Effect of Time, Temperature and Transport Media on the Recovery of Listeria monocytogenes from Environmental Swabs

2020 ◽  
Author(s):  
Diana Stewart ◽  
Yadwinder Singh Rana ◽  
Kaiping Deng ◽  
Geethaanjali Vijayakumar ◽  
Lanlan Yin ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Logistic Regression ◽  
Listeria Monocytogenes ◽  
Sodium Hypochlorite ◽  
Food Processing ◽  
Storage Time ◽  
Cheese Whey ◽  
Storage Temperature ◽  
Food Matrix ◽  
Processing Facility

Environmental monitoring for Listeria monocytogenes in food processing environments is key for ensuring the safety of ready-to-eat foods. For sampling, swabs are often hydrated with a wetting or transport medium which may contain neutralizers and other ingredients. After swabbing the environment, the swabs may then be transported or shipped cold to an off-site laboratory for testing, ideally within 48 h. Extended shipping times may subject the pathogen to increased temperatures in the presence of the wetting medium, organics, and other chemicals from the processing facility which may confound detection. This study evaluated growth and detection of L. monocytogenes on stainless steel exposed to either buffer or sodium hypochlorite prior to drying. Swabs were rehydrated with Butterfield’s Phosphate Buffer, Neutralizing Buffer, Letheen Broth or Dey-Engley Neutralizing Broth prior to swabbing. Swabs were stored in the presence of no added food, cheese whey or ice cream under both optimal (4°) and sub-optimal (15°C) temperatures for up to 72 h. Overall, there was no growth of L. monocytogenes at 4°C through 72 h storage, though enrichment from these swabs was dependent on the presence and type of food matrix. Pathogen growth during storage at 15°C was more variable and depended on both the food matrix and transport media used, with Dey-Engley and Letheen Broth allowing for the highest population increases. Overall, more enrichments resulting in L. monocytogenes detections were observed when using Letheen Broth and Neutralizing Buffer than Dey-Engley which resulted in fewer detections at 15°C. Logistic regression and Cochran-Mantel-Haenszel (CMH) analyses determined that storage temperature, transport media, and food matrix all significantly affected detection of L. monocytogenes , while storage time did not have a clear effect on recovery from swabs.

scholarly journals Effectiveness of Phage-Based Inhibition of Listeria monocytogenes in Food Products and Food Processing Environments

2020 ◽  
Vol 8 (11) ◽  
pp. 1764
Author(s):  
Iwona Kawacka ◽  
Agnieszka Olejnik-Schmidt ◽  
Marcin Schmidt ◽  
Anna Sip
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Food Industry ◽  
Storage Temperature ◽  
Bacterial Pathogen ◽  
Food Contamination ◽  
Food Products ◽  
Pathogen Resistance ◽  
Food Matrix ◽  
Matrix Properties

Providing safe products and compliance of legal requirements is still a great challenge for food manufacturers regarding microbiological safety, especially in the context of Listeria monocytogenes food contamination. L. monocytogenes is a human pathogen, which, due to the ability of survival and proliferation in preservation conditions such as high salinity, acidity and refrigeration temperatures, is a significant threat to the food industry. Novel methods of elimination of the bacterial pathogen in food products and food processing environments are required. Among emerging technologies, one of the very promising solutions is using bacteriophages as natural control agents. This review focus on the major aspects of phage-based inhibition of L. monocytogenes in aspects of food safety. We describe an overview of foods and technological factors influencing the efficacy of phage use in biocontrol of L. monocytogenes. The most noteworthy are food matrix properties, phage concentration and stability, the time of phage application and product storage temperature. The combined methods, phage immobilization (active packing), pathogen resistance to phages and legislation aspects of antilisterial bacteriophage use in the food industry are also discussed.

Chlorine Resistance of Listeria monocytogenes Biofilms and Relationship to Subtype, Cell Density, and Planktonic Cell Chlorine Resistance

2006 ◽  
Vol 69 (6) ◽  
pp. 1292-1296 ◽  
Author(s):  
JAMES P. FOLSOM ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cell Density ◽  
Sodium Hypochlorite ◽  
Resistance Mechanisms ◽  
Planktonic Cell ◽  
Planktonic Cells ◽  
Planktonic Culture

Strains of Listeria monocytogenes vary in their ability to produce biofilms. This research determined if cell density, planktonic chlorine resistance, or subtype are associated with the resistance of L. monocytogenes biofilms to chlorine. Thirteen strains of L. monocytogenes were selected for this research based on biofilm accumulation on stainless steel and rep-PCR subtyping. These strains were challenged with chlorine to determine the resistance of individual strains of L. monocytogenes. Planktonic cells were exposed to 20 to 80 ppm sodium hypochlorite in 20 ppm increments for 5 min in triplicate per replication, and the experiment was replicated three times. The number of tubes with surviving L. monocytogenes was recorded for each isolate at each level of chlorine. Biofilms of each strain were grown on stainless steel coupons. The biofilms were exposed 60 ppm of sodium hypochlorite. When in planktonic culture, four strains were able to survive exposure to 40 ppm of chlorine, whereas four strains were able to survive 80 ppm of chlorine in at least one of three tubes. The remaining five strains survived exposure to 60 ppm of chlorine. Biofilms of 11 strains survived exposure to 60 ppm of chlorine. No association of biofilm chlorine resistance and planktonic chlorine resistance was observed; however, biofilm chorine resistance was similar for strains of the same subtype. Biofilm cell density was not associated with chlorine resistance. In addition, biofilms that survived chlorine treatment exhibited different biofilm morphologies. These data suggest that chlorine resistance mechanisms of planktonic cells and biofilms differ, with planktonic chlorine resistance being more affected by inducible traits, and biofilm chlorine resistance being more affected by traits not determined in this study.

Incidence and Survival of Listeria monocytogenes in Ready-To-Eat Seafood Products

1997 ◽  
Vol 60 (4) ◽  
pp. 372-376 ◽  
Author(s):  
SUSAN A. MCCARTHY
Keyword(s):  
Listeria Monocytogenes ◽  
Storage Time ◽  
Storage Temperature ◽  
Storage Conditions ◽  
Plate Count ◽  
Standard Plate Count ◽  
Smoked Salmon ◽  
Standard Plate ◽  
Seafood Products ◽  
Survival And Growth

The effects of processing and postprocess storage conditions on the incidence and survival of Listeria monocytogenes on crawfish (Procambaris sp.), crabmeat (Callinectus sapidus), and smoked salmon (Salmo salar) were evaluated. L. monocytogenes was recovered from 3% of whole boiled market crawfish samples and 17% of frozen vacuum-packaged partially cooked crawfish tail meat, but not from boiled crabmeat or smoked salmon. Contamination was most likely due to postprocess handling as commonly used methods of cooking (5 min boil or 20 min steep) reduced L. monocytogenes to nondetectable levels in laboratory-contaminated crawfish. In postprocess storage temperature abuse studies, cooked whole crawfish were inoculated internally and externally with 3.0 log CFU of L. monocytogenes per g and incubated at 22 or 30°C for 6 h. The greatest increase in numbers of cells, 1.9 log CFU/g (determined by standard plate count), occurred at 30°C on externally contaminated crawfish. There was little change in numbers of L. monocytogenes during cold storage (6°C, 5 days; −20°C, 15 days). There was little change in cell numbers associated with products stored at 22 or −20°C. At 6°C, numbers of cells associated with crabmeat increased by 3.8 log MPN/g after 6 days; however, there was no increase in numbers of cells associated with salmon. The results show that the survival and growth characteristics of L. monocytogenes are dependent on storage time and temperature and the nature of the seafood product.

scholarly journals Persistent Listeria monocytogenes Isolates from a Poultry-Processing Facility Form More Biofilm but Do Not Have a Greater Resistance to Disinfectants than Sporadic Strains

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 250 ◽  
Author(s):  
Daniel Rodríguez-Campos ◽  
Cristina Rodríguez-Melcón ◽  
Carlos Alonso-Calleja ◽  
Rosa Capita
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Biofilm Formation ◽  
Benzalkonium Chloride ◽  
Bacterial Persistence ◽  
Crystal Violet Assay ◽  
Processing Facility ◽  
Poultry Processing ◽  
Sessile Cells ◽  
Selection Of

Some strains of Listeria monocytogenes can persist in food-processing environments, increasing the likelihood of the contamination of foodstuffs. To identify traits that contribute to bacterial persistence, a selection of persistent and sporadic L. monocytogenes isolates from a poultry-processing facility was investigated for biofilm-forming ability (crystal violet assay). The susceptibility of sessile cells to treatments (five minutes) with sodium hypochlorite having 10% active chlorine (SHY: 10,000 ppm, 25,000 ppm, and 50,000 ppm) and benzalkonium chloride (BZK: 2500 ppm, 10,000 ppm, and 25,000 ppm) was also studied. All isolates exhibited biofilm formation on polystyrene. Persistent strains showed larger (p < 0.001) biofilm formation (OD580 = 0.301 ± 0.097) than sporadic strains (OD580 = 0.188 ± 0.082). A greater susceptibility to disinfectants was observed for biofilms of persistent strains than for those of sporadic strains. The application of SHY reduced biofilms only for persistent strains. BZK increased OD580 in persistent strains (2500 ppm) and in sporadic strains (all concentrations). These results indicate that the use of BZK at the concentrations tested could represent a public health risk. Findings in this work suggest a link between persistence and biofilm formation, but do not support a relationship between persistence and the resistance of sessile cells to disinfectants.

Destruction of Listeria monocytogenes by Sodium Hypochlorite and Quaternary Ammonium Sanitizers

1989 ◽  
Vol 52 (5) ◽  
pp. 306-311 ◽  
Author(s):  
A. MUSTAPHA ◽  
M. B. LIEWEN
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Sodium Hypochlorite ◽  
Quaternary Ammonium ◽  
Ammonium Compound ◽  
Electron Microscopic ◽  
Acidic Polysaccharide ◽  
Scanning Electron Microscopic ◽  
Dairy Plant

The antimicrobial effects of two commonly used dairy plant sanitizers on Listeria monocytogenes ATCC 7644 were studied. The two sanitizers used were commercial sodium hypochlorite and quaternary ammonium compound (QAC). The effects were studied on L. monocytogenes in vitro and on stainless steel chips inoculated with the organism. Cells were exposed to concentrations of 0, 50, 100, 200, 400, and 800 ppm chlorine and QAC for 1, 2, and 5 minutes, and neutralized with tryptic soy broth. Decreases in cell numbers ranged from 3-logs to &gt;4-logs in vitro, whereas with the stainless steel, it ranged from 1-log to &gt;4-logs. Scanning electron microscopic (SEM) studies were done to evaluate the attachment characteristics of L. monocytogenes as compared to those of Escherichia coli on stainless steel. L. monocytogenes was found to produce a fibrous-like material similar in appearance to acidic polysaccharide fibrils produced by Pseudomonas sp., which appeared to be removed by the sanitizer solutions.

scholarly journals Variable Adhesion of Listeria monocytogenes Isolates from Food-Processing Facilities and Clinical Cases to Inert Surfaces

2007 ◽  
Vol 70 (7) ◽  
pp. 1569-1578 ◽  
Author(s):  
ODILE TRESSE ◽  
KELLY SHANNON ◽  
ANTHONY PINON ◽  
PIERRE MALLE ◽  
MICHÈLE VIALETTE ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Processing ◽  
Microtiter Plate ◽  
Clinical Strains ◽  
Microtiter Plates ◽  
Industrial Strains ◽  
Cheese Industry ◽  
Adhesion Rate ◽  
Inert Surfaces

One hundred one strains of Listeria monocytogenes isolated from seafood and cheese industry samples and from patients with listeriosis were assessed using a microtiter plate method for adhesion to polystyrene and stainless steel surfaces. The adhesion rate for these strains ranged from 3.10 to 35.29% with an inoculum of 8 × 108 cells per well. A strong correlation was found between adhesion to polystyrene and stainless steel microtiter plates, indicating that the intrinsic ability of L. monocytogenes to adhere to inert surfaces is stronger than the influence of the surface's physicochemical properties. The clinical strains were less adherent to inert surfaces than were the industrial strains. By integrating other factors such as location of the industrial strains, contamination type of the clinical strains, serotype, and pulsotype into the analysis, some weak but significant differences were noted. For the industrial isolates, the number of cells attached to both surfaces differed significantly depending on whether they were isolated from food or food-processing environments in the seafood and cheese industry. For clinical isolates, sporadic strains exhibited greater adhesion to polystyrene than did epidemic strains. Strains belonging to the pulsed-field gel electrophoretype clusters A and M (lineages II and I, respectively) were less able to adhere to polystyrene and stainless steel than were strains in the more common clusters.

Growth of Listeria monocytogenes as a Biofilm on Various Food-Processing Surfaces

1996 ◽  
Vol 59 (8) ◽  
pp. 827-831 ◽  
Author(s):  
ISABEL C. BLACKMAN ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Processing ◽  
Biofilm Formation ◽  
Minimal Medium ◽  
Processing Plant ◽  
Biofilm Growth ◽  
Sanitary Condition ◽  
Plant Environment ◽  
Substantial Risk

The objective of this research was to determine the ability of Listeria monocytogenes to grow as a biofilm on various food-processing surfaces including stainless steel, Teflon®, nylon, and polyester floor sealant. Each of these surfaces was able to support biofilm formation when incubation was at 21°C in Trypticase soy broth (TSB). Biofilm formation was greatest on polyester floor sealant (40% of surface area covered after 7 days of incubation) and least on nylon (3% coverage). The use of chemically defined minimal medium resulted in a lack of biofilm formation on polyester floor sealant, and reduced biofilm levels on stainless steel. Biofilm formation was reduced with incubation at 10°C, but Teflon® and stainless steel still allowed 23 to 24% coverage after incubation in TSB for 18 days. Biofilm growth of L. monocytogenes was sufficient to provide a substantial risk of this pathogen contaminating the food-processing plant environment if wet surfaces are not maintained in a sanitary condition.

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