria that make them more susceptible or drug-resistant,” Jayarao said. “The science of genomics and proper interpretation of the genome data will truly be able to find and answer for us.”

Drug resistance within serotype Salmonella Kentucky has largely increased overseas in recent years, posing a significant problem in Africa and the Middle East and sounding an alarm among researchers, food-safety professionals and public health specialists in the U.S.

“If it comes to this country and gets into our poultry farms, we will run out of antibiotics to treat it,” said Susan Vaughn Grooters, food-safety research and policy associate at the Center for Science in the Public Interest.

Improper agricultural use of antibiotics is often pegged as a main contributor to the problem of drug-resistant Salmonella, but other studies have failed to find evidence that these practices contribute to increased antibiotic resistance. Other theories for the development of resistance exist, such as improper use of antibiotics among humans, or even, as Jayarao noted, the spread of antibiotic-resistant clonal types not influenced by antibiotic use in animals or humans.

“The most recent evidence is to suggest the spread of CTX-M resistance that was first observed in Indonesia, then in India, Pakistan and the Middle East, which then spread to Europe and very recently has emerged in Canada and the U.S.,” Jayarao said.

Consumer awareness of resistance and a demand for transparency surrounding it is important, as is increased regulation regarding antibiotic use.

“This is a public-health crisis and a key area for interest for CSPI and food-safety advocates and should be on the radar screen of consumers far above issues that have been getting more attention but are actually much less urgent,” Grooters said. “We have to act before it’s too late. It’s not if a multi-drug-resistant outbreak that’s too deadly to treat will occur, but when.”

Food Safety News

Letter From The Editor: Let the War on Poultry Pathogens Begin!

When I was a kid, Julia Child gave me great comfort because she would go on television to handle big chickens under the kitchen faucet to show how to wash away the germs that come with poultry and she did it just like my mother and aunts did. Indeed, my earliest lessons in food safety were about how those chickens and turkeys had to be washed because they contained germs.

So, it was a little discomforting to hear from a well-spoken nutrition scientist at Drexel University all these years later that raw poultry is now so contaminated that if you wash it as Julia Child taught us back in the day that you are going to just spread Campylobacter and Salmonella in little microscopic droplets all over your kitchen.

Drexel’s Dr. Jennifer Quinian says don’t risk that cross-contamination, just get the bird in the oven and cook it to temperature.

Julia Child being wrong after all these years was one of those cute little NPR stories and it came complete with “Germ-Vision” animation, which was pretty neat.

But the more I thought about it, the more helpless I felt about this whole issue of pathogens being rampant in our chicken. It’s like we are supposed to just accept the fact, according to independent researchers, that about two of three raw chickens we purchase at the local supermarket are contaminated with Campylobacter or Salmonella or both.

Most of it is Campylobacter, but the Salmonella strains showing up are increasingly of the anti-biotic resistant variety. Consider this little factoid. New pathogens are emerging faster than we can even reform our poultry inspection system to more fully address the existing Campylobacter and Salmonella contamination.

I suppose germ evolution moving faster than the speed of government should come as no surprise. But it’s sAd, really, that politics has been allowed to trumpet pathogens in poultry inspection for most of the last 15 years or so.

The way we inspect chickens in the United States has hardly changed in 56 years. Oh, we’ve added Hazard Analysis and Critical Control Point (HACCP) planning and held out some standards for the poultry industry to achieve. But the shift to pathogen reduction forced on the rest of the meat industry with some great success has largely skipped over poultry.

USDA’s Food Safety and Inspection Service (FSIS) knows it needs to change the system. The HACCP-based Inspection Model Project, or HIMP for short, is supposed to be the change agent for the U.S poultry system, but it has not yet happened.

HIMP was attacked from the get-go by the meat inspectors union, who took it to court under the Poultry Products Inspection Act of 1957.

It’s gone on and on ever since. Judges ordered studies and data, USDA brought in third party experts, and the latest was the Government Accounting Office nitpicking about the math. The union, with its enlisted (and probably paid) partisans, keeps a well-oiled machine going in order to scare the Obama Administration from moving to a new HIMP-based inspection system.

Prior to 1957, the U.S. Food and Drug Administration was responsible for U.S. poultry inspection and a big scandal erupted because FDA was rarely doing any actual inspection at all. After 50 years of USDA-inspected beef and pork, “Ike” decided to calm a nation about chickens and give poultry the same treatment. Chickens and turkeys were moved to USDA and eyes-on inspection of every bird slaughtered got underway.

At that time, nobody was thinking about pathogens. Back then, chickens going to slaughter were not as healthy as they are now, nor were they as uniform in age and weight. Inspectors were on the lookout for tumors, abscesses and signs of sepsis.

Poultry inspectors standing on platforms watching chickens go by today strikes me as both incredibly boring and a complete waste of precious time. I can guarantee that not a single inspector will see a pathogen on a chicken, even if the line speed is really slowed or even if the line is run reverse.

Somebody apparently has to do it because the 1957 law mandates it, but poultry inspectors watching birds whiz by is the poultry inspection equivalent of the old “poke and sniff” system used on beef.

USDA’s proposed new inspection system, drawn on the HIMP experience, seems to me to empower the inspectors to get into plant records, enforce the HACCP plan, test for pathogens and focus on sanitation. Why the union does not want to have its members have opportunities for more money and more responsibility by actually doing something is a bit puzzling to me.

The bottom line here is pretty simple. When two thirds of the birds going out the door with “USDA inspected” marks are contaminated with pathogens that make folks sick, the 1957 system is clearly not working.

No, it is not only a failure, it is a dismal failure that food safety leaders like Dr. Elisabeth Hagen, USDA’s Under Secretary for Food Safety, and Food Safety and Inspection Service (FSIS) Administrator Al Almanza fully recognize and are courageously proposing to change.

What’s been missing from this equation is the union accepting that its members who are our poultry inspectors are failing. Instead, they are in denial and have made this about who has political power, not about food safety or who is right.

The only thing we should be talking about is that too many raw chickens and turkeys sold at meat counters all over America with their “USDA inspected” marks are contaminated with one or more pathogens, and what we are going to do about it.

The same problem with poultry contamination exists in England, Scotland, Ireland and Whales and the United Kingdom decided last week to do whatever it takes to bring about some reductions in pathogen levels no matter whose feathers are ruffled.

Dr. Hagen and Al Almanza are ready to implement a new poultry inspection system. We trust Secretary of Agriculture Tom Vilsack and whomever he has to report to at the White House won’t chicken out.

Food Safety News

QUAFETY project shows the prevalence and biodiversity of bacterial pathogens in produce

QUAFETY project shows the prevalence and biodiversity of bacterial pathogens in produce

Scientists of the Department of Food Science and Technology at Agricultural University of Athens (Greece), within the QUAFETY European project (2011-2014), determined the prevalence of Listeria monocytogenes and Escherichia coli O157:H7 in fresh-cut rocket, cucumbers and strawberries.

The detection of both pathogens was based on the respective ISO methods with a parallel study for the comparison of two chromogenic culture media: ALOA and RAPID’L. mono in the former case, CT – SMAC and Fluorocult in the latter.

Confirmation of the suspect colonies was performed by hemolysis, rhamnose and xylose fermentation as well as specific PCR for L. monocytogenes; Latex Test and specific PCR for E. coli O157:H7.

The results of biochemical tests and molecular analyses showed that the prevalence of L. monocytogenes was 7% in rocket, 6% in cucumbers and 3.8% in strawberries, while prevalence of E. coli O157: H7 was 7% in rocket, 3% in cucumbers and 3.8% in strawberries. Furthermore, it was concluded that parallel use of more than one chromogenic media is necessary for accurate estimation of L. monocytogenes and E. coli O157:H7 prevalence.

The same scientists have also assessed the biodiversity of 22 L. monocytogenes and 12 Escherichia coli Ο157:Η7 strains isolated from rocket, cucumber and strawberry samples, as well as the detection of virulence – associated genes.

Genotypic diversity of both pathogens was assessed by RAPD – PCR using M13, UBC155 and HLWL85 as primers and by rep – PCR using (GTG)5 as primer. Results showed that all L. monocytogenes strains belonged to 4b serotype. Many virulence associated genes such as plcB, plcA, actA, hlyA regarding L. monocytogenes and stx2, eae and some of their variants regarding E. coli O157:H7 have been detected. However, none of the isolates contained all necessary genes required for pathogenicity, as detected by published specific – PCR protocols, most probably due to variations in the primer hybridization sequences.

Source: Hadjilouka A., Madjourani K.S., Katsarou A., Koubou V., Paramithiotis S., Mataragas M., Drosinos, E.H., Laboratory of Food Quality Control and Hygiene, Department of Food Science and Technology, Agricultural University of Athens, Greece. www.quafety.eu

Publication date: 9/10/2013
Author: Emanuela Fontana
Copyright: www.freshplaza.com


FreshPlaza.com

QUAFETY project shows the prevalence and biodiversity of bacterial pathogens in produce

QUAFETY project shows the prevalence and biodiversity of bacterial pathogens in produce

Scientists of the Department of Food Science and Technology at Agricultural University of Athens (Greece), within the QUAFETY European project (2011-2014), determined the prevalence of Listeria monocytogenes and Escherichia coli O157:H7 in fresh-cut rocket, cucumbers and strawberries.

The detection of both pathogens was based on the respective ISO methods with a parallel study for the comparison of two chromogenic culture media: ALOA and RAPID’L. mono in the former case, CT – SMAC and Fluorocult in the latter.

Confirmation of the suspect colonies was performed by hemolysis, rhamnose and xylose fermentation as well as specific PCR for L. monocytogenes; Latex Test and specific PCR for E. coli O157:H7.

The results of biochemical tests and molecular analyses showed that the prevalence of L. monocytogenes was 7% in rocket, 6% in cucumbers and 3.8% in strawberries, while prevalence of E. coli O157: H7 was 7% in rocket, 3% in cucumbers and 3.8% in strawberries. Furthermore, it was concluded that parallel use of more than one chromogenic media is necessary for accurate estimation of L. monocytogenes and E. coli O157:H7 prevalence.

The same scientists have also assessed the biodiversity of 22 L. monocytogenes and 12 Escherichia coli Ο157:Η7 strains isolated from rocket, cucumber and strawberry samples, as well as the detection of virulence – associated genes.

Genotypic diversity of both pathogens was assessed by RAPD – PCR using M13, UBC155 and HLWL85 as primers and by rep – PCR using (GTG)5 as primer. Results showed that all L. monocytogenes strains belonged to 4b serotype. Many virulence associated genes such as plcB, plcA, actA, hlyA regarding L. monocytogenes and stx2, eae and some of their variants regarding E. coli O157:H7 have been detected. However, none of the isolates contained all necessary genes required for pathogenicity, as detected by published specific – PCR protocols, most probably due to variations in the primer hybridization sequences.

Source: Hadjilouka A., Madjourani K.S., Katsarou A., Koubou V., Paramithiotis S., Mataragas M., Drosinos, E.H., Laboratory of Food Quality Control and Hygiene, Department of Food Science and Technology, Agricultural University of Athens, Greece. www.quafety.eu

Publication date: 9/10/2013
Author: Emanuela Fontana
Copyright: www.freshplaza.com


FreshPlaza.com

QUAFETY European project: fast and reliable analytical method to detect pathogens in fresh produce

QUAFETY European project: fast and reliable analytical method to detect pathogens in fresh produce

The presence of pathogens in fresh produce, responsible for foodborne illness outbreaks, is a serious problem in terms of safety and economic losses.

To avoid outbreaks and the distribution of contaminated food on the market, food producers must assure that safety and control measures are followed throughout the entire production chain.

The international standard protocols for food-borne pathogens detection and enumeration are available, but they require 4-5 days before reaching results, this makes them not suitable for short shelf-life food products, such as fresh and fresh-cut produce. Furthermore, in the last years, the use of fast and reliable methods is needed to detect even low pathogen levels before produce packaging.

To respond to this need, the scientists from the Department of Agricultural and Environmental Sciences at the University of Milano (Italy) and the scientists from the Laboratory of Food Science and Technology at the Agricultural University of Athens (Greece), within QUAFETY European Project (2011-2014) on quality and safety of fresh-cut vegetables, have developed an indirect ELISA assay to detect the presence of Escherichia coli O157 and Listeria monocytogenes.

Bacteria isolation protocol, antibody working concentration and limit of detection were studied and optimized to verify the presence of the two bacterial pathogens in cucumber. The incubation times for antigens (overnight at 4°C), antibodies (60 minutes at 25°C) and for matrix reaction (30 minutes at 25°C) were selected.
The results show that the ELISA method is very sensitive with a detection limit lower than 103 cfu/g and it allows to isolate bacteria from 1 to 7 hours.

The analytical procedure can be completed in 1 day compared to the 4-5 days required when the respective ISO methods are applied. In addition, since vegetables might also contain non pathogenic bacteria along with the pathogenic ones, the choice of specific antibodies is crucial.

The scientists conclude that the protocol developed can be applied to detect the presence of other bacteria or viruses by choosing specific antibodies to be optimized in the ELISA assay.

Source: Cavaiuolo M., Paramithiotis S., Drosinos E.H., Ferrante A., “Development and optimization of an ELISA based method to detect Listeria monocytogenes and Escherichia coli O157 in fresh vegetables“, 2013, Analytical Methods, 5: 4622-4627.

Further info: http://pubs.rsc.org/en/Content/ArticleLanding/2013/AY/C3AY40893K#!divAbstract

Contacts: www.quafety.eu

Publication date: 9/6/2013
Author: Emanuela Fontana
Copyright: www.freshplaza.com


FreshPlaza.com