Category Archives: Listeria innocua

USA – FOOD SAFETY AND FARMER’S MARKETS

Posted on August 5, 2021 by | Leave a comment

Click to access Food%20Safety%20and%20the%20Farmers%20Market.pdf

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Posted in E.coli, Food Microbiology Research, Food Safety, Listeria, Listeria innocua, Norovirus, Research, Salmonella

Research – Condensation removal practices and its potential for contributing to environmental pathogen contamination in food processing facilities

Posted on January 21, 2021 by | Leave a comment

Journal of Food Protection

listeria

Food manufacturers often use squeegees as a tool to remove condensation from overhead surfaces. This practice is done to reduce the likelihood of environmental pathogen contamination by eliminating condensed water droplets that could fall from overhead surfaces during production. However, this practice may actually spread environmental pathogens across these surfaces, defeating its purpose and further increasing the risk for contamination in the processing area. To understand the risk associated with this common practice, test pipes inoculated with Listeria innocua ATCC 33090 were exposed to steam to produce condensation, which was then removed by squeegees. The pipe surfaces, droplets, and squeegees were subsequently analysed for Listeria to determine the distance the organism spread across the pipe, and how many organisms were transferred to the droplets and the squeegees. Results showed that Listeria travelled as far as 16 inches across the surface of the pipe, and bacterial transfer to the droplets decreased as the squeegee travelled further away from the contaminated area. Sanitisers alone were able to remove about 1 – 2 log CFU/in 2 of Listeria from the squeegee blades. Among the cleaning protocol evaluated, an extensive cleaning regimen was able to remove 3 – 4 log CFU/in 2 , which would be recommended to reduce the risk associated with environmental pathogens transfer. This study provides evidence that supports recommendations for minimising the cross-contamination risk associated with condensation management practices.

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Posted in Environmental Monitoring, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Listeria, Listeria innocua, microbial contamination, Microbiology, Research

Research – Virulence Characterization of Listeria monocytogenes, Listeria innocua, and Listeria welshimeri Isolated from Fish and Shrimp Using In Vivo Early Zebrafish Larvae Models and Molecular Study

Posted on December 11, 2020 by | Leave a comment

MDPI

Listeriosis is one of the most notable foodborne diseases and is characterized by high rates of mortality. L. monocytogenes is the main cause of human listeriosis outbreaks, however, there are isolated cases of disease caused by other species of the genus Listeria. The aim of this study was to evaluate strains of L. monocytogenes (n = 7), L. innocua (n = 6), and L. welshimeri (n = 2) isolated from fish and shrimps for their virulence based on the presence of virulence genes and the in vivo Danio rerio (zebrafish) larvae models. A total of 15 strains were analyzed. The zebrafish larvae model showed that the larvae injected with L. monocytogenes strains were characterized by the lowest survival rate (46.5%), followed by L. innocua strains (64.2%) and L. welshimeri (83.0%) strains. Multiplex PCRs were used for detection of selected virulence genes (luxS, actA2, prfA, inlB, rrn, iap, sigB, plcB, actA, hlyA), the majority of which were present in L. monocytogenes. Only a few virulence-related genes were found in L. welshimeri, however, no correlation between the occurrence of these genes and larval survival was confirmed. This research highlights the importance of the potential impact that Listeria spp. strains isolated from fish and shrimps may have on consumers. View Full-Text

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria innocua, Listeria monocytogenes, listeriosis, microbial contamination, Microbiology, Research

Canada – Smoked Trout Spread – Listeria monocytogenes

Posted on August 18, 2020 by | Leave a comment

MAPAQ

 

Quebec  , August 17, 2020 – MAPAQ, in collaboration with the Food Inspection Division of the City of Montreal and the Company National Herring Importation Ltd., located at 9820, boulevard Ray-Lawson, in Montreal , advises the public not to consume the product indicated in the table below, because this food is likely to contain the bacteria Listeria monocytogenes .

 

Product name Format Targeted lot
“Smoked trout spread” 160 g Units sold bearing the use-by date (“best before”) of September 14, 2020

The product that is the subject of this advisory was available for sale at several locations across the province . It was packaged in a clear plastic container with a black plastic lid and was sold refrigerated. The label includes, in addition to the proper name of the product, the words “LA BOUCANERIE”.

The operator is voluntarily recalling the product in question. He agreed with the MAPAQ and the Food Inspection Division of the City of Montreal to disseminate this notice as a precautionary measure. It should be noted that no case of illness associated with the consumption of this food has been reported to MAPAQ to date.

People who have this product in their possession are therefore advised not to consume it. They must either return it to the establishment where they bought it or throw it away. Even if the product does not show any signs of spoilage or a suspicious odor, consuming food contaminated with Listeria monocytogenes bacteria can cause listeriosis, a foodborne illness that can lead to high fever, severe headache, stiff neck or nausea. In this regard, pregnant women and their unborn children, the elderly, children and people with weakened immune systems are considered to be the most vulnerable.

Additional information

Media relations
Communications
Department Ministry of Agriculture, Fisheries
and Food
Tel. : 418 380-2100, ext. 3512
http://www.mapaq.gouv.qc.ca
Information

Press relations division
Ville de Montréal
Tel. : 514 872-4946

Product (s)

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Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Testing, Food Pathogen, food recall, Food Safety, Food Safety Alert, Food Testing, Listeria innocua, Listeria monocytogenes, mapaq, Uncategorized

Research – Study suggests green tea extracts could reduce risk of infection with diarrhoea-causing Norovirus

Posted on July 24, 2020 by | Leave a comment

First Post

Scientists also found that green tea extract in combination with chitosan films can reduce levels of bacteria such as E coli and L innocua to undetectable levels after 24 hours of exposure

It’s not uncommon for one to get an upset stomach occasionally, particularly after eating outside food. This is often the result of different kinds of bacteria and viruses present in the food items. In a research, published in the International Journal of Food Science on 4 July 2020, scientists found that green tea extracts can help in reducing the risk of getting infected with a diarrhoea-causing virus known as norovirus.

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Posted in E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Listeria, Listeria innocua, microbial contamination, Microbiology, Norovirus, Research, Uncategorized

Research – Cold plasma enhances the efficacy of aerosolized hydrogen peroxide in reducing populations of Salmonella Typhimurium and Listeria innocua on grape tomatoes, apples, cantaloupe and romaine lettuce

Posted on December 26, 2019 by | Leave a comment

Science Direct

In the present study, we investigated whether cold plasma activation affected the efficacy of aerosolized hydrogen peroxide against S. Typhimurium and L. innocua. Stem scars and smooth surfaces of grape tomatoes, surfaces of Granny Smith apples and Romaine lettuce (both midrib and upper leaves) and cantaloupe rinds were inoculated with two-strain cocktails of S. Typhimurium and 3-strain cocktails of L. innocua. The inoculated samples were treated with 7.8% aerosolized H2O2 with and without cold plasma for various times. For all fresh produce items and surfaces, cold plasma significantly (P < 0.05) improved the efficacy of aerosolized H2O2 against Salmonella and L. innocua. Without cold plasma activation, H2O2 aerosols only reduced populations of Salmonella by 1.54–3.17 log CFU/piece while H2O2 with cold plasma achieved 2.35–5.50 log CFU/piece reductions of Salmonella. L. innocua was more sensitive to the cold plasma-activated H2O2 than Salmonella. Cold plasma activated H2O2 aerosols reduced Listeria populations by more than 5 log CFU/piece on all types and surfaces of fresh produce except for the tomato stem scar area. Without cold plasma, the reductions by H2O2 were only 1.35–3.77 log CFU/piece. Overall, our results demonstrated that cold plasma activation significantly enhanced the efficacy of H2O2 mist against bacteria on fresh produce.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Listeria, Listeria innocua, Listeria monocytogenes, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized

Research – Interaction and inactivation of Listeria and Lactobacillus cells in single and mixed species biofilms exposed to different disinfectants

Posted on December 5, 2019 by | Leave a comment

Wiley Online

Abstract

Listeria spp. are ubiquitously found in both the natural and the food processing environment, of which Listeria monocytogenes is of an important health risk. Here, we report on the formation of single and mixed species biofilms of L. monocytogenes/Listeria innocua and Lactobacillus plantarum strains in 24‐well polystyrene microtiter plates and on the inactivation of 24‐hr and 72‐hr biofilms using quaternary ammonium compound‐, tertiary alkyl amine‐, and chlorine‐based disinfectants. Fluorescent in situ hybridization (FISH) and LIVE/DEAD BacLight staining were applied for 72‐hr L. innocua–L. plantarum mixed biofilms in the LabTek system for the species identification and the reaction of biofilm cells to disinfectants, respectively. L. monocytogenes/L. innocua were more resistant to disinfectants in 72‐hr than in 24‐hr biofilms, whereas L. plantarum strains did not show any significant differences between 72‐hr and 24‐hr biofilms. Furthermore, L. innocua when grown with L. plantarum was more resistant to all disinfection treatments, indicating a protective effect from lactobacilli in the mixed species biofilm. The biofilm formation and reaction to disinfectants, microscopically verified using fluorescence in situ hybridization and LIVE/DEAD staining, showed that L. innocua and L. plantarum form a dense mixed biofilm and also suggested the shielding effect of L. plantarum on L. innocua in the mixed species biofilm.

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Posted in Biofilm, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Lactobacillus, Lactobacillus plantarum, Listeria, Listeria innocua, Listeria monocytogenes, microbial contamination, Microbiology, Research, Technology, Uncategorized

Research -Efficacy of Surfactant Combined with Peracetic Acid in Removing Listeria innocua from Fresh Apples

Posted on November 1, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Large amounts of water used in the apple packing process, the presence of organic matter, and difficult-to-clean equipment are vectors for contaminating apples with foodborne pathogens, such as Listeria monocytogenes. There is a need to develop new cleaning methods for fresh apples and evaluate their antimicrobial efficacy. A series of surfactants of different chemical properties (cationic lauric arginate [LAE], anionic sodium dodecyl sulfate [SDS], and nonionic Tween 20 [T20]) alone and combined with peracetic acid (PAA) were evaluated for their efficiency in the removal of L. innocua, a surrogate of L. monocytogenes, from fresh apples. Whole fresh apples were inoculated with L. innocua (7 log CFU/mL) by a dipping method, dried, and subjected to wash treatments with selected cleaning solutions (water, PAA, PAA-LAE, PAA-SDS, and PAA-T20). The contact angle between the cleaning solutions and the surface of the apples was measured. The antimicrobial activity of the cleaning solutions and the efficacy of the cleaning treatment were evaluated by enumeration of L. innocua from treated apples and visualized by scanning electron microscopy. Stem bowl and calyx cavities of the apple harbored higher bacteria concentrations (∼4.82 log CFU per apple), compared with the equatorial section (∼2.66 log CFU per apple). Addition of 0.1% of selected surfactants led to a significant decrease in surface tension of cleaning solutions and allowed better spreading on the apple surface. Surfactants combined with PAA solution resulted in higher L. innocua reduction compared with PAA alone; however, their efficacy was limited. The most effective cleaning solution was PAA-T20, with reduction of approximately 2.2 log. Scanning electron microscopy imaging confirmed that most bacteria were harbored inside the surface irregularities. PAA alone and with surfactants caused damage and deformation of bacteria cells. Cleaning apples with PAA combined with surfactants may improve microbial safety in whole apples; however, the efficiency of the decontamination treatment can be reduced because of variations in apple morphology.

HIGHLIGHTS

  • Combining surfactants with PAA decreased the population of L. innocua on apples.

  • Treating apples with PAA-T20 reduced the load of L. innocua by 2.2 log.

  • Stem bowl and calyx cavity are difficult-to-reach areas during the cleaning operation.

  • Cleaning treatments were not effective in removing all L. innocua from apples.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Listeria, Listeria innocua, microbial contamination, Microbiology, Research, Uncategorized

Research – Interaction and inactivation of Listeria and Lactobacillus cells in single and mixed species biofilms exposed to different disinfectants

Posted on October 31, 2019 by | Leave a comment

Wiley Online

Abstract

Listeria spp. are ubiquitously found in both the natural and the food processing environment, of which Listeria monocytogenes is of an important health risk. Here, we report on the formation of single and mixed species biofilms of L. monocytogenes/Listeria innocua and Lactobacillus plantarum strains in 24‐well polystyrene microtiter plates and on the inactivation of 24‐hr and 72‐hr biofilms using quaternary ammonium compound‐, tertiary alkyl amine‐, and chlorine‐based disinfectants. Fluorescent in situ hybridization (FISH) and LIVE/DEAD BacLight staining were applied for 72‐hr L. innocua–L. plantarum mixed biofilms in the LabTek system for the species identification and the reaction of biofilm cells to disinfectants, respectively. L. monocytogenes/L. innocua were more resistant to disinfectants in 72‐hr than in 24‐hr biofilms, whereas L. plantarum strains did not show any significant differences between 72‐hr and 24‐hr biofilms. Furthermore, L. innocua when grown with L. plantarum was more resistant to all disinfection treatments, indicating a protective effect from lactobacilli in the mixed species biofilm. The biofilm formation and reaction to disinfectants, microscopically verified using fluorescence in situ hybridization and LIVE/DEAD staining, showed that L. innocua and L. plantarum form a dense mixed biofilm and also suggested the shielding effect of L. plantarum on L. innocua in the mixed species biofilm.

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Posted in Biofilm, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Lactobacillus, Listeria, Listeria innocua, Listeria monocytogenes, Research, Technology, Uncategorized

Research – Distribution of Listeria spp. on Carcasses of Regularly Slaughtered Swine for Italian Dry Cured Ham

Posted on June 29, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

In recent years, the role of Listeria monocytogenes as a foodborne pathogen in public health has increased. Its presence poses a risk for humans, especially in ready-to-eat foods, such as ham. Understanding the presence and distribution of Listeria spp. on swine carcasses meant for Italian dry-cured hams can be a useful tool to improve food safety. This study assessed the distribution of Listeria spp. (as a marker of contamination with L. monocytogenes) on slaughtered pig carcasses intended for the production of high-quality, Italian, dry-cured ham and examined the roles of the site sampled on the carcass, farming cycle (open versus closed), farm-to-slaughterhouse distance, and time spent in lairage. Samples were collected from swine carcasses (n = 150) before refrigeration, from three different carcass locations (head, shoulder, and thigh), and assessed for the presence of listeriae. A total of 115 carcasses were contaminated with Listeria spp. in at least one location. In all, 178 listeriae were isolated and identified: 130 Listeria innocua, 28 Listeria welshimeri, 17 Listeria ivanovii, and 3 L. monocytogenes. Listeriae were detected on 62.7% of heads, on 25.3% of shoulders, and on 30.7% of thighs, with significant differences between heads versus shoulders and thighs. Animals reared in closed-cycle farms were more contaminated (P < 0.05) than were animals from open-cycle farms (90 versus 71.8%). The distance between farms and slaughterhouse was not related to the contamination rate. Carcasses of swine that stayed in lairage before slaughtering for more than 10 h showed a higher degree of contamination (90%) and were positive for Listeria spp. in more sample sites (55%) compared with those held for less than 2 h (73% of carcasses and 33.3% of samples). Our results show that heads should be detached from carcasses immediately after slaughter for meat-safety purposes and the amount of time animals stay in lairage should be limited. These results will be useful for a more-valid implementation of good manufacturing processes for slaughtering.

HIGHLIGHTS

  • Swine carcasses are often contaminated with Listeria spp.

  • Heads are more contaminated than shoulders and thighs.

  • Lairage time higher than 10 h is a risk factor for Listeria spp. contamination.

  • Closed-cycle farms presented greater carcass contamination.

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Posted in food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology Blog, Food Pathogen, Food Safety, Food Testing, Listeria, Listeria innocua, Listeria invanovi, Listeria monocytogenes, Listeria welshimeri, Uncategorized