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  • BarbaraCorreiaFaustino 3:48 pm on November 20, 2015 Permalink | Reply
    Tags: Cheese, Dairy, , , , , Listeriosis,   

    Another multistate Listeria outbreak: this time from contaminated soft cheese 


    Recalled soft cheese products. Source: CDC

    An outbreak regarding soft cheese contaminated with Listeria monocytogenes finally arrived to a conclusion after five years of investigation. Starting in June 2010, thirty cases of listeriosis caused by the consumption of a specific type of cheese happened throughout the United States. Most of the cases were reported in California, but there was also a great number of cases happening specially in the eastern portion of the country, occurring in nine other states. According to the Center for Disease Control and Prevention, aside from California, there were also cases in Colorado, Illinois, Massachusetts, Michigan, New York, Ohio, Tennessee and Washington, and overall the outbreak resulted in 28 hospitalizations and 3 deaths, two in California and one in Ohio. Five illnesses were pregnancy-related, and one resulted in miscarriage.

    The Center for Disease Control and Prevention was able to link all those cases together using whole genome sequencing, which is a molecular subtyping method that is recently becoming more used by publich health authorities to identify foodborne pathogens. This method relies on sequencing the nucleic acid of the target microorganism and detecting the differences in that nucleic acid sequence.


    People infected with the outbreak strains of Listeria monocytogenes by contaminated soft cheese. Source: CDC

    Whole genome sequencing, as its name suggests, is a method that provides a nearly complete sequencing of bacterial nucleic acids, and that is what makes it a very accurate method, since it becomes much easier to compare and differentiate between serotypes of a specific bacteria. The first generation was not very user-friendly for the detection of foodborne illnesses outbreaks, as it was a very time-consuming, labor-intensive and expensive method. However, nowadays the development and improvement of next-generation sequencing methods have made these tools more available and affordable for laboratories, making it easier to use them routinely and ensuring not only precise, but also fast results, and at a reasonable cost. These methods are rapidly becoming more accepted by public health and regulatory agencies, and in the next few years they will probably replace the most commonly used method currently, which is pulsed-field gel electrophoresis (PFGE). Compared to the latter, whole genome sequencing methods have a higher discriminatory power for outbreak detection and allow for the sequencing of different pathogens in the same batch.

    The whole genome sequencing methods provide better discrimination between the subtypes, and therefore it can distinguish isolates that have a similar or equal PFGE profile, therefore improving the detection of a possible outbreak. This is what happened in this case, as the public health agencies could not properly connect all the cases that happened throughout the country with only one pathogen for over five years, and the whole genome sequencing showed that five rare DNA fingerprints of Listeria monocytogenes were related, connecting serotypes identified in this last August with serotypes found in the cases from around five years ago.

    The types of cheese involved in this outbreak were soft cheese, including Middle Eastern, Eastern European, Mediterranean and Mexican-style cheeses. The contaminated products likely responsible for the outbreak were from the brands Karoun, Arz, Gopi, Queso Del Valle, Central Valley Creamery, and Yanni, all of which were manufactured by Karoun Dairies, Inc. This company announced a voluntary recall of the products from those brands and stopped the production of other cheese products that might be contaminated with Listeria on September 16, 2015.

    Even though the incident was not very recent, a lot of restaurants and people may still have cheese products from those brands as the recall happened this year, and they are advised not to serve or consume these products as they may be contaminated with Listeria monocytogenes. It is very important that people don’t consume them, as listeriosis is a very severe disease, specially for children, the elderly and immunosuppressed population.

    Centers for Disease Control and Prevention. (2015). Multistate Outbreak of Listeriosis Linked to Soft Cheeses Distributed by Karoun Dairies, Inc. (Final Update). Retrieved from: http://www.cdc.gov/listeria/outbreaks/soft-cheeses-09-15/index.html

    Zuraw, L. (2015). Final Update: 3 Deaths, 30 Illnesses in Outbreak Linked to Soft Cheese. Retrieved from: http://www.foodsafetynews.com/2015/10/1-death-24-illnesses-in-listeria-outbreak-linked-to-soft-cheese/

    Wiedmann, M. (2015). Use of Whole-Genome Sequencing in Food Safety. Retrieved from: http://www.foodsafetymagazine.com/magazine-archive1/junejuly-2015/use-of-whole-genome-sequencing-in-food-safety/

    • cvalencia 10:47 pm on December 3, 2015 Permalink | Reply

      I don’t really consume a lot of soft cheeses, but it is interesting to know that there is a risk associated with it. Listeriosis is a very serious problem, especially for high-risk individuals (immunocompromised people and pregnant women). I heard of a case where a mom-to-be had a miscarriage because of eating soft cheese contaminated with Listeria, while on vacation.. Sad how these things can happen, so everyone should be aware of such risks.

    • Carissa Li 2:58 am on December 13, 2015 Permalink | Reply

      It is pretty cool how we can still investigate the same pathogen DNA from 5 years ago to identify its type using whole genome sequencing. As we all know, soft cheese is under category 1 according to the regulation from Health Canada, so it can grow throughout the stated shelf life. Listeria is known to be tolerant at low temperature, that’s why it is not surprising that it can grow on soft cheese. This case happened around 5 years ago so I think the risk of having Listeria contaminated soft cheese from this industry is not that high now if no new cases occur after that. But of course being caution is priority to not having any chance of getting sick!

    • MichelleLui 9:05 pm on December 18, 2015 Permalink | Reply

      Good summary of recalled soft cheese and how it relates to the techniques learned in class. Soft cheese belongs to Category 1 RTE foods. Consumers should be educated on the risk of consuming food listed under Category 1 RTE foods. Especially the high risk groups, such as children, elderly, pregnant women and people with weakened immune system.

    • mustafa akhtar 12:25 am on December 19, 2015 Permalink | Reply

      I am happy that the surveillance methods available in the industry are growing and developing. However, coupled with this, it is very important that we educate the public as well. It is not uncommon to hear of miscarriages happening because of consumption of soft cheese. As they say, prevention is better than cure.

  • AngeliMalimban 7:06 pm on October 30, 2015 Permalink | Reply
    Tags: , , , , Listeriosis,   

    Listeria Monocytogenes in Adolf’s Deli Meats and Whole Foods Curry Chicken 

    American Thanksgiving is coming up, which is a prime time for meat producers as they will be selling a lot of turkey, ham, chicken, and many other meats that most families traditionally consume on Thanksgiving. If families are tight for time to prepare food, or have a lot of people to prepare food for, some will resort to getting Ready-to-Eat meats from the deli, such as ordering deli turkey breasts or deli ham.
    With the purchase of ready-to-eat (RTE) meats comes the risk of Listeriosis, as RTE meats are one of the favourite breeding grounds for L. monocytogenes.

    On October 29th, 2015, and still currently, American consumers have been warned about meat that could be potentially contaminated with Listeria monocytogenes. This particular outbreak was attributed to smoked kielbasa, hams, Canadian Bacon, bone-in pork loins, and liverwurst that were produced on October 20th, 2015 that was produced by Adolf’s Meat Products in Connecticut. About 224 pounds of meat have been recalled.

    In another incident, a Whole Foods supplier in Massachusetts is recalling curry chicken products, such as their salad, salad wraps, and salad roll-ups that could also possibly have been infected with L. monocytogenes. Customers who have purchased these items are told not to consume them and to return the products straight to the store.
    This problem was confirmed during FSIS sample testing, although there have not been any cases or adverse reactions reported due to consumption of these meat products.

    L. monocytogenes favours growth in refrigerated to room temperature (4 to 37 degrees C), which is the reason why they are so prevalent in these meats that are eaten on their own without cooking. It is also present in many raw foods such as milk, ice cream, and produce. Despite this, most of the big outbreaks in Central/Eastern North America have been attributed to RTE meats. To put statistics into the prevalence of L. monocytogenes in the USA, 1600 illnesses and 260 deaths happen annually due to the contamination of food. Per 100,000 people, 0.26 cases are estimated. Despite these statistics, listeriosis has declined by 42% in 2013 compared to 1996-1998. An example of a major outbreak was the big Listeria outbreak at a Maple Leaf foods branch in Toronto in 2008, which resulted in 57 cases of illness and 23 deaths. This outbreak cost the company $20 million dollars, and 23 of their products were recalled. L. monocytogenes proved to be a forced to be reckoned with as the company had lost not only the money, but their image as well.

    In North America, Listeria is considered to be an increasing threat to human health due to antimicrobial resistance, its ability to grow in refrigerated temperatures, and its large prevalence in the environment. Listeriosis can be fatal in those who are elderly and those that are still young children. Luckily this was found before the outbreak actually had caused illness in a consumer, however, it is still early to tell as the outbreak was very recent.

    It is important that consumers understand that they must be vigilant when consuming RTE meats. Although hot dogs, luncheon meat (SPAM), and deli meats are convenient because they are already pre-cooked, the risk of contracting listeriosis is very real.
    Hopefully this thanksgiving, those who choose to purchase RTE meats to serve at dinner cook it very thoroughly past 40 degrees C. It is advised that they use thermometers and put it into the deepest part of the meat to ensure that this temperature is meat. If there are any leftovers (which is definitely bound to happen) they should divide them into shallow containers to promote rapid cooling.

    What do you think about this outbreak? Do you think that the government and companies generally do a good job in recalling products and preventing illnesses? How do you consume your RTE meats?







    • ayra casuga 3:57 pm on November 5, 2015 Permalink | Reply

      Interesting blog. I think because the meats are sold as “read-to-eat”, people usually do not think to apply more cooking preparations for it. I feel like thats what makes eating “ready-to-eat” foods so risky because we have to put a lot of trust to the food manufacturers that they’re consistently implementing stringent food safe procedures when preparing their ready-to-eat products. Especially because Listeria Monocytogenes is a very resistant bacteria.

    • Silvia Low 6:38 pm on November 8, 2015 Permalink | Reply

      Reading about listeria in RTE meats really scares me as i regularly purchase my lunches from places such as subway, deli stores, sandwich stores, etc. The employees working there seem to adequately clean up their stations but I dont think they understand why it is important that they clean it well or the repercussions that come from foodborne pathogens such as l.monocytogenes. Or maybe i’m wrong and theyve all been trained very thoroughly about common deli meat pathogens. Who knows.

    • EmilyLi 6:19 pm on November 10, 2015 Permalink | Reply

      This is an engaging blog post. I like how this instance didn’t cause any major problem in the population. This could be due to the rapid detection and efficient recall procedure from both the company and government to prevent any death and illness. I think the role that government plays in recalling food is very important. This is because that companies may not have enough resources to spread the word rapid enough, and I think with the government helps the recall process is faster. Also that many people trust government officials with providing legitimate facts. After learning about that ready to eat food are not the safest to be consume, I had been cooking some of the ready to eat products, such as ham. However some ready to eat food products such as salad, wouldn’t taste the same and as good if I cook it, so recently I been staying away from those foods.

    • WinnieLiao 10:45 am on November 18, 2015 Permalink | Reply

      I agree with Ayra about the fact that “ready-to-eat” “reminds” people that the meat is well prepared and that further cooking preparations are unnecessary. However this can probably contribute to why L.monocytogenes can be so prevalent in deli meats. Nowadays people are fond of sandwiches, since they are easy to make and “everything into one”. This gives rise to more opportunities for exposure. In terms of government, I think they have been doing quite a good job in quickly recalling the products and acting quick in the investigations. Even though there has been many outbreaks, I will continue to consume these products, and try my best to reduce the chances of getting foodborne illnesses by preventing the cross contamination of deli meats with other foods. Keep proper sanitation when handling the food and consuming it asap are also my goals!

    • CindyDai 5:27 pm on December 1, 2015 Permalink | Reply

      Outbreaks in RTE foods really caught my attention. Nowadays people are so used to the concept of “grab and go”. Consumers trust the safety of RTE foods and do not usually perform any more processing before consumption. Therefore, food vendors and government surveillance agents have huge responsibility to ensure food safety and establish an efficient problem-detecting system. As consumers, we should also try to prevent cross-contamination by separating RTE food from raw food. Any leftover RTE food products should be reprocessed or discarded.

    • CandiceZheng 3:31 pm on December 14, 2015 Permalink | Reply

      It is not surprised that RTE meats are the most favorable breeding grounds for L. monocytogenes, as RTE meats do provide an environment for Listeria growth, while people simply eat RTE meats without any further processing. Since Listeria are able to grow under refrigeration temperature, keeping deli meats in the fridge does not prevent the growth of Listeria at all. However, nowadays consumers trust the fridge so well and believe that proper refrigeration temperature would solve everything. As a consequence it is very essential to raise people’s awareness about this issue and especially for the immune suppressed population like pregnant women, further thermal processing of deli meat might needed to ensure food safety. As listeriosis in pregnant women would be a very serious issue.

  • csontani 1:13 pm on October 30, 2015 Permalink | Reply
    Tags: , Denmark, , , , Listeriosis   

    Another Visit by Listeria in Denmark 

    In May 2015, Statens Serum Institut (SSI) detected another five cases of Listeria in Denmark. The five cases showed up in one week, which makes it unusual if there was only one source. The source of the cases is still undetermined; with deli meats being the most suspected, as it is the cause of last year’s outbreak. All five people had the underlying illnesses and two have died since.


    Listeria is one of the low-key food pathogen in Denmark, but it is considered to be one of the deadliest. The European Food Safety Authority (EFSA) declared that Listeriosis cases have increased by 8.6% between 2012 and 2013, and have been increasing for the past five years. Overall, the number of cases reported in Europe is low but the main concern would be the fact that each infection that occurred is the most severe and has the highest death rate.

    It seems that Listeria has been coming back to Denmark for the past 3 years. In September 2013, 5 people were diagnosed with Listeriosis and the case continued on until August 2014 where approximately 38 people were sickened and 15 deaths. This particular outbreak was considered to be the deadliest food pathogen outbreak in Denmark. The main cause of this outbreak was the contaminated deli meat used to prepare Rullepoelse (picture above). The company that distributed the deli meat was shut down after the source traced back to them last year, but has reopen again this year. However, the Danish Veterinary and Food Administration (DVFA) have ruled out that company as the source of this year’s outbreak.

    SSI stated that two out of the five people infected with Listeriosis this year are infected by the same strain that caused last year’s outbreak. As of now, the SSI is still trying to trace back the source for the cases they’ve found and is trying to sample the possible food source that they could think of. They have not found any more new cases and are hoping to not have another outbreak just like last year. However, with the current number of cases, it is very difficult for them to figure out the source of Listeria.

    In order for the health agency to trace back the source of the contamination, they need an adequate amount of cases to easily determine the source. This is kind of an issue for Denmark where in one year they would only detect a small amount of cases, which they can’t use to find the source easily, and the case would continue the following year with a greater number of cases.

    It might be possible that in the near future, the department responsible for food safety can create a better sampling and detection technologies that could help them to trace the source of contamination with a small amount of cases available. With your knowledge about Listeria, what solutions would you suggest them? Would you think that better detecting and sampling technologies would make a big difference to the country? Comment below!

    Denny, J., McLauchlin, J. (2008). HUMAN LISTERIA MONOCYTOGENES INFECTIONS IN EUROPE – AN OPPORTUNITY FOR IMPROVED EUROPEAN SURVEILLANCE. Retrieved from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=8082

    EFSA. (2015). Campylobacteriosis cases stable, listeriosis cases continue to rise, say EFSA and ECDC. Retrieved from: http://www.efsa.europa.eu/en/press/news/150128

    SSI. (2014). Listeria outbreak – suspected source: deli meats. Retrieved from: http://www.ssi.dk/English/News/News/2014/2014_08_listeria.aspx

    Whitworth, J. (2015). Denmark investigating new Listeria outbreak. Retrieved from: http://www.foodqualitynews.com/Food-Outbreaks/Listeria-sickens-five-and-a-factor-in-two-deaths

    Whitworth, J. (2014). Listeria from deli meat kills 12 in Denmark. Retrieved from: http://www.foodqualitynews.com/Food-Outbreaks/Joern-A.-Rullepoelser-closed-as-Denmark-investigates-Listeria-outbreak

    • shinnie 3:06 pm on October 31, 2015 Permalink | Reply

      Thank you for this blog post. It is interesting to compare the mortality rates of the same pathogen from different geographical areas– the mortality rate is much lower in the U.S. and in Canada as compared to Denmark. I wonder why? Perhaps it is because our health care system is better, or maybe our surveillance of pathogen is also more developed? I am assuming they are using a case-control study to identify the source of the outbreak –and the weaknesses of this source attribution method is evident in the Denmark outbreaks.
      I feel that people in Denmark should push the notion that high-risk people should avoid eating Category 1 foods all in all, although it limits the variety of the foods someone can consume. But, better safe than sorry right? Looking at the pathogen safety data sheets from PHAC, it is so interesting to note that outbreaks from Listeria Monocytogenes were from different food types in the past! For example, from vegetable products in the early 1980s, to dairy products in the mid 1980s and early 1990s, to ready-to-eat meat and poultry products in the late 1990s to early 2000s. How did that evolve?!?!

    • dgozali 8:51 pm on November 2, 2015 Permalink | Reply

      Perhaps one of the solutions for this problem is to have better food production practices and more routine quality checks in the processing facility. It is better to improve the prevention strategies in the production plant than to work backwards to determine the cause only after the outbreak has happened. Nevertheless, it is still important to improve on pathogen detection methods to trace the source of Listeria before more people fall ill.

    • elaine chan 1:15 pm on November 14, 2015 Permalink | Reply

      It is definitely unfortunate to hear that the number of reported Listeriosis is increasing throughout the years in Denmark. What I find interesting though is that the cause of the outbreak is from the same strain of Listeria, but from different sources. This could possibly suggest that this particular strain has better survivability; hence, it’s able to survive, persist and cause subsequent outbreaks in Denmark. I agree with dgozali’s idea on focusing to better improve the prevention strategies. Rather than waiting and trying to work backwards to determine the cause, which will cost more time and more outbreaks to determine the answer, it is more practical focus on what can actually be done, prevention. It will be important for food manufacturing facilities to implement more strict sanitization and processing conditions to ensure the elimination of Listeria survival. At the same time, it will also be equally important to improve sampling and detection methods at the food production level to ensure that if Listeria is present, it can be readily detected and subsequently stop production to prevent the outbreak.

    • flyingsquirrel 5:50 pm on December 2, 2015 Permalink | Reply

      If there were small outbreaks in two consecutive years of the same strain of Listeria, could the contamination been at a different level aside from the manufacturers? Perhaps there is something going on at the stores that sell the deli? I wonder what places they have checked for cross-contamination because if it is the same strain, there could likely be a common point of contact between all the deli meats involved.

    • Carissa Li 12:26 am on December 14, 2015 Permalink | Reply

      It is very surprising how Listeria is affecting Denmark compare to its influence on the US. From the outbreak investigation lecture we learnt that finding more cases is very critical since it helps us to understand more about the time frame, size and the source of contamination. I would say a better detection method will help the case a lot since it can help identify which food is being contaminated with Listeria and narrow down the suspecting food list.

  • catherine wong 1:27 pm on October 27, 2015 Permalink | Reply
    Tags: , , Fried Rice, , Listeriosis, ,   

    Listeria Monocytogenes Recall in Australian Fried Rice: No Ending 

    In Australia, there was a recall on September 3, 2015 due to pre-packaged fried rice from the company JL King & Co due to Listeria monocytogenes. Both packagings of 1kg and 450g were on the recall. As of now, there is still no information about the source of contamination, how many or if there were any consumers who got sick. The best before date for this product was September 15, 2015, which was only 12 days from the date the recall was announced. (Australian Competition Consumer Commission, 2015)

    Similar to most other ready to eat foods that Listeria monocytogenes like to grow in, the shelf life is quite short and some consumers consume the ready to eat products right after purchasing. Other products such as canned foods that Clostridium botulinum can grow in, the shelf life can be up to 2 years which gives plenty of time for recalls as those consumers may not consume them immediately after purchase. The recalls for ready to eat foods such as the pre-packaged fried rice can serve the purpose of taking the food off store shelves to prevent future consumers from getting sick. However for the consumers who have consumed contaminated products before any recall notification, some of them may not even get sick due to the natural microflora present on their intestinal surfaces.

    The ones who are most susceptible to falling ill from Listeria monocytogenes are pregnant women and their unborn or newborn children, seniors and the immunocompromised. For pregnant women in the first three months of pregnancy, being sick with Listeria monocytogenes can cause a miscarriage. If the bacteria is contracted later on in the pregnancy, premature birth, stillbirth or the birth of a severely ill child may happen. The immunocompromised are much more likely to get sick but according to the Public Health Agency of Canada, people suffering from AIDS are 300 times more susceptible to being infected by Listeria monocytogenes compared to healthy individuals. (Public Health Agency of Canada, 2012)

    Listeria Monocytogenes luckily cannot grow in all ready to eat food products as long as the food product falls under one of the following three criteria according to Australia’s Food Standards (Food Standards, 2014):
    1. pH less than 4.4, no matter the water activity value
    2. Water activity less than 0.92, no matter the pH value
    3. pH less than 5.0 and water activity less than 0.94

    However, if Listeria monocytogenes is present it can survive in acid conditions and in products with low water activity for a long period of time, especially for refrigerated products. Even if the product has gone through a drying process, Listeria monocytogenes may survive. (Lawley, 2013)

    If the ready to eat food product is frozen and is consumed frozen, thawed but still eaten cold or heated before consumption then it is most likely safe from Listeria Monocytogenes. (Food Standards, 2014) If the ready to eat food product does not fit with the above criteria, then heating to an internal temperature of 74°C before eating can help in minimizing the chance of Listeria monocytogenes surviving in the food. (Public Health Agency of Canada, 2012)

    With all the conditions Listeria monocytogenes can grow or survive in ready to eat products, I feel that one of the better ways to minimize the risks of getting ill from Listeria monocytogenes is to heat ready to eat products except for frozen products before consuming. Although this might be difficult for ready to eat foods that are generally eaten at room temperature such as sandwiches.

    Are there any other methods that you think are sufficient in eliminating Listeria monocytogenes?


    Andersen, L. (2015) Listeria and Bacteriocin-Producing Starter Culture. Retrieved from http://www.foodsafetynews.com/2015/08/listeria-and-bacteriocin-producing-starter-cultures/#.Vi3XUmSrToB

    Australian Competition Consumer Commission. (2015). Product Safety Recalls Australia. Retrieved from http://www.recalls.gov.au/content/index.phtml/itemId/1076441

    Food Standards. (2014). Supporting document 1 – Guidance On the Application of Microbiological Criteria for Listeria Monocytogenes. Retrieved from

    Lawley, R. (2013). Food Safety Watch. Retrieved from http://www.foodsafetywatch.org/factsheets/listeria/

    Public Health Agency of Canada. (2012). Listeria. Retrieved from

    • ColleenChong 5:16 pm on October 27, 2015 Permalink | Reply

      I am glad you brought up that listeria monocytogenes can survive acid and low water activity environments, just as Trish has mentioned in her presentation. Although L. Monocytogenes is a heat sensitive microorganism once it contaminates processing equipment it will be a major issue because it can form biofilms, which protects the pathogen. Contamination usually occurs after post-processing as you mentioned ready to eat products. I think the general public does not need to be too concern when consuming these products. However, young children, pregnant women and immunocompromised individuals should be careful. If possible the susceptible population to try to avoid these foods in general because the serious consequences can result in listeriosis or even death.

    • Jasmine Lee 2:56 pm on October 31, 2015 Permalink | Reply

      I agree with Colleen that Listeria monocytogenes may have been introduced to this product through post-processing contamination. Potential sources may be due to unsanitary premises, unclean air ventilation, contaminated packaging and/or temperature abuse. Even though this product may pose a serious health risk for immunocompromised individuals, I find it rather surprising that there are no further details available since the date of the recall. Since Listeria monocytogenes is ubiquitous in the environment, I strongly believe multiple methods are necessary to control the presence of this pathogen. These measures may include reassessing the company’s HACCP program to reinforce proper sanitation practices, frequent microbiological monitoring and appropriate storage temperatures. A combination of rapid pathogen detection methods should be utilized because some techniques, such as PCR, may detect false positives. Alternatively, the company could look into reformulating the product to include more hurdles, such as adding antimicrobial agents and increasing lethality of the heat treatment. Applying different treatments and storing susceptible food components in separate packages (combined by the end user during consumption) may lower favorable conditions for bacterial growth. These methods may also extend the product’s shelf life.

    • RainShen 1:01 pm on November 4, 2015 Permalink | Reply

      Comparing to other pathogenic microorganisms, Listeria monocytogenes can be resistant to many stresses during the processing and before consumption which causes it becomes one of the biggest concern for consuming the ready to eat food. I agree that the best way to eliminate L. monocytogenes in the high risk ready to eat food is heating the product to at least 74C. However, the manufacturer of the ready to ear food should improve their food safety system as well which may include sanitation procedure, regular equipment checking, personnel hygiene etc, especially that L. monocytogenes can form biofilm on the surface of the equipment, so regular microbiological testing will be necessary in the ready to eat manufacturing company. Complete final products checking and testing will be needed to ensure the absence of L. monocytogenes in the ready to eat foods.

    • MarinaMoon 2:50 am on November 13, 2015 Permalink | Reply

      As Listeria monocytogenes is one of the pathogens that can withstand many hurdles during food production and storage, it should be especially cautious and have very strict regulation system regarding production that is easily susceptible to Listeria Monocytogenes contamination. However, in this article in particular, I believe that these pre-packaged fried rice would be mostly consumed by healthy individuals probably those who do not have the time to make one themselves such as college students and workers. Thus, although we should be concerned and pay close attention to be able to prevent further contamination, I don’t think it would result in severe outbreaks like some other pathogens. As elderly, pregnant women and infants are most vulnerable to contamination, I do not think this particular product would create such a disaster. Nonetheless, I think better sanitation in the production environment and more strict regulations could possibly lead to prevention of this pathogen.

    • cvalencia 5:07 pm on December 4, 2015 Permalink | Reply

      Great article on Listeria! I think that it is surprising to find this pathogen in pre-packaged, since most of the time they are found on high-risk foods such as soft cheeses and deli meats. This just goes to show that we must take extra precaution to ensure food safety, even in unexpected food items such as the case for this food item. Also, it shows that we have a long way to go in food safety to ensure that cases like these don’t happen in the future

    • Ya Gao 9:24 pm on December 15, 2015 Permalink | Reply

      It is interesting to learn the specific details about how Listeria affect vulnerable people like pregnant women and their unborn or newborn children, seniors and the immunocompromised. And it is shocking to see how AIDS change life by looking at the number “people suffering from AIDS are 300 times more susceptible to being infected by Listeria monocytogenes compared to healthy individuals”. Ready to eat food can be a great threat since people tend not to process them at home after purchasing and consume them directly. A better controlling on production, distribution and retailing of ready to eat food products is important to protect these vulnerable people from getting harm.

    • MichelleLui 10:59 pm on December 18, 2015 Permalink | Reply

      Good information on Listeria Monocytogenes. Contaminated ingredient is mostly likely the starting agent to the contamination as there has to be an introduction of Listeria Monocytogenes into the processing facility or food. There could be other contaminants such as rodents due to poor pest control program at the processing facility. Just browsing through their website, it looks like they process many items, including dairy and produce. Good sanitation standard procedures should be in place to prevent cross contamination. The firm should monitor their suppliers by testing their ingredients and packagings for pathogens or indicator organisms.

  • FeliciaYuwono 11:49 pm on October 25, 2015 Permalink | Reply
    Tags: Blue Bell, Ice Cream, , , Listeriosis, ,   

    Listeria Outbreak Associated with Blue Bell Ice Cream 

    Blue Bell Creameries recently did product recall for the first time in their 108 years of company’s history caused by an outbreak of Listeria monocytogenes. There were in total 10 cases in 4 states & 3 deaths affected by the outbreak. They have 3 production facilities and all of them were contaminated with Lm: one in Texas (which is the headquarters), and two auxiliary production lines in Oklahoma and Alabama. In this post, I’m focusing on what happened in the Oklahoma facility.

    The first 5 Listeriosis cases that were reported in Kansas early March 2015. They were all hospital inpatients and immunocompromised, and 3 of them actually died, which made up the total deaths for this outbreak. In late March 2015, using PFGE and Whole Genome Sequencing, Kansas Department of Health and Environment found out that the same strains of Lm found in the patients were traced back to unopened Blue Bell Creameries’ 3 oz. Institutional/Food Service Chocolate Ice Cream cups served in the hospital, which were manufactured in the Oklahoma production facility. Interestingly, this product was distributed to 23 states and only sold in schools, nursing homes, and hospitals, which mainly accomodate individuals at risk. This suggests that there were probably unreported cases of listeriosis linked to the Blue Bell Creameries’ products.


    In May 7, 2015, the FDA released findings from Blue Bell Creameries’ production facility in Oklahoma. In this report, there are 12 observations being made but I’m only going to outline several points.


    This report mentions that the Oklahoma Department of Agriculture, Food, and Forestry established a requirement of 20 CFU/mL of Lm or less in finished products of frozen dairy desserts. In March 2015, 275 CFU/mL Lm was found in the finished product half-gallon Dutch Chocolate Ice Cream, more than thirteen times the recommended levels. Now, if we assume that there is 275 CFU/mL of Lm in a 3 oz. (88mL) Institutional/Food Service Chocolate Ice Cream cup, then there is in total 24,200 CFU of Lm in one cup. However, several hospital patients fell ill after consuming the particular product, which means that the amount of Lm in that product is at least at an infectious dose of 0.1 to 10 million CFU for at risk individuals. Based on these assumptions, Lm might continue to grow under freezing temperatures, but more research needs to be done on this subject. Another possibility is that some finished products of the chocolate ice cream already had enough Lm in it to infect at risk individuals, therefore any more Lm growth would not make any impact.


    This report also mentions that the plant’s production line is not designed to prevent cross-contamination from drippings and condensate from pipes and tank lids. The lids on top of the tanks containing post-pasteurized Dutch Chocolate Ice Cream were not closed tightly, hence condensate from another product line installed horizontally right above it drips into the tanks, which makes a potential source of Lm contamination. Additionally, a worker was observed spraying the top of the lids and switching lids between other post-pasteurized Dutch Chocolate Ice Cream tanks, which may contribute to Lm cross-contamination in the tanks. The rest of the report states that lack of employee hygiene and inadequate facilities for cleaning and sanitizing equipments might be some contributing factors to the growth of Lm in their products.


    Now, if you were to be part of Blue Bell Creameries’ quality control team at the Oklahoma production facility, what would you do? What recommendations would you offer to make the production line safer?

    • wen liao 9:19 am on October 26, 2015 Permalink | Reply

      It is definitely amazing how Listeria can survive and still being infectious in made ice-creams, considering it is an environment low in temperature and water activity. As we have discussed in class before, ice-cream is considered as one of the products where there should be no growth of Listeria what’s so ever. Thus the problem here definitely are due to the ingredients. Since ice cream production are considered as low Listeria risk, people work here might pay less attention on sampling and checking on listeria load, which might be the cause of the problem. Therefore, it is important that people working in food industry pay extreme attention on what they are doing to ensure food safety.

    • YaoWang 1:39 pm on October 27, 2015 Permalink | Reply

      We all know that Listeria is a main concern in ready to eat meat products, but it’s amazing to know that it can be a problem even in ice cream. Normally, since ice cream provides low temperature and low water activity, we assume there shouldn’t be Listeria present. I’m very curious about how listeria can survive and may even grow under such environment. But this recall reminds us that even though the food is of less possibility of certain microbial contamination, the manufacture must still follow proper handling techniques to avoid potential cross contamination.

    • amreenj 7:18 pm on October 28, 2015 Permalink | Reply

      Wow! As we have previously learned, ice cream is considered a Category 2B food, which is a ready to eat foods in which Listeria monocytogenes cannot grow. So the occurrence of Lm. in ice cream is surprising. Im interested to see if they can actually trace the source of the Lm. and report back their findings. The worse part is that it was given to individuals whose immunity is low (ie. high risk groups- longer term care facilities, hospitals) and thus the impact could have been so much worse. Having preparing sanitation and handling protocols is imperative to recurring the risk of food borne illnesses. As we can we that failing to do so can lead to contamination in even the most unlikely of places/foods!

    • mustafa akhtar 10:18 am on October 29, 2015 Permalink | Reply

      I am so surprised that they ONLY distributed this product to schools, nursing homes, and such. I wonder if any research was put into developing the product at all. If not, then atleast the product shouldn’t have been sent to places where immunocompromised people reside.

    • Susanna Ko 4:55 pm on October 29, 2015 Permalink | Reply

      I think it shows that people must be diligent when deciding on the food menu for certain populations such as elderly or immunocompromised. Also, it’s surprising that the company survived so far without failing an inspection. Was it because it was categorized as a low-risk food, meaning that it is inspected less frequently? Also, how many spontaneous abortions occurred from pregnant women consuming this product because they wanted to enjoy a special treat? It’s really unfortunate.

    • Stephanie Chen 6:00 pm on November 19, 2015 Permalink | Reply

      It is really quite sad that even a delicious treat such as ice cream can harbor foodborne pathogens, and with a company that must have had good reputation for so many decades. Bluebell also explained that the reason they did not test their ice cream after positive tests of Listeria in their plant in previous years was because Listeria was found on non-food surfaces that did not come in contact with ice cream products. It was also not required at the time to report Listeria findings to the FDA. This shows that practices in the industry need to be routinely evaluated and food safety regulations should be strictly enforced.

    • meggyli 10:11 pm on November 27, 2015 Permalink | Reply

      Another interesting class-related blog! We learned in class that ice cream belongs in a category 2B food where the chances of Listeria growth/contamination is really rare. Similar to the above caramel apple blog, this just goes to show that we can never be too careful. It always causes the most damage to our health and economy when it’s the most unexpected food that contracts a pathogen. Who would have thought that something like ice cream which inhibits most microbial growth due to its cold storage temperature could cause something as severe as stillbirths & spontaneous abortions.

    • Mandy Tam 9:02 pm on December 1, 2015 Permalink | Reply

      I think a lot of time when people think of outbreak in related to Listeria Monocytogenes are related to ready to eat meat or deli product. I think this article provides a great example that Listeria growth could happen in other foods as well.
      North America very emphasis in HACCP and GMP in food plants but there are still many problems. I think what will help food plant to improve food safety in the future is to have a database approved by government agency where companies can share and excess information in regard of good plant design and HACCP program information in all food type. Therefore, it avoids problems caused by bad equipment design or inexperience HACCP team.
      Anyhow, great article and it provides a lot of insight in term of Listeria Monocutogenes!

    • cheryl lau 3:19 pm on December 4, 2015 Permalink | Reply

      Very interesting article! I am also surprised that this is the first time that the company has recalled their products due to Listeria monocytogenes contamination from the conditions mentioned in the FDA report. Condensed water from pipes in food manufacturing is often a problem if not dealt with. These problems usually present over time, I am surprised that the plant allowed production to continue. Perhaps the quality control personnel should ensure that the workers realize the risk involved from contamination due to irregular working conditions. The workers could then report to the supervisor when the equipment is not functioning at the optimum level to prevent these outbreaks from happening.

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