scholarly journals Listeria monocytogenes in Milk: Occurrence and Recent Advances in Methods for Inactivation

Beverages ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 14 ◽  
Author(s):  
Sarah Lee ◽  
Leandro Cappato ◽  
Jonas Guimarães ◽  
Celso Balthazar ◽  
Ramon Rocha ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Electric Fields ◽  
Culture Medium ◽  
Thermal Treatments ◽  
Important Food ◽  
Minimally Processed ◽  
Recent Advances ◽  
Processing Plants ◽  
Nutritional Qualities ◽  
Traditional Processing

Milk is one of the most important food items consumed by humans worldwide. In addition to its nutritional importance, milk is an excellent culture medium for microorganisms, which may include pathogens such as Listeria monocytogenes (L. monocytogenes). Traditional processing of milk for direct consumption is based on thermal treatments that efficiently eliminate pathogens, including pasteurization or sterilization. However, the occurrence of L. monocytogenes in milk as a consequence of failures in the pasteurization process or postpasteurization contamination is still a matter of concern. In recent years, consumer demand for minimally processed milk has increased due to the perception of better sensory and nutritional qualities of the products. This review deals with the occurrence of L. monocytogenes in milk in the last 10 years, including regulatory aspects, and recent advances in technologies for the inactivation of this pathogen in milk. The results from studies on nonthermal technologies, such as high hydrostatic pressure, pulsed electric fields, ultrasounds, and ultraviolet irradiation, are discussed, considering their potential application in milk processing plants.

scholarly journals Strain and Growth Conditions may Regulate Resistance of Listeria monocytogenes Biofilms to Benzalkonium Chloride

2020 ◽  
Vol 10 (3) ◽  
pp. 988 ◽  
Author(s):  
Lourenço Bonneville ◽  
Sagrario Ortiz ◽  
Vera Maia ◽  
Luisa Brito ◽  
Joaquín V. Martínez-Suárez
Keyword(s):  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Benzalkonium Chloride ◽  
Culture Medium ◽  
Wild Type Strain ◽  
Inhibitory Concentration ◽  
Resistant Mutant ◽  
Growth Conditions ◽  
Processing Plants ◽  
Mutant Derivative

Listeria monocytogenes is one of the main foodborne pathogens. The formation of biofilms by L. monocytogenes contributes to its resistance to disinfectants, which represents a serious risk for food production plants. The aim of this study was to compare the effect of sub-inhibitory concentrations of benzalkonium chloride (BAC) (1.25 or 2.5 mg/L) on biofilm production and on biofilm reduction after exposure to an inhibitory concentration of BAC (1280 mg/L) in two isogenic L. monocytogenes strains: the BAC-sensitive wild-type strain S2-1 and its BAC-resistant mutant derivative S2BAC, which presented a multidrug resistance phenotype. The biofilm-forming ability of the strains under different BAC concentrations was evaluated by the resazurin method using polystyrene microplates. The biofilm reduction after BAC exposure was evaluated by using stainless steel coupons (SSCs). When the resazurin method was used, S2BAC produced significantly more biofilm in the presence of a sub-inhibitory concentration of BAC compared to that in the culture medium without BAC (p < 0.05). When the SSC method was used, the presence of sub-inhibitory concentrations of BAC resulted in a higher resistance of the biofilm for S2BAC compared to that in the culture medium without BAC (p < 0.05). This was not observed with the sensitive S2-1 strain. These results suggest that biofilm behavior depends on the strain and sub-inhibitory concentrations of disinfectants and may explain the ability of certain isolates to persist in niches of food processing plants.

Prevalence of Listeria monocytogenes in Retail Lightly Pickled Vegetables and Its Successful Control at Processing Plants

2017 ◽  
Vol 80 (3) ◽  
pp. 467-475 ◽  
Author(s):  
Masumi Taguchi ◽  
Masashi Kanki ◽  
Yuko Yamaguchi ◽  
Hideichi Inamura ◽  
Yosuke Koganei ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Food Poisoning ◽  
Salmonella Spp ◽  
Minimally Processed ◽  
Processing Plants ◽  
Large Outbreak ◽  
Contamination Levels ◽  
Minimally Processed Vegetables ◽  
Pickled Vegetables ◽  
Microbiological Surveillance

ABSTRACT Incidences of food poisoning traced to nonanimal food products have been increasingly reported. One of these was a recent large outbreak of Shiga toxin–producing Escherichia coli (STEC) O157 infection from the consumption of lightly pickled vegetables, indicating the necessity of imposing hygienic controls during manufacturing. However, little is known about the bacterial contamination levels in these minimally processed vegetables. Here we examined the prevalence of STEC, Salmonella spp., and Listeria monocytogenes in 100 lightly pickled vegetable products manufactured at 55 processing factories. Simultaneously, we also performed quantitative measurements of representative indicator bacteria (total viable counts, coliform counts, and β-glucuronidase–producing E. coli counts). STEC and Salmonella spp. were not detected in any of the samples; L. monocytogenes was detected in 12 samples manufactured at five of the factories. Microbiological surveillance at two factories (two surveys at factory A and three surveys at factory B) between June 2014 and January 2015 determined that the areas predominantly contaminated with L. monocytogenes included the refrigerators and packaging rooms. Genotyping provided further evidence that the contaminants found in these areas were linked to those found in the final products. Taken together, we demonstrated the prevalence of L. monocytogenes in lightly pickled vegetables sold at the retail level. Microbiological surveillance at the manufacturing factories further clarified the sources of the contamination in the retail products. These data indicate the necessity of implementing adequate monitoring programs to minimize health risks attributable to the consumption of these minimally processed vegetables.

Prevalence and level of Listeria monocytogenes and other Listeria sp. in ready-to-eat minimally processed and refrigerated vegetables

2012 ◽  
Vol 29 (4) ◽  
pp. 707-712 ◽  
Author(s):  
Mira Kovačević ◽  
Jelena Burazin ◽  
Hrvoje Pavlović ◽  
Mirela Kopjar ◽  
Vlasta Piližota
Keyword(s):  
Listeria Monocytogenes ◽  
Minimally Processed

Effect of Gamma Radiation on the Reduction of Salmonella strains, Listeria monocytogenes, and Shiga Toxin–Producing Escherichia coli and Sensory Evaluation of Minimally Processed Spinach (Tetragonia expansa)

2014 ◽  
Vol 77 (10) ◽  
pp. 1768-1772 ◽  
Author(s):  
ANA CAROLINA B. REZENDE ◽  
MARIA CRYSTINA IGARASHI ◽  
MARIA TERESA DESTRO ◽  
BERNADETTE D. G. M. FRANCO ◽  
MARIZA LANDGRAF
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Gamma Radiation ◽  
Shiga Toxin ◽  
Radiation Doses ◽  
Minimally Processed ◽  
Tetragonia Expansa ◽  
Effects Of Irradiation On ◽  
Spinach Leaves

This study evaluated the effects of irradiation on the reduction of Shiga toxin–producing Escherichia coli (STEC), Salmonella strains, and Listeria monocytogenes, as well as on the sensory characteristics of minimally processed spinach. Spinach samples were inoculated with a cocktail of three strains each of STEC, Salmonella strains, and L. monocytogenes, separately, and were exposed to gamma radiation doses of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. Samples that were exposed to 0.0, 1.0, and 1.5 kGy and kept under refrigeration (4°C) for 12 days were submitted to sensory analysis. D10-values ranged from 0.19 to 0.20 kGy for Salmonella and from 0.20 to 0.21 for L. monocytogenes; for STEC, the value was 0.17 kGy. Spinach showed good acceptability, even after exposure to 1.5 kGy. Because gamma radiation reduced the selected pathogens without causing significant changes in the quality of spinach leaves, it may be a useful method to improve safety in the fresh produce industry.

scholarly journals Complete Genome Sequences of Six Listeria monocytogenes Sequence Type 9 Isolates from Meat Processing Plants in Norway

2018 ◽  
Vol 6 (7) ◽  
Author(s):  
Annette Fagerlund ◽  
Solveig Langsrud ◽  
Birgitte Moen ◽  
Even Heir ◽  
Trond Møretrø
Keyword(s):  
Listeria Monocytogenes ◽  
Complete Genome ◽  
Foodborne Pathogen ◽  
Sequence Type ◽  
Nanopore Sequencing ◽  
Meat Processing ◽  
Sequencing Data ◽  
Genome Sequences ◽  
Fatal Disease ◽  
Processing Plants

ABSTRACT Listeria monocytogenes is a foodborne pathogen that causes the often-fatal disease listeriosis. We present here the complete genome sequences of six L. monocytogenes isolates of sequence type 9 (ST9) collected from two different meat processing facilities in Norway. The genomes were assembled using Illumina and Nanopore sequencing data.

Behavior of Listeria monocytogenes in a Pseudomonas putida Biofilm on a Condensate-Forming Surface

2004 ◽  
Vol 67 (2) ◽  
pp. 322-327 ◽  
Author(s):  
ASHRAF N. HASSAN ◽  
DAWN M. BIRT ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Pseudomonas Putida ◽  
Microscopic Observation ◽  
Pure Culture ◽  
Extracellular Polymeric Substances ◽  
Plate Count ◽  
Free Surfaces ◽  
Processing Plants ◽  
Humidity Chamber

Listeria monocytogenes has been isolated from condensate-forming surfaces in food processing plants. The objective of this research was to observe the behavior of L. monocytogenes on condensate-covered stainless steel with a Pseudomonas putida biofilm. L. monocytogenes–containing biofilms, either with or without added chicken protein, were incubated in a high humidity chamber at 12°C to allow formation of condensate. Samples were analyzed for attached and unattached L. monocytogenes and total plate count periodically for 35 days. Samples were also taken for microscopic observation of Listeria and bacterial extracellular polymeric substances (EPS). L. monocytogenes attached in significantly greater numbers (&gt;3-log difference) to surfaces with preexisting P. putida biofilms than to Pseudomonas-free surfaces. L. monocytogenes survived in the presence or absence of P. putida with no added nutrients for 35 days, with numbers of survivors in the range of 3 to 4 log CFU/cm2 in the presence of P. putida and less than 2.9 log CFU/cm2 in pure culture. Attached and unattached L. monocytogenes were at similar levels throughout the incubation under all conditions studied. The addition of protein to the biofilms allowed growth of L. monocytogenes in pure culture during the first 7 days of incubation. Numbers of L. monocytogenes were not affected by the presence of P. putida when protein was present. Unattached L. monocytogenes were at levels of 3.6 to 6.7 log CFU/cm2 on the protein-containing surfaces. Microscopic observation of the condensate-covered biofilms indicated that L. monocytogenes formed microcolonies embedded within an EPS matrix over a 28-day period. This research demonstrates that L. monocytogenes can survive on condensate-forming stainless steel in low and high nutrient conditions, with or without the presence of Pseudomonas biofilm. The Listeria can detach and, therefore, have the potential to contaminate product.

Comparison of Four Commercial DNA Extraction Kits for PCR Detection of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Staphylococcus aureus in Fresh, Minimally Processed Vegetables

2008 ◽  
Vol 71 (10) ◽  
pp. 2110-2114 ◽  
Author(s):  
P. ELIZAQUÍVEL ◽  
R. AZNAR
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Dna Extraction ◽  
Pcr Detection ◽  
Escherichia Coli O157 ◽  
Minimally Processed ◽  
Green Pepper ◽  
Minimally Processed Vegetables ◽  
And Staphylococcus Aureus

Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytogenes, and E. coli O157:H7 and in onion for S. aureus. Despite being the most expensive of the methods compared, the DNeasy Tissue Kit can be successfully applied for any of the four most commonly studied pathogens, thus saving time and overall reducing the cost of the analysis.

scholarly journals Occurrence of Listeria monocytogenes in Ready-to-Eat Meat Products and Meat Processing Plants in Spain

Foods ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 271-282 ◽  
Author(s):  
Diego Gómez ◽  
Laura Iguácel ◽  
Mª Rota ◽  
Juan Carramiñana ◽  
Agustín Ariño ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Meat Products ◽  
Meat Processing ◽  
Processing Plants

scholarly journals The inlA Gene of Listeria monocytogenesLO28 Harbors a Nonsense Mutation Resulting in Release of Internalin

1998 ◽  
Vol 66 (7) ◽  
pp. 3420-3422 ◽  
Author(s):  
Renaud Jonquières ◽  
Hélène Bierne ◽  
Jérôme Mengaud ◽  
Pascale Cossart
Keyword(s):  
Cell Adhesion ◽  
Listeria Monocytogenes ◽  
Virulence Factor ◽  
Adhesion Molecule ◽  
Nonsense Mutation ◽  
Cell Adhesion Molecule ◽  
Culture Medium ◽  
Surface Protein ◽  
Truncated Protein

ABSTRACT Internalin is a surface protein that mediates entry ofListeria monocytogenes EGD into epithelial cells expressing the cell adhesion molecule human E-cadherin or its chicken homolog, L-CAM, which act as receptors for internalin. After observing that entry of L. monocytogenes LO28 into S180 fibroblasts, in contrast to that of EGD, did not increase after transfection with L-CAM, we examined both the expression and the structure of internalin in strain LO28. We discovered a nonsense mutation in inlA which results in a truncated protein released in the culture medium. Mutations leading to release of internalin were also detected in clinical and food isolates. These results question the role of internalin as a virulence factor in murine listeriosis.

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