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Sample records for listeria monocytogenes durante

  1. Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of Listeria monocytogenes (Lm) in food is a critical public health concern given that it can grow and/or survive during storage at refrigeration and/or mildly abusive storage temperatures, thus contributing to the burden of food borne listeriosis associated with the consumption of conta...

  2. Listeria monocytogenes

    PubMed Central

    Liang, Zach Z; Sherrid, Ashley M; Wallecha, Anu; Kollmann, Tobias R

    2014-01-01

    Vaccination as a medical intervention has proven capable of greatly reducing the suffering from childhood infectious disease. However, newborns and infants in particular are age groups for whom adequate vaccine-mediated protection is still largely lacking. With the challenges that the neonatal immune system faces and the required highest level of stringency for safety, designing vaccines for early life in general and the newborn in particular poses great difficulty. Nevertheless, recent advances in our understanding of neonatal immunity and its responses to vaccines and adjuvants suggest that neonatal vaccination is a task fully within reach. Among the most promising developments in neonatal vaccination is the use of Listeria monocytogenes (Lm) as a delivery platform. In this review, we will outline key properties of Lm that make it such an ideal neonatal and early life vaccine vehicle, and also discuss potential constraints of Lm as a vaccine delivery platform. PMID:24513715

  3. Handbook of Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Once feared as a deadly intracellular bacterium with the extraordinary capacity to survive a wide array of arduous external stressors, Listeria monocytogenes is increasingly recognized as a preferred vector for delivering anti-infective and anti-cancer vaccine molecules. A reliable, single-source re...

  4. Listeria monocytogenes Endovascular Graft Infection

    PubMed Central

    Heysell, Scott K.; Hughes, Molly A.

    2016-01-01

    Although best managed by surgical resection, we present a case of Listeria monocytogenes endovascular graft infection alternatively treated with graft retention and antibiotic induction followed by a lifelong suppressive course. The epidemiological, pathological, and clinical features of this unique entity are reviewed. PMID:26835477

  5. Phylogenomic grouping of Listeria monocytogenes.

    PubMed

    Doijad, Swapnil; Weigel, Markus; Barbuddhe, Sukhadeo; Blom, Jochen; Goesmann, Alexander; Hain, Torsten; Chakraborty, Trinad

    2015-09-01

    The precise delineation of lineages and clonal groups are a prerequisite to examine within-species genetic variations, particularly with respect to pathogenic potential. A whole-genome-based approach was used to subtype and subgroup isolates of Listeria monocytogenes. Core-genome typing was performed, employing 3 different approaches: total core genes (CG), high-scoring segment pairs (HSPs), and average nucleotide identity (ANI). Examination of 113 L. monocytogenes genomes available in-house and in public domains revealed 33 phylogenomic groups (PGs). Each PG could be differentiated into a number of genomic types (GTs), depending on the approach used: HSPs (n = 57 GTs), CG (n = 71 GTs), and ANI (n = 83 GTs). Demarcation of the PGs was concordant with the 4 known lineages and led to the identification of sublineages in the lineage groups I, II, and III. In addition, PG assignments had discriminatory power similar to multi-virulence-locus sequence typing types and clonal complexes of multilocus sequence typing. Clustering of genomically highly similar isolates from different countries, sources, and isolation dates using whole-genome-based PG suggested that dispersion of phylogenomic clones of L. monocytogenes preceded their subsequent evolution. Classification according to PG may act as a guideline for future epidemiological studies. PMID:26245135

  6. Aerosol studies with Listeria innocua and Listeria monocytogenes.

    PubMed

    Zhang, Guodong; Ma, Li; Oyarzabal, Omar A; Doyle, Michael P

    2007-08-01

    Aerosol studies of Listeria monocytogenes in food processing plants have been limited by lack of a suitable surrogate microorganism. The objective of this study was to investigate the potential of using green fluorescent protein-labeled strains of Listeria innocua as a surrogate for L. monocytogenes for aerosol studies. These studies were conducted in a laboratory bioaerosol chamber and a pilot food-processing facility. Four strains of L. innocua and five strains of L. monocytogenes were used. In the laboratory chamber study, Listeria cells were released into the environment at two different cell numbers and under two airflow conditions. Trypticase soy agar (TSA) plates and oven-roasted breasts of chicken and turkey were placed in the chamber to monitor Listeria cell numbers deposited from aerosols. A similar experimental design was used in the pilot plant study; however, only L. innocua was used. Results showed that L. monocytogenes and L. innocua survived equally well on chicken and turkey breast meats and TSA plates. No-fan and continuous fan applications, which affected airflow, had no significant effect on settling rates of aerosolized L. monocytogenes and L. innocua in the bioaerosol chamber or L. innocua in the pilot plant study. Listeriae cell numbers in the air decreased rapidly during the first 1.5 h following release, with few to no listeriae detected in the air at 3 h. Aerosol particles with diameters of 1 and 2 microM correlated directly with the number of Listeria cells in the aerosol but not with particles that were 0.3, 0.5, and 5 microM in diameter. Results indicate that L. innocua can be used as a surrogate for L. monocytogenes in an aerosol study. PMID:17803142

  7. How does Listeria monocytogenes combat acid conditions?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes, a major foodborne pathogen, possesses a number of mechanisms which enable it to combat the challenges posed by acidic environments such as acidic foods and the acidity in the gastrointestinal tract. These mechanisms include the acid tolerance response, a two-component regula...

  8. Detection of Listeria monocytogenes by using the polymerase chain reaction

    SciTech Connect

    Bessesen, M.T.; Luo, Q.; Blaser, M.J.; Ellison, R.T. III.; Rotbart. H.A. )

    1990-09-01

    A method was developed for detection of Listeria monocytogens by polymerase chain reaction amplification followed by agarose gel electrophoresis or dot blot analysis with {sup 32}P-labeled internal probe. The technique identified 95 of 95 L. monocytogenes strains, 0 of 12 Listeria strains of other species, and 0 of 12 non-Listeria strains.

  9. [Unusual location of a brain abscess due to Listeria monocytogenes].

    PubMed

    Coste, J-F; Duval, V; Nguyen, Y; Guillard, T; Brasme, L; David, C; Strady, C; Lecuit, M; de Champs, C

    2012-10-01

    Here we report a case of sustentorial brain abscess due to Listeria monocytogenes. Blood culture and procalcitonine blood measurement were negative. L. monocytogenes was isolated from CSF after inoculation in Castañeda medium. PMID:21835558

  10. Internalization of Listeria monocytogenes in Whole Avocado.

    PubMed

    Chen, Yi; Evans, Peter; Hammack, Thomas S; Brown, Eric W; Macarisin, Dumitru

    2016-08-01

    In recent years, tree fruits have emerged as a new concern for Listeria monocytogenes contamination. The objective of the current study was to evaluate the potential internalization of L. monocytogenes from the surface of avocados into the edible portions of the fruit during certain postharvest practices simulated in a laboratory setting. One set of intact avocados was spot inoculated with L. monocytogenes on the stem scar, and the second set was hydrocooled in water contaminated with L. monocytogenes. Under these experimental conditions, L. monocytogenes internalized into the avocado pulp through the stem or stem scar after both spot inoculation and hydrocooling. In avocados spot inoculated with 50, 130, 500, and 1,300 CFU per fruit, bacteria were detected in the edible portion adjacent to the stem scar within 15 days postinoculation during storage at 4°C. In avocados hydrocooled in water containing L. monocytogenes at 10(6) and 10(8) CFU/ml, bacteria reached the bottom end of the fruit, and the populations in the edible portion adjacent to the stem scar reached up to 5.90 to 7.19 log CFU/g within 10 to 15 days during storage at 4°C. Dye mixed with inoculum was useful for guiding subsequent sampling, but dye penetration patterns were not always consistent with bacterial penetration. PMID:27497134

  11. Cytotoxicity of Rabbit Blood for Listeria monocytogenes

    PubMed Central

    Shultz, Leonard D.; Wilder, M. S.

    1971-01-01

    Our studies reveal that normal rabbit blood contains a potent bactericidin active against Listeria monocytogenes. The factor is present in greatest amounts in fresh undiluted serum but is absent in platelet extracts. A correlation was observed between the virulence of Listeria strains and their relative ability to survive in serum. The bactericidal titers obtained for plasma and plasma serum indicate that clotting must occur for optimum expression of antilisterial activity. The lethal action is not elevated after immunization with viable Listeria nor does it appear to depend on heat-labile components of complement. The active factor was removed from serum by filtration through a cellulose asbestos filter pad and further purified by carboxymethyl cellulose chromatography. Iron significantly diminishes serum lethality and completely abolishes the action of the purified component. The listericidal factor resembles β-lysin but may be a distinct part of a multiple system of similar bactericidins. PMID:5005312

  12. Effect of Listeria seeligeri or Listeria welshimeri on Listeria monocytogenes detection in and recovery from buffered Listeria enrichment broth.

    PubMed

    Dailey, Rachel C; Welch, Lacinda J; Hitchins, Anthony D; Smiley, R Derike

    2015-04-01

    The presence of multiple species of Listeria in regulated food products is not uncommon and can complicate the recovery of Listeria monocytogenes particularly on a non-differentiating medium. The potential complications of Listeria seeligeri and Listeria welshimeri on the recovery of L. monocytogenes from inoculated food test samples using the U.S. Food and Drug Administration's (FDA) selective enrichment procedure was investigated. Post-enrichment enumeration, in the absence of food product, indicates that some L. seeligeri and L. monocytogenes pairings may have population differentials as great as 2.7 ± 0.1 logs with L. seeligeri being the predominant species. A similar observation was noted for L. welshimeri and L. monocytogenes pairings which resulted in population differentials as large as 3.7 ± 0.2 logs with L. welshimeri being the predominant species. Select strain pairings were used to inoculate guacamole, crab meat, broccoli, and cheese with subsequent recovery by the FDA Bacteriological Analytical Manual (BAM) method with 10 colonies per sample selected for confirmation. The presence of L. seeligeri had little effect on the recovery of L. monocytogenes. The presence of L. welshimeri resulted in the failure to recover L. monocytogenes in three out of the four food matrices. This work extends the observation that non-pathogenic species of Listeria can complicate the recovery of L. monocytogenes and that competition during selective enrichment is not limited to the presence of just Listeria innocua. PMID:25475325

  13. NATURAL ATYPICAL LISTERIA INNOCUA STRAINS WITH LISTERIA MONOCYTOGENES PATHOGENICITY ISLAND 1 GENES

    EPA Science Inventory

    The detection of the human foodborne pathogen, Listeria monocytogenes, in food, environmental samples and clinical specimens associated with cases of listeriosis, a rare but high mortality-rate disease, requires distinguishing the pathogen from other Listeria species. Speciation...

  14. Harnessing Listeria monocytogenes to target tumors

    PubMed Central

    Gravekamp, Claudia; Paterson, Yvonne

    2010-01-01

    Because of its cytosolic localization, Listeria monocytogenes (LM) has long been considered an attractive tool for delivering tumor-associated antigens (TAA) antigens in vivoto combat cancer. LM directly infects antigen-presenting cells (APC) such as monocytes, macrophages and dendritic cells (DC), thereby delivering the TAA into their cytoplasm, resulting in processing, and presentation of the antigen to the immune system. This activates adaptive and innate immune responses to the TAA, mediating tumor cell cytolysis. Recently we discovered additional pathways by which Listeria can be harnessedto induce tumor cell death, which suggest new directions in the development of vaccines or therapies against cancer. In one approach, we have used Listeria to induce immune responses that destroy tumor vasculature. Another new pathway involves selective infection of cancer cells with Listeria, followed by tumor cell death through the production of high levels of reactive oxygen species (ROS) and through Listeria-specific cytotoxic T lymphocytes (CTL). This review will focus on the most recent studies on the multiple pathways of LM and how they can be harnessed in the battle against cancer. PMID:20139702

  15. Recombinant phage probes for Listeria monocytogenes

    NASA Astrophysics Data System (ADS)

    Carnazza, S.; Gioffrè, G.; Felici, F.; Guglielmino, S.

    2007-10-01

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 104 cells ml-1. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products.

  16. Highly selective medium for isolation of Listeria monocytogenes from food.

    PubMed Central

    al-Zoreky, N; Sandine, W E

    1990-01-01

    A new selective medium (Al-Zoreky-Sandine listeria medium [ASLM]) was formulated to recover Listeria monocytogenes from food specimens; the medium completely inhibited common food microflora. Recognition of Listeria colonies is evident by black discoloration of the medium due to esculin hydrolysis without need for special illuminating equipment. The medium contains acriflavin, ceftazidime, and moxalactam as selective agents. Compared with Listeria Selective Agar, ASLM was equally effective in recovering L. monocytogenes. However, ASLM inhibited micrococci, enterococci, and gram-negative bacteria, especially a strain that mimicked L. monocytogenes on Listeria Selective Agar. The new medium was able to recover heat injured cells with only 15% less count than the nonselective medium. Images PMID:2126701

  17. Detection of hemolytic Listeria monocytogenes by using DNA colony hybridization

    SciTech Connect

    Datta, A.R.; Wentz, B.A.; Hill, W.E.

    1987-09-01

    A fragment of about 500 base pairs of the beta-hemolysin gene from Listeria monocytogenes was used to screen different bacterial strains by DNA colony hybridization. The cells in the colonies were lysed by microwaves in the presence of sodium hydroxide. Of 52 different strains of Listeria species screened, only the DNA from beta-hemolytic (CAMP-positive) strains of L. monocytogenes hybridized with this probe.

  18. Identification of Potential Cold-Related Genes in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a foodborne pathogen with the atypical ability to grow at refrigeration temperatures. One approach to identifying genes and proteins involved in growth in the cold is through creation of cold-sensitive mutants by transposon mutagenesis. L. monocytogenes strain 10403S was ra...

  19. Bacteriophage significantly reduces Listeria monocytogenes on raw salmon fillet tissue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have demonstrated the antilisterial activity of generally recognized as safe (GRAS) bacteriophage LISTEX P100 (phage P100) on the surface of raw salmon fillet tissue against Listeria monocytogenes serotypes 1/2a and 4b. In a broth model system, phage P100 completely inhibited L. monocytogenes gro...

  20. Toward an Improved Laboratory Definition of Listeria monocytogenes Virulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is an opportunistic foodborne pathogen that encompasses a diversity of strains with varied virulence. The ability to rapidly determine the pathogenic potential of L. monocytogenes strains is integral to the control and prevention campaign against listeriosis. Early methods for...

  1. Attachment Strength of Listeria monocytogenes and Its Internalin Negative Mutants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A single cell of Listeria monocytogenes attached on food contact surfaces can be a potential source of cross-contamination in a food-processing plant. To see whether internalin A (InlA) and B (InlB), major surface proteins on L. monocytogenes, play a significant role in the attachment process, wild-...

  2. Evolutionary analyses of Listeria monocytogenes and application to molecular subtyping

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to test hypotheses regarding Listeria monocytogenes evolution, ecology, taxonomy, and lineage composition, a robust phylogenetic framework was developed based on allelic variation identified at more than 20 genes from across the genomes of more than 200 L. monocytogenes isolates. These ana...

  3. Listeria monocytogenes, a food-borne pathogen.

    PubMed Central

    Farber, J M; Peterkin, P I

    1991-01-01

    The gram-positive bacterium Listeria monocytogenes is an ubiquitous, intracellular pathogen which has been implicated within the past decade as the causative organism in several outbreaks of foodborne disease. Listeriosis, with a mortality rate of about 24%, is found mainly among pregnant women, their fetuses, and immunocompromised persons, with symptoms of abortion, neonatal death, septicemia, and meningitis. Epidemiological investigations can make use of strain-typing procedures such as DNA restriction enzyme analysis or electrophoretic enzyme typing. The organism has a multifactorial virulence system, with the thiol-activated hemolysin, listeriolysin O, being identified as playing a crucial role in the organism's ability to multiply within host phagocytic cells and to spread from cell to cell. The organism occurs widely in food, with the highest incidences being found in meat, poultry, and seafood products. Improved methods for detecting and enumerating the organism in foodstuffs are now available, including those based on the use of monoclonal antibodies, DNA probes, or the polymerase chain reaction. As knowledge of the molecular and applied biology of L. monocytogenes increases, progress can be made in the prevention and control of human infection. PMID:1943998

  4. Outbreak of Listeria Monocytogenes in Pheasants.

    PubMed

    Gu, Yufang; Liang, Xiongyan; Huang, Zhuan; Yang, Yuying

    2015-12-01

    Listeria monocytogenes is capable of infecting almost all animals. However, outbreaks of listeriosis are infrequent in birds. This report describes an outbreak of listeriosis in a small pheasant (Phasianus colchicus) breeder farm with more than 2,000 pheasants from Hubei province of the People's Republic of China. The affected flock consisted of adult and young birds. Approximately 300 young birds and a few adult birds were found dead within a few days of the onset of clinical signs. Twenty-five dead birds were collected for further examination. Histopathological lesions in the visceral organs were characterized by monocyte infiltration and proliferation. Localized encephalitis and meningitis were detected in the brains of dead birds. Gram-positive organisms were observed in heart blood smear, liver, and brain impression smears. The organisms were isolated from fresh liver and were identified as L. monocytogenes serotype 4b based on multiplex polymerase chain reaction (PCR) and hlyA gene sequence analysis. This is the first report describing outbreak of listeriosis in pheasant flock. PMID:26476090

  5. Silver As Antibacterial toward Listeria monocytogenes.

    PubMed

    Belluco, Simone; Losasso, Carmen; Patuzzi, Ilaria; Rigo, Laura; Conficoni, Daniele; Gallocchio, Federica; Cibin, Veronica; Catellani, Paolo; Segato, Severino; Ricci, Antonia

    2016-01-01

    Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs) or silver nitrate (AgNO3). Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action. PMID:27014230

  6. Silver As Antibacterial toward Listeria monocytogenes

    PubMed Central

    Belluco, Simone; Losasso, Carmen; Patuzzi, Ilaria; Rigo, Laura; Conficoni, Daniele; Gallocchio, Federica; Cibin, Veronica; Catellani, Paolo; Segato, Severino; Ricci, Antonia

    2016-01-01

    Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs) or silver nitrate (AgNO3). Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action. PMID:27014230

  7. Foodborne Listeria monocytogenes: A Real Challenge in Quality Control.

    PubMed

    Pusztahelyi, Tünde; Szabó, Judit; Dombrádi, Zsuzsanna; Kovács, Szilvia; Pócsi, István

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen, and the detection and differentiation of this bacterium from the nonpathogenic Listeria species are of great importance to the food industry. Differentiation of Listeria species is very difficult, even with the sophisticated MALDI-TOF MS technique because of the close genetic relationship of the species and the usual gene transfer. The present paper emphasizes the difficulties of the differentiation through the standardized detection and confirmation according to ISO 11290-1:1996 and basic available L. monocytogenes detection methods and tests (such as API Listeria test, MALDI-TOF MS analysis, and hly gene PCR). With the increase of reports on the pathogenesis of atypical Listeria strains in humans, the significance of species level determination has become questionable, especially in food quality control, and the detection of pathogenic characteristics seems to be more relevant. PMID:27239376

  8. Foodborne Listeria monocytogenes: A Real Challenge in Quality Control

    PubMed Central

    Pusztahelyi, Tünde; Szabó, Judit; Dombrádi, Zsuzsanna; Kovács, Szilvia; Pócsi, István

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen, and the detection and differentiation of this bacterium from the nonpathogenic Listeria species are of great importance to the food industry. Differentiation of Listeria species is very difficult, even with the sophisticated MALDI-TOF MS technique because of the close genetic relationship of the species and the usual gene transfer. The present paper emphasizes the difficulties of the differentiation through the standardized detection and confirmation according to ISO 11290-1:1996 and basic available L. monocytogenes detection methods and tests (such as API Listeria test, MALDI-TOF MS analysis, and hly gene PCR). With the increase of reports on the pathogenesis of atypical Listeria strains in humans, the significance of species level determination has become questionable, especially in food quality control, and the detection of pathogenic characteristics seems to be more relevant. PMID:27239376

  9. Prevalence and Contamination Patterns of Listeria monocytogenes in Fresh Catfish Fillets and their Processing Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Catfish skins, intestines, fresh fillets, processing surfaces at different production stages, chiller water and non-food contact surfaces were sampled for Listeria monocytogenes and other Listeria species. Among 315 samples, prevalence of L. monocytogenes, Listeria innocua and a group of Listeria se...

  10. Analytical bioconjugates, aptamers, enable specific quantitative detection of Listeria monocytogenes.

    PubMed

    Lee, Sang-Hee; Ahn, Ji-Young; Lee, Kyeong-Ah; Um, Hyun-Ju; Sekhon, Simranjeet Singh; Sun Park, Tae; Min, Jiho; Kim, Yang-Hoon

    2015-06-15

    As a major human pathogen in the Listeria genus, Listeria monocytogenes causes the bacterial disease listeriosis, which is a serious infection caused by eating food contaminated with the bacteria. We have developed an aptamer-based sandwich assay (ABSA) platform that demonstrates a promising potential for use in pathogen detection using aptamers as analytical bioconjugates. The whole-bacteria SELEX (WB-SELEX) strategy was adopted to generate aptamers with high affinity and specificity against live L. monocytogenes. Of the 35 aptamer candidates tested, LMCA2 and LMCA26 reacted to L. monocytogenes with high binding, and were consequently chosen as sensing probes. The ABSA platform can significantly enhance the sensitivity by employing a very specific aptamer pair for the sandwich complex. The ABSA platform exhibited a linear response over a wide concentration range of L. monocytogenes from 20 to 2×10(6) CFU per mL and was closely correlated with the following relationship: y=9533.3x+1542.3 (R(2)=0.99). Our proposed ABSA platform also provided excellent specificity for the tests to distinguish L. monocytogenes from other Listeria species and other bacterial genera (3 Listeria spp., 4 Salmonella spp., 2 Vibrio spp., 3 Escherichia coli and 3 Shigella spp.). Improvements in the sensitivity and specificity have not only facilitated the reliable detection of L. monocytogenes at extremely low concentrations, but also allowed for the development of a 96-well plate-based routine assay platform for multivalent diagnostics. PMID:25590973

  11. The challenge of enumerating Listeria monocytogenes in food.

    PubMed

    Auvolat, Anais; Besse, Nathalie Gnanou

    2016-02-01

    Listeria monocytogenes is recognised as a serious foodborne pathogen in humans. However, food products are usually contaminated at low levels (i.e. <100 CFU/g) and there is still no adequate enumeration method for testing food. Much research has been carried out to improve Listeria enumeration methods, leading to several proposed alternative methods such as the most probable number technique, molecular-based methods and bacterial cell concentration techniques. Here, we catalogue the current knowledge concerning L. monocytogenes enumeration, with a particular focus on the problem of enumerating low level contamination. PMID:26678141

  12. Solitary supratentorial Listeria monocytogenes brain abscess in an immunocompromised patient

    PubMed Central

    Onofrio, Anthony R.; Martinez, Lauren C.; Opatowsky, Michael J.; Spak, Cedric W.; Layton, Kennith F.

    2015-01-01

    We describe an 81-year-old man receiving azacitidine monotherapy for myelodysplastic syndrome who was improving from Listeria monocytogenes bacteremia after receiving antibiotic therapy during an earlier hospital admission. Shortly after discharge he developed new-onset seizure activity, with brain imaging on subsequent admissions demonstrating a posterior right frontal lobe mass. Specimen cultures after resection of the mass revealed this to be a cerebral abscess related to L. monocytogenes. Brain abscesses related to this organism are rare. PMID:26130881

  13. A Case of Leukocytoclastic Vasculitis Caused by Listeria monocytogenes Bacteremia.

    PubMed

    Bunker, Daniel R; Sullivan, Timothy

    2016-01-01

    Importance. Infections can cause leukocytoclastic vasculitis. Observations. We report the case of a patient with a left ventricular assist device who presented with acute kidney injury and biopsy proven leukocytoclastic vasculitis. Blood cultures grew Listeria monocytogenes. The patient's rash improved with treatment of the underlying Listeria infection. Conclusion. Clinicians should be aware that there are a number of broad categories of disease associated with the histologic finding of vasculitis, including infection. It is important to keep in mind the risk factors of a particular patient when formulating a differential diagnosis. This is the first reported case of Listeria bacteremia causing leukocytoclastic vasculitis. PMID:27313916

  14. A Case of Leukocytoclastic Vasculitis Caused by Listeria monocytogenes Bacteremia

    PubMed Central

    2016-01-01

    Importance. Infections can cause leukocytoclastic vasculitis. Observations. We report the case of a patient with a left ventricular assist device who presented with acute kidney injury and biopsy proven leukocytoclastic vasculitis. Blood cultures grew Listeria monocytogenes. The patient's rash improved with treatment of the underlying Listeria infection. Conclusion. Clinicians should be aware that there are a number of broad categories of disease associated with the histologic finding of vasculitis, including infection. It is important to keep in mind the risk factors of a particular patient when formulating a differential diagnosis. This is the first reported case of Listeria bacteremia causing leukocytoclastic vasculitis. PMID:27313916

  15. Inhibition of Listeria monocytogenes by Enterococcus mundtii isolated from soil.

    PubMed

    Bigwood, T; Hudson, J A; Cooney, J; McIntyre, L; Billington, C; Heinemann, J A; Wall, F

    2012-12-01

    Two bacterial isolates with inhibitory activity against Listeria monocytogenes and Enterococcus faecalis were obtained from soil. Genotypic and phenotypic characterization identified them as Enterococcus mundtii, a species whose ability to compete with L. monocytogenes is relatively unexplored compared to other members of the genus. The thermal stability of the inhibitory factor and its sensitivity to proteolytic enzymes indicate that it is most likely a bacteriocin. Both isolates grew at comparable rates to L. monocytogenes at 5 °C and 10 °C in vitro. One isolate killed L. monocytogenes when it reached concentrations of 10(6)-10(8) CFU ml(-1). Minimum inocula of 10(6) and 10(5) CFU ml(-1) of E. mundtii were required to reduce and maintain L. monocytogenes concentrations beneath the level of detection at 5 °C and 10 °C, respectively. In situ experiments at 5 °C showed that E. mundtii inhibited the growth of L. monocytogenes on vacuum-packed cold smoked salmon during its four week shelf life. E. mundtii could, therefore, control the growth of L. monocytogenes at low temperatures, indicating a potential application in controlling this pathogen in chilled foods. To control growth of Listeria, the concentration of E. mundtii needs to be high, but it is possible that a purified bacteriocin could be used to achieve the same effect. PMID:22986201

  16. Metabolic gene expression shift by Listeria monocytogenes in coculture biofilms.

    PubMed

    Tirumalai, Prem Saran

    2015-05-01

    Coculture communities of microbes are more realistic and common in nature than in laboratory-grown pure cultures. In a mixed community, when resources with a potential role in growth are shared, conflict (as a consequence of competition) or cooperation is certain. In our study, this situation of conflict and cooperation was explored to understand the population dynamics and community behavior of Listeria monocytogenes. The social behavioral response of L. monocytogenes to the presence of Bacillus subtilis was studied in terms of divergence in gene expression of L. monocytogenes. It is evident from the results that social behavior of L. monocytogenes changes from competition for survival in broth to cooperation and coexistence in biofilm. Furthermore, the gene expression pattern is clearly indicative of L. monocytogenes switching from aerobic to fermentative metabolism in broth and biofilm conditions, respectively. PMID:25776109

  17. Direct Identification in Food Samples of Listeria spp. and Listeria monocytogenes by Molecular Methods

    PubMed Central

    Cocolin, Luca; Rantsiou, Kalliopi; Iacumin, Lucilla; Cantoni, Carlo; Comi, Giuseppe

    2002-01-01

    A new molecular approach for the detection and identification of Listeria spp. and Listeria monocytogenes in food is presented here. The method is based on the PCR amplification of a fragment of the iap gene from the five species belonging to the genus and on the analysis of the PCR products obtained by denaturing gradient gel electrophoresis (DGGE). The protocol was first optimized by using strains from international collections. Based on the differences present in the sequences amplified, it was possible to obtain species-specific DGGE migration that allowed fast and easy identification of L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, and L. ivanovii. Moreover, for L. monocytogenes serotypes, partial differentiation was possible. The optimized protocol was used for identification of Listeria strains traditionally isolated from food and for direct detection and identification of Listeria members in food after an overnight enrichment. Identification of 48 food isolates and direct detection of Listeria spp. in 73 food samples show the potential of the method that can be used as a fast screening test to investigate the presence of Listeria spp. and L. monocytogenes in food. PMID:12450852

  18. MODELLING TRANSFER OF LISTERIA MONOCYTOGENES DURING SLICING OF "GRAVAD" SALMON

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transfer of a rifampicin-resistant mutant of Listeria monocytogenes strain F2365 from an inoculated slicing blade to slices of gravad salmon (Salmo salar), and from inoculated salmon fillet to the slicing machine and subsequently to slices of uninoculated fillet was studied. The effect of slicing te...

  19. Influence of temperature on alkali stress adaptation in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes cells may induce alkali stress adaptation when exposed to sublethal concentrations of alkaline cleaners and sanitizers that may be frequently used in the food processing environment. In the present study, the effect of temperature on the induction and the stability of such alk...

  20. Genome sequesnce of lineage III Listeria monocytogenes strain HCC23

    Technology Transfer Automated Retrieval System (TEKTRAN)

    More than 98% of reported human listeriosis cases are caused by Listeria monocytogenes serotypes within lineages I and II. Serotypes within lineage III (4a and 4c) are commonly isolated from environmental and food specimens. We report the first complete genome sequence of a lineage III isolate, HCC2...

  1. An overview of stress response proteomes in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes adapts to diverse stress conditions including cold, osmotic, heat, acid, and alkali stresses encountered during food processing and preservation which is a serious food safety threat. In this review, we have presented the major findings on this bacterium’s stress response prot...

  2. Growth of Listeria monocytogenes in Salmon Roe - a kinetic analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to investigate the growth kinetics of Listeria monocytogenes in unsalted and salted (3%) salmon roe. Growth curves, developed using inoculated samples incubated at constant temperatures between 5 and 30 degrees C, were analyzed by curve-fitting to the Huang and Baran...

  3. Assay to measure efficacy of dininfectants against Listeria monocytogenes biofilms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is responsible for a 20 to 30% death rate in humans, and more food product recalls than any other pathogen in recent years. Many disinfectants have been tested against this pathogen. This study provides a method for testing and comparison of disinfectant product claims. Two...

  4. 78 FR 27939 - Draft Interagency Risk Assessment-Listeria monocytogenes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ...The United States Department of Agriculture (USDA)/Food Safety and Inspection Service (FSIS) and the Food and Drug Administration (FDA)/Center for Food Safety and Applied Nutrition (CFSAN) are announcing the availability of the draft ``Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens.'' This draft quantitative risk assessment (QRA) includes an Interpretive Summary......

  5. Elimination of Listeria monocytogenes on Hotdogs by Infrared Surface Treatment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to develop an infrared pasteurization process with automatic temperature control for inactivation of surface-contaminated Listeria monocytogenes on ready-to-eat meats such as hotdogs. The pasteurization system contained 4 basic elements: an infrared emitter, a hot...

  6. Genome Sequences of Five Nonvirulent Listeria monocytogenes Serovar 4 Strains

    PubMed Central

    Shen, Yang; Loessner, Martin J.

    2016-01-01

    We present the complete genome sequences of five nonpathogenic Listeria monocytogenes serovar 4 strains: WSLC 1018 (4e), 1019 (4c), 1020 (4a), 1033 (4d), and 1047 (4d). These sequences may help to uncover genes involved in the synthesis of the serovar antigens—phenotypic determinants of virulence deemed clinically relevant. PMID:27034489

  7. Listeria monocytogenes biofilm formation on silver ion impregnated cutting boards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a human pathogen that can be a member of a biofilm community attached to surfaces in poultry processing plants. When present as a biofilm on product contact surfaces, this organism can effectively cross contaminate fully cooked ready-to-eat meat. Plastic cutting boards ca...

  8. Listeria monocytogenes Biofilm Formation on Silver Ion Impregnated Cutting Boards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a human pathogen that can be a member of a biofilm community attached to surfaces in poultry processing plants. When present as a biofilm on product contact surfaces, this organism can effectively cross contaminate fully cooked ready-to-eat meat. Plastic cutting boards ca...

  9. LOW PREVALENCE OF LISTERIA MONOCYTOGENES IN CULL SOWS AND PORK

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The goal of this study was to determine the prevalence of Listeria monocytogenes in cull sows slaughtered at a single plant on two occasions (Trial 1, n=179 cull sows and Trial 2, n= 160 cull sows). Fecal samples collected antemortem (Trial 1) as well as animal tissues, and carcass swabs collected ...

  10. Draft Genome Sequence of a 94-Year-Old Listeria monocytogenes Isolate, SLCC208

    PubMed Central

    Hyden, Patrick; Pietzka, Ariane; Allerberger, Franz; Springer, Burkhard; Sensen, Christoph

    2016-01-01

    We report here the draft genome sequence of Listeria monocytogenes strain SLCC208 from Seeliger’s historical Special Listeria Culture Collection, initially cultured from a human case in France in 1921. This is, to our knowledge, the oldest L. monocytogenes isolate available and may be useful for comparative genomic studies of L. monocytogenes. PMID:26798096

  11. [A case of Listeria monocytogenes meningitis in an immunocompetent infant].

    PubMed

    Pattarino, G; Arrigoni, S; Grazioli, R; De Palma, A; di Natale, B

    2006-08-01

    Listeria Monocytogenes meningitis is a rare affection after the neonatal period, but in immunocompromised patients. Listeria Monocytogenes is a Gram-positive, facultative intracellular bacterium frequently causing infection in pregnant women, in patients with cell-mediated immunity deficit and in the early and late stages of life. We present a case of Listeria Monocytogenes meningitis in an immunocompetent nomad 8-month-child, preceded by gastroenteritis. Although gastrointestinal symptoms may be due to intestinal infection by Listeria, the concomitant presence of other bacteric or viral enteric pathogens may have promoted bacterium intestinal translocation and generated disseminated disease. The main transmission route of infection after the neonatal period is ingestion of contaminated food. A diet history was taken after isolation of the bacterium in liquor and showed that the child was an eater of undercooked hot-dogs. Despite the frequency of clinical complication in such affection, the outcome in this patient was a complete recovery. Although the infection is extremely infrequent in healthy children, physicians should always consider Listeria as a possible etiologic agent of meningitis in pediatric patients, regardless of their age or immunological status, especially in patients living in precarious sanitary conditions, where weaning times and conditions are not respected and a suitable food cooking is not assured. PMID:17008849

  12. Identification of small Hfq-binding RNAs in Listeria monocytogenes

    PubMed Central

    Christiansen, Janne K.; Nielsen, Jesper S.; Ebersbach, Tine; Valentin-Hansen, Poul; Søgaard-Andersen, Lotte; Kallipolitis, Birgitte H.

    2006-01-01

    The RNA-binding protein Hfq plays important roles in bacterial physiology and is required for the activity of many small regulatory RNAs in prokaryotes. We have previously shown that Hfq contributes to stress tolerance and virulence in the Gram-positive human pathogen Listeria monocytogenes. In the present study, we performed coimmunoprecipitations followed by enzymatic RNA sequencing to identify Hfq-binding RNA molecules in L. monocytogenes. The approach resulted in the discovery of three small RNAs (sRNAs). The sRNAs are conserved between Listeria species, but were not identified in other bacterial species. The initial characterization revealed a number of unique features displayed by each individual sRNA. The first sRNA is encoded from within an annotated gene in the L. monocytogenes EGD-e genome. Analogous to most regulatory sRNAs in Escherichia coli, the stability of this sRNA is highly dependent on the presence of Hfq. The second sRNA appears to be produced by a transcription attenuation mechanism, and the third sRNA is present in five copies at two different locations within the L. monocytogenes EGD-e genome. The cellular levels of the sRNAs are growth phase dependent and vary in response to growth medium. All three sRNAs are expressed when L. monocytogenes multiplies within mammalian cells. This study represents the first attempt to identify sRNAs in L. monocytogenes. PMID:16682563

  13. Invading slugs (Arion vulgaris) can be vectors for Listeria monocytogenes

    PubMed Central

    Gismervik, K; Aspholm, M; Rørvik, LM; Bruheim, T; Andersen, A; Skaar, I

    2015-01-01

    Aims Listeriosis is a frequent silage-associated disease in ruminants. The slugs Arion vulgaris are invaders in gardens, vegetable crops and meadows for silage production. Field and laboratory studies were conducted to clarify whether slugs could host Listeria monocytogenes and thereby constitute a threat to animal feed safety. Methods and Results Selective culture of L. monocytogenes from 79 pooled slug samples (710 slugs) resulted in 43% positive, 16% with mean L. monocytogenes values of 405 CFU g−1 slug tissues. Of 62 individual slugs cultured, 11% also tested positive from surface/mucus. Multilocus sequence typing analysis of 36 isolates from different slug pools identified 20 sequence types belonging to L. monocytogenes lineages I and II. Slugs fed ≅4·0 × 105 CFUL. monocytogenes, excreted viable L. monocytogenes in faeces for up to 22 days. Excretion of L. monocytogenes decreased with time, although there were indications of a short enrichment period during the first 24 h. Conclusions Arion vulgaris may act as a vector for L. monocytogenes. Significance and Impact of the Study Highly slug-contaminated grass silage may pose a potential threat to animal feed safety. PMID:25580873

  14. Rapid detection and differentiation of Listeria monocytogenes and Listeria species in deli meats by a new multiplex PCR method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is an important foodborne pathogen. To effectively control this pathogen, it is necessary to have a method that can detect and differentiate L. monocytogenes from other Listeria species in food, environmental, and clinical samples. A new multiplex PCR method using new primers ...

  15. A mouse model of food borne Listeria monocytogenes infection

    PubMed Central

    Bou Ghanem, Elsa N.; Myers-Morales, Tanya

    2014-01-01

    Listeria monocytogenes cause foodborne disease in humans that ranges in severity from mild, self-limiting gastroenteritis to life-threatening systemic infections of the blood, brain, or placenta. The most commonly used animal model of listeriosis is intravenous infection of mice. This systemic model is highly reproducible, and thus, useful for studying cell-mediated immune responses against an intracellular bacterial pathogen, but it completely bypasses the gastrointestinal phase of L. monocytogenes infection. Intragastric inoculation of L. monocytogenes produces more variable results and may cause direct bloodstream invasion in some animals. The food borne transmission model described here does not require specialized skills to perform and results in infections that more closely mimic human disease. This natural feeding model can be used to study both the host and pathogen-derived factors that govern susceptibility or resistance to orally acquired L. monocytogenes. PMID:24510293

  16. Susceptibility of Listeria monocytogenes, L. innocua, and L. welshimeri Isolated from Various Sources to Antibiotics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Listeriosis is a leading cause of death from foodborne illnesses in the United States. Emergence of antimicrobial resistant strains of Listeria monocytogenes could cause major public health concerns. Few studies have examined antimicrobial susceptibility of L. monocytogenes isolated fr...

  17. Inhibitory effects of raw carrots on Listeria monocytogenes.

    PubMed Central

    Beuchat, L R; Brackett, R E

    1990-01-01

    The survival and growth of two strains of Listeria monocytogenes on raw and cooked carrots stored at 5 and 15 degrees C and in carrot juice media at 30 degrees C were investigated. The influence of shredding, chlorine treatment, and packaging under an atmosphere containing 3% O2 and 97% N2 on the behavior of L. monocytogenes and naturally occurring microflora was determined. Populations of viable L. monocytogenes decreased upon contact with whole and shredded raw carrots but not cooked carrots. Viable populations also decreased in cell suspensions in which raw carrots were dipped. Small populations of L. monocytogenes detected on whole carrots immediately after dipping were essentially nondetectable after 7 days of storage at 5 or 15 degrees C. After a lag of 7 days at 5 degrees C, significant (P less than or equal to 0.05) increases in populations were detected on shredded carrots after 24 days of storage. Carrots stored at 5 or 15 degrees C spoiled before L. monocytogenes grew. Populations of mesophilic aerobes, psychrophiles, and yeasts and molds increased throughout storage at 5 and 15 degrees C. Cutting treatment (whole or shredded carrots), chlorine treatment, and modified-atmosphere packaging had no effect on the survival or growth of L. monocytogenes or naturally occurring microflora. The presence of raw carrot juice in tryptic phosphate broth at a concentration as low as 1% substantially reduced the maximum population of L. monocytogenes reached after 24 h at 30 degrees C. The anti-Listeria effect of carrots was essentially eliminated when the carrots were cooked.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2116759

  18. Intracellular Gene Expression Profile of Listeria monocytogenes

    PubMed Central

    Chatterjee, Som Subhra; Hossain, Hamid; Otten, Sonja; Kuenne, Carsten; Kuchmina, Katja; Machata, Silke; Domann, Eugen; Chakraborty, Trinad; Hain, Torsten

    2006-01-01

    Listeria monocytogenes is a gram-positive, food-borne microorganism responsible for invasive infections with a high overall mortality. L. monocytogenes is among the very few microorganisms that can induce uptake into the host cell and subsequently enter the host cell cytosol by breaching the vacuolar membrane. We infected the murine macrophage cell line P388D1 with L. monocytogenes strain EGD-e and examined the gene expression profile of L. monocytogenes inside the vacuolar and cytosolic environments of the host cell by using whole-genome microarray and mutant analyses. We found that ∼17% of the total genome was mobilized to enable adaptation for intracellular growth. Intracellularly expressed genes showed responses typical of glucose limitation within bacteria, with a decrease in the amount of mRNA encoding enzymes in the central metabolism and a temporal induction of genes involved in alternative-carbon-source utilization pathways and their regulation. Adaptive intracellular gene expression involved genes that are associated with virulence, the general stress response, cell division, and changes in cell wall structure and included many genes with unknown functions. A total of 41 genes were species specific, being absent from the genome of the nonpathogenic Listeria innocua CLIP 11262 strain. We also detected 25 genes that were strain specific, i.e., absent from the genome of the previously sequenced L. monocytogenes F2365 serotype 4b strain, suggesting heterogeneity in the gene pool required for intracellular survival of L. monocytogenes in host cells. Overall, our study provides crucial insights into the strategy of intracellular survival and measures taken by L. monocytogenes to escape the host cell responses. PMID:16428782

  19. Uncovering Listeria monocytogenes hypervirulence by harnessing its biodiversity

    PubMed Central

    Charlier, Caroline; Touchon, Marie; Chenal-Francisque, Viviane; Leclercq, Alexandre; Criscuolo, Alexis; Gaultier, Charlotte; Roussel, Sophie; Brisabois, Anne; Disson, Olivier; Rocha, Eduardo P. C.; Brisse, Sylvain; Lecuit, Marc

    2016-01-01

    Microbial pathogenesis studies are typically performed with reference strains, thereby overlooking microbial intra-species virulence heterogeneity. Here we integrated human epidemiological and clinical data with bacterial population genomics to harness the biodiversity of the model foodborne pathogen Listeria monocytogenes and decipher the basis of its neural and placental tropisms. Taking advantage of the clonal structure of this bacterial species, we identify clones epidemiologically associated with either food or human central nervous system (CNS) and maternal-neonatal (MN) listeriosis. The latter are also most prevalent in patients without immunosuppressive comorbidities. Strikingly, CNS and MN clones are hypervirulent in a humanized mouse model of listeriosis. By integrating epidemiological data and comparative genomics, we uncovered multiple novel putative virulence factors and demonstrated experimentally the contribution of the first gene cluster mediating Listeria monocytogenes neural and placental tropisms. This study illustrates the exceptional power of harnessing microbial biodiversity to identify clinically relevant microbial virulence attributes. PMID:26829754

  20. Discrimination of Listeria monocytogenes from other Listeria species by ligase chain reaction.

    PubMed Central

    Wiedmann, M; Czajka, J; Barany, F; Batt, C A

    1992-01-01

    A ligase chain reaction assay based on a single-base-pair difference in the V9 region of the 16S rRNA gene (16S rDNA) was developed to distinguish between Listeria monocytogenes and other Listeria species. For this purpose, two pairs of primers were designed, with one primer of each pair being radioactively labeled. The ligated product was separated from the primers by denaturing polyacrylamide gel electrophoresis and then detected by autoradiography. To achieve a higher sensitivity, the 16S rDNA was initially amplified by polymerase chain reaction prior to the ligase chain reaction. The ligase chain reaction was tested on 19 different Listeria species and strains and proved to be a highly specific diagnostic method for the detection of L. monocytogenes. Images PMID:1482171

  1. Occurrence of genetic variants of Listeria monocytogenes strains.

    PubMed

    Tham, Wilhem; Lopez-Valladares, Gloria; Helmersson, Seved; Wennström, Stefan; Österlund, Anders; Danielsson-Tham, Marie-Louise

    2013-09-01

    Isolates of Listeria monocytogenes saved from outbreaks of listeriosis, cases of sporadic listeriosis, and similar events do not always belong to a solitary genetic variant. Variants of the same strain may have evolved from a unique clone, and plasmid loss or gain and phage-mediated genetic changes are suggested as the main mechanism. Some of these reports are summarized in this short communication. PMID:23988078

  2. Listeria monocytogenes, a down-to-earth pathogen

    PubMed Central

    Vivant, Anne-Laure; Garmyn, Dominique; Piveteau, Pascal

    2013-01-01

    Listeria monocytogenes is the causative agent of the food-borne life threatening disease listeriosis. This pathogenic bacterium received much attention in the endeavor of deciphering the cellular mechanisms that underlie the onset of infection and its ability to adapt to the food processing environment. Although information is available on the presence of L. monocytogenes in many environmental niches including soil, water, plants, foodstuff and animals, understanding the ecology of L. monocytogenes in outdoor environments has received less attention. Soil is an environmental niche of pivotal importance in the transmission of this bacterium to plants and animals. Soil composition, microbial communities and macrofauna are extrinsic edaphic factors that direct the fate of L. monocytogenes in the soil environment. Moreover, farming practices may further affect its incidence. The genome of L. monocytogenes presents an extensive repertoire of genes encoding transport proteins and regulators, a characteristic of the genome of ubiquitous bacteria. Postgenomic analyses bring new insights in the process of soil adaptation. In the present paper focussing on soil, we review these extrinsic and intrinsic factors that drive environmental adaptation of L. monocytogenes. PMID:24350062

  3. Inhibition of sortase A by chalcone prevents Listeria monocytogenes infection.

    PubMed

    Li, Hongen; Chen, Yutao; Zhang, Bing; Niu, Xiaodi; Song, Meng; Luo, Zhaoqing; Lu, Gejin; Liu, Bowen; Zhao, Xiaoran; Wang, Jianfeng; Deng, Xuming

    2016-04-15

    The critical role of sortase A in gram-positive bacterial pathogenicity makes this protein a good potential target for antimicrobial therapy. In this study, we report for the first time the crystal structure of Listeria monocytogenes sortase A and identify the active sites that mediate its transpeptidase activity. We also used a sortase A (SrtA) enzyme activity inhibition assay, simulation, and isothermal titration calorimetry analysis to discover that chalcone, an agent with little anti-L. monocytogenes activity, could significantly inhibit sortase A activity with an IC50 of 28.41 ± 5.34 μM by occupying the active site of SrtA. The addition of chalcone to a co-culture of L. monocytogenes and Caco-2 cells significantly inhibited bacterial entry into the cells and L. monocytogenes-mediated cytotoxicity. Additionally, chalcone treatment decreased the mortality of infected mice, the bacterial burden in target organs, and the pathological damage to L. monocytogenes-infected mice. In conclusion, these findings suggest that chalcone is a promising candidate for the development of treatment against L. monocytogenes infection. PMID:26826492

  4. Listeria monocytogenes brain abscess in a patient with multiple myeloma.

    PubMed

    Al-Khatti, Adil A; Al-Tawfiq, Jaffar A

    2010-12-01

    Listeria monocytogenes is an uncommon cause of illness in the general population. Meningoencephalitis is the most common central nervous system (CNS) manifestation of listeriosis. However, brain abscess represents 1-10% of all CNS listeriosis. To our knowledge, L. monocytogenes brain abscess in multiple myeloma patients has not been previously reported. Thus we report a 58-year-old male patient with multiple myeloma who developed a brain abscess due to L. monocytogenes. Due to a history of penicillin allergy, he was treated with intravenous trimethoprim/sulfamoxazole (TMP-SMX) for a total of 12 weeks, and gentamicin for the first two weeks, followed by oral therapy of TMP-SMX for a total of nine months. He is alive six and a half years after the diagnosis of myeloma with occasional brief seizures despite being on two anticonvulsants. PMID:21252468

  5. Growth of Listeria monocytogenes in melon, watermelon and papaya pulps.

    PubMed

    Penteado, Ana L; Leitão, Mauro F F

    2004-04-01

    Growth of Listeria monocytogenes in low-acid fruits (melon, watermelon and papaya) at different times of incubation and at temperatures of 10, 20 and 30 degrees C was studied. Fruit pulp portions with an average pH of 5.87, 5.50 and 4.87 for melon, watermelon and papaya, respectively, were obtained aseptically, homogenized, weighed and inoculated with suspensions (approximately 10(2) CFU/g) of L. monocytogenes. Generation times of 7.12, 13.03 and 15.05 h at 10 degrees C, 1.74, 2.17 and 6.42 h at 20 degrees C and 0.84, 1.00 and 1.16 h at 30 degrees C were obtained, respectively, for melon, watermelon and papaya. The results showed that L. monocytogenes grew in low-acid fruits at all tested temperatures, although growth was diminished, but not inhibited at 10 degrees C. PMID:15033271

  6. Differentiation of Listeria monocytogenes and Listeria innocua by 16S rRNA genes and intraspecies discrimination of Listeria monocytogenes strains by random amplified polymorphic DNA polymorphisms.

    PubMed Central

    Czajka, J; Bsat, N; Piani, M; Russ, W; Sultana, K; Wiedmann, M; Whitaker, R; Batt, C A

    1993-01-01

    Differences in the 16S rRNA genes (16S rDNA) which can be used to discriminate Listeria monocytogenes from Listeria innocua have been detected. The 16S rDNA were amplified by polymerase chain reaction with a set of oligonucleotide primers which flank a 1.5-kb fragment. Sequence differences were observed in the V2 region of the 16S rDNA both between L. monocytogenes Scott A and L. innocua and between different L. monocytogenes serotypes. Although L. monocytogenes SLCC2371 had the same V2 region sequence as L. innocua, the two species were different within the V9 region at nucleotides 1259 and 1292, in agreement with previous studies (R.-F. Wang, W.-W. Cao, and M.G. Johnson, Appl. Environ. Microbiol. 57:3666-3670, 1991). Intraspecies discrimination of L. monocytogenes strains was achieved by using the patterns generated by random amplified polymorphic DNA primers. Although some distinction can be made within the L. monocytogenes species by their 16S rDNA sequence, a far greater discrimination within species could be made by generating random amplified polymorphic DNA patterns from chromosomal DNA. By using a number of 10-bp primers, unique patterns for each isolate which in all cases examined differentiate between various L. monocytogenes serotypes, even though they may have the same 16S rRNA sequences, could be generated. Images PMID:8439157

  7. Validation of the ANSR(®) Listeria monocytogenes Method for Detection of Listeria monocytogenes in Selected Food and Environmental Samples.

    PubMed

    Caballero, Oscar; Alles, Susan; Le, Quynh-Nhi; Gray, R Lucas; Hosking, Edan; Pinkava, Lisa; Norton, Paul; Tolan, Jerry; Mozola, Mark; Rice, Jennifer; Chen, Yi; Ryser, Elliot; Odumeru, Joseph

    2016-01-01

    Work was conducted to validate performance of the ANSR(®) for Listeria monocytogenes method in selected food and environmental matrixes. This DNA-based assay involves amplification of nucleic acid via an isothermal reaction based on nicking enzyme amplification technology. Following single-step sample enrichment for 16-24 h for most matrixes, the assay is completed in 40 min using only simple instrumentation. When 50 distinct strains of L. monocytogenes were tested for inclusivity, 48 produced positive results, the exceptions being two strains confirmed by PCR to lack the assay target gene. Forty-seven nontarget strains (30 species), including multiple non-monocytogenes Listeria species as well as non-Listeria, Gram-positive bacteria, were tested, and all generated negative ANSR assay results. Performance of the ANSR method was compared with that of the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook reference culture procedure for detection of L. monocytogenes in hot dogs, pasteurized liquid egg, and sponge samples taken from an inoculated stainless steel surface. In addition, ANSR performance was measured against the U.S. Food and Drug Administration Bacteriological Analytical Manual reference method for detection of L. monocytogenes in Mexican-style cheese, cantaloupe, sprout irrigation water, and guacamole. With the single exception of pasteurized liquid egg at 16 h, ANSR method performance as quantified by the number of positives obtained was not statistically different from that of the reference methods. Robustness trials demonstrated that deliberate introduction of small deviations to the normal assay parameters did not affect ANSR method performance. Results of accelerated stability testing conducted using two manufactured lots of reagents predicts stability at the specified storage temperature of 4°C of more than 1 year. PMID:26833248

  8. Environmental prevalence and persistence of Listeria monocytogenes in cold-smoked trout processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of Listeria monocytogenes on the surfaces of equipment and workers' hands during different production stages, as well as on fish skin and meat during processing and storage of cold-smoked trout, was investigated. Listeria monocytogenes was recovered from 10 (6.06%) of a total 165 cotto...

  9. Small-Molecule Modulators of Listeria monocytogenes Biofilm Development

    PubMed Central

    Nguyen, Uyen T.; Wenderska, Iwona B.; Chong, Matthew A.; Koteva, Kalinka; Wright, Gerard D.

    2012-01-01

    Listeria monocytogenes is an important food-borne pathogen whose ability to form disinfectant-tolerant biofilms on a variety of surfaces presents a food safety challenge for manufacturers of ready-to-eat products. We developed here a high-throughput biofilm assay for L. monocytogenes and, as a proof of principle, used it to screen an 80-compound protein kinase inhibitor library to identify molecules that perturb biofilm development. The screen yielded molecules toxic to multiple strains of Listeria at micromolar concentrations, as well as molecules that decreased (≤50% of vehicle control) or increased (≥200%) biofilm formation in a dose-dependent manner without affecting planktonic cell density. Toxic molecules—including the protein kinase C antagonist sphingosine—had antibiofilm activity at sub-MIC concentrations. Structure-activity studies of the biofilm inhibitory compound palmitoyl-d,l-carnitine showed that while Listeria biofilm formation was inhibited with a 50% inhibitory concentration of 5.85 ± 0.24 μM, d,l-carnitine had no effect, whereas palmitic acid had stimulatory effects. Saturated fatty acids between C9:0 and C14:0 were Listeria biofilm inhibitors, whereas fatty acids of C16:0 or longer were stimulators, showing chain length specificity. De novo-synthesized short-chain acyl carnitines were less effective biofilm inhibitors than the palmitoyl forms. These molecules, whose activities against bacteria have not been previously established, are both useful probes of L. monocytogenes biology and promising leads for the further development of antibiofilm strategies. PMID:22194285

  10. Listeria monocytogenes: Strain Heterogeneity, Methods, and Challenges of Subtyping.

    PubMed

    Nyarko, Esmond B; Donnelly, Catherine W

    2015-12-01

    Listeria monocytogenes is a food-borne bacterial pathogen that is associated with 20% to 30% case fatality rate. L. monocytogenes is a genetically heterogeneous species, with a small fraction of strains (serotypes 1/2a, 1/2b, 4b) implicated in human listeriosis. Monitoring and source tracking of L. monocytogenes involve the use of subtyping methods, with the performance of genetic-based methods found to be superior to phenotypic-based ones. Various methods have been used to subtype L. monocytogenes isolates, with the pulsed-field gel electrophoresis (PFGE) being the gold standard. Although PFGE has had a massive impact on food safety through the establishment of the PulseNet, there is no doubt that whole genome sequence (WGS) typing is accurate, has a discriminatory power superior to any known method, and allows genome-wide differences between strains to be quantified through the comparison of nucleotide sequences. This review focuses on the different techniques that have been used to type L. monocytogenes strains, their performance challenges, and the tremendous impact WGS typing could have on the food safety landscape. PMID:26588067

  11. Synergistic effect of copper and low temperature over Listeria monocytogenes.

    PubMed

    Latorre, Mauricio; Quesille-Villalobos, Ana María; Maza, Felipe; Parra, Angel; Reyes-Jara, Angélica

    2015-12-01

    The capacity to grow at low temperatures has allowed Listeria monocytogenes to become one of the primary food pathogens to date, representing a major public health problem worldwide. Several works have described the homeostatic response of L. monocytogenes under different copper (Cu) treatments growing at mild temperature (30 °C). The aims of this report were to evaluate if changes in the external concentration of Cu affected viability and Cu homeostasis of L. monocytogenes growing at low temperature. Ours results showed that L. monocytogenes growing at 8 °C had a reduced viability relative to 30 °C when exposed to Cu treatments. This decrease was correlated with an increase in the internal concentration of Cu, probably linked to the transcriptional down-regulation of mechanisms involved in Cu homeostasis. This combined effect of Cu and low temperature showed a synergistic impact over the viability and homeostasis of L. monocytogenes, where low temperature exacerbated the toxic effect of Cu. These results can be useful in terms of the use of Cu as an antibacterial agent. PMID:26515293

  12. Prevalence of Listeria monocytogenes in raw milk in Kerman, Iran

    PubMed Central

    Mansouri-Najand, Ladan; Kianpour, Mehrnoush; Sami, Masoud; Jajarmi, Maziar

    2015-01-01

    Listeria monocytogenes as one of the most important pathogen in public health concerns is transmitted through consumption of contaminated food. The pathogen has been considered as a potential source of contamination of raw milk and dairy products. This research was aimed to investigate prevalence of L. monocytogenes in raw milk in Kerman region. In the summer of 2011, a total number of one hundred raw milk samples were collected from bulk tanks of some dairy farms and tested for iap and actA genes using polymerase chain reaction. Among the 100 samples, five isolates (5.0%) were detected as L. monocytogenes based on phenotypic and genotypic characteristics. Considering the low frequency of L. monocytogenes in this study, raw milk cannot be omitted as a potential source of food contamination for the population of the region. To achieve more accurate isolation, identification and control of L. monocytogenes in raw milk, it is suggested that new standard laboratory methods be implemented as well as biosafety outreach programs, management techniques and education. PMID:26893812

  13. The Listeria monocytogenes strain 10403S BioCyc database.

    PubMed

    Orsi, Renato H; Bergholz, Teresa M; Wiedmann, Martin; Boor, Kathryn J

    2015-01-01

    Listeria monocytogenes is a food-borne pathogen of humans and other animals. The striking ability to survive several stresses usually used for food preservation makes L. monocytogenes one of the biggest concerns to the food industry, while the high mortality of listeriosis in specific groups of humans makes it a great concern for public health. Previous studies have shown that a regulatory network involving alternative sigma (σ) factors and transcription factors is pivotal to stress survival. However, few studies have evaluated at the metabolic networks controlled by these regulatory mechanisms. The L. monocytogenes BioCyc database uses the strain 10403S as a model. Computer-generated initial annotation for all genes also allowed for identification, annotation and display of predicted reactions and pathways carried out by a single cell. Further ongoing manual curation based on published data as well as database mining for selected genes allowed the more refined annotation of functions, which, in turn, allowed for annotation of new pathways and fine-tuning of previously defined pathways to more L. monocytogenes-specific pathways. Using RNA-Seq data, several transcription start sites and promoter regions were mapped to the 10403S genome and annotated within the database. Additionally, the identification of promoter regions and a comprehensive review of available literature allowed the annotation of several regulatory interactions involving σ factors and transcription factors. The L. monocytogenes 10403S BioCyc database is a new resource for researchers studying Listeria and related organisms. It allows users to (i) have a comprehensive view of all reactions and pathways predicted to take place within the cell in the cellular overview, as well as to (ii) upload their own data, such as differential expression data, to visualize the data in the scope of predicted pathways and regulatory networks and to carry on enrichment analyses using several different annotations

  14. Transcriptpome analysis of Listeria monocytogenes grown on a ready to eat meat matrix

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contamination of ready-to-eat (RTE) meat products with Listeria monocytogenes is a major concern for the food industry. For a better understanding of the adaptation and survival ability of L. monocytogenes grown on turkey deli meat, the transcriptome of L. monocytogenes strain F2365 was determin...

  15. Quantitative Detection of Listeria monocytogenes in Biofilms by Real-Time PCR

    PubMed Central

    Guilbaud, Morgan; de Coppet, Pierre; Bourion, Fabrice; Rachman, Cinta; Prévost, Hervé; Dousset, Xavier

    2005-01-01

    A quantitative method based on a real-time PCR assay to enumerate Listeria monocytogenes in biofilms was developed. The specificity for L. monocytogenes of primers targeting the listeriolysin gene was demonstrated using a SYBR Green I real-time PCR assay. The number of L. monocytogenes detected growing in biofilms was 6 × 102 CFU/cm2. PMID:15812058

  16. ISG15 counteracts Listeria monocytogenes infection

    PubMed Central

    Radoshevich, Lilliana; Impens, Francis; Ribet, David; Quereda, Juan J; Nam Tham, To; Nahori, Marie-Anne; Bierne, Hélène; Dussurget, Olivier; Pizarro-Cerdá, Javier; Knobeloch, Klaus-Peter; Cossart, Pascale

    2015-01-01

    ISG15 is an interferon-stimulated, linear di-ubiquitin-like protein, with anti-viral activity. The role of ISG15 during bacterial infection remains elusive. We show that ISG15 expression in nonphagocytic cells is dramatically induced upon Listeria infection. Surprisingly this induction can be type I interferon independent and depends on the cytosolic surveillance pathway, which senses bacterial DNA and signals through STING, TBK1, IRF3 and IRF7. Most importantly, we observed that ISG15 expression restricts Listeria infection in vitro and in vivo. We made use of stable isotope labeling in tissue culture (SILAC) to identify ISGylated proteins that could be responsible for the protective effect. Strikingly, infection or overexpression of ISG15 leads to ISGylation of ER and Golgi proteins, which correlates with increased secretion of cytokines known to counteract infection. Together, our data reveal a previously uncharacterized ISG15-dependent restriction of Listeria infection, reinforcing the view that ISG15 is a key component of the innate immune response. DOI: http://dx.doi.org/10.7554/eLife.06848.001 PMID:26259872

  17. Characterization of antimicrobial resistance of foodborne Listeria monocytogenes.

    PubMed

    Conter, Mauro; Paludi, Domenico; Zanardi, Emanuela; Ghidini, Sergio; Vergara, Alberto; Ianieri, Adriana

    2009-01-15

    The objective of this study was to evaluate the susceptibility of 120 Listeria monocytogenes strains isolated from food and food-processing environments to 19 antibiotics currently used in veterinary and human therapy. Susceptibility tests were performed by using the automated VITEK2 system. Apart from penicillin, ampicillin and trimethoprim-sulfamethoxazole, for which clinical breakpoints for Listeria susceptibility testing are defined according to the Clinical and Laboratory Standard Institute (CLSI), in the present study the CLSI criteria for staphylococci were applied. Among the 120 tested strains, 14 (11.7%) displayed resistance to at least one antibiotic. In particular, resistance to one antibiotic was more common than multiple resistance, i.e., 10 (8.3%) isolates were resistant to one antibiotic, 3 (2.5%) to two antibiotics and one (0.8%) to five antibiotics. Resistance to clindamycin was the most common, followed by linezolid, ciprofloxacin, ampicillin and rifampicin, trimethoprim/sulphamethoxazole and, finally, vancomycin and tetracycline. This study shows that L. monocytogenes strains from food and food-processing environments are susceptible to the antibiotics commonly used in veterinary and human listeriosis treatment. Considering that L. monocytogenes is slowly becoming antibiotic resistant, a continued surveillance of emerging antimicrobial resistance of this pathogen is important to ensure effective treatment of human listeriosis. These data are useful in improving background data on antibiotic resistance of strains isolated from food and food environment. PMID:19012982

  18. Listeria monocytogenes and Listeria spp. contamination patterns in retail delicatessen establishments in three U.S. states.

    PubMed

    Simmons, Courtenay; Stasiewicz, Matthew J; Wright, Emily; Warchocki, Steven; Roof, Sherry; Kause, Janell R; Bauer, Nathan; Ibrahim, Salam; Wiedmann, Martin; Oliver, Haley F

    2014-11-01

    Postprocessing contamination in processing plants has historically been a significant source of Listeria monocytogenes in ready-to-eat delicatessen meats, and therefore a major cause of human listeriosis cases and outbreaks. Recent risk assessments suggest that a majority of human listeriosis cases linked to consumption of contaminated deli meats may be due to L. monocytogenes contamination that occurs at the retail level. To better understand the ecology and transmission of Listeria spp. in retail delicatessens, food and nonfood contact surfaces were tested for L. monocytogenes and other Listeria spp. in a longitudinal study conducted in 30 retail delis in three U.S. states. In phase I of the study, seven sponge samples were collected monthly for 3 months in 15 delis (5 delis per state) prior to start of daily operation; in phase II, 28 food contact and nonfood contact sites were sampled in each of 30 delis during daily operation for 6 months. Among the 314 samples collected during phase I, 6.8% were positive for L. monocytogenes. Among 4,503 samples collected during phase II, 9.5% were positive for L. monocytogenes; 9 of 30 delis showed low L. monocytogenes prevalence (<1%) for all surfaces. A total of 245 Listeria spp. isolates, including 184 Listeria innocua, 48 Listeria seeligeri, and 13 Listeria welshimeri were characterized. Pulsed-field gel electrophoresis (PFGE) was used to characterize 446 L. monocytogenes isolates. PFGE showed that for 12 of 30 delis, one or more PFGE types were isolated on at least three separate occasions, providing evidence for persistence of a given L. monocytogenes subtype in the delis. For some delis, PFGE patterns for isolates from nonfood contact surfaces were distinct from patterns for occasional food contact surface isolates, suggesting limited cross-contamination between these sites in some delis. This study provides longitudinal data on L. monocytogenes contamination patterns in retail delis, which should facilitate further

  19. Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples.

    PubMed

    Salazar, Joelle K; Carstens, Christina K; Bathija, Vriddi M; Narula, Sartaj S; Parish, Mickey; Tortorello, Mary Lou

    2016-05-01

    An outbreak of listeriosis in late 2014 and early 2015 associated with caramel apples led to questions about how this product became a vector for Listeria monocytogenes. This investigation aimed to determine information about the survival and growth of L. monocytogenes in both fresh apples and caramel apples, specifically examining the effects of site and level of inoculation, inoculum drying conditions, and storage temperature. At a high inoculation level (7 log CFU per apple), L. monocytogenes inoculated at the stem end proliferated on Gala caramel apples at both 5 and 25°C and on Granny Smith caramel apples at 25°C by as much as 3 to 5 log CFU per apple. Fresh apples and caramel apples inoculated at the equatorial surface supported survival but not growth of the pathogen. Growth rates (μmax) for apples inoculated at the stem end, as determined using the Baranyi and Roberts growth model, were 1.64 ± 0.27 and 1.38 ± 0.20 log CFU per apple per day for Gala and Granny Smith caramel apples, respectively, stored at 25°C. At a low inoculation level (3 log CFU per apple), L. monocytogenes inoculated at the stem end and the equatorial surface survived but did not grow on fresh Gala and Granny Smith apples stored at 25°C for 49 days; however, on caramel apples inoculated at the stem end, L. monocytogenes had significant growth under the same conditions. Although certain conditions did not support growth, the pathogen was always detectable by enrichment culture. The inoculation procedure had a significant effect on results; when the inoculum was allowed to dry for 24 h at 5°C, growth was significantly slowed compared with inoculum allowed to dry for 2 h at 25°C. Variation in stick materials did affect L. monocytogenes survival, but these differences were diminished once sticks were placed into caramel apples. PMID:27296414

  20. Numerical spatio-temporal characterization of Listeria monocytogenes biofilms.

    PubMed

    Mosquera-Fernández, M; Rodríguez-López, P; Cabo, M L; Balsa-Canto, E

    2014-07-16

    As the structure of biofilms plays a key role in their resistance and persistence, this work presents for the first time the numerical characterization of the temporal evolution of biofilm structures formed by three Listeria monocytogenes strains on two types of stainless-steel supports, AISI 304 SS No. 2B and AISI 316 SS No. 2R. Counting methods, motility tests, fluorescence microscopy and image analysis were combined to study the dynamic evolution of biofilm formation and structure. Image analysis was performed with several well-known parameters as well as a newly defined parameter to quantify spatio-temporal distribution. The results confirm the interstrain variability of L. monocytogenes species regarding biofilm structure and structure evolution. Two types of biofilm were observed: homogeneous or flat and heterogeneous or clustered. Differences in clusters and in attachment and detachment processes were due mainly to the topography and composition of the two surfaces although an effect due to motility was also found. PMID:24858448

  1. Listeria monocytogenes: survival and adaptation in the gastrointestinal tract.

    PubMed

    Gahan, Cormac G M; Hill, Colin

    2014-01-01

    The foodborne pathogen Listeria monocytogenes has the capacity to survive and grow in a diverse range of natural environments. The transition from a food environment to the gastrointestinal tract begins a process of adaptation that may culminate in invasive systemic disease. Here we describe recent advances in our understanding of how L. monocytogenes adapts to the gastrointestinal environment prior to initiating systemic infection. We will discuss mechanisms used by the pathogen to survive encounters with acidic environments (which include the glutamate decarboxylase and arginine deiminase systems), and those which enable the organism to cope with bile acids (including bile salt hydrolase) and competition with the resident microbiota. An increased understanding of how the pathogen survives in this environment is likely to inform the future design of novel prophylactic approaches that exploit specific pharmabiotics; including probiotics, prebiotics, or phages. PMID:24551601

  2. Listeria monocytogenes: survival and adaptation in the gastrointestinal tract

    PubMed Central

    Gahan, Cormac G. M.; Hill, Colin

    2014-01-01

    The foodborne pathogen Listeria monocytogenes has the capacity to survive and grow in a diverse range of natural environments. The transition from a food environment to the gastrointestinal tract begins a process of adaptation that may culminate in invasive systemic disease. Here we describe recent advances in our understanding of how L. monocytogenes adapts to the gastrointestinal environment prior to initiating systemic infection. We will discuss mechanisms used by the pathogen to survive encounters with acidic environments (which include the glutamate decarboxylase and arginine deiminase systems), and those which enable the organism to cope with bile acids (including bile salt hydrolase) and competition with the resident microbiota. An increased understanding of how the pathogen survives in this environment is likely to inform the future design of novel prophylactic approaches that exploit specific pharmabiotics; including probiotics, prebiotics, or phages. PMID:24551601

  3. Actin network disassembly powers dissemination of Listeria monocytogenes.

    PubMed

    Talman, Arthur M; Chong, Ryan; Chia, Jonathan; Svitkina, Tatyana; Agaisse, Hervé

    2014-01-01

    Several bacterial pathogens hijack the actin assembly machinery and display intracellular motility in the cytosol of infected cells. At the cell cortex, intracellular motility leads to bacterial dissemination through formation of plasma membrane protrusions that resolve into vacuoles in adjacent cells. Here, we uncover a crucial role for actin network disassembly in dissemination of Listeria monocytogenes. We found that defects in the disassembly machinery decreased the rate of actin tail turnover but did not affect the velocity of the bacteria in the cytosol. By contrast, defects in the disassembly machinery had a dramatic impact on bacterial dissemination. Our results suggest a model of L. monocytogenes dissemination in which the disassembly machinery, through local recycling of the actin network in protrusions, fuels continuous actin assembly at the bacterial pole and concurrently exhausts cytoskeleton components from the network distal to the bacterium, which enables membrane apposition and resolution of protrusions into vacuoles. PMID:24155331

  4. Uncovering Listeria monocytogenes hypervirulence by harnessing its biodiversity.

    PubMed

    Maury, Mylène M; Tsai, Yu-Huan; Charlier, Caroline; Touchon, Marie; Chenal-Francisque, Viviane; Leclercq, Alexandre; Criscuolo, Alexis; Gaultier, Charlotte; Roussel, Sophie; Brisabois, Anne; Disson, Olivier; Rocha, Eduardo P C; Brisse, Sylvain; Lecuit, Marc

    2016-03-01

    Microbial pathogenesis studies are typically performed with reference strains, thereby overlooking within-species heterogeneity in microbial virulence. Here we integrated human epidemiological and clinical data with bacterial population genomics to harness the biodiversity of the model foodborne pathogen Listeria monocytogenes and decipher the basis of its neural and placental tropisms. Taking advantage of the clonal structure of this bacterial species, we identify clones epidemiologically associated either with food or with human central nervous system (CNS) or maternal-neonatal (MN) listeriosis. The latter clones are also most prevalent in patients without immunosuppressive comorbidities. Strikingly, CNS- and MN-associated clones are hypervirulent in a humanized mouse model of listeriosis. By integrating epidemiological data and comparative genomics, we have uncovered multiple new putative virulence factors and demonstrate experimentally the contribution of the first gene cluster mediating L. monocytogenes neural and placental tropisms. This study illustrates the exceptional power in harnessing microbial biodiversity to identify clinically relevant microbial virulence attributes. PMID:26829754

  5. Infective endocarditis caused by Listeria monocytogenes forming a pseudotumor.

    PubMed

    Uehara Yonekawa, Akiko; Iwasaka, Sho; Nakamura, Hisataka; Fukata, Mitsuhiro; Kadowaki, Masako; Uchida, Yujiro; Odashiro, Keita; Shimoda, Shinji; Shimono, Nobuyuki; Akashi, Koichi

    2014-01-01

    A 73-year-old woman with breast cancer and metastasis under chemotherapy suffered from fever, pleural effusion and pericardial effusion. Despite the administration of treatment with cefozopran and prednisolone, the patient's fever relapsed. An electrocardiogram identified a new complete atrioventricular block and an echocardiogram revealed vegetation with an unusual pseudotumoral mass in the right atrium. Blood cultures grew Listeria monocytogenes. The patient was eventually diagnosed with right-sided infective endocarditis, which improved following the six-week administration of ampicillin and gentamicin. Homemade yoghurt was suspected to be the cause of infection in this case. Listeria endocarditis is rare; however, physicians should pay more attention to preventing this fatal disease in immunocompromised patients. PMID:24785898

  6. Mechanisms of Pathogenesis in Listeria monocytogenes Infection III. Carbohydrate Metabolism

    PubMed Central

    Wilder, Martin S.; Sword, C. P.

    1967-01-01

    Several enzymes and metabolites concerned with carbohydrate metabolism were examined in mice infected with Listeria monocytogenes. Liver glycogen and glucose decreased parallel to severity of infection. The concentration of glucose in the blood fell to abnormally low levels with a hypoglycemia being most evident at 72 hr. There was a significant decrease in the activity of hepatic uridine diphosphate glucose-glycogen transglucosylase. This decrease in enzymatic activity correlated with the rate of glycogen depletion. Phosphorylase activity declined in a similar fashion, contraindicating enhanced glycogenolysis as the mechanism responsible for glycogen depletion. Although glucose-6-phosphatase decreased throughout the infection period, it did not appear to be the major metabolic defect causing hypoglycemia in Listeria-infected mice. Further distortion of carbohydrate metabolism was indicated by findings of increased levels of pyruvate and lactate in the blood of infected animals. PMID:4289850

  7. Inhibition of Listeria monocytogenes by fatty acids and monoglycerides.

    PubMed Central

    Wang, L L; Johnson, E A

    1992-01-01

    Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl monopalmitate were not inhibitory at 200 micrograms/ml. The bactericidal activity in brain heart infusion broth was higher at pH 5 than at pH 6. In whole milk and skim milk, K-conjugated linoleic acid was bacteriostatic and prolonged the lag phase especially at 4 degrees C. Monolaurin inactivated L. monocytogenes in skim milk at 4 degrees C, but was less inhibitory at 23 degrees C. Monolaurin did not inhibit L. monocytogenes in whole milk because of the higher fat content. Other fatty acids tested were not effective in whole or skim milk. Our results suggest that K-conjugated linoleic acids or monolaurin could be used as an inhibitory agent against L. monocytogenes in dairy foods. Images PMID:1610184

  8. The Continuous Challenge of Characterizing the Foodborne Pathogen Listeria monocytogenes.

    PubMed

    Camargo, Anderson Carlos; Woodward, Joshua John; Nero, Luís Augusto

    2016-08-01

    Listeria monocytogenes is an important foodborne pathogen commonly isolated from food processing environments and food products. This organism can multiply at refrigeration temperatures, form biofilms on different materials and under various conditions, resist a range of environmental stresses, and contaminate food products by cross-contamination. L. monocytogenes is recognized as the causative agent of listeriosis, a serious disease that affects mainly individuals from high-risk groups, such as pregnant women, newborns, the elderly, and immunocompromised individuals. Listeriosis can be considered a disease that has emerged along with changing eating habits and large-scale industrial food processing. This disease causes losses of billions of dollars every year with recalls of contaminated foods and patient medical treatment expenses. In addition to the immune status of the host and the infecting dose, the virulence potential of each strain is crucial for the development of disease symptoms. While many isolates are naturally virulent, other isolates are avirulent and unable to cause disease; this may vary according to the presence of molecular determinants associated with virulence. In the last decade, the characterization of genetic profiles through the use of molecular methods has helped track and demonstrate the genetic diversity among L. monocytogenes isolates obtained from various sources. The purposes of this review were to summarize the main methods used for isolation, identification, and typing of L. monocytogenes and also describe its most relevant virulence characteristics. PMID:27120361

  9. Listeria monocytogenes in Irish Farmhouse cheese processing environments.

    PubMed

    Fox, Edward; Hunt, Karen; O'Brien, Martina; Jordan, Kieran

    2011-03-01

    Sixteen cheesemaking facilities were sampled during the production season at monthly intervals over a two-year period. Thirteen facilities were found to have samples positive for Listeria monocytogenes. Samples were divided into 4 categories; cheese, raw milk, processing environment and external to the processing environment (samples from the farm such as silage, bedding, and pooled water). In order to attempt to identify the source, persistence and putative transfer routes of contamination with the L. monocytogenes isolates, they were differentiated using PFGE and serotyping. Of the 250 isolates, there were 52 different pulsotypes. No pulsotype was found at more than one facility. Two facilities had persistent pulsotypes that were isolated on sampling occasions at least 6 months apart. Of the samples tested, 6.3% of milk, 13.1% of processing environment and 12.3% of samples external to the processing environment, respectively, were positive for L. monocytogenes. Pulsotypes found in raw milk were also found in the processing environment, however, one of the pulsotypes from raw milk was found in cheese on only one occasion. One of the pulsotypes isolated from the environment external to the processing facility was found on the surface of cheese, however, a number of them were found in the processing environment. The results suggest that the farm environment external to the processing environment may in some cases be the source of processing environment contamination with L. monocytogenes. PMID:21087802

  10. MICROBIOLOGICAL AND MOLECULAR DETECTION OF LISTERIA SPP. AND LISTERIA MONOCYTOGENES IN A CULL SOWS PROCESS PLANT IN USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria spp. and Listeria monocytogenes present in a cull sow processing plant in the USA was evaluated by a PCR multiplex method. 160 cull sows were surveyed after slaughter. Samples were collected from sub-iliac node, ileocecal node, cecal contents and carcass swabs. Additionally, samples were...

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

    PubMed

    Kovačević, Mira; Burazin, Jelena; Pavlović, Hrvoje; Kopjar, Mirela; Piližota, Vlasta

    2013-04-01

    Minimally processed and refrigerated vegetables can be contaminated with Listeria species bacteria including Listeria monocytogenes due to extensive handling during processing or by cross contamination from the processing environment. The objective of this study was to examine the microbiological quality of ready-to-eat minimally processed and refrigerated vegetables from supermarkets in Osijek, Croatia. 100 samples of ready-to-eat vegetables collected from different supermarkets in Osijek, Croatia, were analyzed for presence of Listeria species and Listeria monocytogenes. The collected samples were cut iceberg lettuces (24 samples), other leafy vegetables (11 samples), delicatessen salads (23 samples), cabbage salads (19 samples), salads from mixed (17 samples) and root vegetables (6 samples). Listeria species was found in 20 samples (20 %) and Listeria monocytogenes was detected in only 1 sample (1 %) of cut red cabbage (less than 100 CFU/g). According to Croatian and EU microbiological criteria these results are satisfactory. However, the presence of Listeria species and Listeria monocytogenes indicates poor hygiene quality. The study showed that these products are often improperly labeled, since 24 % of analyzed samples lacked information about shelf life, and 60 % of samples lacked information about storage conditions. With regard to these facts, cold chain abruption with extended use after expiration date is a probable scenario. Therefore, the microbiological risk for consumers of ready-to-eat minimally processed and refrigerated vegetables is not completely eliminated. PMID:23225207

  12. [Prevention of Listeria monocytogenes contamination on dairy farms and in the cheese industry].

    PubMed

    Stahl, V; Garcia, E; Hezard, B; Fassel, C

    1996-11-01

    Listeria monocytogenes remains a pathogen bacteria the prevention of which, in food products, stays delicate. A complete organization, from the farmer's production to the industry and the consumer is necessary to eliminate Listeria in a type of food product. Listeria monocytogenes is susceptible of contaminate raw milk. The silage may be a major source of the occurrence of Listeria monocytogenes in raw milk. In this case, the contamination sources in a dairy farm and the good hygienic practices must be well-defined. In dairy industry, the contamination must be managed by the application of a systematic and methodically system like H.A.C.C.P. (Hazard Analysis Critical Control Points). It is useful for the study of Listeria monocytogenes contamination and involve the hazard analysis of each industry plant. In fact, the raw products, food products, manufacturing process, environmental conditions, process equipment, materials and staff organizational are specific and characteristic. PMID:8977904

  13. Various Ready-to-Eat Products from Retail Stores Linked to Occurrence of Diverse Listeria monocytogenes and Listeria spp. Isolates.

    PubMed

    Vongkamjan, Kitiya; Fuangpaiboon, Janejira; Turner, Matthew P; Vuddhakul, Varaporn

    2016-02-01

    Listeriosis outbreaks have been associated with a variety of foods. This study investigated the prevalence and diversity of Listeria monocytogenes and Listeria spp. in ready-to-eat (RTE) products and evaluated the performance of a rapid detection method, the 3M molecular detection assay for L. monocytogenes (MDA-LM), for detection of L. monocytogenes. Assay results were compared with those obtained using the U.S. Food and Drug Administration standard culture method described in the Bacteriological Analytical Manual. Products (n = 200) were purchased from retail stores: 122 aquatic products, 22 products of animal origin, 18 vegetarian products, 15 deli meat products, 13 salad and vegetable products, 4 desserts, 2 egg-based products, and 4 other products. L. monocytogenes prevalence was comparable with both methods. Overall, 15 (7.5%) of 200 samples were positive for L. monocytogenes: 3% of aquatic products, 1.5% of products of animal origin, 1% of vegetarian products, and 2% of deli meat products. Compared with the standard culture method, the sensitivity, specificity, and the accuracy of the MDA-LM were 86.7% (95% confidence interval, 58.4 to 97.7%), 98.4% (95% confidence interval, 95.0 to 99.6%), and 97.5%, respectively. Using the culture-based method, 18 (9%) of 200 samples were positive for Listeria species other than L. monocytogenes. Listeria isolates from these samples were classified into nine allelic types (ATs). The majority of isolates were classified as ATs 58 and 74, which were identified as L. monocytogenes lineages I and IV, respectively. Listeria innocua and Listeria welshimeri also were represented by isolates of multiple ATs. The MDA-LM is a rapid and reliable technique for detecting L. monocytogenes in various RTE foods. Further study is needed to develop effective control strategies to reduce L. monocytogenes contamination in RTE foods. PMID:26818984

  14. Fate of Listeria monocytogenes in experimentally contaminated French sausages.

    PubMed

    Thévenot, D; Delignette-Muller, M L; Christieans, S; Vernozy-Rozand, C

    2005-05-25

    Listeria monocytogenes has been recognized as one of the most important foodborne pathogens dealt with by the food. The bacterium has been found in every part along the pork processing industry from the slaughterhouse to the cutting room and the delicatessen factories. During the fermentation and drying of sausages, L. monocytogenes tends to decrease substantially. However, despite the various hurdles in the dry sausage manufacturing process, L. monocytogenes is able to survive and is detected in the final products. The present study has evaluated growth and survival of eight different L. monocytogenes strains (originating from sausage, sausage industry environment and from clinical cases of listeriosis) in experimentally inoculated French sausages with 10(4) cfu g(-1). This study points out the fact that the decrease of L. monocytogenes contamination rate during the manufacturing process of sausages is strain dependent (p < 0.001) and mainly due to the drying and maturation step than to the fermentation itself. Whatever the strains studied, almost no decrease of the contamination rate was noted during the fermentation step. However hurdle-adapted strains (those isolated from sausages or sausage industry environment) were more difficult to cure from sausages (decrease by 1.5 log10) than non-adapted strains (decrease by 3 log10) at the end of the drying period (day 35), when sausages were ready for consumption. These sausages became safe only at the best before date. As a consequence, L. monocytogenes and more particularly those "adapted" strains might represent a very important issue for hygienists since these strains originating from sausages or production environment themselves are likely to contaminate sausages during manufacturing and remain in the final products. However, the high inoculum levels used in the study (10(4) cfu g(-1)) are not representative of the natural contamination of L. monocytogenes commonly encountered in the raw material for sausages. If

  15. Comparison of the Prevalences and Diversities of Listeria Species and Listeria monocytogenes in an Urban and a Rural Agricultural Watershed.

    PubMed

    Stea, Emma C; Purdue, Laura M; Jamieson, Rob C; Yost, Chris K; Truelstrup Hansen, Lisbeth

    2015-06-01

    Foods and related processing environments are commonly contaminated with the pathogenic Listeria monocytogenes. To investigate potential environmental reservoirs of Listeria spp. and L. monocytogenes, surface water and point source pollution samples from an urban and a rural municipal water supply watershed in Nova Scotia, Canada, were examined over 18 months. Presumptive Listeria spp. were cultured from 72 and 35% of rural and urban water samples, respectively, with 24% of the positive samples containing two or three different Listeria spp. The L. innocua (56%) and L. welshimeri (43%) groups were predominant in the rural and urban watersheds, respectively. Analysis by the TaqMan assay showed a significantly (P < 0.05) higher prevalence of L. monocytogenes of 62% versus 17% by the culture-based method. Both methods revealed higher prevalences in the rural watershed and during the fall and winter seasons. Elevated Escherichia coli (≥ 100 CFU/100 ml) levels were not associated with the pathogen regardless of the detection method. Isolation of Listeria spp. were associated with 70 times higher odds of isolating L. monocytogenes (odds ratio = 70; P < 0.001). Serogroup IIa was predominant (67.7%) among the 285 L. monocytogenes isolates, followed by IVb (16.1%), IIb (15.8%), and IIc (0.4%). L. monocytogenes was detected in cow feces and raw sewage but not in septic tank samples. Pulsotyping of representative water (n = 54) and local human (n = 19) isolates suggested genetic similarities among some environmental and human L. monocytogenes isolates. In conclusion, temperate surface waters contain a diverse Listeria species population and could be a potential reservoir for L. monocytogenes, especially in rural agricultural watersheds. PMID:25819965

  16. Comparison of the Prevalences and Diversities of Listeria Species and Listeria monocytogenes in an Urban and a Rural Agricultural Watershed

    PubMed Central

    Stea, Emma C.; Purdue, Laura M.; Jamieson, Rob C.; Yost, Chris K.

    2015-01-01

    Foods and related processing environments are commonly contaminated with the pathogenic Listeria monocytogenes. To investigate potential environmental reservoirs of Listeria spp. and L. monocytogenes, surface water and point source pollution samples from an urban and a rural municipal water supply watershed in Nova Scotia, Canada, were examined over 18 months. Presumptive Listeria spp. were cultured from 72 and 35% of rural and urban water samples, respectively, with 24% of the positive samples containing two or three different Listeria spp. The L. innocua (56%) and L. welshimeri (43%) groups were predominant in the rural and urban watersheds, respectively. Analysis by the TaqMan assay showed a significantly (P < 0.05) higher prevalence of L. monocytogenes of 62% versus 17% by the culture-based method. Both methods revealed higher prevalences in the rural watershed and during the fall and winter seasons. Elevated Escherichia coli (≥100 CFU/100 ml) levels were not associated with the pathogen regardless of the detection method. Isolation of Listeria spp. were associated with 70 times higher odds of isolating L. monocytogenes (odds ratio = 70; P < 0.001). Serogroup IIa was predominant (67.7%) among the 285 L. monocytogenes isolates, followed by IVb (16.1%), IIb (15.8%), and IIc (0.4%). L. monocytogenes was detected in cow feces and raw sewage but not in septic tank samples. Pulsotyping of representative water (n = 54) and local human (n = 19) isolates suggested genetic similarities among some environmental and human L. monocytogenes isolates. In conclusion, temperate surface waters contain a diverse Listeria species population and could be a potential reservoir for L. monocytogenes, especially in rural agricultural watersheds. PMID:25819965

  17. Biofilm Formation among Clinical and Food Isolates of Listeria monocytogenes

    PubMed Central

    Barbosa, Joana; Borges, Sandra; Camilo, Ruth; Magalhães, Rui; Ferreira, Vânia; Santos, Isabel; Silva, Joana; Almeida, Gonçalo; Teixeira, Paula

    2013-01-01

    Objective. A total of 725 Listeria monocytogenes isolates, 607 from various foods and 118 from clinical cases of listeriosis, were investigated concerning their ability to form biofilms, at 4°C during 5 days and at 37°C during 24 h. Methods. Biofilm production was carried out on polystyrene tissue culture plates. Five L. monocytogenes isolates were tested for biofilm formation after being exposed to acidic and osmotic stress conditions. Results. Significant differences (P < 0.01) between clinical and food isolates were observed. At 37°C for 24 h, most food isolates were classified as weak or moderate biofilm formers whereas all the clinical isolates were biofilm producers, although the majority were weak. At 4°C during 5 days, 65 and 59% isolates, from food and clinical cases, respectively, were classified as weak. After both sublethal stresses, at 37°C just one of the five isolates tested was shown to be more sensitive to subsequent acidic exposure. However, at 4°C both stresses did not confer either sensitivity or resistance. Conclusions. Significant differences between isolates origin, temperature, and sublethal acidic stress were observed concerning the ability to form biofilms. Strain, origin, and environmental conditions can determine the level of biofilm production by L. monocytogenes isolates. PMID:24489549

  18. Toward a Systemic Understanding of Listeria monocytogenes Metabolism during Infection

    PubMed Central

    Fuchs, Thilo M.; Eisenreich, Wolfgang; Kern, Tanja; Dandekar, Thomas

    2011-01-01

    Listeria monocytogenes is a foodborne human pathogen that can cause invasive infection in susceptible animals and humans. For proliferation within hosts, this facultative intracellular pathogen uses a reservoir of specific metabolic pathways, transporter, and enzymatic functions whose expression requires the coordinated activity of a complex regulatory network. The highly adapted metabolism of L. monocytogenes strongly depends on the nutrient composition of various milieus encountered during infection. Transcriptomic and proteomic studies revealed the spatial–temporal dynamic of gene expression of this pathogen during replication within cultured cells or in vivo. Metabolic clues are the utilization of unusual C2- and C3-bodies, the metabolism of pyruvate, thiamine availability, the uptake of peptides, the acquisition or biosynthesis of certain amino acids, and the degradation of glucose-phosphate via the pentose phosphate pathway. These examples illustrate the interference of in vivo conditions with energy, carbon, and nitrogen metabolism, thus affecting listerial growth. The exploitation, analysis, and modeling of the available data sets served as a first attempt to a systemic understanding of listerial metabolism during infection. L. monocytogenes might serve as a model organism for systems biology of a Gram-positive, facultative intracellular bacterium. PMID:22347216

  19. Dual roles of plcA in Listeria monocytogenes pathogenesis

    PubMed Central

    Camilli, Andrew; Tilney, Lewis G.; Portnoy, Daniel A.

    2016-01-01

    Summary The plcA gene of Listeria monocytogenes encodes a secreted phosphatidylinositol-specific phospholipase C (PI-PLC). Recent studies have established that transposon mutations within plcA result in avirulence for mice and pleiotropic effects when examined in tissue-culture models of infection. Genetic analysis reveals that many of the effects of the transposon insertions are due to loss of readthrough transcription from plcA into the downstream gene prfA, which encodes an essential transcription factor of numerous L. monocytogenes virulence genes. Construction of an in-frame deletion within plcA had no effect on expression of prfA thus allowing direct assignment of a role of the PI-PLC in pathogenesis. PI-PLC was shown to play a significant role in mediating escape of L. monocytogenes from phagosomes of primary murine macrophages. Interestingly, this defect manifested itself in vivo in the liver but not in the spleen of infected mice. PMID:8388529

  20. The contribution of transcriptomic and proteomic analysis in elucidating stress adaptation responses of Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The foodborne transmission of Listeria monocytogenes requires physiological adaptation to various conditions, including the cold, osmotic, heat, acid, alkaline, and oxidative stresses, associated with food hygiene, processing, and preservation measures. We review the current knowledge on the molecul...

  1. Comparative antimicrobial susceptibility of Listeria monocytogenes, L. innocua, and L. welshimeri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current study compared antimicrobial susceptibility of Listeria innocua, L. welshimeri and L. monocytogenes isolated from various sources. Antimicrobial susceptibility testing was performed using a microbroth procedure with Sensititre® minimum inhibitory concentration (MIC) plates containing 18...

  2. Ecology of Listeria spp. in a fish farm and molecular typing of Listeria monocytogenes from fish farming and processing companies.

    PubMed

    Miettinen, Hanna; Wirtanen, Gun

    2006-11-01

    This study focused on the ecology of Listeria monocytogenes in a fish farm by following the changes in its occurrence in different types of samples for a three year period. In addition, L. monocytogenes isolates from different seafood industry areas were compared with pulsed field gel electrophoresis (PFGE) typing to discover possible associations between primary production, further processing and final products. Weather conditions were found to have a strong influence on the probability of finding Listeria spp. in a fish farm environment. The number of samples contaminated with Listeria spp. was typically bigger after rainy periods. Brook and river waters as well as other runoff waters seemed to be the main contamination source at the farm studied. The farmed fish originally found to carry L. monocytogenes become gradually Listeria free. The time needed for the purification of the fish was several months. The sea bottom soil samples were the ones that preserved the L. monocytogenes contamination the longest time. It can be stated that the fish and fish farm equipment studied did not spread listeria contamination. On the contrary, they were found to suffer from listeria contamination coming from outside sources like the brook water. There was a wide range of different L. monocytogenes PFGE-pulsotypes (30) found at 15 Finnish fish farms and fish processing factories. L. monocytogenes isolates from the final products often belonged to the same pulsotypes as did the isolates from the processing environment as well as from the raw fish. This suggests that, in addition to the fish processing factory environment, the fish raw materials are important sources of L. monocytogenes contamination in final products. PMID:16842875

  3. Distribution of the bacteria Listeria monocytogenes in the western part of the Sea of Okhotsk

    NASA Astrophysics Data System (ADS)

    Terekhova, V. E.; Sosnin, V. A.; Buzoleva, L. S.; Shakirov, R. B.

    2010-04-01

    The Amur River’s influence on the distribution of the opportunistic bacteria Listeria monocytogenes in the western part of the Sea of Okhotsk is discussed. The presence of Listeria in the seawater, sea ice, and sediments on the northeastern Sakhalin shelf and slope supports the idea of its connection with the Amur River discharge. The hypothesis of the allochtonic parentage of L. monocytogenes in the sea’s development is proved.

  4. Variation in Biofilm Formation among Strains of Listeria monocytogenes

    PubMed Central

    Borucki, Monica K.; Peppin, Jason D.; White, David; Loge, Frank; Call, Douglas R.

    2003-01-01

    Contamination of food by Listeria monocytogenes is thought to occur most frequently in food-processing environments where cells persist due to their ability to attach to stainless steel and other surfaces. Once attached these cells may produce multicellular biofilms that are resistant to disinfection and from which cells can become detached and contaminate food products. Because there is a correlation between virulence and serotype (and thus phylogenetic division) of L. monocytogenes, it is important to determine if there is a link between biofilm formation and disease incidence for L. monocytogenes. Eighty L. monocytogenes isolates were screened for biofilm formation to determine if there is a robust relationship between biofilm formation, phylogenic division, and persistence in the environment. Statistically significant differences were detected between phylogenetic divisions. Increased biofilm formation was observed in Division II strains (serotypes 1/2a and 1/2c), which are not normally associated with food-borne outbreaks. Differences in biofilm formation were also detected between persistent and nonpersistent strains isolated from bulk milk samples, with persistent strains showing increased biofilm formation relative to nonpersistent strains. There were no significant differences detected among serotypes. Exopolysaccharide production correlated with cell adherence for high-biofilm-producing strains. Scanning electron microscopy showed that a high-biofilm-forming strain produced a dense, three-dimensional structure, whereas a low-biofilm-forming strain produced a thin, patchy biofilm. These data are consistent with data on persistent strains forming biofilms but do not support a consistent relationship between enhanced biofilm formation and disease incidence. PMID:14660383

  5. Mechanistic studies of the agmatine deiminase from Listeria monocytogenes.

    PubMed

    Soares, Charles A; Knuckley, Bryan

    2016-06-01

    Listeria monocytogenes is a Gram-positive food-borne pathogen that is capable of living within extreme environments (i.e. low temperatures and pH). This ability to survive in such conditions may arise, at least in part, from agmatine catabolism via the agmatine deiminase system (AgDS). This catabolic pathway utilizes an agmatine deiminase (AgD) to hydrolyse agmatine into N-carbamoylputrescine (NCP), with concomitant release of ammonia, which increases the pH, thus mitigating the ill effects of the acidic environment. Given the potential significance of this pathway for cell survival, we set out to study the catalytic mechanism of the AgD encoded by L. monocytogenes In the present paper, we describe the catalytic mechanism employed by this enzyme based on pH profiles, pKa measurements of the active site cysteine and solvent isotope effects (SIE). In addition, we report inhibition of this enzyme by two novel AgD inhibitors, i.e. N-(4-aminobutyl)-2-fluoro-ethanimidamide (ABFA) and N-(4-aminobutyl)-2-chloro-ethanimidamide (ABCA). In contrast with other orthologues, L. monocytogenes AgD does not use the reverse protonation or substrate-assisted mechanism, which requires an active site cysteine with a high pKa and has been commonly seen in other members of the guanidinium-modifying enzyme (GME) superfamily. Instead, the L. monocytogenes AgD has a low pKa cysteine in the active site leading to an alternative mechanism of catalysis. This is the first time that this mechanism has been observed in the GME superfamily and is significant because it explains why previously developed mechanism-based inactivators of AgDs are ineffective against this orthologue. PMID:27034081

  6. How Listeria monocytogenes organizes its surface for virulence

    PubMed Central

    Carvalho, Filipe; Sousa, Sandra; Cabanes, Didier

    2014-01-01

    Listeria monocytogenes is a Gram-positive pathogen responsible for the manifestation of human listeriosis, an opportunistic foodborne disease with an associated high mortality rate. The key to the pathogenesis of listeriosis is the capacity of this bacterium to trigger its internalization by non-phagocytic cells and to survive and even replicate within phagocytes. The arsenal of virulence proteins deployed by L. monocytogenes to successfully promote the invasion and infection of host cells has been progressively unveiled over the past decades. A large majority of them is located at the cell envelope, which provides an interface for the establishment of close interactions between these bacterial factors and their host targets. Along the multistep pathways carrying these virulence proteins from the inner side of the cytoplasmic membrane to their cell envelope destination, a multiplicity of auxiliary proteins must act on the immature polypeptides to ensure that they not only maturate into fully functional effectors but also are placed or guided to their correct position in the bacterial surface. As the major scaffold for surface proteins, the cell wall and its metabolism are critical elements in listerial virulence. Conversely, the crucial physical support and protection provided by this structure make it an ideal target for the host immune system. Therefore, mechanisms involving fine modifications of cell envelope components are activated by L. monocytogenes to render it less recognizable by the innate immunity sensors or more resistant to the activity of antimicrobial effectors. This review provides a state-of-the-art compilation of the mechanisms used by L. monocytogenes to organize its surface for virulence, with special focus on those proteins that work “behind the frontline”, either supporting virulence effectors or ensuring the survival of the bacterium within its host. PMID:24809022

  7. Mechanistic studies of the agmatine deiminase from Listeria monocytogenes

    PubMed Central

    Soares, Charles A.; Knuckley, Bryan

    2016-01-01

    Listeria monocytogenes is a Gram-positive food-borne pathogen that is capable of living within extreme environments (i.e. low temperatures and pH). This ability to survive in such conditions may arise, at least in part, from agmatine catabolism via the agmatine deiminase system (AgDS). This catabolic pathway utilizes an agmatine deiminase (AgD) to hydrolyse agmatine into N-carbamoylputrescine (NCP), with concomitant release of ammonia, which increases the pH, thus mitigating the ill effects of the acidic environment. Given the potential significance of this pathway for cell survival, we set out to study the catalytic mechanism of the AgD encoded by L. monocytogenes. In the present paper, we describe the catalytic mechanism employed by this enzyme based on pH profiles, pKa measurements of the active site cysteine and solvent isotope effects (SIE). In addition, we report inhibition of this enzyme by two novel AgD inhibitors, i.e. N-(4-aminobutyl)-2-fluoro-ethanimidamide (ABFA) and N-(4-aminobutyl)-2-chloro-ethanimidamide (ABCA). In contrast with other orthologues, L. monocytogenes AgD does not use the reverse protonation or substrate-assisted mechanism, which requires an active site cysteine with a high pKa and has been commonly seen in other members of the guanidinium-modifying enzyme (GME) superfamily. Instead, the L. monocytogenes AgD has a low pKa cysteine in the active site leading to an alternative mechanism of catalysis. This is the first time that this mechanism has been observed in the GME superfamily and is significant because it explains why previously developed mechanism-based inactivators of AgDs are ineffective against this orthologue. PMID:27034081

  8. Modelling transfer of Listeria monocytogenes during slicing of 'gravad' salmon.

    PubMed

    Aarnisalo, Kaarina; Sheen, Shiowshuh; Raaska, Laura; Tamplin, Mark

    2007-08-15

    Transfer of a rifampicin-resistant mutant of Listeria monocytogenes from an inoculated slicing blade to slices of 'gravad' salmon (Salmo salar), and from inoculated salmon fillet to the slicing machine and subsequently to slices of uninoculated fillet was studied. The effect of slicing temperature (0 degrees C, 10 degrees C and room temperature), inoculum level (approx. 3, 5 and 8 log CFU/blade), and attachment time of inoculum to blade (10 min and 2.5 h) were investigated and predictive models of the transfer were produced. In the tests of transfer from inoculated blade (5.9-9.0 log CFU/blade) initially 2.5-5.3 log CFU/g was present on the slices, slowly decreasing to an overall average decrease of 1.6+/-0.2 log CFU/g during slicing of 39 slices; the lowest reduction being 1.3 log CFU/g at 0 degrees C. In tests of transfer from contaminated salmon (7.6+/-0.1 log CFU/fillet) to uninoculated blade and further to uninoculated salmon, the reduction in number of L. monocytogenes in slices was 1.5 log CFU/g during slicing of 39 slices. For example 5.3+/-0.3 log CFU/g was transferred to second slice when the inoculum level was 8.4+/-0.4 log CFU/blade, but clearly (p<0.05) lower total number of L. monocytogenes were transferred to slices when the inoculum level was lower, the temperature was colder or the attachment time was longer. There was a progressive exponential reduction in the quantity of L. monocytogenes transferred and, based on statistical parameters, an exponential model (y=ae((-x/b))) fit the data from different test conditions and was suitable for predicting an expected number of L. monocytogenes on the salmon slices. Based on the predicted values, the logarithmic reduction in number of L. monocytogenes in slices was highest at room temperature with an inoculum level of 8.4+/-0.4 log CFU/blade (attachment time 10 min); the other test conditions differed significantly from this (p<0.05). Despite statistically significant differences, in all test conditions

  9. Determination of antibiotic resistance pattern and bacteriocin sensitivity of Listeria monocytogenes strains isolated from different foods in turkey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to determine the antibiotic resistance pattern and bacteriocin sensitivity of Listeria monocytogenes strains isolated from animal derived foods. With disc diffusion assay, all fourteen L. monocytogenes strains were susceptible to the antibiotics, including penicillin G, vancomycin, ...

  10. Health professionals' knowledge and understanding about Listeria monocytogenes indicates a need for improved professional training.

    PubMed

    Buffer, Janet L; Medeiros, Lydia C; Kendall, Patricia; Schroeder, Mary; Sofos, John

    2012-07-01

    Listeria monocytogenes causes listeriosis, an uncommon but potentially fatal disease in immunocompromised persons, with a public health burden of approximately $2 billion annually. Those consumers most at risk are the highly susceptible populations otherwise known as the immunocompromised. Health professionals have a considerable amount of interaction with the immunocompromised and are therefore a valuable resource for providing appropriate safe food handling information. To determine how knowledgeable health professionals are about Listeria monocytogenes, a nationwide Web-based survey was distributed targeting registered nurses (RNs) and registered dietitians (RDs) who work with highly susceptible populations. Responses were received from 499 health professionals. Knowledge and understanding of Listeria monocytogenes was assessed descriptively. Parametric and nonparametric analyses were used to detect differences between RNs and RDs. The major finding is that there are gaps in knowledge and a self-declared lack of understanding by both groups, but especially RNs, about Listeria monocytogenes. RDs were more likely than RNs to provide information about specific foods and food storage behaviors to prevent a Listeria infection. Notably, neither group of health professionals consistently provided Listeria prevention messages to their immunocompromised patients. Pathogens will continue to emerge as food production, climate, water, and waste management systems change. Health professionals, represented by RNs and RDs, need resources and training to ensure that they are providing the most progressive information about various harmful pathogens; in this instance, Listeria monocytogenes. PMID:22980015

  11. Listeria monocytogenes Meningitis in an Immunosuppressed Patient with Autoimmune Hepatitis and IgG4 Subclass Deficiency

    PubMed Central

    Gaini, Shahin

    2015-01-01

    A 51-year-old Caucasian woman with Listeria monocytogenes meningitis was treated and discharged after an uncomplicated course. Her medical history included immunosuppressive treatment with prednisolone and azathioprine for autoimmune hepatitis. A diagnostic work-up after the meningitis episode revealed that she had low levels of the IgG4 subclass. To our knowledge, this is the first case report describing a possible association between autoimmune hepatitis and the occurrence of Listeria monocytogenes meningitis, describing a possible association between Listeria monocytogenes meningitis and deficiency of the IgG4 subclass and finally describing a possible association between Listeria monocytogenes meningitis and immunosuppressive therapy with prednisolone and azathioprine. PMID:26558118

  12. Occurrence and characterization of Listeria monocytogenes isolated from food markets in Culiacan, Sinaloa, Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a food borne pathogen associated with severe disease in humans. We determined the prevalence, levels, antimicrobial susceptibility, and pulsotypes of L. monocytogenes in foodstuffs of common sale in three retail markets of Culiacan, Sinaloa, Mexico. The pathogen was isolate...

  13. Gene expression profiling of Listeria monocytogenes strain F2365 in UHT pasteurized skim milk

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Listeria monocytogenes is a food-borne pathogen of significant threat to public health. L. monocytogenes has the ability to grow or survive at refrigeration temperatures and under conditions of relatively low pH, high salt and low water activity in foods. However, the factors contri...

  14. Stability of sublethal acid stress adaptaion and induced cross protection against lauric arginate in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The stability of acid stress adaptation in Listeria monocytogenes and its induced cross protection effect against GRAS (generally recognized as safe) antimicrobial compounds has never been investigated before. In the present study, the acid stress adaptation in L. monocytogenes was initially induced...

  15. Influence of temperature on acid-stress adaptation in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several factors play critical roles in controlling the induction of acid-stress adaptation in L. monocytogenes. Our findings show that temperature plays a significant role in the induction of acid-stress adaptation in Listeria monocytogenes and two distinct patterns were observed: (I) Presence of su...

  16. Antimicrobial resistance of Listeria monocytogenes isolated from a poultry further processing plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to compare antimicrobial resistance profiles of distinct types of Listeria monocytogenes isolated from a commercial poultry cooking plant. One hundred fifty seven L. monocytogenes isolates representing 14 different ActA types were tested for susceptibility to 19 ant...

  17. A dynamical systems approach to actin-based motility in Listeria monocytogenes

    NASA Astrophysics Data System (ADS)

    Hotton, S.

    2010-11-01

    A simple kinematic model for the trajectories of Listeria monocytogenes is generalized to a dynamical system rich enough to exhibit the resonant Hopf bifurcation structure of excitable media and simple enough to be studied geometrically. It is shown how L. monocytogenes trajectories and meandering spiral waves are organized by the same type of attracting set.

  18. Isolation and characterization of an atypical Listeria monocytogenes associated with a canine urinary tract infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes, a well described neurologic, gastrointestinal, and potential abortion-causing agent in humans, is rarely associated with disease in companion animals. A case of urinary tract infection associated with an atypical, weakly hemolytic L. monocytogenes strain is described here in ...

  19. Isolation and characterization of an atypical Listeria monocytogenes associated with a canine urinary tract infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes, a well-described cause of encephalitis and abortion in ruminants and of food-borne illness in humans, is rarely associated with disease in companion animals. A case of urinary tract infection associated with an atypical, weakly hemolytic L. monocytogenes strain is described i...

  20. A novel suicide plasmid for efficient gene mutation in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although several plasmids have been used in Listeria monocytogenes for generating mutants by allelic exchange, construction of L. monocytogenes mutants has been inefficient due to lack of effective selection markers for first and second recombination events. To address this problem, we have develope...

  1. Effect of a native microflora on the growth of Listeria monocytogenes in cooked ham

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Refrigerated ready-to-eat meat products contaminated with Listeria monocytogenes have been linked to outbreaks of foodborne illnesses. L. monocytogenes contamination was mainly caused by improper processing and/or cross-contamination. This study examined the growth characteristics of L. monocytoge...

  2. Modeling Transfer of Listeria monocytogenes on Deli Meat During Mechanical Slicing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes has been implicated in several listeriosis outbreaks linked to the consumption of pre-sliced ready-to-eat (RTE) deli meats. The possible contamination of sliced RTE meats by L. monocytogenes during the slicing process has become a public health concern. The objectives of thi...

  3. INHIBITION OF LISTERIA MONOCYTOGENES BY BOVICIN HC5, A BACTERIOCIN PRODUCED BY STREPTOCOCCUS BOVIS HC5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A bacteriocin from Streptococcus bovis HC5 (bovicin HC5) inhibited ten strains of Listeria monocytogenes that had been isolated from plant materials, soil, contaminated silage and infected cattle. Growth experiments indicated that all of the L. monocytogenes strains were inhibited by 100 AU of bovic...

  4. Proteomic expression profiles of virulent and avirulent strains of Listeria monocytogenes isolated from macrophages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is able to survive and proliferate within macrophages. In the current study, the ability of three L. monocytogenes strains (serovar 1/2a strain EGDe, serovar 4b strain F2365, and serovar 4a strain HCC23) to proliferate in the murine macrophage cell line J774.1 was analyzed. We...

  5. Effect of storage at 4 and 10 C on growth of listeria monocytogenes in Queso Fresco

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A five-strain rifampicin - resistant Listeria monocytogenes cocktail (ca. 3.0 loglOCFU/g) was introduced as a post-pasteurization contaminant in Queso Fresco (QF) that was manufactured using a commercial make procedure. L. monocytogenes was either inoculated into (IN) the curds before slicing or on...

  6. Effect of storage at 4 and 10 C on growth of Listeria monocytogenes in Queso Fresco

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A five-strain rifampicin – resistant Listeria monocytogenes cocktail (ca. 3.0 log10CFU/g) was introduced as a post-pasteurization contaminant in Queso Fresco (QF) that was manufactured using a commercial make procedure. L. monocytogenes was either inoculated into (IN) the curds before slicing or on...

  7. Occurrence and antimicrobial susceptibility of Listeria monocytogenes isolated from brined white cheese in Jordan.

    PubMed

    Osaili, Tareq M; Al-Nabulsi, Anas A; Taha, Mohammad H; Al-Holy, Murad A; Alaboudi, Akram R; Al-Rousan, Walid M; Shaker, Reyad R

    2012-09-01

    Listeria monocytogenes is a serious foodborne pathogen that has been isolated from different dairy food products. Several foodborne outbreaks of listeriosis have been associated with consumption of cheese. The aims of this study were to determine the occurrence of L. monocytogenes and Listeria spp. in brined white cheese (BWC) sold in Jordan, and to determine the susceptibility of isolated L. monocytogenes to antimicrobials. Three hundred and fifty samples of 5 different types of BWC (akkawi, boiled, halloumi, pasteurized, and shellal) were collected from a local market in Jordan. The ISO (11290-1) procedure was followed for isolation and identification of Listeria spp. from cheese samples and a polymerase chain reaction (PCR) technique was used for confirmation of L. monocytogenes isolates. The VITEK2 automated system was used for testing antimicrobial susceptibility of L. monocytogenes isolates. The overall prevalence of Listeria spp. in cheese sample was 27.1%. L. monocytogenes was isolated from 39 (11.1%) samples. Other isolated species were L. grayi (6.9%), L. innocua (2%), L. ivanovii (4%), L. seeligeri (2%), and L. welshimeri (0.3%). The pH values and salt concentrations of L. monocytogenes positive cheese samples ranged from 5.10 to 6.32 and 5.64 to 13.16, respectively. L. monocytogenes isolates were sensitive or intermediate susceptible to imipenem, gentamicin, linezolid, teicoplanin, vancomycin, fusidic acid, trimethoprim/sulfamethoxazole, benzylpenicillin, ciprofloxacin, erythromycin, tetracycline, and rifampicin, but resistant to fosfomycin, oxacillin, and clindamycin. PMID:22897495

  8. Listeria monocytogenes DNA glycosylase AdiP affects flagellar motility, biofilm formation, virulence, and stress responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The temperature-dependent alteration of flagellar motility gene expression is critical for the foodborne pathogen Listeria monocytogenes to respond to a changing environment. In this study, a genetic determinant, L. monocytogenes f2365_0220 (lmof2365_0220), encoding a putative protein that is struct...

  9. Listeria monocytogenes from slaughter plant to fully cooked product – sources, sites and potential for intervention

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a human pathogen that has been associated with fully cooked poultry products. This organism is not highly prevalent on live broilers; prevalence tends to increase as carcasses proceed through an initial processing plant. In one study we found no L. monocytogenes on pre-sc...

  10. Potentiometric aptasensing of Listeria monocytogenes using protamine as an indicator.

    PubMed

    Ding, Jiawang; Lei, Jiahong; Ma, Xia; Gong, Jun; Qin, Wei

    2014-10-01

    Exposure to pathogens in recreational or drinking water is a serious public health concern. It is important to rapidly determine and identify trace levels of pathogens in real environmental samples. We report here on a label-free potentiometric aptasensor for rapid, sensitive, and selective detection of Listeria monocytogenes (LM), a pathogen widely distributed in the environment. An aptamer binds specifically to internalin A, a surface protein present in LM cells. The target-binding event prevents the aptamer from electrostatically interacting with protamine, which can be sensitively detected using a polycation-sensitive membrane electrode. Using this method, LM can be detected down to 10 CFU mL(-1). Coupled to an online filtration system, the bioassay has been evaluated with spiked coastal seawater samples and shows good recovery and high accuracy. This work demonstrates the possibility of developing potentiometric aptasensors for determination and identification of various bacteria in environmental samples. PMID:25220163

  11. A Complex Lipoate Utilization Pathway in Listeria monocytogenes*

    PubMed Central

    Christensen, Quin H.; Hagar, Jon A.; O'Riordan, Mary X. D.; Cronan, John E.

    2011-01-01

    Although a complete pathway of lipoic acid metabolism has been established in Escherichia coli, lipoic acid metabolism in other bacteria is more complex and incompletely understood. Listeria monocytogenes has been shown to utilize two lipoate-protein ligases for lipoic acid scavenging, whereas only one of the ligases can function in utilization of host-derived lipoic acid-modified peptides. We report that lipoic acid scavenging requires not only ligation of lipoic acid but also a lipoyl relay pathway in which an amidotransferase transfers lipoyl groups to the enzyme complexes that require the cofactor for activity. In addition, we provide evidence for a new lipoamidase activity that could allow utilization of lipoyl peptides by lipoate-protein ligase. These data support a model of an expanded, three-enzyme pathway for lipoic acid scavenging that seems widespread in the Firmicutes phylum of bacteria. PMID:21768091

  12. Phenotypic and Genotypic Characterization of Atypical Listeria monocytogenes and Listeria innocua Isolated from Swine Slaughterhouses and Meat Markets

    PubMed Central

    Moreno, Luisa Zanolli; Paixão, Renata; Sena de Gobbi, Debora Dirani; Raimundo, Daniele Cristine; Porfida Ferreira, Thais Sebastiana; Micke Moreno, Andrea; Hofer, Ernesto; dos Reis, Cristhiane Moura Falavina; Matté, Glavur Rogério; Matté, Maria Helena

    2014-01-01

    In the last decade, atypical Listeria monocytogenes and L. innocua strains have been detected in food and the environment. Because of mutations in the major virulence genes, these strains have different virulence intensities in eukaryotic cells. In this study, we performed phenotypic and genotypic characterization of atypical L. monocytogenes and L. innocua isolates obtained from swine slaughterhouses and meat markets. Forty strains were studied, including isolates of L. monocytogenes and L. innocua with low-hemolytic activity. The isolates were characterized using conventional phenotypic Listeria identification tests and by the detection and analysis of L. monocytogenes-specific genes. Analysis of 16S rRNA was used for the molecular identification of the Listeria species. The L. monocytogenes isolates were positive for all of the virulence genes studied. The atypical L. innocua strains were positive for hly, plcA, and inlC. Mutations in the InlC, InlB, InlA, PI-PLC, PC-PLC, and PrfA proteins were detected in the atypical isolates. Further in vitro and transcriptomic studies are being developed to confirm the role of these mutations in Listeria virulence. PMID:24987702

  13. Bacteriophage predation promotes serovar diversification in Listeria monocytogenes.

    PubMed

    Eugster, Marcel R; Morax, Laurent S; Hüls, Vanessa J; Huwiler, Simona G; Leclercq, Alexandre; Lecuit, Marc; Loessner, Martin J

    2015-07-01

    Listeria monocytogenes is a bacterial pathogen classified into distinct serovars (SVs) based on somatic and flagellar antigens. To correlate phenotype with genetic variation, we analyzed the wall teichoic acid (WTA) glycosylation genes of SV 1/2, 3 and 7 strains, which differ in decoration of the ribitol-phosphate backbone with N-acetylglucosamine (GlcNAc) and/or rhamnose. Inactivation of lmo1080 or the dTDP-l-rhamnose biosynthesis genes rmlACBD (lmo1081-1084) resulted in loss of rhamnose, whereas disruption of lmo1079 led to GlcNAc deficiency. We found that all SV 3 and 7 strains actually originate from a SV 1/2 background, as a result of small mutations in WTA rhamnosylation and/or GlcNAcylation genes. Genetic complementation of different SV 3 and 7 isolates using intact alleles fully restored a characteristic SV 1/2 WTA carbohydrate pattern, including antisera reactions and phage adsorption. Intriguingly, phage-resistant L. monocytogenes EGDe (SV 1/2a) isolates featured the same glycosylation gene mutations and were serotyped as SV 3 or 7 respectively. Again, genetic complementation restored both carbohydrate antigens and phage susceptibility. Taken together, our data demonstrate that L. monocytogenes SV 3 and 7 originate from point mutations in glycosylation genes, and we show that phage predation represents a major driving force for serovar diversification and evolution of L. monocytogenes. PMID:25825127

  14. Development of a Novel Selective and Differential Medium for the Isolation of Listeria monocytogenes

    PubMed Central

    Park, Sang-Hyun; Chang, Pahn-Shick; Ryu, Sangryeol

    2014-01-01

    A new medium (lecithin and levofloxacin [LL] medium) is described for the isolation of Listeria monocytogenes from food samples. LL medium includes lecithin from soybeans for the detection of phosphatidylinositol-specific phospholipase C (PI-PLC) and phosphatidylcholine-specific phospholipase C (PC-PLC) produced by L. monocytogenes. Levofloxacin is incorporated to inhibit the growth of microorganisms other than L. monocytogenes, especially Bacillus cereus, shown to possess PI-PLC and PC-PLC activities. L. monocyogenes produced white colonies with a halo on LL medium, whereas Listeria innocua appeared as white colonies without a halo. Levofloxacin at 0.20 mg/liter completely inhibited the growth of B. cereus, while the growth of L. monocytogenes was unaffected. In the second phase of the study, the sensitivity and the specificity of LL medium were compared to those of modified Oxford agar (MOX) and two chromogenic media (Brilliance Listeria agar and CHROMagar Listeria), using a total of 250 food samples. From 200 unspiked food samples, the specificity of LL medium (96.0%) was superior to that of MOX (72.0%) and similar to the specificities of Brilliance Listeria agar (96.5%) and CHROMagar Listeria (94.5%). From 50 spiked food samples, LL medium and CHROMagar Listeria represented the highest sensitivities (96.0%), followed by Brilliance Listeria agar (92.0%) and MOX (54.0%). Also, LL medium showed the highest confirmation rate (98.8%), followed by Brilliance Listeria agar (98.7%), CHROMagar Listeria (98.3%), and MOX (52.0%). On the basis of its good specificity and cost effectiveness, LL medium is useful for the isolation of L. monocytogenes from food samples. PMID:24271177

  15. Liofilchem® O.A. Listeria agar and direct CAMP test provided sooner Listeria monocytogenes identification from neonatal bacteremia

    PubMed Central

    Savini, Vincenzo; Marrollo, Roberta; Serio, Annalisa; Paparella, Antonello; Argentieri, Angela Valentina; D’Antonio, Marianna; Coclite, Eleonora; Fusilli, Paola; Fazii, Paolo

    2014-01-01

    Listeria monocytogenes infection in pregnant women and newborns is a cause for serious concern, and invasive disease outcome strongly depends on prompt antibiotic therapy. To provide sooner identification from neonatal bacteremia we performed a CAMP test directly on positive blood aliquots and inoculated the Liofilchem® O.A. Listeria chromogenic agar as well, thus providing a 24-h turn-around time for response. PMID:24695762

  16. Thermal inactivation of Listeria monocytogenes within bovine milk phagocytes.

    PubMed Central

    Bunning, V K; Donnelly, C W; Peeler, J T; Briggs, E H; Bradshaw, J G; Crawford, R G; Beliveau, C M; Tierney, J T

    1988-01-01

    Thermal resistance of intracellular and freely suspended Listeria monocytogenes that was associated with a milkborne outbreak of listeriosis was studied by using the sealed tube and slug flow heat exchanger methods. Test temperatures for the former method were 57.8, 62.8, 66.1, and 68.9 degrees C (136, 145, 151, and 156 degrees F, respectively); whereas those for the latter method were 66.1, 68.9, 71.7, and 74.4 degrees C (151, 156, 161, and 166 degrees F, respectively). The heating menstruum was sterile, whole milk. The intracellular inoculum was generated from an in vitro phagocytosis reaction by using endotoxin-induced bovine milk phagocytes. The phagocyte population consisted of 88% neutrophils, 8% macrophages, and 4% lymphocytes. Neutrophils harbored the majority of intracellular L. monocytogenes. The mean level of infectivity in the phagocyte population was 43%, and there were 26.1 +/- 19.3 bacteria per cell (10(4) viable cells per ml of test milk). Initial bacterial counts for the freely suspended and intracellular experiments (the latter was based on a sonically disrupted sample) were 10(6) L. monocytogenes cells per ml. Heat-stressed bacteria were recovered by direct plating in parallel with recovery from an enrichment broth; both methods gave comparable results. The predicted D62.8 degrees C (145 degrees F) value for intracellular sealed tube studies was 53.8 s (ZD = 5.6 degrees C [10.0 degrees F]), indicating a safe 33.4 D margin of inactivation for vat pasteurization (62.8 degrees C for 30 min).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3128163

  17. Comparative analysis of CRISPR loci in different Listeria monocytogenes lineages.

    PubMed

    Di, Huiling; Ye, Lei; Yan, He; Meng, Hecheng; Yamasak, Shinji; Shi, Lei

    2014-11-21

    Listeria monocytogenes, an important food-borne pathogen, causes high mortality rate of listeriosis. Pan-genomic comparisons revealed the species genome of L. monocytogenes is highly stable but not completely clonal. The population structure of this species displays at least four evolutionary lineages (I-IV). Isolates of different lineages displayed distinct genetic, phenotypic and ecologic characteristics, which appear to affect their ability to be transmitted through foods and to cause human disease, as well as their ability to thrive in markedly phage-rich environments. CRISPR (clustered regularly interspaced short palindrome repeats), a recently described adaptive immunity system, not only confers defense against invading elements derived from bacteriophages or plasmids in many bacteria and archaeal, but also displays strains-level variations in almost any given endowed species. This work was aimed to investigate CRISPR diversity in L. monocytogenes strains of different lineages and estimated the potential practicability of the CRISPR-based approach to resolve this species' biodiversity. Only a third of strains contained all three CRISPR loci (here defined as LMa, LMb and LMc) at same time. Combined the strain-level variations in presence/absence of each CRISPR locus and its relative size and spacer arrangements, a total of 29 CRISPR genotypes and 11 groups were defined within a collection of 128 strains covering all serotypes. The CRISPR-based approach showed powerful ability to subtype the more commonly food-borne isolates of serotype 1/2a (lineage II) and serotypes 1/2b (lineage I), but limited by the absence of typical CRISPR structure in many lineage I isolates. Strikingly, we found a long associated cas1 gene as well as two self-targeting LMb spacers accidently homologous with endogenous genes in a fraction of serotype 1/2a isolations, demonstrated that CRISPR I B system might involve in bacterial physiology besides antiviral immunity. PMID:25445602

  18. Intracellular Induction of Listeria monocytogenes actA Expression

    PubMed Central

    Shetron-Rama, Lynne M.; Marquis, Hélène; Bouwer, H. G. Archie; Freitag, Nancy E.

    2002-01-01

    Following entry into the host cytosol, the bacterial pathogen Listeria monocytogenes dramatically increases the expression of several key virulence factors. The expression of actA, whose protein product is required for L. monocytogenes actin-based intracellular motility, is increased by more than 200-fold in cytosolic bacteria in comparison to broth-grown cultures. Two distinct promoter elements have been reported to regulate actA expression. One promoter is located immediately upstream of actA coding sequences, while the second promoter is contributed by the upstream mpl gene via the generation of an mpl-actA-plcB transcript. A series of L. monocytogenes mutants were constructed to define the contributions of individual promoter elements to actA expression. The intracellular induction of actA expression was found to be dependent upon the actA proximal promoter; the mpl promoter appeared to contribute to the extracellular induction of actA but did not affect intracellular levels of expression. The actA promoter is dependent upon a regulatory factor known as PrfA for transcriptional activation; however, no increase in actA expression was detected following the introduction of a high-affinity PrfA binding site within the actA promoter. The presence of a mutationally activated form of PrfA, known as PrfA*, increased overall actA expression in broth-grown cultures of both wild-type and actA promoter mutant strains, but the levels of induction observed were still approximately 50-fold lower than those observed for intracellularly grown L. monocytogenes. Collectively, these results indicate that the dramatic induction of actA expression that occurs in the host cell cytosol is mediated through a single promoter element. Furthermore, intracellular induction of actA appears to require additional steps or factors beyond those necessary for the activation and binding of PrfA to the actA promoter. PMID:11854187

  19. Increased Detection of Listeria Species and Listeria Monocytogenes in Raw Beef, Using the Assurance GDS Molecular Detection System with Culture Isolation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Testing for Listeria is challenging due to its slow growth rate. Recently, we described a rapid Listeria culture isolation method. This method can be improved by utilizing a rapid molecular detection test such as the Assurance GDS tests for Listeria and L. monocytogenes (L. mono). These two metho...

  20. Low, medium and high heat tolerant strains of Listeria monocytogenes and increased heat stress resistance after exposure to sublethal heat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes exhibits sophisticated adaptive mechanisms to counteract higher levels of lethal acid, heat, salt or oxidative stresses after pre-exposure to sublethal concentrations of homogenous stress. A group of 37 strains representing all 13 serotypes of Listeria monocytogenes with initi...

  1. Gene expression profiling of a nisin-sensitive Listeria monocytogenes Scott A CtsR deletion mutant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a food-borne pathogen of significant threat to public health. Nisin is the only bacteriocin that can be used as a food preservative. Due to its antimicrobial activity, it can be used to control Listeria monocytogenes in food; however, the antimicrobial mechanism of nisin ...

  2. Visualisation of morphological interaction of diamond and silver nanoparticles with Salmonella Enteritidis and Listeria monocytogenes.

    PubMed

    Sawosz, Ewa; Chwalibog, André; Mitura, Katarzyna; Mitura, Stanisław; Szeliga, Jacek; Niemiec, Tomasz; Rupiewicz, Marlena; Grodzik, Marta; Sokołowska, Aleksandra

    2011-09-01

    Currently, medicine intensively searches for methods to transport drugs to a target (sick) point within the body. The objective of the present investigation was to evaluate morphological characteristics of the assembles of silver or diamond nanoparticles with Salmonella Enteritidis (G-) or Listeria monocytogenes (G+), to reveal possibilities of constructing nanoparticle-bacteria vehicles. Diamond nanoparticles (nano-D) were produced by the detonation method. Hydrocolloids of silver nanoparticles (nano-Ag) were produced by electric non-explosive patented method. Hydrocolloids of nanoparticles (200 microl) were added to bacteria suspension (200 microl) in the following order: nano-D + Salmonella E.; nano-D + Listeria monocytogenes; nano-Ag + Salmonella E; nano-Ag + Listeria monocytogenes. Samples were inspected by transmission electron microscopy. Visualisation of nanoparticles and bacteria interaction showed harmful effects of both nanoparticles on bacteria morphology. The most spectacular effect of nano-D were strong links between nano-D packages and the flagella of Salmonella E. Nano-Ag were closely attached to Listeria monocytogenes but not to Salmonella E. There was no evidence of entering nano-Ag inside Listeria monocytogenes but smaller particles were placed inside Salmonella E. The ability of nano-D to attach to the flagella and the ability of nano-Ag to penetrate inside bacteria cells can be utilized to design nano-bacteria vehicles, being carriers for active substances attached to nanoparticles. PMID:22097468

  3. [Bacteriostatic effect and/or xylitol bactericide of crops on Listeria Monocytogenes].

    PubMed

    Morón de Salim, Alba Rosa; Ramírez Mérida, Luis Guillermo

    2013-06-01

    Listeria monocytogenes has been considered as an emerging pathogen causing foodborne illness. In the search for an alternate route biocontrol propagation, xylitol has been proposed as a possible bacteriostatic and / or bactericide. Xylitol is a polyol derived from the hydrogenation of xylose monosaccharide of importance in the pharmaceutical industry for its anti-cariogenic effect. To check the possible effect of xylitol as bacteriostatic and/or bactericidal against Listeria monocytogenes, it was determined the minimum inhibitory concentration (MIC), the time minimum inhibition (TMI) and minimum bactericidal concentration (MBC) of xylitol solutions on Listeria monocytogenes ATCC 7635. The agar diffusion method was applied, using xylitol solutions at concentrations of 0-10%, respectively, for the MIC. The TMI was determined by growth curves in trypticase soy broth with solutions 1, 2, 3, 5, 8, 9, 10 and 20% of xylitol, respectively, with an initial inoculum of 108 CFU per ml of Listeria monocytogenes in each solution. MIC observed was the solution 1% of xylitol; the TMI was 10 hours to concentrations of 1 to 10% and 7 hours to apply 20% xylitol. It was found that xylitol has bacteriostatic power on Listeria monocytogenes (p < 0.001), but not bactericide effect. PMID:24934074

  4. [Bacteriostatic and/or bactericidal extract of Aloe vera gel on cultures of Listeria monocytogenes].

    PubMed

    Ramírez Mérida, Luis Guillermo; Morón de Salim, Alba; Catinella, Rosangela; Castillo, Luis

    2012-03-01

    Listeria monocytogenes is a bacteria responsible for food borne diseases (FBD). The effect of Aloe vera gel extract as a possible bacteriostatic and/or bactericidal against Listeria monocytogenes, was checked by determined the minimum inhibitory concentration (MIC), the time of minimum inhibition (TMI) and minimum bactericidal concentration (MBC) solutions extract of Aloe vera gel in different concentrations on cultures of Listeria monocytogenes ATCC 7635. We applied the agar diffusion method, using solutions of extract of Aloe vera gel at concentrations of 0 to 100% for the MIC. The TMI was determined by growth curves in trypticase soy broth with an initial inoculum of Listeria monocytogenes ATCC 7635 of 108 CFU/mL in each solution. It was determined that the MIC was 10% extract of Aloe vera gel and TMI was 5 hours at concentrations of 10%, 20% and 30% of Aloe vera, while concentrations of 50, 80, 90 and 100%, the time was 8 hours. It was found that indeed the Aloe vera gel is bacteriostatic power on Listeria monocytogenes (p < 0.001), but yet, no bactericidal effect was obtained in our study. PMID:23477211

  5. Listeria monocytogenes lineages: Genomics, evolution, ecology, and phenotypic characteristics.

    PubMed

    Orsi, Renato H; den Bakker, Henk C; Wiedmann, Martin

    2011-02-01

    Listeria monocytogenes consists of at least 4 evolutionary lineages (I, II, III, and IV) with different but overlapping ecological niches. Most L. monocytogenes isolates seem to belong to lineages I and II, which harbor the serotypes more commonly associated with human clinical cases, including serotype 1/2a (lineage II) and serotypes 1/2b and 4b (lineage I). Lineage II strains are common in foods, seem to be widespread in the natural and farm environments, and are also commonly isolated from animal listeriosis cases and sporadic human clinical cases. Most human listeriosis outbreaks are associated with lineage I isolates though. In addition, a number of studies indicate that, in many countries, lineage I strains are overrepresented among human isolates, as compared to lineage II strains. Lineage III and IV strains on the other hand are rare and predominantly isolated from animal sources. The apparent differences in the distribution of strains representing the L. monocytogenes lineages has lead to a number of studies aimed at identifying phenotypic differences among the different lineages. Interestingly, lineage II isolates seem to carry more plasmids than lineage I isolates and these plasmids often confer resistance to toxic metals and possibly other compounds that may be found in the environment. Moreover, lineage II isolates seem to be more resistant to bacteriocins than lineage I isolates, which probably confers an advantage in environments where bacteriocin-producing organisms are abundant. A large number of lineage II isolates and strains have been shown to be virulence-attenuated due to premature stop codon mutations in inlA and mutations in prfA. A subset of lineage I isolates carry a listeriolysin S hemolysin, which is not present in isolates belonging to lineages II, III, or IV. While lineage II isolates also show higher recombination rates than lineage I isolates, possibly facilitating adaptation of lineage II strains to diverse environments, lineage I

  6. Comparative evaluation of the VIDAS Listeria monocytogenes Xpress (LMX) for the detection of Listeria monocytogenes in a variety of foods.

    PubMed

    Johnson, Ronald; Mills, John; Pittet, Jean-Louis; Hughes, Denise

    2013-01-01

    The VIDAS Listeria monocytogenes Xpress (LMX) test is an enzyme-linked fluorescent immunoassay designed for use with the automated VIDAS or mini-VIDAS instruments for the specific detection of L. monocytogenes using a 26 h proprietary enrichment broth. The VIDAS LMX method was validated according to harmonized AOAC Research Institute (RI) and Official Methods of Analysis guidelines in both the AOAC Performance Tested Method (PTM) and GovVal programs. In the PTM comparison studies, the VIDAS LMX method was compared to the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook, the U.S. Food and Drug Administration Bacteriological Analytical Manual, and AOAC Official Methods. The comparative food studies consisted of two main parts: internal testing and AOAC independent laboratory testing, which included seven food matrixes (deli ham, processed cheese, vanilla ice cream, cooked shrimp, smoked white fish, frozen spinach, and peanut butter). As part of the AOAC R1 GovVal program, the VIDAS LMX method was compared to the Health Canada MFHPB-30 method for the detection of L. monocytogenes in five ready-to-eat (RTE) meats (hot dogs, deli turkey, deli ham, fermented sausage, and liver paté). Twenty replicates of each inoculation level and five uninoculated controls were evaluated in each study. The LMX method also included the use ofchromogenic media, chromID Ottaviani Agosti agar and chromID L. mono. agar, for confirmation of LMX presumptive results. In both the PTM and GovVal evaluations, there were no significant differences in the Chi-square values for the LMX method when compared to reference methods. The additional parameters tested in the PTM evaluation (inclusivity, exclusivity, ruggedness, stability, and lot-to-lot) satisfied the AOAC RI performance requirements. In both the PTM and GovVal validation studies, the VIDAS LMX method demonstrated reliability as a rapid qualitative method for next-day detection of L

  7. An in silico DNA vaccine against Listeria monocytogenes.

    PubMed

    Jahangiri, Abolfazl; Rasooli, Iraj; Gargari, Seyed Latif Mousavi; Owlia, Parviz; Rahbar, Mohammad Reza; Amani, Jafar; Khalili, Saeed

    2011-09-16

    Listeria monocytogenes causes listeriosis with mortality rate >20%. Listeriolysin-O (LLO), a pore-forming hemolysin, belongs to the family of cholesterol-dependent toxins (CDTX) and plays roles in the pathogenicity. In this study bioinformatic analyses were carried out on LLO sequence as a major immunodominant listerial antigen toward designing a DNA vaccine stimulating cytotoxic T-lymphocytes (CTLs). Mouse and human constructs were designed based on predicted T cell epitopes and MHC class I binders, which were then tandemly fused together. LLO-derived construct codons and a variety of critical gene expression efficiency parameters were optimized. Post-translational modifications such as glycosylation, phosphorylation were analysed. The constructs corresponded to LLO sequences of L. monocytogenes in BLAST search. Neither human nor mouse construct was allergen. Secretory pathway was location of the human construct that enhances immune induction and contribute to the efficacy of the vaccine candidate. mRNAs from optimized DNA sequences of both human and mouse constructs are more stable than the native and are suitable for initiation of translation. The constructs contain several sites for phosphorylation that could improve its degradation and subsequent entry into the MHC class I pathway. Addition of GPI anchor, myristoylation and ubiquitin signals or proline (P), glutamic acid (E), serine (S), threonine (T) (PEST)-like motifs at the N-terminal of constructs increase efficacy of the DNA vaccine. Close physical contact between the favorable immunogen and the suitable CpG oligodeoxynucleotides (CpG ODN) promotes immune response. Vectors for checking the expression of constructs in mammalian cells and for harboring the foreign genes as DNA vaccine are suggested. PMID:21791233

  8. The Effect of Oxygen on Bile Resistance in Listeria monocytogenes

    PubMed Central

    Wright, Morgan L; Pendarvis, Ken; Nanduri, Bindu; Edelmann, Mariola J; Jenkins, Haley N; Reddy, Joseph S; Wilson, Jessica G; Ding, Xuan; Broadway, Paul R; Ammari, Mais G; Paul, Oindrila; Roberts, Brandy; Donaldson, Janet R

    2016-01-01

    Listeria monocytogenes is a Gram-positive facultative anaerobe that is the causative agent of the disease listeriosis. The infectious ability of this bacterium is dependent upon resistance to stressors encountered within the gastrointestinal tract, including bile. Previous studies have indicated bile salt hydrolase activity increases under anaerobic conditions, suggesting anaerobic conditions influence stress responses. Therefore, the goal of this study was to determine if reduced oxygen availability increased bile resistance of L. monocytogenes. Four strains representing three serovars were evaluated for changes in viability and proteome expression following exposure to bile in aerobic or anaerobic conditions. Viability for F2365 (serovar 4b), EGD-e (serovar 1/2a), and 10403S (serovar 1/2a) increased following exposure to 10% porcine bile under anaerobic conditions (P < 0.05). However, HCC23 (serovar 4a) exhibited no difference (P > 0.05) in bile resistance between aerobic and anaerobic conditions, indicating that oxygen availability does not influence resistance in this strain. The proteomic analysis indicated F2365 and EGD-e had an increased expression of proteins associated with cell envelope and membrane bioenergetics under anaerobic conditions, including thioredoxin-disulfide reductase and cell division proteins. Interestingly, HCC23 had an increase in several dehydrogenases following exposure to bile under aerobic conditions, suggesting that the NADH:NAD+ is altered and may impact bile resistance. Variations were observed in the expression of the cell shape proteins between strains, which corresponded to morphological differences observed by scanning electron microscopy. These data indicate that oxygen availability influences bile resistance. Further research is needed to decipher how these changes in metabolism impact pathogenicity in vivo and also the impact that this has on susceptibility of a host to listeriosis. PMID:27274623

  9. [Electrochemical detection of toxin gene in Listeria monocytogenes].

    PubMed

    Wu, Ling-Wei; Liu, Quan-Jun; Wu, Zhong-Wei; Lu, Zu-Hong

    2010-05-01

    Listeria monocytogenes (LM) is a food-borne pathogen inducing listeriosis, an illness characterized by encephalitis, septicaemia, and meningitis. Listeriolysin O (LLO) is absolutely required for virulence by L. monocytogenes, and is found only in virulent strains of the species. One of the best ways to detect and confirm the pathogen is detection of one of the virulence factors, LLO, produced by the microorganism. This paper focused on the electrical method used to detect the LLO toxin gene in food products and organism without labeling the target DNA. The electrochemical sensor was obtained by immobilizing single-stranded oligonucleotides onto the gold electrode with the mercaptan activated by N-hydroxysulfosuccinimide (NHS) and N-(3-dimethylamion)propyl-N'-ethyl carbodiimidehydrochloride (EDC). The hy-bridization reaction that occurred on the electrode surface was evidenced by Cyclic Voltammetry (CV) analysis using [Co(phen)3](ClO4)3 as an indicator. The covalently immobilized single-stranded DNA could selectively hybridize to its complementary DNA in solution to form double-stranded DNA on the gold surface. A significant increase of the peak cur-rent of Cyclic Voltammetry (CV) upon hybridization of immobilized ssDNA with PCR amplification products in the solu-tion was observed. This peak current change was used to monitor the amount of PCR amplification products. Factors deter-mining the sensitivity of the electrochemical assay, such as DNA target concentration and hybridization conditions, were investigated. The coupling of DNA to the electrochemical sensors has the potential of the quantitative evaluation of gene. PMID:20466642

  10. A riboswitch-regulated antisense RNA in Listeria monocytogenes.

    PubMed

    Mellin, J R; Tiensuu, Teresa; Bécavin, Christophe; Gouin, Edith; Johansson, Jörgen; Cossart, Pascale

    2013-08-01

    Riboswitches are ligand-binding elements located in 5' untranslated regions of messenger RNAs, which regulate expression of downstream genes. In Listeria monocytogenes, a vitamin B12-binding (B12) riboswitch was identified, not upstream of a gene but downstream, and antisense to the adjacent gene, pocR, suggesting it might regulate pocR in a nonclassical manner. In Salmonella enterica, PocR is a transcription factor that is activated by 1,2-propanediol, and subsequently activates expression of the pdu genes. The pdu genes mediate propanediol catabolism and are implicated in pathogenesis. As enzymes involved in propanediol catabolism require B12 as a cofactor, we hypothesized that the Listeria B12 riboswitch might be involved in pocR regulation. Here we demonstrate that the B12 riboswitch is transcribed as part of a noncoding antisense RNA, herein named AspocR. In the presence of B12, the riboswitch induces transcriptional termination, causing aspocR to be transcribed as a short transcript. In contrast, in the absence of B12, aspocR is transcribed as a long antisense RNA, which inhibits pocR expression. Regulation by AspocR ensures that pocR, and consequently the pdu genes, are maximally expressed only when both propanediol and B12 are present. Strikingly, AspocR can inhibit pocR expression in trans, suggesting it acts through a direct interaction with pocR mRNA. Together, this study demonstrates how pocR and the pdu genes can be regulated by B12 in bacteria and extends the classical definition of riboswitches from elements governing solely the expression of mRNAs to a wider role in controlling transcription of noncoding RNAs. PMID:23878253

  11. Comparison of growth kinetics for healthy and heat-injured Listeria monocytogenes in eight enrichment broths.

    PubMed

    Silk, Todd M; Roth, Tatiana M T; Donnelly, C W

    2002-08-01

    Detection of Listeria in food products is often limited by performance of enrichment media used to support growth of Listeria to detectable levels. In this study, growth curves were generated using healthy and heat-injured Listeria monocytogenes strain F5069 in three nonselective and five selective enrichment broths. Nonselective enrichment media included the current Food and Drug Administration Bacteriological Analytical Manual Listeria enrichment broth base (BAM), Listeria repair broth (LRB), and Trypticase soy broth. Selective enrichment media included BAM with selective agents and LRB with selective agents, BCM L. monocytogenes preenrichment broth, Fraser broth, and UVM-modified Listeria enrichment broth. The Gompertz equation was used to model the growth of L. monocytogenes. Gompertz parameters were used to calculate exponential growth rate, lag-phase duration (LPD), generation time, maximum population density (MPD), and time required for repair of injured cells. Statistical differences (P < 0.05) in broth performance were noted for LPD and MPD when healthy and injured cells were inoculated into the broths. With the exception of Fraser broth, there were no significant differences in the time required for the repair of injured cells. Results indicate that the distinction between selective and nonselective broths in their ability to grow healthy Listeria and to repair sublethally injured cells is not solely an elementary issue of presence or absence of selective agents. PMID:12182490

  12. Quantifying strain variability in modeling growth of Listeria monocytogenes.

    PubMed

    Aryani, D C; den Besten, H M W; Hazeleger, W C; Zwietering, M H

    2015-09-01

    Prediction of microbial growth kinetics can differ from the actual behavior of the target microorganisms. In the present study, the impact of strain variability on maximum specific growth rate (μmax) (h(-1)) was quantified using twenty Listeria monocytogenes strains. The μmax was determined as function of four different variables, namely pH, water activity (aw)/NaCl concentration [NaCl], undissociated lactic acid concentration ([HA]), and temperature (T). The strain variability was compared to biological and experimental variabilities to determine their importance. The experiment was done in duplicate at the same time to quantify experimental variability and reproduced at least twice on different experimental days to quantify biological (reproduction) variability. For all variables, experimental variability was clearly lower than biological variability and strain variability; and remarkably, biological variability was similar to strain variability. Strain variability in cardinal growth parameters, namely pHmin, [NaCl]max, [HA]max, and Tmin was further investigated by fitting secondary growth models to the μmax data, including a modified secondary pH model. The fitting results showed that L. monocytogenes had an average pHmin of 4.5 (5-95% prediction interval (PI) 4.4-4.7), [NaCl]max of 2.0mM (PI 1.8-2.1), [HA]max of 5.1mM (PI 4.2-5.9), and Tmin of -2.2°C (PI (-3.3)-(-1.1)). The strain variability in cardinal growth parameters was benchmarked to available literature data, showing that the effect of strain variability explained around 1/3 or less of the variability found in literature. The cardinal growth parameters and their prediction intervals were used as input to illustrate the effect of strain variability on the growth of L. monocytogenes in food products with various characteristics, resulting in 2-4 logCFU/ml(g) difference in growth prediction between the most and least robust strains, depending on the type of food product. This underlined the importance

  13. The RAB5-GEF Function of RIN1 Regulates Multiple Steps During Listeria monocytogenes Infection

    PubMed Central

    Balaji, Kavitha; French, Christopher T.; Miller, Jeff F.; Colicelli, John

    2014-01-01

    Listeria monocytogenes is a food-borne pathogenic bacterium that invades intestinal epithelial cells through a phagocytic pathway that relies on activation of host cell RAB5 GTPases. L. monocytogenes must subsequently inhibit RAB5, however, in order to escape lysosome-mediated destruction. Relatively little is known about upstream RAB5 regulators during L. monocytogenes entry and phagosome escape processes in epithelial cells. Here we identify RIN1, a RAS effector and RAB5-directed GEF, as a host cell factor in L. monocytogenes infection. RIN1 is rapidly engaged following L. monocytogenes infection and is required for efficient invasion of intestinal epithelial cells. RIN1-mediated RAB5 activation later facilitates the fusion of phagosomes with lysosomes, promoting clearance of bacteria from the host cell. These results suggest that RIN1 is a host cell regulator that performs counterbalancing functions during early and late stages of L. monocytogenes infection, ultimately favoring pathogen clearance. PMID:25082076

  14. Genome Sequences for a Cluster of Human Isolates of Listeria monocytogenes Identified in South Africa in 2015

    PubMed Central

    Naicker, Preneshni; Bamford, Colleen; Shuping, Liliwe; McCarthy, Kerrigan M.; Sooka, Arvinda; Smouse, Shannon L.; Tau, Nomsa; Keddy, Karen H.

    2016-01-01

    Listeria monocytogenes is a Gram-positive bacterium with a ubiquitous presence in the environment. There is growing concern about the increasing prevalence of L. monocytogenes associated with food-borne outbreaks. Here we report genome sequences for a cluster of human isolates of L. monocytogenes identified in South Africa in 2015. PMID:27056221

  15. Genetic characteristics of Japanese clinical Listeria monocytogenes isolates.

    PubMed

    Miya, Satoko; Takahashi, Hajime; Nakagawa, Miku; Kuda, Takashi; Igimi, Shizunobu; Kimura, Bon

    2015-01-01

    Listeria monocytogenes causes foodborne illnesses through consumption of ready-to-eat foods. Although 135-201annual listeriosis cases have been estimated in Japan, the details regarding the clinical isolates such as infection source, virulence level, and other genetic characteristics, are not known. In order to uncover the trends of listeriosis in Japan and use the knowledge for prevention measures to be taken, the genetic characteristics of the past human clinical isolates needs to be elucidated. For this purpose, multilocus tandem-repeat sequence analysis (MLTSA) and multi-virulence-locus sequence typing (MVLST) were used in this study. The clinical isolates showed a variety of genetically distant genotypes, indicating they were from sporadic cases. However, the MVLST profiles of 7 clinical isolates were identical to those of epidemic clone (EC) I isolates, which have caused several serious outbreaks in other countries, suggesting the possibility that they have strong virulence potential and originated from a single outbreak. Moreover, 6 Japanese food isolates shared their genotypes with ECI isolates, indicating that there may be risks for listeriosis outbreak in Japan. This is the first investigational study on genetic characteristics of Japanese listeriosis isolates. The listeriosis cases happened in the past are presumably sporadic, but it is still possible that some isolates with strong virulence potential have caused listeriosis outbreaks, and future listeriosis risks also exist. PMID:25826318

  16. Molecular Serogrouping of Listeria monocytogenes from Brazil Using PCR.

    PubMed

    Camargo, Anderson Carlos; Vallim, Deyse Christina; Hofer, Ernesto; Nero, Luís Augusto

    2016-01-01

    We assessed the serotype distribution of Listeria monocytogenes isolates from clinical, beef, and environment samples using two PCR-based protocols for serogrouping. A panel of 134 isolates (22 clinical samples, 79 samples of beef cuts, and 33 samples from the beef processing environment) were subjected to conventional serology and identified as serotypes 1/2a (n = 12), 1/2b (n = 21), 1/2c (n = 71), and 4b (n = 30). Isolates from clinical samples were predominantly serotype 4b, and the most prevalent serotype among the beef cut and environment samples was 1/2c. The protocol described by M. Doumith, C. Buchrieser, P. Glaser, C. Jacquet, and P. Martin (J. Clin. Microbiol. 42:3819-3822, 2004) produced contradictory results for seven 1/2a isolates, which were positive for lmo1118 and had the profile IIc (serotypes 1/2c and 3c). Fifteen serotype 4b isolates amplified the target lmo0737, with the atypical profile IVb variant 1. The results obtained with the protocol described by M. K. Borucki and D. R. Call (J. Clin. Microbiol. 41:5537-5540, 2003) were in full agreement with those of the conventional serology. We recommend using this multiplex PCR approach by adding one pair of the reported primers to the panel to reduce total effort by one PCR while maintaining specificity. We present additional recommendations to improve the efficiency and reproducibility of this serogrouping assay. PMID:26735041

  17. Economic Cost of a Listeria monocytogenes Outbreak in Canada, 2008

    PubMed Central

    Vriezen, Rachael; Farber, Jeffrey M.; Currie, Andrea; Schlech, Walter; Fazil, Aamir

    2015-01-01

    Abstract Estimates of the economic costs associated with foodborne disease are important to inform public health decision-making. In 2008, 57 cases of listeriosis and 24 deaths in Canada were linked to contaminated delicatessen meat from one meat processing plant. Costs associated with the cases (including medical costs, nonmedical costs, and productivity losses) and those incurred by the implicated plant and federal agencies responding to the outbreak were estimated to be nearly $242 million Canadian dollars (CAD, 2008). Case costs alone were estimated at approximately $2.8 million (CAD, 2008) including loss of life. This demonstrates the considerable economic burden at both the individual and population levels associated with foodborne disease and foodborne outbreaks in particular. Foodborne outbreaks due to severe pathogens, such as Listeria monocytogenes and those that result in product recalls, are typically the most costly from the individual and/or societal perspective. Additional economic estimates of foodborne disease would contribute to our understanding of the burden of foodborne disease in Canada and would support the need for ongoing prevention and control activities. PMID:26583272

  18. Molecular characterization of Listeria monocytogenes isolated from fresh seafood samples in Iran

    PubMed Central

    2013-01-01

    Background Among all species of Listeria, Listeria monocytogenes (L. monocytogenes) is a major pathogenic microorganism of humans and animals and L. ivanovii is rarely pathogenic for humans. The objective of this study was to isolate and characterize Listeria species and to determine the frequencies of virulence genes in L. monocytogenes serotypes in fresh fish, shrimp, crab and lobster in Isfahan and Shahrekord, Iran. Methods From September 2010 to April 2011, a total of 300 marine food samples were purchased from supermarkets of Isfahan and Shahrekord cities, Iran. All samples were cultured and the positive samples for L. monocytogenes were analyzed for presence of serotypes and virulence genes. Results From the total 300 samples, 23 (10.45%) fresh fish and 1 (2.5%) shrimp samples were positive for Listeria spp., but there were no positive lobster and crab samples for Listeria species. Only L. monocytogenes was isolated from 17 fish (7.25%) and 1 shrimp (2.5%) samples while L. innocua, L. ivanovii and L. seeligeri only detected in fish samples (2 (0.9%), 3 (1.36%) and 1 (0.45%)), respectively. The plcA, prfA, actA, hlyA and iap virulence genes were detected in all of the 18 L. monocytogenes isolates. Totally, the 4b, 1/2a and 1/2b serotypes were detected in 66.66%, 5.55% and 27.77% bacterial isolates, respectively. Conclusions Consumption of these sea foods, either raw or undercooked, may contribute to food-borne illness due to L. monocytogenes in Iran. The hygienic quality of sea food products should be observe. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3422944359800606 PMID:24033984

  19. Rapid detection of Listeria monocytogenes in milk using confocal micro-Raman spectroscopy and chemometric analysis.

    PubMed

    Wang, Junping; Xie, Xinfang; Feng, Jinsong; Chen, Jessica C; Du, Xin-jun; Luo, Jiangzhao; Lu, Xiaonan; Wang, Shuo

    2015-07-01

    Listeria monocytogenes is a facultatively anaerobic, Gram-positive, rod-shape foodborne bacterium causing invasive infection, listeriosis, in susceptible populations. Rapid and high-throughput detection of this pathogen in dairy products is critical as milk and other dairy products have been implicated as food vehicles in several outbreaks. Here we evaluated confocal micro-Raman spectroscopy (785 nm laser) coupled with chemometric analysis to distinguish six closely related Listeria species, including L. monocytogenes, in both liquid media and milk. Raman spectra of different Listeria species and other bacteria (i.e., Staphylococcus aureus, Salmonella enterica and Escherichia coli) were collected to create two independent databases for detection in media and milk, respectively. Unsupervised chemometric models including principal component analysis and hierarchical cluster analysis were applied to differentiate L. monocytogenes from Listeria and other bacteria. To further evaluate the performance and reliability of unsupervised chemometric analyses, supervised chemometrics were performed, including two discriminant analyses (DA) and soft independent modeling of class analogies (SIMCA). By analyzing Raman spectra via two DA-based chemometric models, average identification accuracies of 97.78% and 98.33% for L. monocytogenes in media, and 95.28% and 96.11% in milk were obtained, respectively. SIMCA analysis also resulted in satisfied average classification accuracies (over 93% in both media and milk). This Raman spectroscopic-based detection of L. monocytogenes in media and milk can be finished within a few hours and requires no extensive sample preparation. PMID:25863337

  20. Genome Sequence of Listeria monocytogenes Strain HPB5415, Collected during a 2008 Listeriosis Outbreak in Canada

    PubMed Central

    Pightling, Arthur W.

    2015-01-01

    Listeria monocytogenes strain HPB5415—isolated from deli meat—was found in 2008 to have the same pulsed-field gel electrophoresis patterns as a clinical strain (08-5923). However, whether nucleotide differences (single nucleotide polymorphisms [SNPs]) exist between their genomes was not determined. We sequenced the L. monocytogenes strain HPB5415 genome and identified 52 SNPs relative to strain 08-5923. PMID:26067972

  1. Comparative Evaluation of Veriflow® Listeria monocytogenes to USDA and AOAC Culture Based Methods for the Detection of Listeria monocytogenes in Food.

    PubMed

    Joelsson, Adam C; Brown, Ashley S; Puri, Amrita; Keough, Martin P; Gaudioso, Zara E; Siciliano, Nicholas A; Snook, Adam E

    2015-01-01

    Veriflow® Listeria monocytogenes (LM) is a molecular based assay for the presumptive detection of Listeria monocytogenes from environmental surfaces, dairy, and ready-to-eat (RTE) food matrixes (hot dogs and deli meat). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post PCR amplification and requires only 24 h of enrichment for maximum sensitivity. The Veriflow LM system eliminates the need for sample purification, gel electrophoresis, or fluorophore-based detection of target amplification, and does not require complex data analysis. This Performance Tested Method(SM) validation study demonstrated the ability of the Veriflow LM method to detect low levels of artificially inoculated L. monocytogenes in seven distinct environmental and food matrixes. In each unpaired reference comparison study, probability of detection analysis indicated no significant difference between the Veriflow LM method and the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook 8.08 or AOAC 993.12 reference method. Fifty strains of L. monocytogenes were detected in the inclusivity study, while 39 nonspecific organisms were undetected in the exclusivity study. The study results show that Veriflow LM is a sensitive, selective, and robust assay for the presumptive detection of L. monocytogenes sampled from environmental, dairy, or RTE (hot dogs and deli meat) food matrixes. PMID:26525251

  2. Rapid Identification and Classification of Listeria spp. and Serotype Assignment of Listeria monocytogenes Using Fourier Transform-Infrared Spectroscopy and Artificial Neural Network Analysis

    PubMed Central

    Romanolo, K. F.; Gorski, L.; Wang, S.; Lauzon, C. R.

    2015-01-01

    The use of Fourier Transform-Infrared Spectroscopy (FT-IR) in conjunction with Artificial Neural Network software NeuroDeveloper™ was examined for the rapid identification and classification of Listeria species and serotyping of Listeria monocytogenes. A spectral library was created for 245 strains of Listeria spp. to give a biochemical fingerprint from which identification of unknown samples were made. This technology was able to accurately distinguish the Listeria species with 99.03% accuracy. Eleven serotypes of Listeria monocytogenes including 1/2a, 1/2b, and 4b were identified with 96.58% accuracy. In addition, motile and non-motile forms of Listeria were used to create a more robust model for identification. FT-IR coupled with NeuroDeveloper™ appear to be a more accurate and economic choice for rapid identification of pathogenic Listeria spp. than current methods. PMID:26600423

  3. Effect of Filling Type and Heating Method on Prevalence of Listeria species and Listeria monocytogenes in Dumplings Produced in Poland.

    PubMed

    Szymczak, Barbara; Dąbrowski, Waldemar

    2015-05-01

    The count of Listeria monocytogenes was determined, before and after heat treatment, in 200 samples of dumplings of 9 brands and with different types of stuffing. Analyses were conducted according to ISO 11290-1 standard and with real-time PCR method. The highest count of L. monocytogenes was found in meat dumplings (10(2) to 10(4) CFU/g), whereas products with white cheese-potato stuffing and vegetable-mushroom stuffing contained significantly less Listeria, 20 to 80 and 5 to 32 CFU/g, respectively. In cooled meat dumplings the extent of contamination depended significantly on the producer. In addition, a significant (P < 0.05) correlation was determined between contamination level and meat content in the stuffing (rho = 0.418), especially in stuffing containing pork meat (0.464), contrary to beef-containing stuffing (0.284). Heating dumplings in boiling water for 2 min completely eliminated L. monocytogenes in meat dumplings. In contrast, the microwave heating applied for 2 min at 600 W only reduced the count of L. monocytogenes by 1 to 2 logs. Hence, the microwave heating failed to reduce the risk of infection with this pathogen below the level permissible in the EU regulation, especially in the most contaminated samples. In this case, the efficacy of microwave heating was significantly (P < 0.05) affected by the initial count of L. monocytogenes (rho = 0.626), then by meat content in the stuffing (0.476), and to the lowest extent--by the type of meat (0.415 to 0.425). However, no Listeria sp. and L. monocytogenes were isolated from cooked dumplings with fruits (strawberries or blueberries). PMID:25847074

  4. Comparative Study of the Effects of Citral on the Growth and Injury of Listeria innocua and Listeria monocytogenes Cells

    PubMed Central

    Silva-Angulo, Angela B.; Zanini, Surama F.; Rosenthal, Amauri; Rodrigo, Dolores; Klein, Günter; Martínez, Antonio

    2015-01-01

    This study investigates the effect of citral on growth and on the occurrence of sublethal damage in Listeria innocua Serovar 6a (CECT 910) and Listeria monocytogenes Serovar 4b (CECT 4032) cells that were exposed to citral as a natural antimicrobial agent. Two initial inoculum concentrations were considered in this investigation: 102 and 106 cfu/mL. Citral exhibited antilisterial activity against L. innocua and L. monocytogenes, and the observed effects were dependent on the concentration of citral present in the culture medium (0, 0.150 and 0.250 μL/mL) (p ≤ 0.05). L. innocua had a shorter lag phase than L. monocytogenes, and the two species had nearly identical maximum specific growth rates. These results indicate that L. innocua could be used as surrogate for L. monocytogenes when testing the effects of this antimicrobial. Significant differences in the lag phase and growth rate were observed between the small and large inoculum concentration (p ≤ 0.05). Citral-treated L. innocua and L. monocytogenes that were recovered on selective medium (i.e., TSA-YE-SC) had a shorter lag phase and a higher maximum specific growth rate than cells that were recovered on non-selective medium (i.e., TSA-YE) (p ≤ 0.05). This result suggests that damage occurs at sublethal concentrations of citral. PMID:25643164

  5. In Vivo Transcriptional Profiling of Listeria monocytogenes and Mutagenesis Identify New Virulence Factors Involved in Infection

    PubMed Central

    Camejo, Ana; Buchrieser, Carmen; Couvé, Elisabeth; Carvalho, Filipe; Reis, Olga; Ferreira, Pierre; Sousa, Sandra; Cossart, Pascale; Cabanes, Didier

    2009-01-01

    Listeria monocytogenes is a human intracellular pathogen able to colonize host tissues after ingestion of contaminated food, causing severe invasive infections. In order to gain a better understanding of the nature of host–pathogen interactions, we studied the L. monocytogenes genome expression during mouse infection. In the spleen of infected mice, ≈20% of the Listeria genome is differentially expressed, essentially through gene activation, as compared to exponential growth in rich broth medium. Data presented here show that, during infection, Listeria is in an active multiplication phase, as revealed by the high expression of genes involved in replication, cell division and multiplication. In vivo bacterial growth requires increased expression of genes involved in adaptation of the bacterial metabolism and stress responses, in particular to oxidative stress. Listeria interaction with its host induces cell wall metabolism and surface expression of virulence factors. During infection, L. monocytogenes also activates subversion mechanisms of host defenses, including resistance to cationic peptides, peptidoglycan modifications and release of muramyl peptides. We show that the in vivo differential expression of the Listeria genome is coordinated by a complex regulatory network, with a central role for the PrfA-SigB interplay. In particular, L. monocytogenes up regulates in vivo the two major virulence regulators, PrfA and VirR, and their downstream effectors. Mutagenesis of in vivo induced genes allowed the identification of novel L. monocytogenes virulence factors, including an LPXTG surface protein, suggesting a role for S-layer glycoproteins and for cadmium efflux system in Listeria virulence. PMID:19478867

  6. Pneumonia by Listeria monocytogenes: A Common Infection by an Uncommon Pathogen

    PubMed Central

    Koufakis, Theocharis; Chatzopoulou, Marianneta; Margaritis, Anastasios; Tsiakalou, Maria; Gabranis, Ioannis

    2015-01-01

    Infections by Listeria monocytogenes typically occur in infants, the elderly, pregnant women, and immunosuppressed subjects. Pulmonary infections in adults are extremely uncommon and only few reports can be found in the literature. We here report a case of Listeria pneumonia in an 85-year-old female patient and we discuss our diagnostic and therapeutic approach. Despite being rare and in most cases difficult to be identified, Listeria pneumonia should always be considered in immunosuppressed patients, presenting with fever and symptoms from the lower respiratory system. PMID:25802774

  7. Evaluation of VIDAS Listeria monocytogenes Xpress (LMX) for the detection of Listeria monocytogenes in a variety of foods: First Action 2013.11.

    PubMed

    Crowley, Erin; Bird, Patrick; Flannery, Jonathan; Benzinger, M Joseph; Fisher, Kiel; Boyle, Megan; Huffman, Travis; Bastin, Ben; Bedinghaus, Paige; Judd, William; Hoang, Thao; Agin, James; Goins, David; Johnson, Ronald L

    2014-01-01

    The VIDAS Listeria monocytogenes Xpress (LMX) is an automated rapid screening enzyme immunoassay for the detection of Listeria monocytogenes in food products. The VIDAS LMX method was compared in a multi-laboratory collaborative study to AOAC Official Method 993.12 Listeria monocytogenes in Milk and Dairy Products reference method following current AOAC guidelines. A total of 14 laboratories participated, representing government and industry, throughout the United States. One matrix, queso fresco (soft Mexican cheese), was analyzed using two different test portion sizes, 25 and 125 g. Samples representing each portion size were artificially contaminated with L. monocytogenes at three levels: an uninoculated control level [0 colony forming units (CFU)/test portion], a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). For this evaluation, 1800 unpaired replicate test portions were analyzed by either the VIDAS LMX or AOAC 993.12. Each level was analyzed using the Probability of Detection (POD) statistical model. For the low-level inoculated test portions, difference in collaborator POD (dLPOD) values of 0.04, (-0.08, 0.15) and 0.01, (-0.10, 0.13), with 95% confidence intervals, were obtained, respectively, for 25 and 125 g test portions. The range of the confidence intervals for dLPOD values for both the 25 and 125 g test portions contain the point 0.0 indicating no statistically significant difference in the number of positive samples detected between the VIDAS LMX and the AOAC method. In addition to Oxford Agar (OXA), VIDAS LMX test portions were confirmed using Agar Listeria Ottavani and Agosti (ALOA), a proprietary chromogenic agar for the identification and differentiation of L. monocytogenes and Listeria species. No differences were observed between the two selective agars. The VIDAS LMX method, with the optional ALOA agar confirmation method, was adopted as Official First Action status for the detection of L

  8. Urban prevalence of Listeria spp. and Listeria monocytogenes in public lavatories and on shoe soles of facility patrons in the European capital city Vienna.

    PubMed

    Schoder, D; Schmalwieser, A; Szakmary-Brändle, K; Stessl, B; Wagner, M

    2015-05-01

    The aim of this study was to determine the prevalence of Listeria spp. and Listeria monocytogenes (L. monocytogenes) in urban public lavatories and on shoe soles of facility patrons in a European capital city. More than 91% of all municipal public lavatories in Vienna close to public hubs were included in this study. Overall, 373 swab samples of public lavatories and shoes of facility patrons were enriched, according to ISO 11290-1. Listeria monocytogenes isolates were subtyped using pulsed-field gel electrophoresis. A total of 24 samples were positive for Listeria spp., yielding an overall prevalence of 6.4% (24/373). Listeria monocytogenes was found in 2.1% (8/373) of all samples. Swabs from lavatories in parks, container lavatories and lavatories at markets had the highest prevalences of 20.7% (6/29), 20% (2/10) and 12.5% (1/8) Listeria spp., respectively. These detection rates were statistically significantly higher than those associated with lavatories in shopping centres (P = 0.003, P = 0.002, P = 0.02) and at public transport locations (P = 0.0004, P = 0.005, P = 0.02). Shoes sampled at Christmas markets showed the highest Listeria spp. and L. monocytogenes prevalences of 80% (4/5) and 40% (2/5), respectively. With regard to shoe type, Listeria spp. detection rates were 14.3% (3/21; winter boots), 13.3% (2/15; hiking boots), sport shoes (5.9%; 2/34) and brogues (5.1%; 4/79). No Listeria spp. were found on shoe soles that had smooth treads (0/76), while Listeria spp. were detected on 19.5% (8/41) of medium depth tread shoe types and on 9.4% (3/32) of deep tread shoes. These data suggest that soil environment is still one of the most important reservoirs for the foodborne pathogen L. monocytogenes. PMID:24751465

  9. Incidence of Listeria spp. and Listeria monocytogenes in a poultry processing environment and in poultry products and their rapid confirmation by multiplex PCR.

    PubMed Central

    Lawrence, L M; Gilmour, A

    1994-01-01

    The incidence of Listeria spp. and Listeria monocytogenes in a poultry processing plant and in raw and cooked poultry products was determined over a 6-month period. Within the raw and cooked poultry processing environments, 46% (36 of 79) and 29% (51 of 173) of the samples contained Listeria spp. while 26% (21 of 79) and 15% (27 of 173) contained L. monocytogenes, respectively. Various sites within the processing environment were found to be consistently positive for L. monocytogenes throughout the entire sampling period. Of the raw and cooked products tested, 91% (53 of 58) and 8% (8 of 96) were found to contain Listeria spp. while 59% (34 of 58) and 0% (0 of 96) contained L. monocytogenes, respectively. Although L. monocytogenes was not detected in the cooked products examined, the presence of other Listeria spp. highlights the potential which exists for postprocessing contamination. Multiplex PCR proved to be a convenient and time-saving technique for rapid confirmation of Listeria spp. and L. monocytogenes in a single reaction. Images PMID:7811096

  10. An insight into the isolation, enumeration, and molecular detection of Listeria monocytogenes in food.

    PubMed

    Law, Jodi Woan-Fei; Ab Mutalib, Nurul-Syakima; Chan, Kok-Gan; Lee, Learn-Han

    2015-01-01

    Listeria monocytogenes, a foodborne pathogen that can cause listeriosis through the consumption of food contaminated with this pathogen. The ability of L. monocytogenes to survive in extreme conditions and cause food contaminations have become a major concern. Hence, routine microbiological food testing is necessary to prevent food contamination and outbreaks of foodborne illness. This review provides insight into the methods for cultural detection, enumeration, and molecular identification of L. monocytogenes in various food samples. There are a number of enrichment and plating media that can be used for the isolation of L. monocytogenes from food samples. Enrichment media such as buffered Listeria enrichment broth, Fraser broth, and University of Vermont Medium (UVM) Listeria enrichment broth are recommended by regulatory agencies such as Food and Drug Administration-bacteriological and analytical method (FDA-BAM), US Department of Agriculture-Food and Safety (USDA-FSIS), and International Organization for Standardization (ISO). Many plating media are available for the isolation of L. monocytogenes, for instance, polymyxin acriflavin lithium-chloride ceftazidime aesculin mannitol, Oxford, and other chromogenic media. Besides, reference methods like FDA-BAM, ISO 11290 method, and USDA-FSIS method are usually applied for the cultural detection or enumeration of L. monocytogenes. most probable number technique is applied for the enumeration of L. monocytogenes in the case of low level contamination. Molecular methods including polymerase chain reaction, multiplex polymerase chain reaction, real-time/quantitative polymerase chain reaction, nucleic acid sequence-based amplification, loop-mediated isothermal amplification, DNA microarray, and next generation sequencing technology for the detection and identification of L. monocytogenes are discussed in this review. Overall, molecular methods are rapid, sensitive, specific, time- and labor-saving. In future, there are

  11. An insight into the isolation, enumeration, and molecular detection of Listeria monocytogenes in food

    PubMed Central

    Law, Jodi Woan-Fei; Ab Mutalib, Nurul-Syakima; Chan, Kok-Gan; Lee, Learn-Han

    2015-01-01

    Listeria monocytogenes, a foodborne pathogen that can cause listeriosis through the consumption of food contaminated with this pathogen. The ability of L. monocytogenes to survive in extreme conditions and cause food contaminations have become a major concern. Hence, routine microbiological food testing is necessary to prevent food contamination and outbreaks of foodborne illness. This review provides insight into the methods for cultural detection, enumeration, and molecular identification of L. monocytogenes in various food samples. There are a number of enrichment and plating media that can be used for the isolation of L. monocytogenes from food samples. Enrichment media such as buffered Listeria enrichment broth, Fraser broth, and University of Vermont Medium (UVM) Listeria enrichment broth are recommended by regulatory agencies such as Food and Drug Administration-bacteriological and analytical method (FDA-BAM), US Department of Agriculture-Food and Safety (USDA-FSIS), and International Organization for Standardization (ISO). Many plating media are available for the isolation of L. monocytogenes, for instance, polymyxin acriflavin lithium-chloride ceftazidime aesculin mannitol, Oxford, and other chromogenic media. Besides, reference methods like FDA-BAM, ISO 11290 method, and USDA-FSIS method are usually applied for the cultural detection or enumeration of L. monocytogenes. most probable number technique is applied for the enumeration of L. monocytogenes in the case of low level contamination. Molecular methods including polymerase chain reaction, multiplex polymerase chain reaction, real-time/quantitative polymerase chain reaction, nucleic acid sequence-based amplification, loop-mediated isothermal amplification, DNA microarray, and next generation sequencing technology for the detection and identification of L. monocytogenes are discussed in this review. Overall, molecular methods are rapid, sensitive, specific, time- and labor-saving. In future, there are

  12. Control of Listeria monocytogenes in Turkey Deli Loaves using Organic Acids as Formulation Ingredients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growth of Listeria monocytogenes (LM) in further processed meat products has become a major concern and an important food safety issue. The meat and poultry industries have incorporated interventions such as organic acids in marinades in order to inhibit the growth of LM. In this study, organic...

  13. Growth of Salmonella and Listeria monocytogenes on fresh-cut cantaloupe under different temperature abuse scenarios

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effective cold chain management is a critical component of food safety practice. In this study, we examined the impact of commonly encountered temperature abuse scenarios on the proliferation of Salmonela enterica and Listeria monocytogenes on fresh-cut cantaloupe. During one week of storage, Salmon...

  14. Use of germicidal UV light to reduce low numbers of Listeria monocytogenes on raw chicken meat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a common constituent of the microbiological community in poultry processing plants and as such can be found in low numbers on raw poultry. Raw meat has been shown to be the most important source of this pathogen to commercial cooking facilities. Germicidal ultra violet (U...

  15. Heavy metal and disinfectant resistance of Listeria monocytogenes from foods and food processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The persistence of Listeria monocytogenes in food processing plants and other ecosystems can be attributed to its ability to adapt to numerous stresses. Resistance to arsenic, cadmium and the quaternary ammonium compound benzalkonium chloride (BC) are examples of such adaptations. In this study, we ...

  16. Use of high pressure processing to control Listeria monocytogenes in packaged Queso Fresco

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Queso Fresco (QF), a fresh, Hispanic-style cheese, is manufactured using pasteurized milk; however, its high pH (>6) and moisture content (>50%) coupled with post-pasteurization labor intensive practices may lead to contamination with Listeria monocytogenes (LM). The objective of this study was to ...

  17. The Prevalence of Listeria monocytogenes in Queso Fresco in Sinaloa, Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: The association of Listeria monocytogenes (Lm) outbreaks with Latin-style soft cheese has been well documented. The presence of Lm in fresh cheese, such as “Queso fresco” (QF), is a major public health concern in North, Central, and South America due to the popularity of this style o...

  18. Direct, quantitative detection of Listeria monocytogenes in fresh raw whole milk by qPCR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development and optimization of a method to detect and quantify Listeria monocytogenes in raw milk is described here. Three-step treatment of samples with EDTA, SDS, DNase and trypsin was combined with centrifugation to concentrate bacteria from 10 mL of raw milk and reduce or eliminate potenti...

  19. Sigma B is a determinant of fitness for listeria monocytogenes serotype 4b strain in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In nature the foodborne pathogen Listeria monocytogenes lives as a saprophyte where it can contaminate pre-harvest produce. This environment can present many stresses such as ultraviolet light, variations in temperature and humidity, and oxidative stress from growing plant matter in the soil. The ...

  20. Survival of Listeria monocytogenes in Wilted and Additive-Treated Grass Silage

    PubMed Central

    Pauly, TM; Tham, WA

    2003-01-01

    Grass was field-dried to 3 different dry matter (DM) levels (200, 430 and 540 g/kg) and inoculated with 106–107 cfu/g of a Listeria monocytogenes strain sharing a phagovar occasionally involved in food-borne outbreaks of listeriosis. Formic acid (3 ml/kg) or lactic acid bacteria (8·105/g) with cellulolytic enzymes were applied only to forages with low and intermediate DM levels. Forages were ensiled in laboratory silos (1700 ml) and were stored at 25°C for 30 or 90 days. After 90 days of storage, L. monocytogenes could not be detected in any silo, except one with the high dry matter grass without additive. After 30 days of storage, between 102 and 106 cfu L. monocytogenes/g silage were isolated from the untreated silages. Increasing the DM content from 200 to 540 g/kg did not reduce listeria counts possibly because of the lower production of fermentation acids (higher pH). In silages treated with additives, counts of L. monocytogenes were always lower than in silages without additive. In wet silages (DM 200 g/kg) both additives were effective, but in the wilted silages (DM 430 g/kg) only the bacterial additive reduced listeria counts below detection level. Listeria counts were highly correlated to silage pH (r = 0.92), the concentration of lactic acid (r = -0.80) and the pooled amount of undissociated acids (r = -0.83). PMID:14650546

  1. Listeria monocytogenes in ready-to-eat foods and intervention strategies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a foodborne pathogen capable of causing listeriosis, a severe illness that has a high fatality rate. It has been a significant food safety concern for decades due to its ubiquitous presence in the environment, ability to grow at refrigeration temperature, and resistance to ...

  2. Effect of temperature and salt on thermal inactivation of Listeria monocytogenes in Salmon Roe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a potentially fatal foodborne pathogen that can be found in ready-to-eat seafood products, such as fresh salmon roe. Once contaminated, salmon roe must be decontaminated prior to human consumption. This study was conducted to determine the thermal inactivation kinetics of...

  3. Detection and Rapid Purification of Internalin B as A Protein Marker in Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clinical and food strains of Listeria monocytogenes have been found to express InternalinB (InlB) without polymorphism. InlB, which is a 67-kDa surface protein, behaves as an invasion and adhesion protein of the bacterium into cells. Thus, InlB could be a good candidate as a protein marker to detect...

  4. Comparison of the Stress Response of Listeria monocytogenes Strains with Sprout Colonization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seventeen strains of the foodborne pathogen Listeria monocytogenes were tested for their ability to colonize alfalfa, radish, and broccoli sprouts, as well as their capacity to withstand acid and oxidative stress, two stresses common to the sprout growth environment. Whereas large variations in dif...

  5. Molecular ecology of Listeria monocytogenes: Evidence for a reservoir in milking equipment on a dairy farm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A longitudinal study aimed to detect Listeria monocytogenes on a New York State dairy farm, was conducted between February 2004 and July 2007. Fecal samples were collected every six months from all lactating cows. Approximately 20 environmental samples were obtained every three months. Bulk milk sam...

  6. Colonization of a Newly Constructed Commercial Chicken Further Processing Plant with Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was undertaken to determine potential sources of Listeria monocytogenes in a newly constructed chicken further processing plant and document the eventual colonization of the facility by this pathogen. To ascertain the colonization status of the plant, floor drains were sampled after a pr...

  7. Control of Listeria monocytogenes in Ham Deli Loaves using Organic Acids as Formulation Ingredients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic acids are popular preservatives and are utilized in the industry to inhibit the growth of Listeria monocytogenes (LM) in ready-to-eat (RTE) products. In this study, sodium lactate (SL), potassium lactate (PL) and sodium diacetate (SD) were utilized alone or in combination in the raw product...

  8. Quantitative Assessment of Disinfectant Activity Against Listeria monocytogenes Biofilms Under Flow Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes has a high mortality in humans and is responsible for most food recalls involving bacterial contamination. Our objective was to develop methods to quantitatively assess the pathogen under flow conditions to mimic wet food processing. A reactor was used to grow the bacteria on ...

  9. Germicidal ultra-violet light to eliminate low numbers of Listeria monocytogenes on raw chicken meat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes can be transferred from broiler slaughter plants to commercial cooking plants with raw product. Once in a cooking plant, this organism can become a long term resident and colonize floor drains. Earlier work showed that during plant wash down, an inadvertent short hose spray ...

  10. THE ROLE OF DIETARY VITAMIN E IN EXPERIMENTAL LISTERIA MONOCYTOGENES INFECTIONS IN TURKEYS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This experiment was conducted to evaluate the effect of dietary vitamin E in turkeys experimentally infected with Listeria monocytogenes. One-day-old turkeys (n = 70) were fed diets containing either 0 or 200 IU vitamin E. After 6 weeks on the experimental diet, turkeys were orally inoculated with...

  11. Antimicrobial activity of nisin incorporated in pectin and polylactic acid composite films against Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extruded composite films from 20% pectin and 80% polylactic acids (PLA) were developed and nisin was loaded into films by a diffusion post extrusion. Inhibitory activities of the films against Listeria monocytogenes were evaluated in brain heart infusion (BHI) broth, liquid egg white and orange juic...

  12. Effect of storage and subsequent re-heating on viability of Listeria monocytogenes on pork scrapple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the fate of Listeria monocytogenes on pork scrapple, a regionally-popular, ready-to-eat (RTE) meat product, both during storage and following re-heating. We also conducted an informal survey to address consumer practices for storing and re-heating scrapple. Regarding the survey, of some...

  13. Viability of Listeria monocytogenes on pork scrapple formulated with and without antimicrobials during extended refrigerated storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the addition of select food grade chemicals as ingredients to control Listeria monocytogenes on pork scrapple during refrigerated storage. In each of two trials, loaves (ca. 11 cm wide x ca. 6 cm high x ca. 64 cm long; ca. 5 kg each) of pork scrapple were formulated, with or without cit...

  14. Germicidal Ultraviolet Light to Lower Numbers of Listeria Monocytogenes on Broiler Breast Fillets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raw broiler breast fillets were subjected to germicidal ultraviolet (UV) light (dose of 1,000 µW/cm2 for 5 min at a wavelength of 254 nm) to evaluate its potential to reduce Listeria monocytogenes numbers on raw product before shipment to a poultry further-processing plant. Boneless, skinless breas...

  15. Survival of Aeromonas hydrophila and Listeria monocytogenes on fresh vegetables stored under moderate vacuum.

    PubMed

    Aytac, S A; Gorris, L G

    1994-11-01

    Storage at 6.5°C under moderate vacuum effectively prevented growth of Aeromonas hydrophila on chicory endive, but had only a limited inhibitory effect on the growth of the organism on mung bean sprouts. Growth of Listeria monocytogenes on chicory endive was strongly stimulated under these conditions, whereas it was decreased on mung-bean sprouts. PMID:24421192

  16. Near-Infrared Surface Pasteurization to Eliminate Listeria monocytogenes on Cooked Chicken Breast Meat Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to develop and evaluate a near-infrared (NIR) surface pasteurization process for decontamination of cooked ready-to-eat (RTE) meats to eliminate Listeria monocytogenes. An infrared heating device equipped with two fast-acting NIR-generating quartz lamps, an infrar...

  17. Early gene response of human brain endothelial cells to Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gene expression of human brain microvascular endothelial cells (HBMEC) to Listeria monocytogenes at 4 hour infection was analyzed. Four hours after infection, the expression of 456 genes of HBMEC had changed (p<0.05). We noted that many active genes were involved in the formyl-methionylleucylph...

  18. Comparison of measurement methods for Listeria monocytogenes biofilms under flow conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bacterial pathogen, Listeria monocytogenes, causes a high death rate among its victims and many food product recalls. Our goal was to develop methods to quantitatively assess the pathogen under conditions that mimic food environments. Stainless steel and glass coupons were incubated in aqueous m...

  19. Environmental factors influencing Listeria monocytogenes survival and attachment on surfaces inoculated with droplets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogenic microorganisms residing on food or food contact materials are important sources of food-borne microbial contamination. The objective of this study is to explore factors responsible for Listeria monocytogenes survival and colonization on surfaces when bacteria are inoculated from drying dr...

  20. Two Listeria monocytogenes Pseudo-outbreaks Caused by Contaminated Laboratory Culture Media

    PubMed Central

    Katz, Lee S.; Jackson, Kelly A.; Kucerova, Zuzana; Conrad, Amanda R.; Glover, William A.; Nguyen, Von; Mohr, Marika C.; Marsden-Haug, Nicola; Thompson, Deborah; Dunn, John R.; Stroika, Steven; Melius, Beth; Tarr, Cheryl; Dietrich, Stephen E.; Kao, Annie S.; Kornstein, Laura; Li, Zhen; Maroufi, Azarnoush; Marder, Ellyn P.; Meyer, Rebecca; Perez-Osorio, Ailyn C.; Reddy, Vasudha; Reporter, Roshan; Carleton, Heather; Tweeten, Samantha; Waechter, HaeNa; Yee, Lisa M.; Wise, Matthew E.; Davis, Kim; Jackson, Brendan R.

    2015-01-01

    Listeriosis is a serious foodborne infection that disproportionately affects elderly adults, pregnant women, newborns, and immunocompromised individuals. Diagnosis is made by culturing Listeria monocytogenes from sterile body fluids or from products of conception. This report describes the investigations of two listeriosis pseudo-outbreaks caused by contaminated laboratory media made from sheep blood. PMID:26699704

  1. Multilocus Genotyping Assays for SNP-based Subtyping of Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is responsible for serious invasive illness associated with consumption of contaminated food, and places a significant burden on public health and the agricultural economy. We recently developed a multilocus genotyping (MLGT) assay for high-throughput subtype determination of...

  2. Effect of high pressure processing on reduction of Listeria monocytogenes in packaged Queso Fresco

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of high hydrostatic pressure processing (HPP) on the survival of a five-strain rifampicin-resistant cocktail of Listeria monocytogenes in Queso Fresco (QF) was evaluated as a post-packaging intervention. QF was made using pasteurized, homogenized milk, was starter-free and was not pressed...

  3. Modeling surface transfer of Listeria monocytogenes between Salami and round blade

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several listeriosis outbreaks linked to the consumption of pre-sliced ready-to-eat (RTE) deli meats have drawn increased attention with regard to the possible cross-contamination of Listeria monocytogenes (Lm) during the slicing operations in retail food service establishment. The objective of thi...

  4. Effectiveness of bacteriophage to control the outgrowth of Listeria monocytogenes on the surface of frankfurters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: There have been numerous studies published on the effectiveness of surface-applied food grade chemical antimicrobials to control Listeria monocytogenes on RTE meat products; however, there is little to no information on the effectiveness of using bacteriophage to control this pathogen ...

  5. Virulence of Listeria monocytogenes following repeated exposure to Ultraviolet (254nm) Light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The foodborne pathogen Listeria monocytogenes is an occasional contaminant of ready-to-eat meat products such as frankfurters. Frankfurters can be contaminated following cooking and prior to packaging by contact with contaminated surfaces such as conveyors and packaging equipment. Ultraviolet Ligh...

  6. Characterization of Listeria monocytogenes isolated from Blue Crab Meat and Blue Crab Processing Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is an important food-borne pathogen associated with severe invasive disease in both humans and animals. It can inhabit different niches within food processing plants, including food contact equipment, leading to cross-contamination of finished products. However, there is only ...

  7. Eugenol in combination with lactic acid bacteria attenuates Listeria monocytogenes virulence in vitro and in invertebrate model Galleria mellonella.

    PubMed

    Upadhyay, Abhinav; Upadhyaya, Indu; Mooyottu, Shankumar; Venkitanarayanan, Kumar

    2016-06-01

    Listeria monocytogenes is a human enteric pathogen that causes severe foodborne illness in high-risk populations. Crossing the intestinal barrier is the first critical step for Listeria monocytogenes infection. Therefore, reducing L. monocytogenes colonization and invasion of intestinal epithelium and production of virulence factors could potentially control listeriosis in humans. This study investigated the efficacy of sub-inhibitory concentration (SIC) of the plant-derived antimicrobial eugenol, either alone, or in combination with five lactic acid bacteria (LAB), namely Bifidobacterium bifidum (NRRL-B41410), Lactobacillus reuteri (B-14172), Lactobacillus fermentum (B-1840), Lactobacillus plantarum (B-4496) and Lactococcus lactis subspecies lactis (B-633) in reducing Listeria monocytogenes adhesion to and invasion of human intestinal epithelial cells (Caco-2). Additionally, the effect of the aforementioned treatments on Listeria monocytogenes listeriolysin production, epithelial E-cadherin binding and expression of virulence genes was investigated. Moreover, the in vivo efficacy of eugenol-LAB treatments in reducing Listeria monocytogenes virulence in the invertebrate model Galleria mellonella was studied. Eugenol and LAB, either alone or in combination, significantly reduced Listeria monocytogenes adhesion to and invasion of intestinal cells (P < 0.05). Moreover, eugenol-LAB treatments decreased Listeria monocytogenes haemolysin production, E-cadherin binding and virulence gene expression (P < 0.05). In addition, the eugenol-LAB treatments significantly enhanced the survival rates of G. mellonella infected with lethal doses of Listeria monocytogenes (P < 0.05). The results highlight the antilisterial effect of eugenol either alone or in combination with LAB, and justify further investigations in a mammalian model. PMID:27002648

  8. Isolation of Listeria monocytogenes from goat cheese associated with a case of listeriosis in goat.

    PubMed

    Eilertz, I; Danielsson-Tham, M L; Hammarberg, K E; Reeves, M W; Rocourt, J; Seeliger, H P; Swaminathan, B; Tham, W

    1993-01-01

    Listeria monocytogenes was isolated from the brain of a goat, which was euthanized due to listeriosis. A few weeks later a similar subtype of L. monocytogenes was isolated from an on-farm manufactured fresh cheese which did not contain any milk from the goat which had suffered from listeriosis. A similar subtype was also found on 1 of the shelves in the refrigerator where cheeses were stored. Prior to the onset of listeriosis, 1 fresh cheese had been made of milk from the actual goat, which may have excreted L. monocytogenes in her milk. Thus, the cheese made of this milk may have contaminated the shelves in the refrigerator which then has served as a Listeria reservoir for new cheeses during several weeks. PMID:8266892

  9. Rapid identification and classification of Listeria spp. and serotype assignment of Listeria monocytogenes using fourier transform-infrared spectroscopy and artificial neural network analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of Fourier Transform-Infrared Spectroscopy (FT-IR) in conjunction with Artificial Neural Network software, NeuroDeveloper™ was examined for the rapid identification and classification of Listeria species and serotyping of Listeria monocytogenes. A spectral library was created for 245 strains...

  10. Twenty Years of Listeria in Brazil: Occurrence of Listeria Species and Listeria monocytogenes Serovars in Food Samples in Brazil between 1990 and 2012

    PubMed Central

    Vallim, Deyse Christina; Barroso Hofer, Cristina; Lisbôa, Rodrigo de Castro; Victor Barbosa, André; Alves Rusak, Leonardo; dos Reis, Cristhiane Moura Falavina; Hofer, Ernesto

    2015-01-01

    Listeria spp. isolated from different food products and collected from 12 Brazilian states were sent to the Laboratory of Bacterial Zoonoses (Oswaldo Cruz Institute, Brazil) for identification. The aims of this study were to characterize these isolates, from 1990 to 2012, by using biochemical, morphological, and serotyping tests, and to analyze the distribution of L. monocytogenes serotypes on different food products and geographical locations. Serotyping was performed using polyclonal somatic and flagellar antisera. Of 5953 isolates, 5770 were identified as Listeria spp., from which 3429 (59.4%) were L. innocua, 2248 (38.9%) were L. monocytogenes, and 93 (1.6%) were other Listeria spp. L. innocua was predominantly isolated from 1990 to 2000, while L. monocytogenes was from 2001 to 2012. Regarding the serotype distribution in the foods, serotypes 1/2a and 4b were most common in processed meat and ready-to-eat products, respectively; serotypes 1/2a, 1/2b, and 4b were the most common in nonprocessed meat. The results above confirm the presence of the main serotypes of L. monocytogenes in different parts of the food chain from three regions of the country and emphasize the importance of improving the control measures, as tolerance zero policy and microbiological surveillance in Brazil. PMID:26539507

  11. Different methods to quantify Listeria monocytogenes biofilms cells showed different profile in their viability.

    PubMed

    Winkelströter, Lizziane Kretli; De Martinis, Elaine C P

    2015-03-01

    Listeria monocytogenes is a foodborne pathogen able to adhere and to form biofilms in several materials commonly present in food processing plants. The aim of this study was to evaluate the resistance of Listeria monocytogenes attached to abiotic surface, after treatment with sanitizers, by culture method, microscopy and Quantitative Real Time Polymerase Chain Reaction (qPCR). Biofilms of L. monocytogenes were obtained in stainless steel coupons immersed in Brain Heart Infusion Broth, under agitation at 37 °C for 24 h. The methods selected for this study were based on plate count, microscopic count with the aid of viability dyes (CTC-DAPI), and qPCR. Results of culture method showed that peroxyacetic acid was efficient to kill sessile L. monocytogenes populations, while sodium hypochlorite was only partially effective to kill attached L. monocytogenes (p < 0.05). When, viability dyes (CTC/DAPI) combined with fluorescence microscopy and qPCR were used and lower counts were found after treatments (p < 0.05). Selective quantification of viable cells of L. monocytogenes by qPCR using EMA revelead that the pre-treatment with EMA was not appropriate since it also inhibited amplification of DNA from live cells by ca. 2 log. Thus, the use of CTC counts was the best method to count viable cells in biofilms. PMID:26221112

  12. Genotypic analyses and virulence characterization of Listeria monocytogenes isolates from crayfish (Procambarus clarkii).

    PubMed

    Li, Jinquan; Du, Pujun; Li, Zhi; Zhou, Yang; Cheng, Wei; Wu, Si; Chen, Fusheng; Wang, Xiaohong

    2015-05-01

    Listeria monocytogenes is a foodborne pathogen that can cause invasive illness in humans and farm animals. It is frequently isolated from dairy products and poultry. However, there have been few literatures on the genetic diversity and virulence potential of L. monocytogenes from freshwater animal. Thirty-nine L. monocytogenes strains from crayfish were isolated and identified in this study. Molecular subtyping and polymorphism of each isolate were analyzed by multilocus sequence typing (MLST). MLST divided the isolates into eight sequence types (STs), six of which from crayfish were the same with the isolates from environment and clinic. PCR detection of the eight genes related to virulence and multiplex PCR for serotyping showed that the eight virulence factors were present in the isolates and all the isolates belonged to four major L. monocytogenes serotype groups (1/2a, 1/2b, 1/2c, and 4b) frequently isolated from patients. In vivo pathogenicity of isolates was also evaluated in murine model and survival curve of infected mice suggested that ST1, ST4, and ST9 isolates were as virulent as the reference strain EGDe. This study provides preliminary insights into the genetic diversity of L. monocytogenes from crayfish and the genetic correlation between crayfish and clinical L. monocytogenes isolates. The results indicate the contamination in aquaculture could be the source of Listeria contamination and the isolates are likely to cause human listeriosis. PMID:25586079

  13. Effect of honokiol on exotoxin proteins listeriolysin O and p60 secreted by Listeria monocytogenes.

    PubMed

    Meng, Rizeng; Zhao, Ziwen; Guo, Na; Liu, Zonghui; Zhao, Xingchen; Li, Wenli; Li, Xiaoxu; Shi, Ce; Nie, Dandan; Wang, Weilin; Liu, Tao; Ma, Wenchen; Yu, Lu; Li, Juan

    2015-12-01

    Listeria monocytogenes is considered one of the most important foodborne pathogens. The virulence-related proteins listeriolysin O (LLO) and p60 are critical factors involved in Listeria pathogenesis. In the present study, we investigated the effect of honokiol on LLO and p60 secreted from L. monocytogenes. A listeriolysin assay was used to investigate the haemolytic activities of L. monocytogenes exposed to honokiol, and the secretion of LLO and p60 was detected by immunoblot analysis. Additionally, the influence of honokiol on the transcription of LLO and p60 genes (hly and iap, respectively) was analysed by real-time reverse transcription PCR. TNF-α release assays were performed to elucidate the biological relevance of changes in LLO and p60 secretion induced by honokiol. According to the data, honokiol showed good anti-L. monocytogenes activity, with MICs of 8-16 μg ml(-1), and the secretion of LLO and p60 was decreased by honokiol. In addition, the transcription of hly and iap was inhibited by honokiol. Our results indicate that TNF-α production by RAW264.7 cells stimulated with L. monocytogenes supernatants was inhibited by honokiol. Based on these data, we propose that honokiol could be used as a promising natural compound against L. monocytogenes and its virulence factors. PMID:26445991

  14. Atlas(®) Listeria monocytogenes LmG2 Detection Assay Using Transcription Mediated Amplification to Detect Listeria monocytogenes in Selected Foods and Stainless Steel Surface.

    PubMed

    Bres, Vanessa; Yang, Hua; Hsu, Ernie; Ren, Yan; Cheng, Ying; Wisniewski, Michele; Hanhan, Maesa; Zaslavsky, Polina; Noll, Nathan; Weaver, Brett; Campbell, Paul; Reshatoff, Michael; Becker, Michael

    2014-01-01

    The Atlas Listeria monocytogenes LmG2 Detection Assay, developed by Roka Bioscience Inc., was compared to a reference culture method for seven food types (hot dogs, cured ham, deli turkey, chicken salad, vanilla ice cream, frozen chocolate cream pie, and frozen cheese pizza) and one surface (stainless steel, grade 316). A 125 g portion of deli turkey was tested using a 1:4 food:media dilution ratio, and a 25 g portion for all other foods was tested using 1:9 food:media dilution ratio. The enrichment time and media for Roka's method was 24 to 28 h for 25 g food samples and environmental surfaces, and 44 to 48 h for 125 g at 35 ± 2°C in PALCAM broth containing 0.02 g/L nalidixic acid. Comparison of the Atlas Listeria monocytogenes LmG2 Detection Assay to the reference method required an unpaired approach. For each matrix, 20 samples inoculated at a fractional level and five samples inoculated at a high level with a different strain of Listeria monocytogenes were tested by each method. The Atlas Listeria monocytogenes LmG2 Detection Assay was compared to the Official Methods of Analysis of AOAC INTERNATIONAL 993.12 method for dairy products, the U.S. Department of Agriculture, Food Safety and Inspection Service, Microbiology Laboratory Guidebook 8.08 method for ready-to-eat meat and environmental samples, and the U.S. Food and Drug Administration Bacteriological Analytical Manual, Chapter 10 method for frozen foods. In the method developer studies, Roka's method, at 24 h (or 44 h for 125 g food samples), had 126 positives out of 200 total inoculated samples, compared to 102 positives for the reference methods at 48 h. In the independent laboratory studies, vanilla ice cream, deli turkey and stainless steel grade 316 were evaluated. Roka's method, at 24 h (or 44 h for 125 g food samples), had 64 positives out of 75 total inoculated samples compared to 54 positives for the reference methods at 48 h. The Atlas Listeria monocytogenes LmG2 Detection Assay detected all 50

  15. Combination of immunomagnetic separation with flow cytometry for detection of Listeria monocytogenes.

    PubMed

    Hibi, Kyoko; Abe, Akihisa; Ohashi, Eiji; Mitsubayashi, Kohji; Ushio, Hideki; Hayashi, Tetsuhito; Ren, Huifeng; Endo, Hideaki

    2006-07-28

    Listeria monocytogenes can grow at the low temperature commonly used in the storage and transportation of food, and the number of cases of food poisoning caused by L. monocytogenes has increased recently in the US and Europe. Several methods of detecting L. monocytogenes cells have been proposed; however, all existing methods require approximately 48 h incubation. In this study, we attempted rapid detection of L. monocytogenes using flow cytometry (FCM). The method is based on measuring the number of L. monocytogenes cells by using a combination of FCM and immunomagnetic separation (IMS). First, polyclonal antibodies (anti-L. monocytogenes rabbit IgG-FITC) conjugated with fluorescein isothiocyanate (FITC) were reacted with L. monocytogenes cells, and then FCM was applied. The cell numbers were determined by FCM using a traditional colony-counting method in the range of 10(4)-10(8) cells ml(-1). Tetrameric antibody complexes (TAC) were used because they can recognize both magnetic and FITC molecules on the FITC-conjugated antibodies. FITC-labeled L. monocytogenes cells were reacted with a secondary antibody (TAC) bound to magnetic beads. Then, IMS was used. The method is suitable for detection in the range of 10(2)-10(8)cells ml(-1). The FCM assay enumerated the cells within 1 min and the total assay time, including sample preparation, was less than 2 h. PMID:17723519

  16. Antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts against the growth of Listeria monocytogenes and Salmonella Enteritidis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We studied the antimicrobial effects of berry extracts obtained from four cultivars (Elliott, Darrow, Bluecrop and Duke) of blueberry (Vaccinium corymbosum L.) on the growth of Listeria monocytogenes and Salmonella Enteritidis. The minimal inhibitory concentration (MIC) and minimal bactericidal conc...

  17. Efficacy of direct plating media for recovering Listeria monocytogenes from foods.

    PubMed

    Golden, D A; Brackett, R E; Beuchat, L R

    1990-03-01

    Studies were done to evaluate 14 direct plating media for their suitability to recover Listeria monocytogenes strain Scott A from pasteurized whole milk, chocolate ice cream mix, Brie cheese and raw cabbage. Healthy cells were inoculated into foods to achieve viable populations of 10(2), 10(4), or 10(6) cells/ml(g). Bind's Acriflavine Agar, Trypaflavine Nalidixic Acid Serum Agar, Listeria Transport Enrichment Agar, Doyle and Schoeni Selective Enrichment Agar (DSSEA) and Modified DSSEA were not suitable for recovering L. monocytogenes from milk and Brie cheese and were therefore not evaluated as direct plating media for recovering the organism from ice cream mix and cabbage. McBride Listeria Agar (MLA), Gum Base Nalidixic Acid Tryptone Soya Agar (GBNTSA), Modified Despierres Agar (MDA) and Modified MLA (MMLA) performed best for recovering all inoculum populations from milk and ice cream mix. Enumeration of L. monocytogenes on several test media was complicated by the growth of large numbers of background microflora present in cabbage and Brie cheese, especially at the lowest test inoculum (10(2)/g). Generally, complete recovery of L. monocytogenes from Brie cheese and cabbage was attained on media when the inoculum population was greater than or equal to 10(4) cells/g. For Brie cheese, MLA, MDA, MMLA and Dominguez Rodriguez Isolation Agar were superior for recovering L. monocytogenes, while GBNTSA, DLEA, MDA and MMLA were best for recovering the organism from cabbage. Results of this experiment indicate that direct-plating procedures, without prior enrichment, can successfully be utilized for recovering L. monocytogenes from foods such as pasteurized milk and ice cream mix which contain low populations of background microflora. However, recovery of L. monocytogenes from foods such as raw cabbage and Brie cheese, which contain high populations of other microorganisms, was not satisfactory using the direct-plating procedures evaluated in this investigation. PMID

  18. Development of a repair-enrichment broth for resuscitation of heat-injured Listeria monocytogenes and Listeria innocua.

    PubMed Central

    Busch, S V; Donnelly, C W

    1992-01-01

    The ability of the divalent cations magnesium, iron, calcium and manganese; yeast extract; pyruvate; catalase; and the carbohydrates glucose, lactose, sucrose, esculin, fructose, galactose, maltose, and mannose to facilitate repair of heat-injured Listeria monocytogenes and Listeria innocua was evaluated. Listeria populations were injured by heating at 56 degrees C for 50 min. To determine the effects on repair, Trypticase soy broth (TSB) was supplemented with each medium component to be evaluated. Repair occurred to various degrees within 5 h in TSB supplemented with glucose, lactose, sucrose, yeast extract, pyruvate, or catalase. Chelex-exchanged TSB was supplemented with divalent cations; magnesium and iron cations were found to have a role in repair. Listeria repair broth (LRB) was formulated by utilizing the components that had the greatest impact upon repair. When incubated in LRB, heat-injured Listeria cells completed repair in 5 h. After the repair, acriflavin, nalidixic acid, and cycloheximide were added to LRB to yield final concentrations identical to those of the selective enrichment broths used in the procedures of the Food and Drug Administration and the U.S. Department of Agriculture. The efficacy of LRB in promoting repair and enrichment of heat-injured Listeria cells was compared with that of existing selective enrichment broths. Repair was not observed in the Food and Drug Administration enrichment broth, Listeria enrichment broth, or University of Vermont enrichment broth. The final Listeria populations after 24 h of incubation in selective enrichment media were 1.7 x 10(8) to 9.1 x 10(8) CFU/ml; populations in LRB consistently averaged 2.5 x 10(11) to 8.2 x 10(11) CFU/ml. PMID:1531746

  19. Identification of the agr Peptide of Listeria monocytogenes

    PubMed Central

    Zetzmann, Marion; Sánchez-Kopper, Andrés; Waidmann, Mark S.; Blombach, Bastian; Riedel, Christian U.

    2016-01-01

    Listeria monocytogenes (Lm) is an important food-borne human pathogen that is able to strive under a wide range of environmental conditions. Its accessory gene regulator (agr) system was shown to impact on biofilm formation and virulence and has been proposed as one of the regulatory mechanisms involved in adaptation to these changing environments. The Lm agr operon is homologous to the Staphylococcus aureus system, which includes an agrD-encoded autoinducing peptide that stimulates expression of the agr genes via the AgrCA two-component system and is required for regulation of target genes. The aim of the present study was to identify the native autoinducing peptide (AIP) of Lm using a luciferase reporter system in wildtype and agrD deficient strains, rational design of synthetic peptides and mass spectrometry. Upon deletion of agrD, luciferase reporter activity driven by the PII promoter of the agr operon was completely abolished and this defect was restored by co-cultivation of the agrD-negative reporter strain with a producer strain. Based on the sequence and structures of known AIPs of other organisms, a set of potential Lm AIPs was designed and tested for PII-activation. This led to the identification of a cyclic pentapeptide that was able to induce PII-driven luciferase reporter activity and restore defective invasion of the agrD deletion mutant into Caco-2 cells. Analysis of supernatants of a recombinant Escherichia coli strain expressing AgrBD identified a peptide identical in mass and charge to the cyclic pentapeptide. The Lm agr system is specific for this pentapeptide since the AIP of Lactobacillus plantarum, which also is a pentapeptide yet with different amino acid sequence, did not induce PII activity. In summary, the presented results provide further evidence for the hypothesis that the agrD gene of Lm encodes a secreted AIP responsible for autoregulation of the agr system of Lm. Additionally, the structure of the native Lm AIP was identified. PMID

  20. Interactions in biofilms between Listeria monocytogenes and resident microorganisms from food industry premises.

    PubMed

    Carpentier, Brigitte; Chassaing, Danielle

    2004-12-15

    Twenty nine bacterial strains were grown as binary culture biofilms with Listeria monocytogenes to assess their influence on the settlement of the latter on stainless steel coupons. Most of the strains had been isolated from food processing plants after cleaning and disinfection and were tentatively identified by the APILAB Plus 3.3.3 database (bioMerieux). Sixteen of them decreased L. monocytogenes biofilm colony forming units (CFU) counts. Three strains, Bacillus sp. CCL 9 an unidentified Gram-positive strain CCL 59 and Pseudomonas fluorescens E9. 1, led to a 3-log difference in CFU counts between the pure L. monocytogenes biofilms and the mixed biofilms. Eleven strains had no effect and only four, Kocuria varians CCL 73, Staphylococcus capitis CCL 54, Stenotrophomonas maltophilia CCL 47 and Comamonas testosteroni CCL 24, had a positive effect, with a 0.5- to 1.0-log increase in the L. monocytogenes biofilm CFU counts. On its own, L. monocytogenes settled as single cells, but in binary biofilms, different spatial arrangements were observed: (i) with K. varians CCL 73, K. varians CCL 56 and S. capitis CCL 54, L. monocytogenes cells gathered around the microcolonies of the partner strain; (ii) with the two Gram-negative strains, C. testosteroni CCL 24 and CCL 25, L. monocytogenes cells formed its own microcolonies. No link could be found between the exopolysaccharide production capacity of the bacterial strains in pure-culture biofilms and their effect on the L. monocytogenes population in mixed biofilms. With one strain, C. testosteroni CCL 24, adding filter-sterilized supernatant from a pure-culture biofilm to a pure culture of L. monocytogenes increased the number of L. monocytogenes cells adhering to the stainless steel coupons and forming microcolonies. This study suggests that the "house flora" can have a strong effect on the likelihood of finding L. monocytogenes on inert surfaces. PMID:15541798

  1. Isolation and characterization of atypical Listeria monocytogenes associated with a canine urinary tract infection.

    PubMed

    Palerme, Jean-Sébastien; Pan, Po Ching; Parsons, Cameron T; Kathariou, Sophia; Ward, Todd J; Jacob, Megan E

    2016-09-01

    Listeria monocytogenes, a well-described cause of encephalitis and abortion in ruminants and of food-borne illness in humans, is rarely associated with disease in companion animals. A case of urinary tract infection associated with an atypical, weakly hemolytic L. monocytogenes strain is described in a diabetic dog. The serotype of the L. monocytogenes isolate was determined to be 1/2a (3a), with the multilocus genotyping pattern 2.72_1/2a. A nucleotide substitution (Gly145Asp) was detected at residue 145 in the promoter prfA region. This residue is within the critical helix-turn-helix motif of PrfA. The source of the L. monocytogenes strain remains unknown, and the dog recovered after a 4-week course of cephalexin (30 mg/kg orally twice daily). PMID:27493137

  2. Prevalence and quantification of Listeria monocytogenes in beef offal at retail level in Selangor, Malaysia

    PubMed Central

    Kuan, Chee Hao; Wong, Woan Chwen; Pui, Chai Fung; Mahyudin, Nor Ainy; Tang, John Yew Huat; Nishibuchi, Mitsuaki; Radu, Son

    2013-01-01

    A total of 63 beef offal samples (beef liver = 16; beef lung = 14; beef intestine = 9; beef tripe = 15; beef spleen = 9) from three wet markets (A, B, and C) in Selangor, Malaysia were examined for the prevalence and microbial load of Listeria monocytogenes. A combination of the most probable number and polymerase chain reaction (MPN-PCR) method was employed in this study. It was found that L. monocytogenes detected in 33.33% of the beef offal samples. The prevalence of L. monocytogenes in beef offal purchased from wet markets A, B, and C were 22.73%, 37.50% and 41.18% respectively. The density of L. monocytogenes in all the samples ranged from < 3 up to > 2,400 MPN/g. The findings in this study indicate that beef offal can be a potential vehicle of foodborne listeriosis. PMID:24688507

  3. Inhibitory effect of liposome-entrapped lemongrass oil on the growth of Listeria monocytogenes in cheese.

    PubMed

    Cui, H Y; Wu, J; Lin, L

    2016-08-01

    Listeria monocytogenes infection in dairy products is of mounting public concern. To inhibit bacterial growth, we engineered stimuli-responsive liposomes containing lemongrass oil for this study. The controlled release of liposome-entrapped lemongrass oil is triggered by listerolysin O, secreted by L. monocytogenes. We investigated the antibiotic activities of lemongrass oil liposomes against L. monocytogenes in cheese. We also assessed their possible effects on the quality of the cheese. Liposomes containing lemongrass oil (5.0mg/mL) presented the optimal polydispersity index (0.246), zeta-potential (-58.9mV) and entrapment efficiency (25.7%). The liposomes displayed satisfactory antibiotic activity against L. monocytogenes in cheese over the storage period at 4°C. We observed no effects on the physical and sensory properties of the cheese after the liposome treatment. PMID:27265173

  4. Prevalence and contamination levels of listeria monocytogenes in ready-to-eat foods in Tokyo, Japan

    PubMed Central

    SHIMOJIMA, Yukako; IDA, Miki; NAKAMA, Akiko; NISHINO, Yukari; FUKUI, Rie; KURODA, Sumiyo; HIRAI, Akihiko; KAI, Akemi; SADAMASU, Kenji

    2016-01-01

    We surveyed prevalence and contamination levels of Listeria monocytogenes in ready-to-eat foods between 2000 and 2012 in Tokyo. L. monocytogenes was isolated from 52 (1.7%) out of 2,980 samples. Comparing the prevalence in the study period, 2.2% were positive in the former period (2000–2005) and 1.2% in the latter (2006–2012). Using the most probable number (MPN) technique, 32 samples were contaminated with fewer than 0.3 L. monocytogenes/g, 10 samples with 0.3–1.0/g and 4 samples with more than 1.0/g (the maximum was 2.3/g). The most common serovar was 1/2a, followed by 1/2b, 4b and 1/2c. We revealed that ready-to-eat foods in Tokyo were contaminated with L. monocytogenes, although the contamination levels were low. PMID:27000951

  5. Fisetin inhibits Listeria monocytogenes virulence by interfering with the oligomerization of listeriolysin O.

    PubMed

    Wang, Jianfeng; Qiu, Jiazhang; Tan, Wei; Zhang, Yu; Wang, Hongshu; Zhou, Xuan; Liu, Shui; Feng, Haihua; Li, Wenhua; Niu, Xiaodi; Deng, Xuming

    2015-05-01

    Listeriolysin O (LLO), an essential virulence determinant of Listeria monocytogenes, is a pore-forming toxin whose primary function is to facilitate cytosolic bacterial replication by breaching the phagosomal membranes, which is critical for the pathogen to evade host immune recognition. The critical role of LLO in the virulence of L. monocytogenes renders it an ideal target for designing novel antivirulence therapeutics. We found that fisetin, a natural flavonoid without antimicrobial activity, is a potent antagonist of LLO-mediated hemolysis. Fisetin effectively inhibits L. monocytogenes infection in both tissue culture and animal infection models. Molecular modeling and mutational analysis revealed that fisetin directly engages loop 2 and loop 3 of LLO, leading to the blockage of cholesterol binding and the reduction of its oligomerization, thus inhibiting its hemolytic activity. Our results establish fisetin as an effective antitoxin agent for LLO, which can be further developed into novel therapeutics against infections caused by L. monocytogenes. PMID:25231018

  6. Prevalence and contamination levels of listeria monocytogenes in ready-to-eat foods in Tokyo, Japan.

    PubMed

    Shimojima, Yukako; Ida, Miki; Nakama, Akiko; Nishino, Yukari; Fukui, Rie; Kuroda, Sumiyo; Hirai, Akihiko; Kai, Akemi; Sadamasu, Kenji

    2016-08-01

    We surveyed prevalence and contamination levels of Listeria monocytogenes in ready-to-eat foods between 2000 and 2012 in Tokyo. L. monocytogenes was isolated from 52 (1.7%) out of 2,980 samples. Comparing the prevalence in the study period, 2.2% were positive in the former period (2000-2005) and 1.2% in the latter (2006-2012). Using the most probable number (MPN) technique, 32 samples were contaminated with fewer than 0.3 L. monocytogenes/g, 10 samples with 0.3-1.0/g and 4 samples with more than 1.0/g (the maximum was 2.3/g). The most common serovar was 1/2a, followed by 1/2b, 4b and 1/2c. We revealed that ready-to-eat foods in Tokyo were contaminated with L. monocytogenes, although the contamination levels were low. PMID:27000951

  7. Prevalence and quantification of Listeria monocytogenes in beef offal at retail level in Selangor, Malaysia.

    PubMed

    Kuan, Chee Hao; Wong, Woan Chwen; Pui, Chai Fung; Mahyudin, Nor Ainy; Tang, John Yew Huat; Nishibuchi, Mitsuaki; Radu, Son

    2013-12-01

    A total of 63 beef offal samples (beef liver = 16; beef lung = 14; beef intestine = 9; beef tripe = 15; beef spleen = 9) from three wet markets (A, B, and C) in Selangor, Malaysia were examined for the prevalence and microbial load of Listeria monocytogenes. A combination of the most probable number and polymerase chain reaction (MPN-PCR) method was employed in this study. It was found that L. monocytogenes detected in 33.33% of the beef offal samples. The prevalence of L. monocytogenes in beef offal purchased from wet markets A, B, and C were 22.73%, 37.50% and 41.18% respectively. The density of L. monocytogenes in all the samples ranged from < 3 up to > 2,400 MPN/g. The findings in this study indicate that beef offal can be a potential vehicle of foodborne listeriosis. PMID:24688507

  8. Irrigation Is Significantly Associated with an Increased Prevalence of Listeria monocytogenes in Produce Production Environments in New York State.

    PubMed

    Weller, Daniel; Wiedmann, Martin; Strawn, Laura K

    2015-06-01

    Environmental (i.e., meteorological and landscape) factors and management practices can affect the prevalence of foodborne pathogens in produce production environments. This study was conducted to determine the prevalence of Listeria monocytogenes, Listeria species (including L. monocytogenes), Salmonella, and Shiga toxin-producing Escherichia coli (STEC) in produce production environments and to identify environmental factors and management practices associated with their isolation. Ten produce farms in New York State were sampled during a 6-week period in 2010, and 124 georeferenced samples (80 terrestrial, 33 water, and 11 fecal) were collected. L. monocytogenes, Listeria spp., Salmonella, and STEC were detected in 16, 44, 4, and 5% of terrestrial samples, 30, 58, 12, and 3% of water samples, and 45, 45, 27, and 9% of fecal samples, respectively. Environmental factors and management practices were evaluated for their association with terrestrial samples positive for L. monocytogenes or other Listeria species by univariate logistic regression; analysis was not conducted for Salmonella or STEC because the number of samples positive for these pathogens was low. Although univariate analysis identified associations between isolation of L. monocytogenes or Listeria spp. from terrestrial samples and various water-related factors (e.g., proximity to wetlands and precipitation), multivariate analysis revealed that only irrigation within 3 days of sample collection was significantly associated with isolation of L. monocytogenes (odds ratio = 39) and Listeria spp. (odds ratio = 5) from terrestrial samples. These findings suggest that intervention at the irrigation level may reduce the risk of produce contamination. PMID:26038903

  9. Magnetic bead based immuno-detection of Listeria monocytogenes and Listeria ivanovii from infant formula and leafy green vegetables using the Bio-Plex suspension array system.

    PubMed

    Day, J B; Basavanna, U

    2015-04-01

    Listeriosis, a disease contracted via the consumption of foods contaminated with pathogenic Listeria species, can produce severe symptoms and high mortality in susceptible people and animals. The development of molecular methods and immuno-based techniques for detection of pathogenic Listeria in foods has been challenging due to the presence of assay inhibiting food components. In this study, we utilize a macrophage cell culture system for the isolation and enrichment of Listeria monocytogenes and Listeria ivanovii from infant formula and leafy green vegetables for subsequent identification using the Luminex xMAP technique. Macrophage monolayers were exposed to infant formula, lettuce and celery contaminated with L. monocytogenes or L. ivanovii. Magnetic microspheres conjugated to Listeria specific antibody were used to capture Listeria from infected macrophages and then analyzed using the Bio-Plex 200 analyzer. As few as 10 CFU/mL or g of L. monocytogenes was detected in all foods tested. The detection limit for L. ivanovii was 10 CFU/mL in infant formula and 100 CFU/g in leafy greens. Microsphere bound Listeria obtained from infected macrophage lysates could also be isolated on selective media for subsequent confirmatory identification. This method presumptively identifies L. monocytogenes and L. ivanovii from infant formula, lettuce and celery in less than 28 h with confirmatory identifications completed in less than 48 h. PMID:25475329

  10. Listeria monocytogenes strains isolated from dry milk samples in Mexico: occurrence and antibiotic sensitivity.

    PubMed

    Rodas-Suárez, O R; Quiñones-Ramírez, E I; Fernández, F J; Vázquez-Salinas, C

    2013-09-01

    Dry milk is a particular concern in Mexico, as approximately 150,000 metric tons of dry milk are imported every year at a cost of around $250 million. Dry milk is used to make many products, most of which are dairy products widely distributed among the population covered by welfare programs. The purpose of the study described in this article was to determine the presence of Listeria spp. in imported dry milk samples in Mexico, and to determine the sensitivity of the Listeria monocytogenes isolates to different antimicrobial agents. Listeria isolates (7.8% of 550 bacterial isolates) were identified as L. monocytogenes (53.49%), L. innocua (30.23%), L. seeligeri (13.95%), and L. ivanovii (2.33%). L. monocytogenes strains isolated showed multiresistance to ampicillin, erythromycin, tetracycline, dicloxacillin, and trimethoprim-sulfamethoxazole (9%-14%). The results provide additional evidence of the emergence of multiresistant Listeria strains both in nature and in widely consumed dairy products, representing a potential threat to human health. PMID:24073487

  11. Factors contributes to spontaneous abortion caused by Listeria monocytogenes, in Tehran, Iran, 2015.

    PubMed

    Pourkaveh, B; Ahmadi, M; Eslami, G; Gachkar, L

    2016-01-01

    Spontaneous abortion is the loss of a fetus before the 20th week of pregnancy, when occurring naturally without any surgical or pharmaceutical intervention. On the other hand, Listeria monocytogenes, as one of the foodborne pathogens, is a causative agent of listeriosis. The transfer of L. monocytogenes in pregnant women occurs as self-limited flu-like symptoms which may result in abortion, stillbirth or premature birth of infected infants. The purpose of this study was the identification of Listeria monocytogenes risk factors in women with spontaneous abortion admitted to Tehran Province health care centers in 2015. In this cross-sectional study, 317 women were examined for L. monocytogenes using Polymerase Chain Reaction (PCR) and the related risk factors. Two questionnaires on "L. monocytogenes Probable Risk Factors" and "Socio Economic Factors" were completed. Out of 317 samples of vaginal swabs, 54 (17%) isolates of L. monocytogenes were identified. In addition significant differences in terms of age of mother and her husband, mother and the husband's level of education , house prices, place of residence, gestational age of first abortion, gestational age of current abortion, gestational age of second abortion, consumption of unpasteurized dairy products, consumption of feta and soft cheese, consumption of smoked see food products, consumption of processed meat products and half-cooked meat products, consumption of ready-to-eat vegetables, history of contact with domestic animals three month before pregnancy and during pregnancy and consumption of smoked meat products during pregnancy were studied between two groups of patients positive and negative with L. monocytogens (P < 0.001). Based on the study, the detection of L. monocytogens risk factor during pregnancy as well as taking the issue into account while giving information and counseling in pregnancy can be vital to reduce the incidence of this bacterium and subsequently its side effects during

  12. Validation of the Applied Biosystems 7500 Fast Instrument for Detection of Listeria monocytogenes with the SureTect Listeria monocytogenes PCR Assay.

    PubMed

    Cloke, Jonathan; Arizanova, Julia; Crabtree, David; Simpson, Helen; Evans, Katharine; Vaahtoranta, Laura; Palomäki, Jukka-Pekka; Artimo, Paulus; Huang, Feng; Liikanen, Maria; Koskela, Suvi

    2016-05-01

    In 2013, the Thermo Scientific™ SureTect™ Listeria monocytogenes Real-Time PCR Assay was certified by the AOAC Research Institute (RI) Performance Tested Methods(SM) program as a rapid method for the detection of L. monocytogenes from a wide range of food matrixes and surface samples. This report details the method modification studies undertaken to extend the analysis of this PCR assay to the Applied Biosystems™ 7500 Fast PCR Instrument and Applied Biosystems RapidFinder™ Express 2.0 software allowing the use of the SureTect assay on a 96 well format PCR cycler in addition to the current workflow, which uses the 24 well Thermo Scientific PikoReal™ PCR Instrument and Thermo Scientific SureTect software. Because this study was deemed by AOAC-RI to be a level 2 method modification study, a representative range of food matrixes covering raw ground turkey, 2% fat pasteurized milk, and bagged lettuce as well as stainless steel surface samples were analyzed with the Applied Biosystems 7500 Fast PCR Instrument and RapidFinder Express 2.0 software. All testing was conducted in comparison to the reference method detailed in International Organization for Standardization (ISO) 6579:2002. No significant difference by probability of detection statistical analysis was found between the SureTect Listeria monocytogenes PCR Assay or the ISO reference method methods for any of the matrixes analyzed during the study. PMID:27297838

  13. Detection of low levels of Listeria monocytogenes cells by using a fiber-optic immunosensor.

    PubMed

    Geng, Tao; Morgan, Mark T; Bhunia, Arun K

    2004-10-01

    Biosensor technology has a great potential to meet the need for sensitive and nearly real-time microbial detection from foods. An antibody-based fiber-optic biosensor to detect low levels of Listeria monocytogenes cells following an enrichment step was developed. The principle of the sensor is a sandwich immunoassay where a rabbit polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction to capture Listeria cells on the fiber. Capture of cells on the fibers was confirmed by scanning electron microscopy. A cyanine 5-labeled murine monoclonal antibody, C11E9, was used to generate a specific fluorescent signal, which was acquired by launching a 635-nm laser light from an Analyte 2000 and collected by a photodetector at 670 to 710 nm. This immunosensor was specific for L. monocytogenes and showed a significantly higher signal strength than for other Listeria species or other microorganisms, including Escherichia coli, Enterococcus faecalis, Salmonella enterica, Lactobacillus plantarum, Carnobacterium gallinarum, Hafnia alvei, Corynebacterium glutamicum, Enterobacter aerogenes, Pseudomonas aeruginosa, and Serratia marcescens, in pure or in mixed-culture setup. Fiber-optic results could be obtained within 2.5 h of sampling. The sensitivity threshold was about 4.3 x 10(3) CFU/ml for a pure culture of L. monocytogenes grown at 37 degrees C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10 degrees C with 3.5% NaCl, the detection threshold was 4.1 x 10(4) or 2.8 x 10(7) CFU/ml, respectively. In less than 24 h, this method could detect L. monocytogenes in hot dog or bologna naturally contaminated or artificially inoculated with 10 to 1,000 CFU/g after enrichment in buffered Listeria enrichment broth. PMID:15466560

  14. Bacteriophage biocontrol of Listeria monocytogenes on soft ripened white mold and red-smear cheeses

    PubMed Central

    Guenther, Susanne

    2011-01-01

    Soft-ripened cheeses belong to the type of food most often contaminated with Listeria monocytogenes, and they have been implicated in several outbreaks of listeriosis. Bacteriophages represent an attractive way to combat foodborne pathogens without affecting other properties of the food. We used the broad host range, virulent Listeria phage A511 for control of L. monocytogenes during the production and ripening phases of both types of soft-ripened cheeses, white mold (Camembert-type) cheese, as well as washed-rind cheese with a red-smear surface (Limburger-type). The surfaces of young, unripened cheese were inoculated with 101–103 cfu/cm2 L. monocytogenes strains Scott A (serovar 4b) or CNL 103/2005 (serovar 1/2a). Phage was applied at defined time points thereafter, in single or repeated treatments, at 3 × 108 or 1 × 109 pfu/cm2. With Scott A (103 cfu/cm2) and a single dose of A511 (3 × 108 pfu/cm2) on camembert-type cheese, viable counts dropped 2.5 logs at the end of the 21 day ripening period. Repeated phage application did not further inhibit the bacteria, whereas a single higher dose (1 × 109 pfu/cm2) was found to be more effective. On red-smear cheese ripened for 22 days, Listeria counts were down by more than 3 logs. Repeated application of A511 further delayed re-growth of Listeria, but did not affect bacterial counts after 22 days. With lower initial Listeria contamination (101–102 cfu/cm2), viable counts dropped below the limit of detection, corresponding to more than 6 logs reduction compared to the control. Our data clearly demonstrate the potential of bacteriophage for biocontrol of L. monocytogenes in soft cheese. PMID:22334865

  15. Bacteriophage biocontrol of Listeria monocytogenes on soft ripened white mold and red-smear cheeses.

    PubMed

    Guenther, Susanne; Loessner, Martin J

    2011-03-01

    Soft-ripened cheeses belong to the type of food most often contaminated with Listeria monocytogenes, and they have been implicated in several outbreaks of listeriosis. Bacteriophages represent an attractive way to combat foodborne pathogens without affecting other properties of the food. We used the broad host range, virulent Listeria phage A511 for control of L. monocytogenes during the production and ripening phases of both types of soft-ripened cheeses, white mold (Camembert-type) cheese, as well as washed-rind cheese with a red-smear surface (Limburger-type). The surfaces of young, unripened cheese were inoculated with 10(1)-10(3) cfu/cm(2)L. monocytogenes strains Scott A (serovar 4b) or CNL 10(3)/2005 (serovar 1/2a). Phage was applied at defined time points thereafter, in single or repeated treatments, at 3 × 10(8) or 1 × 10(9) pfu/cm(2). With Scott A (10(3) cfu/cm(2)) and a single dose of A511 (3 × 10(8) pfu/cm(2)) on camembert-type cheese, viable counts dropped 2.5 logs at the end of the 21 day ripening period. Repeated phage application did not further inhibit the bacteria, whereas a single higher dose (1 × 10(9) pfu/cm(2)) was found to be more effective. On red-smear cheese ripened for 22 days, Listeria counts were down by more than 3 logs. Repeated application of A511 further delayed re-growth of Listeria, but did not affect bacterial counts after 22 days. With lower initial Listeria contamination (10(1)-10(2) cfu/cm(2)), viable counts dropped below the limit of detection, corresponding to more than 6 logs reduction compared to the control. Our data clearly demonstrate the potential of bacteriophage for biocontrol of L. monocytogenes in soft cheese. PMID:22334865

  16. Prolongation of acquired cellular resistance to Listeria monocytogenes

    PubMed Central

    Willers, J. M. N.; Hofhuis, F. M. A.; Meer, C. Vander

    1982-01-01

    Intracutaneous immunization of mice with 105 or 106 viable listeria resulted in acquired cellular resistance (ACR) of short duration (7 days) and in delayed-type hypersensitivity (DH) lasting at least 27 days. The ACR was partially non-specific, as 50% of the mice were also protected against a lethal challenge with Salmonella enteritidis. The specific element of the ACR could be transferred by non-adherent spleen cells from immune mice to normal recipient mice. Such transfer was not possible with adherent spleen cells from immune mice or with spleen cells from normal mice. Two systems of multiple immunizations to extend the period during which mice were protected against a challenge with 50 LD50 listeria were used. In the first system, mice were immunized with 106 viable listeria and subsequently challenged with 50 LD50 (= 107) viable listeria. Mice surviving the challenge were actually boosted at the challenge injection for ACR. In the second system mice were immunized and boosted with 108 killed listeria mixed with the adjuvant dimethyl dioctadecyl ammonium bromide (DDA). In the former system after each booster injection with viable listeria the interval during which the mice were protected doubled and reached a maximum of 31 days. In the latter system all intervals between two booster injections were equally long and never exceeded 28 days. In both systems the existence of immunological memory was suggested. The difference in results obtained after immunization with viable listeria and killed listeria mixed with DDA are discussed. PMID:6809603

  17. Growth Characteristics of Listeria monocytogenes and Native Microflora in Smoked Salmon Stored at Refrigerated and Abuse Temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Smoked salmon contaminated with Listeria monocytogenes has been implicated in outbreaks of foodborne listeriosis. The objective of this study was to examine the growth characteristics of L. monocytogenes and native microflora in smoked salmon stored at refrigerated and abuse temperatures. Smoked s...

  18. Complete Genome Sequence of Listeria monocytogenes Strain DPC6895, a Serotype 1/2b Isolate from Bovine Raw Milk.

    PubMed

    Casey, Aidan; McAuliffe, Olivia; Coffey, Aidan; Hunt, Karen; Fanning, Seamus; Fox, Edward; Jordan, Kieran

    2015-01-01

    Listeria monocytogenes is a foodborne pathogen and is the causative agent of listeriosis among humans and animals. The draft genome sequence of L. monocytogenes DPC6895, a serotype 1/2b strain isolated from the raw milk of a cow with subclinical bovine mastitis, is reported. PMID:26067969

  19. Pathogenicity of Listeria monocytogenes Scott A after oral and oculonasal challenges of day-old turkey poults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a ubiquitous environmental pathogen that has contaminated poultry ready to eat products resulting in large scale recalls. Research is needed to determine the source of product and processing plant contamination with L. monocytogenes. The purpose of this study is to compare ...

  20. The Effect of Salt, Smoke Compound and Storage Temperature on the Growth of Listeria Monocytogenes in Simulated Smoked Salmon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Smoked salmon can be contaminated with Listeria monocytogenes. It is important to develop effective control measures by identifying factors that would control L. monocytogenes growth in smoked salmon. The purpose of this study was to evaluate the effect of salt, a liquid smoke, storage temperature...

  1. Competition of Listeria monocytogenes Serotype 1/2a and 4b strains in mixed culture biofilms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The majority of Listeria monocytogenes isolates recovered from foods and the environment are strains of serogroup 1/2. However, serotype 4b strains cause the majority of human listeriosis outbreaks. Our investigation of L. monocytogenes biofilms used a simulated food processing system that consist...

  2. Population Structure of Listeria monocytogenes Serotype 4b Isolates from Sporadic Human Listeriosis in the United States, 2003-2008

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes can cause severe foodborne disease (listeriosis). Serotype 4b strains have resulted in numerous outbreaks, repeatedly involving three epidemic clones (ECI, ECII, and ECIa). Little is known about population structure of L. monocytogenes serotype 4b from sporadic listeriosis, ev...

  3. Methods to measure control of Listeria monocytogenes biofilms on test materials from food production and processing facilities.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The reduction of microbial pathogens in meat and poultry products, particularly Listeria monocytogenes, is a pressing food safety issue. L. monocytogenes is responsible for the most product recalls relating to pathogen contamination, and causes a 20 percent death rate among its victims. The goal of ...

  4. Genes that are involved in high hydrostatic pressure treatments in a Listeria monocytogenes Scott A ctsR deletion mutant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a food-borne pathogen of significant threat to public health. High Hydrostatic Pressure (HHP) treatment can be used to control L. monocytogenes in food. The CtsR (class three stress gene repressor) protein negatively regulates the expression of class III heat shock genes....

  5. Molecular analysis of the iap gene of Listeria monocytogenes isolated from cheeses in rio grande do Sul, Brazil

    PubMed Central

    de Mello, Jozi Fagundes; Einsfeldt, Karen; Frazzon, Ana Paula Guedes; da Costa, Marisa; Frazzon, Jeverson

    2008-01-01

    The polymorphic region sequences in the iap gene were analyzed in 25 strains of Listeria monocytogenes isolated from cheeses in the state of Rio Grande do Sul, and compared with reference strains. This investigation distinguished two clusters of L. monocytogenes: I (20 strains) and II (5 strains). PMID:24031198

  6. Occurrence and Antimicrobial Resistance of Listeria monocytogenes Recovered from Blue Crab Meat and Blue Crab Processing Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is widely distributed in the environment. The ubiquitous nature of this bacterium can result in contamination of foods. Listeriosis is a food-borne disease caused by consumption of L. monocytogenes-contaminated food. It is a public health problem of low incidence but high mort...

  7. Genome Sequence of Listeria monocytogenes Strain F6540 (Sequence Type 360) Collected from Food Samples in Ontario, Canada

    PubMed Central

    Gnaneshan, Saravanamuttu; Hsueh, Ya-Chih; Liang, Lindsay; Teatero, Sarah; Fittipaldi, Nahuel

    2016-01-01

    Comparative genomic analysis between pathogenic and nonpathogenic Listeria monocytogenes strains provides a good model for studying the virulence of this organism. Here, we report the genome sequence of the nonpathogenic L. monocytogenes strain F6540 (sequence type 360) identified specifically in food samples in Ontario, Canada, in 2010. PMID:26769922

  8. The Effect of Salt, Smoke Compound, and Storage Temperature on the Growth of Listeria monocytogenes in Simulated Smoked Salmon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Smoked salmon can be contaminated with Listeria monocytogenes. It is important to identify the factors that are capable of controlling the growth of L. monocytogenes in smoked salmon, so control measures can be developed. The objective of this study was to determine the effect of salt, a smoke com...

  9. Effect of salt, smoke compound and temperature on the survival of Listeria monocytogenes in salmon during simulated smoking processes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In smoked fish processes, smoking is the only step that is capable of inactivating pathogens, such as Listeria monocytogenes, that contaminate the raw fish. The objectives of this study were to examine and develop a model to describe the survival of L. monocytogenes in salmon as affected by salt, s...

  10. Two novel type II restriction-modification (RM) systems occupying genomically equivalent locations on the chromosomes of Listeria monocytogenes strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is responsible for the potentially life-threatening foodborne disease listeriosis. One epidemic-associated clonal group of L. monocytogenes, epidemic clone I (ECI), harbors a Sau3AI-like restriction-modification (RM) system also present in the same genomic region in certain st...

  11. Isolation and Characterization of Listeria monocytogenes from Blue Crab Meat (Callinectus sapidus) and Blue Crab Processing Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a Gram positive, intracellular food borne pathogen which causes a severe disease called listeriosis in high risk groups. However, there is limited information about the prevalence and sources of L. monocytogenes in blue crab and blue crab processing plants in Maryland. The...

  12. Sources of contamination and control of Listeria monocytogenes in milk, cheese, and the environment wherein they are produced

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeriosis is an animal and foodborne human disease caused by bacteria of the genus Listeria, especially Listeria monocytogenes. Listeriosis is a very serious and often fatal infection primarily affecting the elderly and perinates. Immunocompromised adults are also highly susceptible to virulent Li...

  13. Listeria prevalence and L. monocytogenes serovar diversity at cull cow/bull processing plants in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes, the causative agent of epidemic and sporadic listeriosis, is routinely isolated from many sources, including cattle, yet information on the prevalence of Listeria in beef processing plants in the United States is minimal. From July 2005 through April 2006, four commercial co...

  14. DNase-Sensitive and -Resistant Modes of Biofilm Formation by Listeria monocytogenes

    PubMed Central

    Zetzmann, Marion; Okshevsky, Mira; Endres, Jasmin; Sedlag, Anne; Caccia, Nelly; Auchter, Marc; Waidmann, Mark S.; Desvaux, Mickaël; Meyer, Rikke L.; Riedel, Christian U.

    2015-01-01

    Listeria monocytogenes is able to form biofilms on various surfaces and this ability is thought to contribute to persistence in the environment and on contact surfaces in the food industry. Extracellular DNA (eDNA) is a component of the biofilm matrix of many bacterial species and was shown to play a role in biofilm establishment of L. monocytogenes. In the present study, the effect of DNaseI treatment on biofilm formation of L. monocytogenes EGD-e was investigated under static and dynamic conditions in normal or diluted complex medium at different temperatures. Biofilm formation was quantified by crystal violet staining or visualized by confocal laser scanning microscopy. Biomass of surface-attached L. monocytogenes varies depending on temperature and dilution of media. Interestingly, L. monocytogenes EGD-e forms DNase-sensitive biofilms in diluted medium whereas in full strength medium DNaseI treatment had no effect. In line with these observations, eDNA is present in the matrix of biofilms grown in diluted but not full strength medium and supernatants of biofilms grown in diluted medium contain chromosomal DNA. The DNase-sensitive phenotype could be clearly linked to reduced ionic strength in the environment since dilution of medium in PBS or saline abolished DNase sensitivity. Several other but not all species of the genus Listeria display DNase-sensitive and -resistant modes of biofilm formation. These results indicate that L. monocytogenes biofilms are DNase-sensitive especially at low ionic strength, which might favor bacterial lysis and release of chromosomal DNA. Since low nutrient concentrations with increased osmotic pressure are conditions frequently found in food processing environments, DNaseI treatment represents an option to prevent or remove Listeria biofilms in industrial settings. PMID:26733972

  15. Collaborative survey on the colonization of different types of cheese-processing facilities with Listeria monocytogenes.

    PubMed

    Stessl, Beatrix; Fricker, Martina; Fox, Edward; Karpiskova, Renata; Demnerova, Katarina; Jordan, Kieran; Ehling-Schulz, Monika; Wagner, Martin

    2014-01-01

    Cross-contamination via equipment and the food-processing environment has been implicated as the main cause of Listeria monocytogenes transmission. The aim of this study, therefore, was to determine the occurrence and potential persistence of L. monocytogenes in 19 European cheese-processing facilities. A sampling approach in 2007-2008 included, respectively, 11 and two industrial cheese producers in Austria and the Czech Republic, as well as six Irish on-farm cheese producers. From some of the producers, isolates were available from sampling before 2007. All isolates from both periods were included in a strain collection consisting of 226 L. monocytogenes isolates, which were then typed by serotyping and pulsed-field gel electrophoresis (PFGE). In addition, metabolic fingerprints from a subset of isolates were obtained by means of Fourier-transform infrared (FTIR) spectroscopy. PFGE typing showed that six processing environments were colonized with seven persistent PFGE types of L. monocytogenes. Multilocus sequence typing undertaken on representatives of the seven persisting PFGE types grouped them into distinct clades on the basis of country and origin; however, two persistent strains from an Austrian and an Irish food processor were shown to be clonal. It was concluded that despite the fact that elaborate Hazard Analysis and Critical Control Point concepts and cleaning programs are applied, persistent occurrence of L. monocytogenes can take place during cheese making. L. monocytogenes sanitation programs could be strengthened by including rapid analytical tools, such as FTIR, which allow prescreening of potentially persistent L. monocytogenes contaminants. PMID:24138033

  16. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

    PubMed Central

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2015-01-01

    Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

  17. Prevalence and antimicrobial susceptibility of Listeria monocytogenes on chicken carcasses in Bandung, Indonesia.

    PubMed

    Sugiri, Yoni Darmawan; Gölz, Greta; Meeyam, Tongkorn; Baumann, Maximilian P O; Kleer, Josef; Chaisowwong, Warangkhana; Alter, Thomas

    2014-08-01

    This study was conducted to determine the prevalence and quantify the number of Listeria monocytogenes in fresh chicken carcasses sold in traditional markets and supermarkets in Bandung, West Java, Indonesia, and to determine the antimicrobial resistance patterns of the isolated L. monocytogenes strains. The overall prevalence of L. monocytogenes in chicken carcasses was 15.8% (29/184). When comparing samples from traditional markets and supermarkets, no significant difference in the L. monocytogenes prevalence was detectable (15.2 versus 16.3%). Of the samples, 97.3% had L. monocytogenes counts <100 CFU/g, 2.2% had L. monocytogenes counts between 101 and 1,000 CFU/g, and 0.5% had L. monocytogenes counts of 1,001 to 10,000 CFU/g. Of the isolates, 27.6% were resistant to at least one of the 10 antimicrobials tested, with the major resistant phenotypes to penicillin (17.2%), ampicillin (6.9%), and erythromycin (6.9%). All 29 isolates recovered in this study were grouped into the molecular serogroup IIb, comprising the serovars 1/2b, 3b, and 7. PMID:25198605

  18. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes.

    PubMed

    Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

    2015-09-01

    Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

  19. Influence of temperature on acid-stress adaptation in Listeria monocytogenes.

    PubMed

    Shen, Qian; Soni, Kamlesh A; Nannapaneni, Ramakrishna

    2014-01-01

    Our findings show that temperature plays a significant role in the induction of acid-stress adaptation in Listeria monocytogenes, and two distinct patterns were observed: (1) Presence of sublethal acid at 37°C or 22°C significantly induced acid-stress adaptation; and (2) Presence of sublethal acid at 4°C did not induce any acid-stress adaptation. Both patterns were confirmed by two experimental models: (1) L. monocytogenes cells were first grown at 37°C and then exposed to sublethal acid at 37°C, 22°C, and 4°C prior to lethal acid challenge; (2) Alternatively, L. monocytogenes cells were first grown at 4°C for 20 days before pre-exposure to sublethal acid and then challenged with lethal acid. Regardless of whether L. monocytogenes cells were simultaneously exposed with both cold stress and sublethal acid stress, or subjected to cold growth first before exposure to sublethal acid, no acid-stress adaptation was induced at 4°C. We also found that acid-stress adaptation in L. monocytogenes did not occur in acidic whey at 4°C. Bead beating treatment prior to mild acid pre-exposure at 4°C partially induced acid adaptation in L. monocytogenes. Our findings suggest that cold temperature can prevent the risk of acid-stress adaptation in L. monocytogenes. PMID:24102079

  20. Effects of osmotic pressure, acid, or cold stresses on antibiotic susceptibility of Listeria monocytogenes.

    PubMed

    Al-Nabulsi, Anas A; Osaili, Tareq M; Shaker, Reyad R; Olaimat, Amin N; Jaradat, Ziad W; Zain Elabedeen, Noor A; Holley, Richard A

    2015-04-01

    Prevalence of antibiotic resistance of Listeria monocytogenes isolated from a variety of foods has increased in many countries. L. monocytogenes has many physiological adaptations that enable survival under a wide range of environmental stresses. The objective of this study was to evaluate effects of osmotic (2, 4, 6, 12% NaC), pH (6, 5.5, 5.0) and cold (4 °C) stresses on susceptibility of three isolates of L. monocytogenes towards different antibiotics. The minimal inhibitory concentrations (MICs) of tested antibiotics against unstressed (control), stressed or post-stressed L. monocytogenes isolates (an ATCC strain and a meat and dairy isolate) were determined using the broth microdilution method. Unstressed cells of L. monocytogenes were sensitive to all tested antibiotics. In general, when L. monocytogenes cells were exposed to salt, cold and pH stresses, their antibiotic resistance increased as salt concentration increased to 6 or 12%, as pH was reduced to pH 5 or as temperature was decreased to 10 °C. Results showed that both meat and dairy isolates were more resistant than the ATCC reference strain. Use of sub-lethal stresses in food preservation systems may stimulate antibiotic resistance responses in L. monocytogenes strains. PMID:25475279

  1. Listeria monocytogenes contamination of finishing pigs: an exploratory epidemiological survey in France.

    PubMed

    Beloeil, Pierre-Alexandre; Chauvin, Claire; Toquin, Marie-Thérèse; Fablet, Christelle; Le Nôtre, Yolaine; Salvat, Gilles; Madec, François; Fravalo, Philippe

    2003-01-01

    Listeria monocytogenes is a foodborne pathogen of major concern for public health in industrialised countries. Since L. monocytogenes carriage by pigs at the herd level could be a primary source for carcass contamination, control measures should be designed to reduce the L. monocytogenes load at the pre-harvest stage. For this purpose, an exploratory analytical survey was carried out in 2000-2001 in 93 French farrow-to-finish pig farms concerning L. monocytogenes contamination in pigs before they left for the slaughterhouse. On each farm, the L. monocytogenes status of a batch of contemporary fattening pigs housed in the same room was assessed on faecal material samples taken by means of gauze swabs wiped on the perianal region of the pigs. Fourteen percent of the batches studied had at least one contaminated sample and were therefore classified as L. monocytogenes contaminated batches. Two logistic regression models were used to assess the association between managerial and hygiene practices and the risk of L. monocytogenes contamination of the batch at the end of the finishing period on the whole data set (n = 93) and in the wet feeding farms only (n = 57). Wet feeding during the fattening period was identified as a risk factor for L. monocytogenes contamination. Risk factors related to the introduction of L. monocytogenes in pig facilities were identified for both the general and wet feeding farm data sets. Poor care paid to hygiene on the farms was found to increase the risk of being infected (boots cleaning, change room presence). When the duration of the empty period prior to the introduction of growing pigs was less than one day in the fattening section, the risk of L. monocytogenes contamination was significantly increased. For wet feeding farms, a distribution pipeline cleaning procedure including disinfection was found to be associated with a higher risk of contamination than no cleaning or a procedure consisting of rinsing with water only. PMID:14746769

  2. Control of Listeria monocytogenes in a Biofilm by Competitive-Exclusion Microorganisms

    PubMed Central

    Zhao, Tong; Doyle, Michael P.; Zhao, Ping

    2004-01-01

    Biofilms from drains in food processing facilities with a recent history of no detectable Listeria monocytogenes in floor drains were cultured for microorganisms producing antilisterial metabolites. A total of 413 microbial isolates were obtained from 12 drain biofilm samples and were assayed at 15 and 37°C for activities that were bactericidal or inhibitory to L. monocytogenes, by two agar plate assays. Twenty-one of 257 bacterial isolates and 3 of 156 yeast isolates had antilisterial activity. All 24 isolates which produced metabolites inhibitory to L. monocytogenes were assayed for antilisterial activity in coinoculated broth cultures containing tryptic soy broth with yeast extract (TSB-YE). A five-strain mixture of 103 CFU of L. monocytogenes/ml and 105 CFU of the candidate competitive-exclusion microorganism/ml was combined in TSB-YE and incubated at 37°C for 24 h, 15°C for 14 days, 8°C for 21 days, and 4°C for 28 days. Substantial inhibition of L. monocytogenes growth (4 to 5 log CFU/ml) was observed for nine bacterial isolates at 37°C, two at 15 and 8°C, and three at 4°C. The inhibitory isolates were identified as Enterococcus durans (six isolates), Lactococcus lactis subsp. lactis (two isolates), and Lactobacillus plantarum (one isolate). The anti-L. monocytogenes activity of these isolates was evaluated in biofilms of L. monocytogenes on stainless steel coupons at 37, 15, 8, and 4°C. Results revealed that two isolates (E. durans strain 152 and L. lactis subsp. lactis strain C-1-92) were highly inhibitory to L. monocytogenes (growth inhibition of >5 log10 CFU of L. monocytogenes/cm2). These two bacterial isolates appear to be excellent competitive-exclusion candidates to control L. monocytogenes in biofilms at environmental temperatures of 4 to 37°C. PMID:15240275

  3. Growth Modelling of Listeria monocytogenes in Korean Pork Bulgogi Stored at Isothermal Conditions.

    PubMed

    Lee, Na-Kyoung; Ahn, Sin Hye; Lee, Joo-Yeon; Paik, Hyun-Dong

    2015-01-01

    The purpose of this study was to develop predictive models for the growth of Listeria monocytogenes in pork Bulgogi at various storage temperatures. A two-strain mixture of L. monocytogenes (ATCC 15313 and isolated from pork Bulgogi) was inoculated on pork Bulgogi at 3 Log CFU/g. L. monocytogenes strains were enumerated using general plating method on Listeria selective medium. The inoculated samples were stored at 5, 15, and 25℃ for primary models. Primary models were developed using the Baranyi model equations, and the maximum specific growth rate was shown to be dependent on storage temperature. A secondary model of growth rate as a function of storage temperature was also developed. As the storage temperature increased, the lag time (LT) values decreased dramatically and the specific growth rate of L. monocytogenes increased. The mathematically predicted growth parameters were evaluated based on the modified bias factor (B f ), accuracy factor (A f ), root mean square error (RMSE), coefficient of determination (R (2)), and relative errors (RE). These values indicated that the developed models were reliably able to predict the growth of L. monocytogenes in pork Bulgogi. Hence, the predictive models may be used to assess microbiological hygiene in the meat supply chain as a function of storage temperature. PMID:26761807

  4. The effect of short-time microwave exposures on Listeria monocytogenes inoculated onto chicken meat portions

    PubMed Central

    Zeinali, Tayebeh; Jamshidi, Abdollah; Khanzadi, Saeid; Azizzadeh, Mohammad

    2015-01-01

    Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. Listeria monocytogenes has become increasingly important as a food-borne pathogen. The aim of this study was to evaluate the effect of microwave (MW) treatment of chicken meat samples which were inoculated with L. monocytogenes. Drumettes of broiler carcasses were soaked in fully growth of L. monocytogenes in Brain-Heart Infusion broth. The swab samples were taken from the inoculated samples, after various times of radiation (10, 20, 30, 40, 50, 60, 70 and 80 sec), using a domestic MW oven at full power. Following exposures, viable counts and surface temperature measurements were performed. The bacterial counts were performed on Oxford agar. The results indicated that equal or longer than 60 sec exposures of chicken portions to MW heating which enhances the median surface temperature more than 74 ˚C could eliminate the superficial contamination of chicken meat with L. monocytogenes. Statistical analysis showed samples with equal or longer than 60 sec exposures to MW heating had significant decrease in population of inoculated bacteria compared with positive control group (p < 0.05). Pearson correlation showed a significant correlation between the bacterial population and temperature of samples due to MW exposure (p < 0.001, r = – 0.879 and r2 = 0.773). PMID:26261715

  5. Listeria monocytogenes adapts to long-term stationary phase survival without compromising bacterial virulence.

    PubMed

    Bruno, Joseph C; Freitag, Nancy E

    2011-10-01

    Bacteria withstand starvation during long-term stationary phase through the acquisition of mutations that increase bacterial fitness. The evolution of the growth advantage in stationary phase (GASP) phenotype results in the ability of bacteria from an aged culture to outcompete bacteria from a younger culture when the two are mixed together. The GASP phenotype was first described for Escherichia coli, but has not been examined for an environmental bacterial pathogen, which must balance long-term survival strategies that promote fitness in the outside environment with those that promote fitness within the host. Listeria monocytogenes is an environmental bacterium that lives as a saprophyte in soil, but is capable of replicating within the cytosol of mammalian cells. Herein, we demonstrate the ability of L. monocytogenes to express GASP via the acquisition of mutations during long-term stationary growth. Listeria monocytogenes GASP occurred through mechanisms that were both dependent and independent of the stress-responsive alternative sigma factor SigB. Constitutive activation of the central virulence transcriptional regulator PrfA interfered with the development of GASP; however, L. monocytogenes GASP cultures retained full virulence in mice. These results indicate that L. monocytogenes can accrue mutations that optimize fitness during long-term stationary growth without negatively impacting virulence. PMID:22092717

  6. Growth Modelling of Listeria monocytogenes in Korean Pork Bulgogi Stored at Isothermal Conditions

    PubMed Central

    Lee, Na-Kyoung; Ahn, Sin Hye; Lee, Joo-Yeon; Paik, Hyun-Dong

    2015-01-01

    The purpose of this study was to develop predictive models for the growth of Listeria monocytogenes in pork Bulgogi at various storage temperatures. A two-strain mixture of L. monocytogenes (ATCC 15313 and isolated from pork Bulgogi) was inoculated on pork Bulgogi at 3 Log CFU/g. L. monocytogenes strains were enumerated using general plating method on Listeria selective medium. The inoculated samples were stored at 5, 15, and 25℃ for primary models. Primary models were developed using the Baranyi model equations, and the maximum specific growth rate was shown to be dependent on storage temperature. A secondary model of growth rate as a function of storage temperature was also developed. As the storage temperature increased, the lag time (LT) values decreased dramatically and the specific growth rate of L. monocytogenes increased. The mathematically predicted growth parameters were evaluated based on the modified bias factor (Bf), accuracy factor (Af), root mean square error (RMSE), coefficient of determination (R2), and relative errors (RE). These values indicated that the developed models were reliably able to predict the growth of L. monocytogenes in pork Bulgogi. Hence, the predictive models may be used to assess microbiological hygiene in the meat supply chain as a function of storage temperature. PMID:26761807

  7. Serotypes and Pulsotypes diversity of Listeria monocytogenes in a beef-processing environment.

    PubMed

    Camargo, Anderson Carlos; Dias, Mariane Rezende; Cossi, Marcus Vinícius Coutinho; Lanna, Frederico Germano Piscitelli Alvarenga; Cavicchioli, Valéria Quintana; Vallim, Deyse Christina; Pinto, Paulo Sérgio de Arruda; Hofer, Ernesto; Nero, Luís Augusto

    2015-04-01

    Utensils and equipment from meat-processing facilities are considered relevant cross-contamination points of Listeria monocytogenes to foods, demanding tracking studies to identify their specific origins, and predict proper control. The present study aimed to detect L. monocytogenes in a beef-processing facility, investigating the diversity of serotypes and pulsotypes in order to identify the possible contamination routes. Surface samples from knives (n=26), tables (n=78), and employees hands (n=74) were collected before and during the procedures from a beef-processing facility, in addition to surface samples of end cuts: round (n=32), loin (n=30), and chuck (n=32). All samples were subjected to L. monocytogenes screening according ISO 11.290-1, and the obtained isolates were subjected to serotyping and pulsed-field gel electrophoresis. Listeria spp. were identified in all processing steps, in 61 samples, and L. monocytogenes was detected in 17 samples, not being found only in knives. Eighty-five isolates were identified as L. monocytogenes, from serotypes 1/2c (n=65), 4b (n=13), and 1/2b (n=7), being grouped in 19 pulsotypes. Considering these results, cross-contamination among hands, tables, and beef cuts could be identified. The obtained data indicated the relevance of cross-contamination in the beef-processing facility, and the occurrence of serotypes 1/2b and 4b in beef cuts distributed for retail sale is a public health concern. PMID:25835809

  8. Generation of nonpolar deletion mutants in Listeria monocytogenes using the "SOEing" method.

    PubMed

    Rychli, Kathrin; Guinane, Caitriona M; Daly, Karen; Hill, Colin; Cotter, Paul D

    2014-01-01

    The ability to manipulate chromosomally encoded genes is a fundamental biological tool for the analysis of gene function. Here, we provide in greater depth protocols for the creation of nonpolar unlabeled gene deletions in Listeria (L.) monocytogenes that are facilitated by the splicing overlap extension PCR technique. For mutagenesis in L. monocytogenes, we describe two different plasmid-based approaches, which facilitate the introduction of this spliced amplicon in place of the corresponding segment of chromosomal DNA: the pKSV7 system and the pORI280/pVE6007 system. PMID:24792559

  9. Induction of Listeria monocytogenes infection by the consumption of ponderosa pine needles.

    PubMed Central

    Adams, C J; Neff, T E; Jackson, L L

    1979-01-01

    An infectious microorganism, identified as Listeria monocytogenes, has been isolated from the bloodstream of pregnant mice fed a diet containing Pinus ponderosa needles. When the isolate was injected into pregnant mice, reproductive dysfunction and other changes, including speckled livers, spleen atrophy, and hemorrhagic intestines, appeared to mimic the signs of the disease in pregnant mice fed pine needles. Moreover, these pathological changes are similar to those observed in cattle and other mammals experiencing abortions or toxemia, or both, attributed to the ingestion of P. ponderosa needles, suggesting that L. monocytogenes may be a part of the etiology of "pine needle abortion." PMID:113341

  10. Sporadic case of listeriosis associated with the consumption of a Listeria monocytogenes-contaminated 'Camembert' cheese.

    PubMed

    Gilot, P; Hermans, C; Yde, M; Gigi, J; Janssens, M; Genicot, A; André, P; Wauters, G

    1997-09-01

    Listeria monocytogenes is an intracellular gram-positive organism responsible for severe infections in both humans and animals. Whereas the food-borne transmission of listeriosis was demonstrated in several outbreaks, most cases of listeriosis occur sporadically and are rarely linked with consumption of contaminated foods. In this paper a case of septicaemia with L. monocytogenes in a 73-year-old immunocompromised man is described. Evidence for the association of this case of listeriosis with the consumption of a contaminated 'Camembert' cheese is provided by serotyping, esterase typing, DNA macrorestriction patterns analysis and level of virulence of the isolated strains for mice. PMID:9354360

  11. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria.

    PubMed

    Ojima-Kato, Teruyo; Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources. PMID:27442502

  12. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria

    PubMed Central

    Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources. PMID:27442502

  13. Characterization of Listeria monocytogenes isolates from cattle and ground beef by pulsed-field gel electrophoresis.

    PubMed

    Foerster, Claudia; Vidal, Lorena; Troncoso, Miriam; Figueroa, Guillermo

    2012-01-01

    The aims of this study were to determine the occurrence of Listeria monocytogenes in cattle feces and ground beef, to characterize these strains by pulsed-field gel electrophoresis and to compare them to three listeria strains found in humans. Cattle from different origins (n = 250) and ground beef obtained from supermarkets (n = 40) were sampled. The results show low occurrence in cattle feces (0.4 %) but a higher presence in ground beef (37 %). An important part of the ground beef strains (80 %) had > 95 % similarity with a strain isolated from a human sporadic case and the ATCC 19115 used as control. The strain isolated from cattle feces had 93 % similarity to clone 009, previously associated with a listeriosis outbreak related to cheese. Cattle and ground beef can harbor virulent L. monocytogenes strains. Further studies in animals and animal products are needed to improve listeriosis control. PMID:23102469

  14. Potential nosocomial acquisition of epidemic Listeria monocytogenes presenting as multiple brain abscesses resembling nocardiosis.

    PubMed

    Stefanovic, Aleksandra; Reid, James; Nadon, A Celine; Grant, Jennifer

    2010-01-01

    Listerial brain abscesses are rare, and are found mostly in patients with underlying hematological malignancies or solid-organ transplants. A case of a patient with Crohn's disease and multiple brain abscesses involving the left cerebellum and right sylvian fissure is described. The Gram stain and histopathology of the cerebellar abscess revealed Gram-positive, beaded rods suggestive of Nocardia. However, on culture, Listeria monocytogenes was identified. Listeria may appear Gram-variable and has been misidentified as streptococci, enterococci and diphtheroids. The present case is the first reported case of L monocytogenes resembling Nocardia on both microbiological and histopathological assessment. Reported cases of listerial brain abscesses are sporadic, while the current case was part of a nationwide listerial outbreak linked to consumption of contaminated deli meats. Broad antimicrobial therapy (including antilisterial coverage) in immunosuppressed patients presenting with brain abscess is crucial, until cultures confirm the identification of the organism. PMID:21358887

  15. Risk factors for Listeria monocytogenes contamination in French laying hens and broiler flocks.

    PubMed

    Aury, Kristell; Le Bouquin, Sophie; Toquin, Marie-Thérèse; Huneau-Salaün, Adeline; Le Nôtre, Yolène; Allain, Virginie; Petetin, Isabelle; Fravalo, Philippe; Chemaly, Marianne

    2011-03-01

    The objective of this study was to identify potential risk factors for Listeria monocytogenes contamination in French poultry production. Eighty-four flocks of layer hens kept in cages and 142 broiler flocks were included in this study. For each production type, a questionnaire was submitted to farmers and fecal samples were taken to assess the L. monocytogenes status of the flocks during a single visit to the farm. Two logistic regression models (specific to each production) were used to assess the association between management practices and the risk of L. monocytogenes contamination of the flock. The prevalence of L. monocytogenes-positive flocks was 30.9% (95% CI: 21.0; 40.9) and 31.7% (95% CI: 24.0; 39.4) for cage-layers and broiler flocks, respectively. For layer flocks, the risk of L. monocytogenes contamination was increased when pets were present on the production site. When droppings were evacuated by conveyor belt with deep pit storage, the risk of L. monocytogenes contamination decreased significantly. Feed meal was found to be associated with a higher risk of L. monocytogenes contamination than feed crumb. For broiler flocks, the risk of L. monocytogenes contamination was increased when farmers did not respect the principle of two areas (clean and dirty) at the poultry house entrance. A first disinfection by thermal fogging and the absence of pest control of the poultry house before the arrival of the next flock was found to increase the risk of contamination. When litter was not protected during storage and when farm staff also took care of other broiler chicken houses, the risk of L. monocytogenes contamination increased significantly. In the case of the watering system, nipples with cups were found to decrease the risk of contamination. PMID:21176855

  16. Biotic and Abiotic Soil Properties Influence Survival of Listeria monocytogenes in Soil

    PubMed Central

    Locatelli, Aude; Spor, Aymé; Jolivet, Claudy; Piveteau, Pascal; Hartmann, Alain

    2013-01-01

    Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monitoring Network. This soil collection is meant to be representative of the pedology and land use of the whole French territory. The population of L. monocytogenes in inoculated microcosms was enumerated by plate count after 7, 14 and 84 days of incubation. Analysis of survival profiles showed that L. monocytogenes was able to survive up to 84 days in 71% of the soils tested, in the other soils (29%) only a short-term survival (up to 7 to 14 days) was observed. Using variance partitioning techniques, we showed that about 65% of the short-term survival ratio of L. monocytogenes in soils was explained by the soil chemical properties, amongst which the basic cation saturation ratio seems to be the main driver. On the other hand, while explaining a lower amount of survival ratio variance (11%), soil texture and especially clay content was the main driver of long-term survival of L. monocytogenes in soils. In order to assess the effect of the endogenous soils microbiota on L. monocytogenes survival, sterilized versus non-sterilized soils microcosms were compared in a subset of 9 soils. We found that the endogenous soil microbiota could limit L. monocytogenes survival especially when soil pH was greater than 7, whereas in acidic soils, survival ratios in sterilized and unsterilized microcosms were not statistically different. These results point out the critical role played by both the endogenous microbiota and the soil physic-chemical properties in determining the survival of L. monocytogenes in soils. PMID:24116083

  17. Ecology and Transmission of Listeria monocytogenes Infecting Ruminants and in the Farm Environment

    PubMed Central

    Nightingale, K. K.; Schukken, Y. H.; Nightingale, C. R.; Fortes, E. D.; Ho, A. J.; Her, Z.; Grohn, Y. T.; McDonough, P. L.; Wiedmann, M.

    2004-01-01

    A case-control study involving 24 case farms with at least one recent case of listeriosis and 28 matched control farms with no listeriosis cases was conducted to probe the transmission and ecology of Listeria monocytogenes on farms. A total of 528 fecal, 516 feed, and 1,012 environmental soil and water samples were cultured for L. monocytogenes. While the overall prevalence of L. monocytogenes in cattle case farms (24.4%) was similar to that in control farms (20.2%), small-ruminant (goat and sheep) farms showed a significantly (P < 0.0001) higher prevalence in case farms (32.9%) than in control farms (5.9%). EcoRI ribotyping of clinical (n = 17) and farm (n = 414) isolates differentiated 51 ribotypes. L. monocytogenes ribotypes isolated from clinical cases and fecal samples were more frequent in environmental than in feed samples, indicating that infected animals may contribute to L. monocytogenes dispersal into the farm environment. Ribotype DUP-1038B was significantly (P < 0.05) associated with fecal samples compared with farm environment and animal feedstuff samples. Ribotype DUP-1045A was significantly (P < 0.05) associated with soil compared to feces and with control farms compared to case farms. Our data indicate that (i) the epidemiology and transmission of L. monocytogenes differ between small-ruminant and cattle farms; (ii) cattle contribute to amplification and dispersal of L. monocytogenes into the farm environment, (iii) the bovine farm ecosystem maintains a high prevalence of L. monocytogenes, including subtypes linked to human listeriosis cases and outbreaks, and (iv) L. monocytogenes subtypes may differ in their abilities to infect animals and to survive in farm environments. PMID:15294773

  18. Cloning and characterization of T-cell-reactive protein antigens from Listeria monocytogenes.

    PubMed Central

    Beattie, I A; Swaminathan, B; Ziegler, H K

    1990-01-01

    To explore the molecular basis of the T-cell-mediated immune response to Listeria monocytogenes, we cloned and expressed listerial antigens in Escherichia coli using the lambda-ZAP bacteriophage and Bluescript plasmid vectors. A two-stage screening strategy was implemented to identify T-cell-reactive antigens; the first stage involved antibodies or oligonucleotide probes and the second stage was based on assays for T-cell activation. A library of genomic DNA from L. monocytogenes was generated in lambda-ZAP, and then antigens, were detected in infected cells with a polyclonal rabbit anti-L. monocytogenes antiserum and an L. monocytogenes-specific monoclonal antibody. Also, synthetic oligonucleotide probes corresponding to the structural gene for listeriolysin O (LLO) were used to screen the recombinant DNA library. In each case, positive isolates were evaluated for T-cell antigenicity by measuring antigen-induced interleukin-2 production by polyclonal T cells taken from L. monocytogenes-immune mice. Phage clones were subcloned and expressed in the Bluescript plasmid and tested further for antigenic activity and LLO expression. Using this screening strategy, we successfully identified bacterial clones producing recombinant listerial antigens which activate L. monocytogenes-immune T cells in vitro. Antigens operative in the T-cell response during infection with L. monocytogenes include LLO, 62- and 39-kilodalton proteins, and other poorly defined bacterial surface components. We also found that high concentrations of recombinant LLO inhibited macrophage-mediated antigen presentation. These results are discussed in terms of the multiple functions of LLO as a virulence factor, inhibitor of antigen presentation, and potent antigen in the T-cell response to L. monocytogenes. These studies represent the first step toward a genetic definition of the antigens recognized in immune defense to L. monocytogenes. Images PMID:2117570

  19. Detection of multiple virulence-associated genes in Listeria monocytogenes isolated from bovine mastitis cases.

    PubMed

    Rawool, D B; Malik, S V S; Shakuntala, I; Sahare, A M; Barbuddhe, S B

    2007-01-25

    Clinical samples (n=725) were collected from bovines (n=243) which were positive for mastitis using the California mastitis test (CMT) and somatic cell count (SCC). The clinical samples comprising blood (n=239), milk (n=243), and faecal swabs (n=243) were examined for the presence of pathogenic Listeria spp. Isolation of the pathogen was done using selective enrichment in University of Vermont Medium and plating onto Dominguez-Rodriguez isolation agar. Confirmation of the isolates was based on biochemical tests and Christie, Atkins, Munch-Petersen (CAMP) test followed by pathogenicity testing. Pathogenicity of the isolates was tested by phosphatidylinositol-specific phospholipase C (PI-PLC) assay as well as in vivo tests namely, chick embryo and mice inoculation tests. The isolates were subjected to PCR assay for five virulence-associated genes, plcA, prfA, hlyA, actA and iap. Listeria spp. were isolated from 12 (1.66%) samples. Of these 4 (0.55%) and 1 (0.14%) were confirmed as Listeria monocytogenes and Listeria ivanovii, respectively. L. monocytogenes and L. ivanovii were recovered from milk samples (2) and faecal (3) of mastitic cattle (3) and buffaloes (2). L. monocytogenes recovered from the milk of mastitic cattle and L. ivanovii from the faecal swab of buffalo turned out to be pathogenic. However, the remaining three hemolytic isolates exhibiting positive CAMP test turned out to be negative in PI-PLC assay, chick embryo and mice inoculation. L. monocytogenes and L. ivanovii isolates characterized as pathogenic by PI-PLC assay and in vivo pathogenicity tests were found to possess all the five virulence-associated genes and three genes, plcA, prfA and actA respectively. The remaining three hemolytic but non-pathogenic L. monocytogenes isolates were negative for plcA by PCR. It seems that the plcA gene and its expression (in the PI-PLC assay) have an important role as virulence determinants in pathogenic Listeria spp. In conclusion, the PI-PLC assay and

  20. 2-deoxy-D-glucose-induced metabolic stress enhances resistance to Listeria monocytogenes infection in mice

    NASA Technical Reports Server (NTRS)

    Miller, E. S.; Bates, R. A.; Koebel, D. A.; Fuchs, B. B.; Sonnenfeld, G.

    1998-01-01

    Exposure to different forms of psychological and physiological stress can elicit a host stress response, which alters normal parameters of neuroendocrine homeostasis. The present study evaluated the influence of the metabolic stressor 2-deoxy-D-glucose (2-DG; a glucose analog, which when administered to rodents, induces acute periods of metabolic stress) on the capacity of mice to resist infection with the facultative intracellular bacterial pathogen Listeria monocytogenes. Female BDF1 mice were injected with 2-DG (500 mg/kg b. wt.) once every 48 h prior to, concurrent with, or after the onset of a sublethal dose of virulent L. monocytogenes. Kinetics of bacterial growth in mice were not altered if 2-DG was applied concurrently or after the start of the infection. In contrast, mice exposed to 2-DG prior to infection demonstrated an enhanced resistance to the listeria challenge. The enhanced bacterial clearance in vivo could not be explained by 2-DG exerting a toxic effect on the listeria, based on the results of two experiments. First, 2-DG did not inhibit listeria replication in trypticase soy broth. Second, replication of L. monocytogenes was not inhibited in bone marrow-derived macrophage cultures exposed to 2-DG. Production of neopterin and lysozyme, indicators of macrophage activation, were enhanced following exposure to 2-DG, which correlated with the increased resistance to L. monocytogenes. These results support the contention that the host response to 2-DG-induced metabolic stress can influence the capacity of the immune system to resist infection by certain classes of microbial pathogens.

  1. Evaluation of three newly developed direct plating media to enumerate Listeria monocytogenes in foods.

    PubMed

    Cassiday, P K; Brackett, R E; Beuchat, L R

    1989-06-01

    LiCl-phenylethanol-moxalactam Agar (LPMA), ARS Modified McBride Agar, and Modified Vogel Johnson Agar were compared with previously tested plating media in the enumeration of Listeria monocytogenes from pasteurized whole milk, chocolate ice cream mix, Brie cheese, and raw cabbage. LPMA was most suitable for analyzing Brie cheese and cabbage. Gum base-nalidixic acid-tryptone-soya medium (previously tested) was most suitable for analyzing milk and chocolate ice cream mix. PMID:2504112

  2. A simple method for the isolation of phages from Listeria monocytogenes.

    PubMed

    Durst, J; Rau, E; Kemenes, F; Berencsi, G

    1980-02-01

    By application of a combined mitomycin-/heat treatment after freezing, 7 out of 29 Listeria monocytogenes strains which were found to be non-phage carriers by UV irradiation could release phages. Propagation of the obtained phages was promoted by storage at 4 degrees C. Apart from TNSA plates the application of chocolate plates appears to be necessary in order to study these phages. PMID:6775437

  3. A mycotic abdominal aortic aneurysm caused by Listeria monocytogenes in a patient with HIV infection

    PubMed Central

    Gunst, Jesper Damsgaard; Jensen-Fangel, Søren

    2014-01-01

    A 65-year-old man with HIV infection presented with acute severe abdominal pain radiating to the back. A CT scan revealed an infrarenal abdominal aortic aneurysm, and an aortobifemoral bypass was undertaken. Subsequently, tissue specimens from the aortic wall grew Listeria monocytogenes. The patient received 8 weeks of intravenous antibiotic treatment followed by oral sulfotrim as secondary prophylaxis and made an uneventful recovery. PMID:24443338

  4. Listeria monocytogenes isolated from vegetable salads sold at supermarkets in Santiago, Chile: prevalence and strain characterization.

    PubMed

    Cordano, Ana María; Jacquet, Christine

    2009-06-30

    Between 2000 and 2005, 717 samples of three types of salads were analysed for Listeria monocytogenes in Santiago, Chile in order to provide information to Chilean health authorities on the presence of the pathogen in vegetable salad samples and to ascertain the risk of these products for consumers. L. monocytogenes isolates were found in 88 out of 347 (25.4%) samples of frozen vegetable salads and in 22 out of 216 (10.2%) freshly supermarkets prepared, cooked or raw ready-to-eat vegetable salads; no Listeria was isolated from 154 samples of raw minimally processed salads industrially prepared. Enumeration of L. monocytogenes was done by plate count for 20 positive frozen samples, randomly chosen. Most of them (90%) had < 10 cfu/g. MPN technique was performed for 34 another positive samples; 12 had > or = 1100/g, five ranged between 240 and 93, eight between 23 and three and nine had < 3.0. No L. monocytogenes was recovered after cooking 12 contaminated frozen samples. Isolation of strains was done using three selective agars. Sixty-two L. monocytogenes were isolated from lithium chloride phenylethanol moxalactam agar, 95 from Listeria selective agar Oxford formulation, and 103 from polymixin acriflavine lithium chloride ceftazidime aesculin mannitol agar. Fifty isolates (45.5%) belong to PCR group IIb (including strains serovar 1/2b), 41 (37.3%) to PCR group IVb (including strains serovar 4b), 17 (15.5%) to PCR group IIa (including strains serovar 1/2a), and 2 (1.8%) to PCR group IIc. With the use of DNA macrorestriction patterns analysis, 17 different clusters were detected among 71 isolates, with P10, the most frequent with 25 isolates (35.2%) of PCR group IIb. PMID:19410317

  5. Comparative antimicrobial susceptibility of Listeria monocytogenes, L. innocua, and L. welshimeri.

    PubMed

    Davis, Johnnie A; Jackson, Charlene R

    2009-03-01

    The current study compared antimicrobial susceptibility of Listeria innocua, L. welshimeri, and L. monocytogenes isolated from various sources. Antimicrobial susceptibility testing was performed using a microbroth procedure with Sensititre minimum inhibitory concentration plates containing 18 antimicrobials. Resistant isolates were analyzed for the presence of antimicrobial resistance genes using PCR. The majority of L. monocytogenes isolates were resistant to oxacillin (99%, 89/90) and ceftriaxone (72%, 65/90), while few isolates were resistant to clindamycin (21%, 19/90) and ciprofloxacin (2%, 2/90). When selected sources of L. monocytogenes are compared, resistance to ceftriaxone, clindamycin, and oxacillin ranged from 27% to 86%, 7% to 43%, and 96% to 100%, respectively. Resistance to ciprofloxacin (6%, 2/34), quinupristin/dalfopristin (7%, 1/14), and tetracycline (7%, 1/15) was observed with L. monocytogenes isolated from food, animal, and environmental sources, respectively. All L. welshimeri isolates (6/6) were resistant to streptomycin, quinupristin/dalfopristin, ciprofloxacin, rifampin, oxacillin, penicillin, and clindamycin, while most isolates (67%, 4/6) were resistant to trimethoprim/sulfamethoxazole. All L. innocua isolates (4/4) were resistant to oxacillin and penicillin, whereas 75% (3/4) of isolates were resistant to tetracycline, ceftriaxone, and clindamycin. Resistant isolates were negative for aadA, strA-B, sul I-II, penA, vat(A-E), vga(A-B), and vgb(A-B). However, tetM was detected among tetracycline-resistant isolates. L. welshimeri was resistant to more of the tested antimicrobials than the other two Listeria species tested, but resistance was not attributed to selected resistance genes. These data demonstrate the variability in resistance among Listeria species. However, the human pathogen L. monocytogenes appears to be the least resistant among the tested species. PMID:19216646

  6. Inhibitory effect of combinations of caprylic acid and nisin on Listeria monocytogenes in queso fresco.

    PubMed

    Gadotti, Camila; Nelson, Laura; Diez-Gonzalez, Francisco

    2014-05-01

    Queso fresco (QF), a fresh Hispanic cheese has been linked to outbreaks and recalls caused by Listeria contamination. The use antimicrobial treatments may be a potential solution. The goal of this research was to test the addition of nisin (N), caprylic acid (CA) and trans-cinnamaldehyde (CN) as anti-listerial ingredients in QF. QF batches were inoculated with approx. 10(4) CFU/g of 5- or 6-strain mixtures of Listeria monocytogenes and treated with antimicrobials. Samples were stored at 4 °C for three weeks and Listeria counts were determined by plating on PALCAM agar. The impact on the QF's natural indicator microorganisms was also assessed during refrigerated storage. All N and CA combinations (≥0.4 g/kg each) were effective against L. monocytogenes and reduced the final counts by at least 3 log CFU/g after 20 days of storage compared to controls. The levels of most strain mixtures were reduced immediately after treatment and their numbers remained below 10(3) CFU/g during storage. CN (1.2 g/kg) was bacteriostatic against L. monocytogenes, but it did not reduce initial counts. The addition of CN to the combination of N and CA did not enhance their antimicrobial effect. Results indicated that combinations of N and CA could control L. monocytogenes in QF with little impact on the natural flora of the cheese, providing a solution to control post processing L. monocytogenes contamination of QF. PMID:24387845

  7. The inhibitory effect of natural microflora of food on growth of Listeria monocytogenes in enrichment broths.

    PubMed

    Al-Zeyara, Shaikha A; Jarvis, Basil; Mackey, Bernard M

    2011-01-31

    The aims of this study were to (i) compare the inhibitory effects of the natural microflora of different foods on the growth of Listeria monocytogenes during enrichment in selective and non-selective broths; (ii) to isolate and identify components of the microflora of the most inhibitory food; and (iii) to determine which of these components was most inhibitory to growth of L. monocytogenes in co-culture studies. Growth of an antibiotic-resistant marker strain of L. monocytogenes was examined during enrichment of a range of different foods in Tryptone Soya Broth (TSB), Half Fraser Broth (HFB) and Oxoid Novel Enrichment (ONE) Broth. Inhibition of L. monocytogenes was greatest in the presence of minced beef, salami and soft cheese and least with prepared fresh salad and chicken pâté. For any particular food the numbers of L. monocytogenes present after 24h enrichment in different broths increased in the order: TSB, HFB and ONE Broth. Numbers of L. monocytogenes recovered after enrichment in TSB were inversely related to the initial aerobic plate count (APC) in the food but with only a moderate coefficient of determination (R(2)) of 0.51 implying that microbial numbers and the composition of the microflora both influenced the degree of inhibition of L. monocytogenes. In HFB and ONE Broth the relationship between APC and final L. monocytogenes counts was weaker. The microflora of TSB after 24h enrichment of minced beef consisted of lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and enterococci. In co-culture studies of L. monocytogenes with different components of the microflora in TSB, the lactic acid bacteria were the most inhibitory followed by the Enterobacteriaceae. The least inhibitory organisms were Pseudomonas sp., enterococci and B. thermosphacta. In HFB and ONE Broth the growth of Gram-negative organisms was inhibited but lactic acid bacteria still reached high numbers after 24h. A more detailed study of the growth of

  8. Isolation of Listeria monocytogenes from milks used for Iranian traditional cheese in Lighvan cheese factories.

    PubMed

    Moosavy, Mir-Hassan; Esmaeili, Saber; Mostafavi, Ehsan; Bagheri Amiri, Fahimeh

    2014-01-01

    Traditional Lighvan cheese is a semi-hard cheese which has a popular market in Iran and neighboring countries. The aim of this study was evaluating the contamination of milks used for Lighvan cheese making with Listeria monocytogenes. Raw milk samples were randomly collected from different cheese producing factories (sampling carried out from large milk tanks used cheese making in factories). Isolation of L. monocytogenes was performed according to ISO 11290 and biochemical tests were done to identify and confirm L. monocytogenes. 9 samples (50%) of the 18 collected samples from milk tanks in Lighvan cheese producing factories were contaminated with L. monocytogenes. The concentration of L. monocytogenes in all 9 positive samples was 40 CFU/ml. This study is the first report of L. monocytogenes contamination in raw milks used for Lighvan cheese production in Iran. Regarding the fact that these cheeses are produced from raw milk and no heating process is performed on them its milk contamination can be a potential risk for consumers. PMID:25528910

  9. Impedimetric characterization of adsorption of Listeria monocytogenes on the surface of an aluminum-based immunosensor.

    PubMed

    Chai, Changhoon; Lee, Jooyoung; Oh, Se-Wook; Takhistov, Paul

    2014-11-01

    The impedimetric characteristics of an immunosensor depend on the electrical properties of an immunosensor substrate. The impedimetric characteristics of an immunosensor compared with adsorption of Listeria monocytogenes were investigated on an aluminum surface insulated with an electrically resistive aluminum oxide layer. Antibody for L. monocytogenes (anti-L. monocytogenes) was immobilized on an aluminum surface that was insulated with a native air-formed aluminum oxide layer. The resistance of impedance (R) value of an aluminum-based immunosensor decreased, especially at 10(4) to 10(6) Hz, where the effect of the reactance of impedance (X) was minimal when L. monocytogenes was adsorbed on the immunosensor surface. The R value of the immunosensor at 81 kHz decreased proportionally to the concentration of L. monocytogenes from 1.3 to 4.3 log CFU mL(-1) . The adsorption of L. monocytogenes produced local protrusions on the immunosensor surface, causing physicochemical changes in the ionic layer formed on the immunosensor surface by a sinusoidal electrical signal input, which might help electrical current to flow and cause the R value to decrease. PMID:25296910

  10. Sensitive colorimetric detection of Listeria monocytogenes based on isothermal gene amplification and unmodified gold nanoparticles.

    PubMed

    Fu, Zhongyu; Zhou, Xiaoming; Xing, Da

    2013-12-15

    Listeria monocytogenes (L. monocytogenes), one of most problematic food-borne bacteria, is mainly transmitted through the food chain and may cause listeriosis. Therefore, the development of rapid and sensitive L. monocytogenes detection technique has become an urgent task. In this study, we proposed a method using hyperbranching rolling circle amplification (HRCA) combined with gold nanoparticle (GNP) based colorimetric strategy to offer an isothermal, highly sensitive and specific assay for the detection of L. monocytogenes. First, a linear padlock probe targeting a specific sequence in the hly gene was designed and followed with a ligation by Taq DNA ligase. After ligation, further amplification by HRCA with a thiolated primer and an unlabeled primer is performed. The resulting thiolated HRCA products were then captured onto GNP surface and made GNP more salt-tolerant. Detection of the bacteria can be achieved by a facilitated GNP based colorimetric testing using naked eyes. Through this approach, as low as 100 aM synthetic hly gene targets and about 75 copies of L. monocytogenes can be detected. The specificity is evaluated by distinguishing target L. monocytogenes from other bacteria. The artificial contaminated food samples were also detected for its potential applications in real food detection. This method described here is ideal for bacteria detection due to its simplicity and high sensitivity. PMID:23948710

  11. Development of double loop-mediated isothermal amplification to detect Listeria monocytogenes in food.

    PubMed

    Wu, Rina; Liu, Xiang; Guo, Bangcheng; Chen, Fusheng; Wang, Xiaohong

    2014-12-01

    In this study, a double loop-mediated isothermal amplification (dLAMP) based on two target genes hlyA and iap was developed for the rapid detection of Listeria monocytogenes in food. The results revealed that the detection time and temperature of our dLAMP assay for L. monocytogenes were 15 min and 63 °C respectively, with a sensitivity of 10 fg DNA of L. monocytogenes per tube. While normal LAMP (nLAMP) of hlyA or iap was 100 fg DNA of L. monocytogenes per tube for 45 min and 63 °C. Furthermore, mineral oil and GoldViewII nucleic acid stain were chosen as the basic materials to develop a simple visualized identification of the positive samples. A total of 450 food samples were tested for L. monocytogenes using the dLAMP protocol developed in this study. The results showed that the accuracy of the dLAMP and the "gold standard" culture-biotechnical method were 100 % identical, suggesting that the modified dLAMP assay would provide a potential for detection of L. monocytogenes in food products. PMID:25086581

  12. Edible chitosan films on ready-to-eat roast beef for the control of Listeria monocytogenes.

    PubMed

    Beverly, Richelle L; Janes, Marlene E; Prinyawiwatkul, Witoon; No, Hong K

    2008-05-01

    The use of chitosan as an edible film was evaluated for its antimicrobial activity against Listeria monocytogenes (LM) on the surface of ready-to-eat (RTE) roast beef. L. monocytogenes, decimally diluted to give an initial inoculation of >6.50logCFU/g, was inoculated onto the surface of RTE roast beef cubes, and air-dried. The samples were dipped into chitosan (high or low molecular weights) solutions dissolved with acetic or lactic acid at 0.5% (w/v) or 1% (w/v) then bagged and refrigerated at 4 degrees C. The bacterial counts were determined on days 0, 7, 14, 21, and 28. The samples were spread plated onto modified Oxford agar plates and incubated at 37 degrees C for 48h. An initial 6.50logCFU/g of L. monocytogenes inoculated onto the surface of the non-coated RTE roast beef increased too >10logCFU/g by day 28. On day 14, L. monocytogenes counts were significantly different for all the chitosan-coated samples from the control counts by 2-3logCFU/g and remained significantly different on day 28. Our results have shown that the acetic acid chitosan coating were more effective in reducing L. monocytogenes counts than the lactic acid chitosan coating. Our study indicated that chitosan coatings could be used to control L. monocytogenes on the surface of RTE roast beef. PMID:18355679

  13. Listeria monocytogenes--threat to a safe food supply: a review.

    PubMed

    Pearson, L J; Marth, E H

    1990-04-01

    Listeria monocytogenes can cause circling disease, encephalitis, meningitis, septicemia, and mastitis in dairy cattle. Shedding of the pathogen from the udder or contamination from the environment can lead to presence of L. monocytogenes in raw milk. Surveys indicate the pathogen is in about 4% of US raw milks. Although HTST pasteurization commonly inactivates L. monocytogenes, evidence suggests that under unusual circumstances minimal survival is possible. The pathogen grows well in liquid dairy products at 4 to 35 degrees C and achieves higher populations in chocolate than in unflavored milks. When present in cheese milk, growth of L. monocytogenes may be retarded but not stopped by lactic starter cultures. The pathogen is concentrated in the curd with only a small fraction of cells in milk appearing in whey. Once in curd, the behavior of the pathogen ranges from growth (feta cheese making) to death of most but not all cells (cottage cheese making). During ripening of cheese, the numbers of L. monocytogenes decrease gradually (as in Cheddar or Colby cheese), decrease precipitously early during ripening, and then stabilize (as in blue cheese) or increase markedly (as in Camembert cheese). Consumption of foods containing L. monocytogenes can lead to listeriosis in susceptible humans (adults with a compromised immune system), pregnant women, and infants). In large outbreaks of human listeriosis, mortality rates of ca. 30% are common. PMID:2111832

  14. Diversity of Listeria monocytogenes within a U.S. dairy herd, 2004-2010.

    PubMed

    Haley, Bradd J; Sonnier, Jakeitha; Schukken, Ynte H; Karns, Jeffrey S; Van Kessel, Jo Ann S

    2015-10-01

    Listeria monocytogenes, the causative agent of listeriosis, is frequently isolated from the environment. Dairy cows and dairy farm environments are reservoirs of this pathogen, where fecal shedding contributes to its environmental dispersal and contamination of milk, dairy products, and meat. The molecular diversity of 40 L. monocytogenes isolates representing 3 serogroups (1/2a, 1/2b, and 4b) collected between 2004 and 2010 from the feces of dairy cattle on a single dairy farm was assessed using a multivirulence locus sequence typing (MVLST) assay. The dairy farm L. monocytogenes MVLST patterns were compared to those from 138 strains isolated globally from clinical cases, foods, and the environment. Results of the study demonstrated that several distantly related L. monocytogenes strains persisted among members of the herd over the course of the study while other strains were transient. Furthermore, some strains isolated during this study appear to be distantly related to previously isolated L. monocytogenes while others are closely related to Epidemic Clones associated with human illness. This work demonstrates that dairy cows can be reservoirs of a diverse population of potentially human pathogenic L. monocytogenes that represents a risk to consumers of milk, dairy products, and meat. PMID:26325149

  15. Listeria monocytogenes Spreads within the Brain by Actin-Based Intra-Axonal Migration

    PubMed Central

    Henke, Diana; Rupp, Sebastian; Gaschen, Véronique; Stoffel, Michael H.; Frey, Joachim; Vandevelde, Marc

    2015-01-01

    Listeria monocytogenes rhombencephalitis is a severe progressive disease despite a swift intrathecal immune response. Based on previous observations, we hypothesized that the disease progresses by intra-axonal spread within the central nervous system. To test this hypothesis, neuroanatomical mapping of lesions, immunofluorescence analysis, and electron microscopy were performed on brains of ruminants with naturally occurring rhombencephalitis. In addition, infection assays were performed in bovine brain cell cultures. Mapping of lesions revealed a consistent pattern with a preferential affection of certain nuclear areas and white matter tracts, indicating that Listeria monocytogenes spreads intra-axonally within the brain along interneuronal connections. These results were supported by immunofluorescence and ultrastructural data localizing Listeria monocytogenes inside axons and dendrites associated with networks of fibrillary structures consistent with actin tails. In vitro infection assays confirmed that bacteria were moving within axon-like processes by employing their actin tail machinery. Remarkably, in vivo, neutrophils invaded the axonal space and the axon itself, apparently by moving between split myelin lamellae of intact myelin sheaths. This intra-axonal invasion of neutrophils was associated with various stages of axonal degeneration and bacterial phagocytosis. Paradoxically, the ensuing adaxonal microabscesses appeared to provide new bacterial replication sites, thus supporting further bacterial spread. In conclusion, intra-axonal bacterial migration and possibly also the innate immune response play an important role in the intracerebral spread of the agent and hence the progression of listeric rhombencephalitis. PMID:25824833

  16. Listeria monocytogenes Behaviour in Presence of Non-UV-Irradiated Titanium Dioxide Nanoparticles

    PubMed Central

    Ammendolia, Maria Grazia; Iosi, Francesca; De Berardis, Barbara; Guccione, Giuliana; Superti, Fabiana; Conte, Maria Pia; Longhi, Catia

    2014-01-01

    Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO2 NPs) are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO2 NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS) with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO2 NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO2 NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO2 NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO2 NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts. PMID:24416327

  17. Listeria monocytogenes spreads within the brain by actin-based intra-axonal migration.

    PubMed

    Henke, Diana; Rupp, Sebastian; Gaschen, Véronique; Stoffel, Michael H; Frey, Joachim; Vandevelde, Marc; Oevermann, Anna

    2015-06-01

    Listeria monocytogenes rhombencephalitis is a severe progressive disease despite a swift intrathecal immune response. Based on previous observations, we hypothesized that the disease progresses by intra-axonal spread within the central nervous system. To test this hypothesis, neuroanatomical mapping of lesions, immunofluorescence analysis, and electron microscopy were performed on brains of ruminants with naturally occurring rhombencephalitis. In addition, infection assays were performed in bovine brain cell cultures. Mapping of lesions revealed a consistent pattern with a preferential affection of certain nuclear areas and white matter tracts, indicating that Listeria monocytogenes spreads intra-axonally within the brain along interneuronal connections. These results were supported by immunofluorescence and ultrastructural data localizing Listeria monocytogenes inside axons and dendrites associated with networks of fibrillary structures consistent with actin tails. In vitro infection assays confirmed that bacteria were moving within axon-like processes by employing their actin tail machinery. Remarkably, in vivo, neutrophils invaded the axonal space and the axon itself, apparently by moving between split myelin lamellae of intact myelin sheaths. This intra-axonal invasion of neutrophils was associated with various stages of axonal degeneration and bacterial phagocytosis. Paradoxically, the ensuing adaxonal microabscesses appeared to provide new bacterial replication sites, thus supporting further bacterial spread. In conclusion, intra-axonal bacterial migration and possibly also the innate immune response play an important role in the intracerebral spread of the agent and hence the progression of listeric rhombencephalitis. PMID:25824833

  18. Eradication of high viable loads of Listeria monocytogenes contaminating food-contact surfaces

    PubMed Central

    de Candia, Silvia; Morea, Maria; Baruzzi, Federico

    2015-01-01

    This study demonstrates the efficacy of cold gaseous ozone treatments at low concentrations in the eradication of high Listeria monocytogenes viable cell loads from glass, polypropylene, stainless steel, and expanded polystyrene food-contact surfaces. Using a step by step approach, involving the selection of the most resistant strain-surface combinations, 11 Listeria sp. strains resulted inactivated by a continuous ozone flow at 1.07 mg m-3 after 24 or 48 h of cold incubation, depending on both strain and surface evaluated. Increasing the inoculum level to 9 log CFU coupon-1, the best inactivation rate was obtained after 48 h of treatment at 3.21 mg m-3 ozone concentration when cells were deposited onto stainless steel and expanded polystyrene coupons, resulted the most resistant food-contact surfaces in the previous assays. The addition of naturally contaminated meat extract to a high load of L. monocytogenes LMG 23775 cells, the most resistant strain out of the 11 assayed Listeria sp. strains, led to its complete inactivation after 4 days of treatment. To the best of our knowledge, this is the first report describing the survival of L. monocytogenes and the effect of ozone treatment under cold storage conditions on expanded polystyrene, a commonly used material in food packaging. The results of this study could be useful for reducing pathogen cross-contamination phenomena during cold food storage. PMID:26236306

  19. Microbial Diversity and Structure Are Drivers of the Biological Barrier Effect against Listeria monocytogenes in Soil

    PubMed Central

    Vivant, Anne-Laure; Garmyn, Dominique; Maron, Pierre-Alain; Nowak, Virginie; Piveteau, Pascal

    2013-01-01

    Understanding the ecology of pathogenic organisms is important in order to monitor their transmission in the environment and the related health hazards. We investigated the relationship between soil microbial diversity and the barrier effect against Listeria monocytogenes invasion. By using a dilution-to-extinction approach, we analysed the consequence of eroding microbial diversity on L. monocytogenes population dynamics under standardised conditions of abiotic parameters and microbial abundance in soil microcosms. We demonstrated that highly diverse soil microbial communities act as a biological barrier against L. monocytogenes invasion and that phylogenetic composition of the community also has to be considered. This suggests that erosion of diversity may have damaging effects regarding circulation of pathogenic microorganisms in the environment. PMID:24116193

  20. Catalase and superoxide dismutase activities after heat injury of listeria monocytogenes

    SciTech Connect

    Dallmier, A.W.; Martin, S.E.

    1988-02-01

    Four strains of Listeria monocytogenes were examined for catalase (CA) and superoxide dismutase (SOD) activities. The two strains having the highest CA activities (LCDC and Scott A) also possessed the highest SOD activities. The CA activity of heated cell extracts of all four strains examined decreased sharply between 55 and 60/sup 0/C. SOD was more heat labile than CA. Two L. monocytogenes strains demonstrated a decline in SOD activity after heat treatment at 45/sup 0/C, whereas the other two strains demonstrated a decline at 50/sup 0/C. Sublethal heating of the cells at 55/sup 0/C resulted in increased sensitivity to 5.5% NaCl. Exogenous hydrogen peroxide was added to suspensions of L. monocytogenes; strains producing the highest CA levels showed the greatest H/sub 2/O/sub 2/ resistance.

  1. Use Carum copticum essential oil for controlling the Listeria monocytogenes growth in fish model system.

    PubMed

    Rabiey, Soghra; Hosseini, Hedayat; Rezaei, Masoud

    2014-01-01

    This study was conducted to evaluate the antibacterial effect of Carum copticum essential oil (Ajowan EO) against Listeria monocytogenes in fish model system. Ajowan EO chemical composition was determined by gas chromatography/mass spectral analysis and the highest concentration of Carum copticum essential oil without any significant changes on sensory properties of kutum fish (Rutilus frisii kutum) was assigned. Then the inhibitory effect of Ajowan EO at different concentrations in presence of salt and smoke component was tested on L. monocytogenes growth in fish peptone broth (FPB), kutum broth and cold smoked kutum broth at 4 °C for 12 days. Ajowan EO completely decreased the number of L. monocytogenes in FPB after 12 days of storage, however, antimicrobial effect of EO significantly reduced in kutum and cold smoked kutum broth. Addition of 4% NaCl and smoke component improved the anti-listerial activity of Ajowan EO in all fish model broths. PMID:24948918

  2. Use Carum copticum essential oil for controlling the Listeria monocytogenes growth in fish model system

    PubMed Central

    Rabiey, Soghra; Hosseini, Hedayat; Rezaei, Masoud

    2014-01-01

    This study was conducted to evaluate the antibacterial effect of Carum copticum essential oil (Ajowan EO) against Listeria monocytogenes in fish model system. Ajowan EO chemical composition was determined by gas chromatography/mass spectral analysis and the highest concentration of Carum copticum essential oil without any significant changes on sensory properties of kutum fish (Rutilus frisii kutum) was assigned. Then the inhibitory effect of Ajowan EO at different concentrations in presence of salt and smoke component was tested on L. monocytogenes growth in fish peptone broth (FPB), kutum broth and cold smoked kutum broth at 4 °C for 12 days. Ajowan EO completely decreased the number of L. monocytogenes in FPB after 12 days of storage, however, antimicrobial effect of EO significantly reduced in kutum and cold smoked kutum broth. Addition of 4% NaCl and smoke component improved the anti-listerial activity of Ajowan EO in all fish model broths. PMID:24948918

  3. Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage

    PubMed Central

    Sant’Anna, Voltaire; Quadros, Deoni A.F.; Motta, Amanda S.; Brandelli, Adriano

    2013-01-01

    The antimicrobial activity of the bacteriocin-like substance (BLS) P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g−1) previously inoculated with a suspension of 102 cfu g−1 of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe) against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products. PMID:24688506

  4. Optimizing the balance between host and environmental survival skills: lessons learned from Listeria monocytogenes

    PubMed Central

    Xayarath, Bobbi; Freitag, Nancy E

    2012-01-01

    Environmental pathogens – organisms that survive in the outside environment but maintain the capacity to cause disease in mammals – navigate the challenges of life in habitats that range from water and soil to the cytosol of host cells. The bacterium Listeria monocytogenes has served for decades as a model organism for studies of host–pathogen interactions and for fundamental paradigms of cell biology. This ubiquitous saprophy te has recently become a model for understanding how an environmental bacterium switches to life within human cells. This review describes how L. monocytogenes balances life in disparate environments with the help of a critical virulence regulator known as PrfA. Understanding L. monocytogenes survival strategies is important for gaining insight into how environmental microbes become pathogens. PMID:22827306

  5. Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage.

    PubMed

    Sant'Anna, Voltaire; Quadros, Deoni A F; Motta, Amanda S; Brandelli, Adriano

    2013-12-01

    The antimicrobial activity of the bacteriocin-like substance (BLS) P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g(-1)) previously inoculated with a suspension of 10(2) cfu g(-1) of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe) against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products. PMID:24688506

  6. [Measuring the control and decrease in prevalence of Listeria monocytogenes species in foods of animal origin].

    PubMed

    Caplan, Marius Eduard

    2011-01-01

    A large distributed bacterium, Listeria monocytogenes has been isolated from water and fresh vegetables, raw meat and processed meat (all types), and raw, salted and smoked fish. L. monocytogenes grows at low oxygen concentrations and at low temperatures, surviving for a long time in the environment, in the processing plant, as well as on the equipment, instruments and during storage at the refrigeration temperature. L. monocytogenes causes invasive listeriosis, often affecting immunocompromised individuals. Epidemiologically, listeriosis appears as sporadic cases and outbreaks, with an incidence of 3-8 cases/1000000 inhabitants, run-down in most countries, reflecting the measures compulsory in food processing industry. The purpose of this review is to describe the measures regarding the implementation of Current Good Manufacturing Practice (CGMP), to protrude the integrity of cold chain through preparing, packing and holding food, including household refrigerating, and to increase a good communication, particularly for consumers at increased risk of listeriosis. PMID:23745223

  7. Listeria Monocytogenes – characterization of strains isolated from clinical severe cases

    PubMed Central

    Borcan, AM; Huhulescu, S; Munteanu, A; Rafila, A

    2014-01-01

    Listeria monocytogenes became an increasing pathogen involved more frequently in sporadic severe illnesses and outbreaks of foodborne infections. This study investigates in vitro susceptibility of 26 strains of Listeria monocytogenes isolated from the clinical specimens collected between March 2009 and November 2013, from 24 patients hospitalized in three medical institutions in Bucharest. All isolates were tested by disk diffusion method to 15 antimicrobial agents, by using disk diffusion tests. Among the 26 clinical L. monocytogenes isolates tested, no multidrug resistant strains were detected, but 18 (72%) were found to be resistant to at least one clinically relevant antibiotic. Among them, 18 clinical isolates were resistant against ciprofloxacin also. Resistance to Ciprofloxacin was particularly noticed to the strains in Romania. Serological and molecular typing by Multiplex PCR method detected two molecular types 1/2 a, 3a and 1/2 b, 3b, as to the more frequent isolated among studied cases. These types of L. monocytogenes could be associated to the higher pathogenic activity of immunodeficient patients. PMID:25870672

  8. Improved solubilization of surface proteins from Listeria monocytogenes for 2-DE.

    PubMed

    Mujahid, Sana; Pechan, Tibor; Wang, Chinling

    2007-11-01

    Solubilization of bacterial surface (cell wall and membrane-associated) proteins for 2-DE is challenging, particularly in the case of Gram-positive bacteria. This is primarily due to strong protein association with the cell wall peptidoglycan and protein hydrophobicity. We solubilized surface proteins for 2-DE from the Gram-positive pathogen Listeria monocytogenes using mutanolysin, which digests cell wall peptidoglycan, and one of three different mixtures of zwitterionic detergent and chaotropes: (i) CHAPS/urea, (ii) amidosulfobetaine-14 (ASB-14)/urea/thiourea (iii) N-decyl-N,N'-dimethyl-3-ammonio-1-propanesulfonate/urea/thiourea. Cell lysis with mutanolysin followed by solubilization with ASB-14/urea/thiourea gave the highest overall protein yield with the best 2-DE resolution. Protein spot identification by MALDI-TOF/TOF-MS analysis revealed 29 characterized surface proteins of L. monocytogenes, 17 of which have not previously been reported on the surface proteome map. This is the first report describing the successful solubilization and 2-DE of L. monocytogenes proteins bound to the cell surface via an LPXTG motif or by a hydrophobic tail. The increase in surface proteome coverage obtained by mutanolysin and ASB-14/urea/thiourea solubilization suggests the utility of this method for future analytical and comparative studies of surface proteins from Listeria, and possibly other Gram-positive bacteria, using 2-DE proteomic analysis. An updated 2-DE reference map of L. monocytogenes surface proteins is presented. PMID:17922522

  9. A comparative study of clinical and food isolates of Listeria monocytogenes and related species.

    PubMed Central

    Szabo, E. A.; Desmarchelier, P. M.

    1990-01-01

    Ninety-six isolates of presumptive or confirmed Listeria monocytogenes were obtained from local clinical (30 isolates) or food laboratories (66 isolates). Minimal biochemical analysis identified only 80% of these isolates as L. monocytogenes the remaining included L. seeligeri, 1%, or the non-haemolytic L. innocua, 19%. The 27 clinical and 50 food isolates, mainly from meat products, frozen confectionaries, and cheeses, confirmed as L. monocytogenes were compared biochemically and serologically. Twenty-one isolates, including some strains of L. innocua and L. seeligeri, were examined for pathogenicity in immunocompromized mice and 44 typed using bacterial restriction endonuclease DNA analysis (BRENDA). Only isolates of L. monocytogenes were found to be pathogenic. Biovar-typing of the isolates was unreliable and provided poor discrimination. Serogroups 1/2 and 4 predominated among clinical and food isolates and BRENDA provided better discrimination among isolates. Ten stable and reproducible restriction patterns were observed among the Listeria sp. isolates studied. Overall, a combination of techniques gave the best discrimination and indicated their potential for use as epidemiological tools. Images Fig. 1 PMID:2120079

  10. A Dual Microscopy-Based Assay To Assess Listeria monocytogenes Cellular Entry and Vacuolar Escape

    PubMed Central

    Quereda, Juan J.; Balestrino, Damien; Bobard, Alexandre; Danckaert, Anne; Aulner, Nathalie; Shorte, Spencer; Enninga, Jost; Cossart, Pascale

    2015-01-01

    Listeria monocytogenes is a Gram-positive bacterium and a facultative intracellular pathogen that invades mammalian cells, disrupts its internalization vacuole, and proliferates in the host cell cytoplasm. Here, we describe a novel image-based microscopy assay that allows discrimination between cellular entry and vacuolar escape, enabling high-content screening to identify factors specifically involved in these two steps. We first generated L. monocytogenes and Listeria innocua strains expressing a β-lactamase covalently attached to the bacterial cell wall. These strains were then incubated with HeLa cells containing the Förster resonance energy transfer (FRET) probe CCF4 in their cytoplasm. The CCF4 probe was cleaved by the bacterial surface β-lactamase only in cells inoculated with L. monocytogenes but not those inoculated with L. innocua, thereby demonstrating bacterial access to the host cytoplasm. Subsequently, we performed differential immunofluorescence staining to distinguish extracellular versus total bacterial populations in samples that were also analyzed by the FRET-based assay. With this two-step analysis, bacterial entry can be distinguished from vacuolar rupture in a single experiment. Our novel approach represents a powerful tool for identifying factors that determine the intracellular niche of L. monocytogenes. PMID:26497455

  11. Prevalence and populations of Listeria monocytogenes in meat products retailed in Sao Paulo, Brazil.

    PubMed

    Ristori, Christiane Asturiano; Rowlands, Ruth Estela Gravato; Martins, Cecília Geraldes; Barbosa, Maria Luisa; Yoshida, Júlia T U; Franco, Bernadette D G de Melo

    2014-12-01

    This study evaluated the prevalence of the populations and serotypes of Listeria monocytogenes in 552 refrigerated samples of ground beef, chicken leg, hot dog, and pork sausage collected in supermarkets in the city of Sao Paulo, SP, Brazil, between May 2008 and July 2009. The supermarkets were selected after stratification by geographical region and by random draw. Tests for presence and enumeration of L. monocytogenes were based on ISO 11290-1:1996/Amd.1:2004 and ISO 11290-2:1998 methods, respectively. Listeria spp. were detected in 469 (85.0%) of the studied meat products. The most frequently isolated species was L. innocua (64.1%), followed by L. monocytogenes (48.7%), L. welshimeri (13.4%), L. seeligeri (7.1%), L. ivanovii (0.2%), and L. grayi subspecies murrayi (0.2%). L. monocytogenes was detected in 269 (48.7%) samples, with highest prevalence in ground beef (59.4%) followed by chicken legs (58.0%), pork sausages (39.8%), and hot dogs (37.7%). The populations were <10(2) colony-forming units/g in the majority of samples (62.5%). Prevalence of serotypes varied according to the type of meat product. These data are relevant for estimating the risks of listeriosis associated with consumption of meat products in Sao Paulo, and for establishing science-based intervention strategies aimed at reducing these risks, especially for pregnant women and immunocompromised individuals. PMID:25407460

  12. Isolation of pathogenic Listeria monocytogenes in faeces of wild animals in captivity.

    PubMed

    Kalorey, D R; Kurkure, N V; Warke, S R; Rawool, D B; Malik, S V S; Barbuddhe, S B

    2006-11-01

    The isolation of pathogenic Listeria spp. in faecal samples of captive wild animals was studied. Isolation of the pathogen was attempted from the samples by selective enrichment in University of Vermont Medium and plating onto Dominguez-Rodriguez isolation agar, PALCAM agar and modified McBride Listeria agar. Pathogenicity of the isolates was tested by Christie, Atkins, Munch Petersen test, phosphotidylinositol-specific phospholipase C assay, mice inoculation test and chick embryo bioassay. Listeria monocytogenes was isolated from eight (16%) of 50 faecal samples from six different mammals and one bird. Out of eight isolates, one isolate from jackal proved to be pathogenic by all the pathogenicity testing assays. PCR amplification of virulence genes suggested that the isolate was potentially pathogenic. PMID:17034860

  13. Prevalence and survival of Listeria monocytogenes in Danish aquatic and fish-processing environments.

    PubMed

    Hansen, Cisse Hedegaard; Vogel, Birte Fonnesbech; Gram, Lone

    2006-09-01

    Listeria monocytogenes contamination of ready-to-eat food products such as cold-smoked fish is often caused by pathogen subtypes persisting in food-processing environments. The purpose of the present study was to determine whether these L. monocytogenes subtypes can be found in the outside environment, i.e., outside food processing plants, and whether they survive better in the aquatic environment than do other strains. A total of 400 samples were collected from the outside environment, fish slaughterhouses, fish farms, and a smokehouse. L. monocytogenes was not detected in a freshwater stream, but prevalence increased with the degree of human activity: 2% in seawater fish farms, 10% in freshwater fish farms, 16% in fish slaughterhouses, and 68% in a fish smokehouse. The fish farms and slaughterhouses processed Danish rainbow trout, whereas the smokehouse was used for farm-raised Norwegian salmon. No variation with season was observed. Inside the processing plants, the pattern of randomly amplified polymorphic DNA (RAPD) types was homogeneous, but greater diversity existed among isolates from the outside environments. The RAPD type dominating the inside of the fish smokehouse was found only sporadically in outside environments. To examine survival in different environments, L. monocytogenes or Listeria innocua strains were inoculated into freshwater and saltwater microcosms. Pathogen counts decreased over time in Instant Ocean and remained constant in phosphate-buffered saline. In contrast, counts decreased rapidly in natural seawater and fresh water. The count reduction was much slower when the natural waters were autoclaved or filtered (0.2-microm pore size), indicating that the pathogen reduction in natural waters was attributable to a biological mechanism, e.g., protozoan grazing. A low prevalence of L. monocytogenes was found in the outside environment, and the bacteria did not survive well in natural environments. Therefore, L. monocytogenes in the outer

  14. Antimicrobial effect of Thai spices against Listeria monocytogenes and Salmonella typhimurium DT104.

    PubMed

    Thongson, Chitsiri; Davidson, P Michael; Mahakarnchanakul, Warapa; Vibulsresth, Preeya

    2005-10-01

    The objective of this study was to determine the potential antimicrobial activity of extracts and essential oils of spices from Thailand against foodborne pathogenic bacteria. The antimicrobial efficacy of ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata), and turmeric (Curcuma longa) was evaluated against five strains of Listeria monocytogenes and four strains of Salmonella enterica ssp. enterica serovar Typhimurium DT104. Antimicrobial activity was investigated in microbiological media by using an agar dilution assay and enumeration over time and a model food system, apple juice, by monitoring growth over time. In the agar dilution assay, water extracts of the three spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5 to 10% (vol/ vol) inhibited most L. monocytogenes strains for 24 h in the agar dilution assay. Commercial essential oils (EO) of ginger or turmeric inhibited all L. monocytogenes at < or = 0.6 or < or = 10%, respectively. Fingerroot EO inhibited all strains at < or = 0.4%. In the enumeration-over-time assay, a 5% fingerroot ethanol extract reduced ca. 4 log CFU/ml Listeria by around 2 log in 24 h while 10% inactivated the microorganism in 9 h. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 6 to 9 h. Neither extracts nor commercial EO had any effect on Salmonella Typhimurium DT 104 with the exception of fingerroot EO, which inhibited all strains at < or = 0.7%. Addition of 0.2% fingerroot EO to apple juice reduced 4 log of L. monocytogenes Scott A and both strains of Salmonella Typhimurium to an undetectable level within 1 to 2 days. It was concluded that fingerroot EO and extract have potential for inhibiting pathogens in food systems. PMID:16245707

  15. Growth of Listeria monocytogenes within a Caramel-Coated Apple Microenvironment

    PubMed Central

    Golden, Max C.; Wanless, Brandon J.; Bedale, Wendy; Czuprynski, Charles

    2015-01-01

    ABSTRACT A 2014 multistate listeriosis outbreak was linked to consumption of caramel-coated apples, an unexpected and previously unreported vehicle for Listeria monocytogenes. This outbreak was unanticipated because both the pH of apples (<4.0) and the water activity of the caramel coating (<0.80) are too low to support Listeria growth. In this study, Granny Smith apples were inoculated with approximately 4 log10 CFU of L. monocytogenes (a cocktail of serotype 4b strains associated with the outbreak) on each apple’s skin, stem, and calyx. Half of the apples had sticks inserted into the core, while the remaining apples were left intact. Apples were dipped into hot caramel and stored at either 7°C or 25°C for up to 11 or 28 days, respectively. Data revealed that apples with inserted sticks supported significantly more L. monocytogenes growth than apples without sticks under both storage conditions. Within 3 days at 25°C, L. monocytogenes populations increased >3 log10 in apples with sticks, whereas only a 1-log10 increase was observed even after 1 week for caramel-coated apples without sticks. When stored at 7°C, apples with sticks exhibited an approximately 1.5-log10 increase in L. monocytogenes levels at 28 days, whereas no growth was observed in apples without sticks. We infer that insertion of a stick into the apple accelerates the transfer of juice from the interior of the apple to its surface, creating a microenvironment at the apple-caramel interface where L. monocytogenes can rapidly grow to levels sufficient to cause disease when stored at room temperature. PMID:26463161

  16. Contamination patterns of Listeria monocytogenes in cold-smoked pork processing.

    PubMed

    Bērziņš, Aivars; Hellström, Sanna; Siliņš, Indulis; Korkeala, Hannu

    2010-11-01

    Contamination patterns of Listeria monocytogenes were studied in a cold-smoked pork processing plant to identify the sources and possible reasons for the contamination. Environmental sampling combined with pulsed-field gel electrophoresis (PFGE) subtyping and serotyping were applied to investigate the genetic diversity of L. monocytogenes in the plant environment and ready-to-eat (RTE) cold-smoked pork products. A total of 183 samples were collected for contamination analyses, including samples of the product at different stages during manufacture (n = 136) and environmental samples (n = 47) in 2009. L. monocytogenes isolates, previously recovered from 73 RTE cold-smoked pork samples and collected from the same meat processing plant in 2004, were included in this study. The brining machine and personnel working with brining procedures were the most contaminated places with L. monocytogenes. The overall prevalence of L. monocytogenes in raw pork (18%) increased to 60% after the brining injections. The brining machine harbored six different PFGE types belonging to serotypes 1/2a, 1/2c, 4b, and 4d, which were found on the feeding teeth, smooth surfaces, and spaces of the machine, thus potentially facilitating dissemination of L. monocytogenes contamination. Two PFGE types (2 and 8) belonging to serotypes 1/2a and 1/2c were recovered from RTE cold-smoked pork collected in 2004, and from surfaces of the brining machine sampled in 2009, and may indicate the presence of persistent L. monocytogenes strains in the plant. Due to poor hygiene design, removal of the brining machine from the production of cold-smoked meat products should be considered to reduce L. monocytogenes contamination in the finished products. PMID:21219726

  17. Rapid detection of Listeria monocytogenes by real-time PCR in processed meat and dairy products.

    PubMed

    Heo, Eun Jeong; Song, Bo Ra; Park, Hyun Jung; Kim, Young Jo; Moon, Jin San; Wee, Sung Hwan; Kim, Jin-Seok; Yoon, Yohan

    2014-03-01

    The objectives of this study were to evaluate the detection of Listeria monocytogenes in different ready-to-eat foods using real-time PCR (RT-PCR). Various concentrations (10(0) to 10(5) CFU/ml) of L. monocytogenes ATCC 19115 were inoculated into ham, sausage, ground meat, processed milk, cheese, and infant formula. L. monocytogenes ATCC 19115 in the samples was then enumerated on Oxford agar, and DNA was extracted from the samples before and after incubation at 36°C for 4 h. A set of primers and hybridization probe designed in this study was then used to detect the pathogen. The standard curve was then prepared by plotting cycle threshold values for each dilution versus L. monocytogenes cell counts (log CFU). The specificity of the set of primers and hybridization probe was appropriate. A 4-h incubation at 36°C before DNA extraction produced optimum standard curves in comparison to the results for a 0-h incubation. Thus, a 4-h incubation at 36°C was applied for monitoring L. monocytogenes in collected food samples. To monitor L. monocytogenes in foods, 533 samples (ham, 129; sausage, 226; ground meat, 72; processed cheese, 54; processed milk, 42; and infant formula, 10) were collected from retail markets and from the step before pasteurization in plants. Of all 533 samples, 4 samples (0.8%) showed positive signals in RT-PCR. Two samples from hams (1.6%) and two samples from sausages (0.9%) were determined to be positive for L. monocytogenes at < 100 CFU/g. The results indicate that the RT-PCR detection method with the set of primers and hybridization probe designed in this study should be useful in monitoring for L. monocytogenes in processed meat and milk products. PMID:24674437

  18. Multiplex PCR serogrouping of Listeria monocytogenes isolated in Japan.

    PubMed

    Shimojima, Yukako; Ida, Miki; Nishino, Yukari; Ishitsuka, Rie; Kuroda, Sumiyo; Hirai, Akihiko; Sadamasu, Kenji; Nakama, Akiko; Kai, Akemi

    2016-04-01

    PCR serogrouping methods were used to examine strains of L. monocytogenes isolated in Japan. Among 187 strains, 99.5% were classified into 4 PCR serogroups corresponding to conventional serotypes. Only one isolate had a new PCR profile, which may be a variant of serogroup IVb. PMID:26537550

  19. Multiplex PCR serogrouping of Listeria monocytogenes isolated in Japan

    PubMed Central

    SHIMOJIMA, Yukako; IDA, Miki; NISHINO, Yukari; ISHITSUKA, Rie; KURODA, Sumiyo; HIRAI, Akihiko; SADAMASU, Kenji; NAKAMA, Akiko; KAI, Akemi

    2015-01-01

    PCR serogrouping methods were used to examine strains of L. monocytogenes isolated in Japan. Among 187 strains, 99.5% were classified into 4 PCR serogroups corresponding to conventional serotypes. Only one isolate had a new PCR profile, which may be a variant of serogroup IVb. PMID:26537550

  20. Inactivation of Listeria monocytogenes Scott A 49594 in apple juice supplemented with cinnamon.

    PubMed

    Yuste, J; Fung, D Y C

    2002-10-01

    Normal (pH 3.7) and adjusted (pH 5.0) pasteurized apple juice containing cinnamon (0, 0.1, 0.2, and 0.3%) was inoculated with Listeria monocytogenes Scott A 49594 at 10(4) CFU/ml and stored at 5 and 20 degrees C for 7 days. Counts on tryptic soy agar (TSA), modified Oxford (MOX) medium, and thin agar layer (TAL) were determined at 1 h and 1, 3, and 7 days. The TAL method (MOX medium overlaid with TSA) was used for the recovery of injured cells. In apple juice, both at normal and adjusted pH, with any doses of cinnamon, no L. monocytogenes (a 4.6-log CFU/ml reduction) was detected after 1 h of storage at both temperatures, and no growth occurred at any points of storage. Therefore, cinnamon by itself (regardless of pH) had a pronounced killing effect. A further enrichment step with brain heart infusion agar showed that L monocytogenes was completely inactivated in apple juice stored at 20 degrees C, except in pH 5.0 samples with 0.1% of cinnamon. The TAL method was as effective as TSA in recovering injured cells of L. monocytogenes. Cinnamon considerably inactivates L. monocytogenes in apple juice and thus enhances the safety of this product. PMID:12380758

  1. Interferon γ-induced GTPase promotes invasion of Listeria monocytogenes into trophoblast giant cells

    PubMed Central

    Tachibana, Masato; Hashino, Masanori; Watanabe, Kenta; Shimizu, Takashi; Watarai, Masahisa

    2015-01-01

    Listeria monocytogenes is well known for having the ability to cross the placental barrier, leading to fetal infections and abortion. However, the mechanisms leading to infectious abortion are poorly understood. In this study, we demonstrate that interferon γ-induced GTPase (IGTP) contributes to the invasion of L. monocytogenes into trophoblast giant (TG) cells, which are placental immune cells. Knockdown of IGTP in TG cells decreased the relative efficiencies of L. monocytogenes invasion. Moreover, IGTP accumulated around infected L. monocytogenes in TG cells. Treatment of TG cells with phosphatidylinositol 3-kinase (PI3K)/Akt inhibitors also reduced bacterial invasion. PI3K/Akt inhibitor or IGTP knockdown reduced the amount of phosphorylated Akt. Monosialotetrahexosylganglioside (GM1) gangliosides, lipid raft markers, accumulated in the membrane of L. monocytogenes-containing vacuoles in TG cells. Furthermore, treatment with a lipid raft inhibitor reduced bacterial invasion. These results suggest that IGTP-induced activation of the PI3K/Akt signaling pathway promotes bacterial invasion into TG cells. PMID:25645570

  2. Efficacy of household washing treatments for the control of Listeria monocytogenes on salad vegetables.

    PubMed

    Nastou, Aikaterini; Rhoades, Jonathan; Smirniotis, Petros; Makri, Ioanna; Kontominas, Michael; Likotrafiti, Eleni

    2012-10-15

    The efficacy of household decontamination methods at reducing Listeria monocytogenes on fresh lettuce (Lactuca sativa), cucumber (Cucumis sativus) and parsley (Petroselinum sativum) was studied. Inoculated vegetable pieces were immersed in washing solutions and surviving L. monocytogenes enumerated. Parameters investigated were storage temperature prior to washing, dipping water temperature, agitation, acetic acid concentration and immersion time. The results indicated that the storage temperature significantly affects the efficacy of dipping vegetables in water for the control of L. monocytogenes, as the reduction in count was greatest when products had been stored at cooler temperatures. Decontamination with acetic acid (up to 2.0% v/v) was shown to have some effect in most cases, but the highest observed decrease in count was 2.6 log cfu/g. Experiments investigating the effect of exposure time to acetic acid (0.5% and 1.0% v/v, up to 30 min immersion) indicated that immersing the vegetables for more than 10 min is of minimal benefit. The most significant factor affecting washing and decontamination efficacy was the vegetable itself: L. monocytogenes colonizing cucumber epidermis was far more resistant to removal by washing and to acid treatment than that on the leafy vegetables, and L. monocytogenes on parsley was the most susceptible. This shows that published decontamination experiments (often performed with lettuce) cannot necessarily be extrapolated to other vegetables. PMID:23107504

  3. Dynamics of Listeria monocytogenes colonisation in a newly-opened meat processing facility.

    PubMed

    Bolocan, Andrei Sorin; Nicolau, Anca Ioana; Alvarez-Ordóñez, Avelino; Borda, Daniela; Oniciuc, Elena Alexandra; Stessl, Beatrix; Gurgu, Leontina; Wagner, Martin; Jordan, Kieran

    2016-03-01

    This study determined the colonisation scenario of Listeria monocytogenes in a newly-opened ready-to-eat meat processing facility using a combination of classical microbiology and molecular biology techniques. Samples (n=183), including food contact surfaces, non-food contact surfaces, raw materials and food samples, collected on four sampling occasions, were analysed for L. monocytogenes by the ISO 11290:1996 standard method and by real-time PCR applied to the second enrichment broth from the ISO method. No L. monocytogenes were detected on the first sampling occasion, but by the second sampling occasion a persistent clone had colonised the facility. Analysis of the second enrichment of the ISO method by real-time PCR was more sensitive for the detection of L. monocytogenes than the ISO method alone. In order to reduce the risk of cross contamination and the public health risk, awareness and proactive measures are required to control L. monocytogenes from the first days of production in a newly opened meat processing facility. PMID:26599913

  4. Physiological implications of class IIa bacteriocin resistance in Listeria monocytogenes strains.

    PubMed

    Vadyvaloo, Viveka; Snoep, Jacky L; Hastings, John W; Rautenbach, Marina

    2004-02-01

    High-level resistance to class IIa bacteriocins has been directly associated with the absent EIIAB(Man) (MptA) subunit of the mannose-specific phosphoenolpyruvate-dependent phosphotransferase system (PTS) (EIIt(MAN)) in Listeria monocytogenes strains. Class IIa bacteriocin-resistant strains used in this study were a spontaneous resistant, L. monocytogenes B73-MR1, and a defined mutant, L. monocytogenes EGDe-mptA. Both strains were previously reported to have the EIIAB(Man) PTS component missing. This study shows that these class IIa bacteriocin-resistant strains have significantly decreased specific growth and glucose consumption rates, but they also have a significantly higher growth yield than their corresponding wild-type strains, L. monocytogenes B73 and L. monocytogenes EGDe, respectively. In the presence of glucose, the strains showed a shift from a predominantly lactic-acid to a mixed-acid fermentation. It is here proposed that elimination of the EIIAB(Man) in the resistant strains has caused a reduced glucose consumption rate and a reduced specific growth rate. The lower glucose consumption rate can be correlated to a shift in metabolism to a more efficient pathway with respect to ATP production per glucose, leading to a higher biomass yield. Thus, the cost involved in obtaining bacteriocin resistance, i.e. losing substrate transport capacity leading to a lower growth rate, is compensated for by a higher biomass yield. PMID:14766911

  5. Antimicrobial activity of chitosan coatings and films against Listeria monocytogenes on black radish.

    PubMed

    Jovanović, Gordana D; Klaus, Anita S; Nikšić, Miomir P

    2016-01-01

    The antibacterial activity of chitosan coatings prepared with acetic or lactic acid, as well as of composite chitosan-gelatin films prepared with essential oils, was evaluated in fresh shredded black radish samples inoculated with Listeria monocytogenes ATCC 19115 and L. monocytogenes ATCC 19112 during seven days of storage at 4°C. The chitosan coating prepared with acetic acid showed the most effective antibacterial activity. All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of L. monocytogenes on black radish, although a higher inhibition of pathogens was achieved at higher concentrations of chitosan. The antimicrobial effect of chitosan films was even more pronounced with the addition of essential oils. Chitosan-gelatin films with thyme essential oils showed the most effective antimicrobial activity. A reduction of 2.4log10CFU/g for L. monocytogenes ATCC 19115 and 2.1log10CFU/g for L. monocytogenes ATCC 19112 was achieved in the presence of 1% chitosan film containing 0.2% of thyme essential oil after 24h of storage. PMID:27237426

  6. Review--Persistence of Listeria monocytogenes in food industry equipment and premises.

    PubMed

    Carpentier, Brigitte; Cerf, Olivier

    2011-01-31

    To understand why Listeria monocytogenes may persist in food industry equipment and premises, notably at low temperature, scientific studies have so far focused on adhesion potential, biofilm forming ability, resistance to desiccation, acid and heat, tolerance to increased sublethal concentration of disinfectants or resistance to lethal concentrations. Evidence from studies in processing plants shows that the factors associated with the presence of L. monocytogenes are those that favor growth. Interestingly, most conditions promoting bacterial growth were shown, in laboratory assays, to decrease adhesion of L. monocytogenes cells. Good growth conditions can be found in so-called harborage sites, i.e. shelters due to unhygienic design of equipment and premises or unhygienic or damaged materials. These sites are hard to eliminate. A conceptual model of persistence/no persistence based on the relative weight of growth vs. outcome of cleaning and disinfection is suggested. It shows that a minimum initial bacterial load is necessary for bacteria to persist in a harborage site and that when a low initial bacterial charge is applied, early cleaning and disinfection is the only way to avoid persistence. We conclude by proposing that there are no strains of L. monocytogenes with unique properties that lead to persistence, but harborage sites in food industry premises and equipment where L. monocytogenes can persist. PMID:21276634

  7. A new bovine conjunctiva model shows that Listeria monocytogenes invasion is associated with lysozyme resistance.

    PubMed

    Warren, Jessica; Owen, A Rhys; Glanvill, Amy; Francis, Asher; Maboni, Grazieli; Nova, Rodrigo J; Wapenaar, Wendela; Rees, Catherine; Tötemeyer, Sabine

    2015-08-31

    Listerial keratoconjunctivitis ('silage eye') is a wide spread problem in ruminants causing economic losses to farmers and impacts negatively on animal welfare. It results from direct entry of Listeria monocytogenes into the eye, often following consumption of contaminated silage. An isolation protocol for bovine conjunctival swabbing was developed and used to sample both infected and healthy eyes bovine eyes (n=46). L. monocytogenes was only isolated from one healthy eye sample, and suggests that this organism can be present without causing disease. To initiate a study of this disease, an infection model was developed using isolated conjunctiva explants obtained from cattle eyes post slaughter. Conjunctiva were cultured and infected for 20 h with a range of L. monocytogenes isolates (n=11), including the healthy bovine eye isolate and also strains isolated from other bovine sources, such as milk or clinical infections. Two L. monocytogenes isolates (one from a healthy eye and one from a cattle abortion) were markedly less able to invade conjunctiva explants, but one of those was able to efficiently infect Caco2 cells indicating that it was fully virulent. These two isolates were also significantly more sensitive to lysozyme compared to most other isolates tested, suggesting that lysozyme resistance is an important factor when infecting bovine conjunctiva. In conclusion, we present the first bovine conjunctiva explant model for infection studies and demonstrate that clinical L. monocytogenes isolates from cases of bovine keratoconjunctivitis are able to infect these tissues. PMID:25778543

  8. Commercial biopreservatives combined with salt and sugar to control Listeria monocytogenes during smoked salmon processing.

    PubMed

    Montiel, Raquel; Bravo, Daniel; Medina, Margarita

    2013-08-01

    Three commercial antimicrobials, applied during the salting stage in the preparation of cold-smoked salmon, were investigated for their effect on the behavior of Listeria monocytogenes. Fresh salmon inoculated with L. monocytogenes INIA 2530 was treated with three bacteriocin-based commercial biopreservatives, which were applied in combination with a salt-sugar mix. The product was kept at 8°C for 7 days. L. monocytogenes grew by approximately 3 log CFU/g in control salmon (without the salt-sugar mix or biopreservatives). Pathogen levels were reduced by the three biopreservatives investigated. After 7 days at 8°C, L. monocytogenes counts in salmon treated with biopreservatives combined with the salt-sugar mix were significantly lower than those observed in salmon treated with only salt and sugar. At the end of storage, salmon treated with biopreservative derived from Pediococcus acidilactici had pathogen levels 3.6 log CFU/g lower than in control salmon (without the salt-sugar mix) and 1.5 log CFU/g lower than in the samples treated with only salt and sugar. The application of commercial biopreservatives to fresh salmon during the dry-salting stage might help control L. monocytogenes growth, thus enhancing the safety of cold-smoked salmon during refrigerated storage. PMID:23905807

  9. Behavior of Listeria monocytogenes inoculated into raw tomatoes and processed tomato products.

    PubMed

    Beuchat, L R; Brackett, R E

    1991-05-01

    Rates of death and growth of Listeria monocytogenes inoculated onto raw whole and into chopped tomatoes stored at 10 and 21 degrees C were not influenced by prior treatment of tomatoes with chlorine or packaging under an atmosphere of 3% O2 and 97% N2. Growth of the pathogen occurred in whole tomatoes held at 21 degrees C but not at 10 degrees C, while death occurred in chopped tomatoes stored at these temperatures. Likewise, growth patterns of mesophilic aerobic microorganisms, psychrotrophic microorganisms, and yeasts and molds on whole and chopped tomatoes were essentially unaffected by chlorine and modified atmosphere packaging treatments. Populations of L. monocytogenes inoculated into commercially processed tomato juice and sauce and held at 5 degrees C remained constant for 14 days. A gradual decrease in the number of viable L. monocytogenes cells was observed in juice and sauce held at 21 degrees C. In contrast, the organism died rapidly when suspended in commercial tomato ketchup at 5 and 21 degrees C. Unlike low-acid raw salad vegetables such as lettuce, broccoli, asparagus, and cauliflower on which we have observed L. monocytogenes grow at refrigeration temperatures, tomatoes are not a good growth substrate for the organism. Nevertheless, L. monocytogens can remain viable on raw whole and chopped tomatoes and in commercial tomato juice and sauce for periods extending beyond their normal shelf-life expectancy. PMID:1906697

  10. Pathogen-nematode interaction: Nitrogen supply of Listeria monocytogenes during growth in Caenorhabditis elegans.

    PubMed

    Kern, Tanja; Kutzner, Erika; Eisenreich, Wolfgang; Fuchs, Thilo M

    2016-02-01

    Listeria monocytogenes is a Gram-positive facultatively intracellular human pathogen. Due to its saprophytic lifestyle, L. monocytogenes is assumed to infect and proliferate within soil organisms such as Caenorhabditis elegans. However, little is known about the nutrient usages and metabolite fluxes in this bacterium-nematode interaction. Here, we established a nematode colonization model for L. monocytogenes and a method for the efficient separation of the pathogen from the nematodal gut. Following (15)N labelling of C. elegans and gas chromatography-mass spectrometry-based (15)N isotopologue analysis, we detected a high basal metabolic rate of the nematode, and observed a significant metabolic flux from nitrogenous compounds of the nematode to listerial proteins during proliferation of the pathogen in the worm's intestine. For comparison, we also measured the N fluxes from the gut content into listerial proteins using completely (15)N-labelled Escherichia coli OP50 as food for C. elegans. In both settings, L. monocytogenes prefers the direct incorporation of histidine, arginine and lysine over their de novo biosynthesis. Our data suggest that colonization of nematodes is a strategy of L. monocytogenes to increase its access to N-rich nutrients. PMID:26478569

  11. Effect of gamma-irradiation on the survival of Listeria monocytogenes and allergenicity of cherry tomatoes

    NASA Astrophysics Data System (ADS)

    Todoriki, Setsuko; Bari, Latiful; Kitta, Kazumi; Ohba, Mika; Ito, Yasuhiro; Tsujimoto, Yuka; Kanamori, Norihito; Yano, Erika; Moriyama, Tatsuya; Kawamura, Yukio; Kawamoto, Shinichi

    2009-07-01

    The presence of Listeria monocytogenes in fresh produce is a growing concern because of the possibility of food-borne illness. Ionizing radiation is an effective non-thermal means of eliminating pathogenic bacteria in fresh produce; however, the effect of ionizing irradiation on the allergenic properties of the host commodities remains unknown. This study aimed (i) to determine the effective dose of gamma-irradiation in eliminating L. monocytogenes on whole cherry tomatoes and (ii) to evaluate the effect of gamma-irradiation on the allergenic properties of tomato proteins. Cherry tomatoes that were inoculated with a mixture of five L. monocytogenes strains were treated with gamma-rays from a 60Co source. A 1.25 kGy dose of gamma-irradiation was found to be sufficient to eliminate L. monocytogenes on whole cherry tomatoes. The immunoblot profile of serum samples obtained from two patients with tomato allergy revealed that gamma-irradiation did not affect the allergenicity of tomato proteins for up to 7 days after irradiation when the tomatoes were stored at 20 °C. Additionally, the m-RNA levels of β-fructofuranosidase, polygalacturonase, pectin esterase, and superoxide dismutase, the main allergenic proteins in tomato, were not affected by the applied irradiation dose. Thus, this study demonstrated that a 1.25 kGy dose of gamma-irradiation effectively eliminates L. monocytogenes on cherry tomatoes without affecting the expression of allergenic proteins in the fruits.

  12. Combination of Zinc and All-Trans Retinoic Acid Promotes Protection against Listeria monocytogenes Infection

    PubMed Central

    Nakatsu, Yukiko; Watanabe, Kenta; Shimizu, Takashi; Watarai, Masahisa

    2015-01-01

    Zinc (Zn) is the second most abundant transition metal after iron. It plays a vital role in living organisms and affects multiple aspects of the immune system. All-trans retinoic acid (atRA) is an isomeric form of the vitamin A or retinol. It possesses the greatest biological activity of Vitamin A. Vitamin A and related retinoids influence many aspects of immunity. In this study, we demonstrated that treatment with a combination of Zn and atRA contributes to host resistance against infection by Listeria monocytogenes. Pretreatment with Zn and atRA enhanced resistance against L. monocytogenes infection in mice and treatment with both Zn and atRA showed a higher protective effect than treatment with either alone. Supplementation with Zn, atRA or their combination decreased the number of L. monocytogenes present in target organs. In vitro, supplementation increased the bacterial uptake by macrophage cells and reduced the replication of L. monocytogenes. Our results suggest that the combination of Zn and atRA has a great bacteriostatic impact on L. monocytogenes and its infection. PMID:26351852

  13. Meningoencephalitis and Listeria monocytogenes, Toxoplasma gondii and Brucella spp. coinfection in a dolphin in Italy.

    PubMed

    Grattarola, Carla; Giorda, Federica; Iulini, Barbara; Pintore, Maria Domenica; Pautasso, Alessandra; Zoppi, Simona; Goria, Maria; Romano, Angelo; Peletto, Simone; Varello, Katia; Garibaldi, Fulvio; Garofolo, Giuliano; Di Francesco, Cristina Esmeralda; Marsili, Letizia; Bozzetta, Elena; Di Guardo, Giovanni; Dondo, Alessandro; Mignone, Walter; Casalone, Cristina

    2016-02-25

    Listeria monocytogenes, Toxoplasma gondii and Brucella spp. can infect a wide range of species, including humans. In cetaceans, meningoencephalitis has been associated with T. gondii and Brucella spp. infection, whereas to our knowledge, L. monocytogenes infection has not previously been reported. Meningoencephalitis and L. monocytogenes, T. gondii and Brucella spp. were identified by means of both direct and indirect laboratory techniques in an adult female striped dolphin Stenella coeruleoalba found stranded in January 2015 on the Ligurian Sea coast, northwestern Italy. The animal was emaciated, and histopathology disclosed severe meningoencephalitis. The nature of the inflammatory response and intra-lesional protozoa were consistent with a mixed infection by L. monocytogenes, T. gondii and Brucella spp. We believe this is an unprecedented case of infection by 3 zoonotic pathogens and also the first bacteriologically confirmed case report of neurolisteriosis in cetaceans. Cerebral toxoplasmosis and neurobrucellosis may have led to the animal's disorientation and stranding, with L. monocytogenes having likely exacerbated the coinfection leading to the demise of this dolphin. PMID:26912047

  14. Genomes of sequence type 121 Listeria monocytogenes strains harbor highly conserved plasmids and prophages

    PubMed Central

    Schmitz-Esser, Stephan; Müller, Anneliese; Stessl, Beatrix; Wagner, Martin

    2015-01-01

    The food-borne pathogen Listeria (L.) monocytogenes is often found in food production environments. Thus, controlling the occurrence of L. monocytogenes in food production is a great challenge for food safety. Among a great diversity of L. monocytogenes strains from food production, particularly strains belonging to sequence type (ST)121 are prevalent. The molecular reasons for the abundance of ST121 strains are however currently unknown. We therefore determined the genome sequences of three L. monocytogenes ST121 strains: 6179 and 4423, which persisted for up to 8 years in food production plants in Ireland and Austria, and of the strain 3253 and compared them with available L. monocytogenes ST121 genomes. Our results show that the ST121 genomes are highly similar to each other and show a tremendously high degree of conservation among some of their prophages and particularly among their plasmids. This remarkably high level of conservation among prophages and plasmids suggests that strong selective pressure is acting on them. We thus hypothesize that plasmids and prophages are providing important adaptations for survival in food production environments. In addition, the ST121 genomes share common adaptations which might be related to their persistence in food production environments such as the presence of Tn6188, a transposon responsible for increased tolerance against quaternary ammonium compounds, a yet undescribed insertion harboring recombination hotspot (RHS) repeat proteins, which are most likely involved in competition against other bacteria, and presence of homologs of the L. innocua genes lin0464 and lin0465. PMID:25972859

  15. Comparison of Culture, Conventional and Real-time PCR Methods for Listeria monocytogenes in Foods

    PubMed Central

    Moon, Jin-San

    2014-01-01

    We compared standard culture methods as well as conventional PCR and real-time PCR for the detection of Listeria monocytogenes (L. monocytogenes) in milk, cheese, fresh-cut vegetables, and raw beef that have different levels of background microflora. No statistical differences were observed in sensitivity between the two selective media in all foods. In total, real-time PCR assay exhibited statistically excellent detection sensitivity (p<0.05) and was less time consuming and laborious as compared with standard culture methods. Conventional culture methods showed poor performance in detecting L. monocytogenes in food with high levels of background microflora, generating numerous false negative results. While the detection of L. monocytogenes in fresh cut vegetable by culture methods was hindered only by L. innocua, various background microflora, such as L. innocua, L. welshimeri, L. grayi, and Enterococcus faecalis appeared on the two selective media as presumptive positive colonies in raw beef indicating the necessity of improvement of current selective media. It appears that real-time PCR is an effective and sensitive presumptive screening tool for L. monocytogenes in various types of foods, especially foods samples with high levels of background microflora, thus complementing standard culture methodologies. PMID:26761501

  16. Proteomic Differences between Listeria monocytogenes Isolates from Food and Clinical Environments

    PubMed Central

    Huang, Ge; Mason, Susan L.; Hudson, J. Andrew; Clerens, Stefan; Plowman, Jeffrey E.; Hussain, Malik A.

    2014-01-01

    Listeria monocytogenes is an organism associated with a wide range of foods. It causes listeriosis, a severe illness that mainly affects people with weakened immune systems. Proteomic profiles of three different L. monocytogenes isolates were studied using 1D SDS PAGE, 2DE and mass spectrometry. The protein banding patterns generated by 1D SDS PAGE of three strains of L. monocytogenes were found to be similar. Visual observations from 2DE gel maps revealed that certain spots appeared to have intensity differences. Key differences in proteins synthesis of three strains of L. monocytogenes were found using the PDQest TM 2DE Analysis software. Comparison showed that the clinical isolate (strain SB92/844) had 53.4% and 53.9% protein profile similarity with dairy isolate (strain V7) and seafood isolate (SB92/870), respectively. The identity of selected protein spots was achieved using MALDI-TOF and ion trap mass spectrometry. It was found that certain identified proteins (i.e., a major cold shock protein and superoxide dismutase) were expressed differently between two local strains of L. monocytogenes (SB92/844, SB92/870) and one strain from overseas (V7). PMID:25513735

  17. Listeria monocytogenes in two different poultry facilities: Manual and automatic evisceration.

    PubMed

    Chiarini, E; Tyler, K; Farber, J M; Pagotto, F; Destro, M T

    2009-04-01

    Listeriosis is a serious foodborne disease caused by Listeria monocytogenes, a pathogen often found in food processing plants. Poultry meat and its derivatives may harbor L. monocytogenes even if good manufacturing practices are implanted in abattoirs. Little information exists in Brazil on the frequency of L. monocytogenes contamination, even though the country is considered the top poultry meat exporter in the world. This study attempted to compare 2 exporters poultry facilities following same the standards but differing only in manual (plant M) or automatic (plant A) evisceration. Eight hundred fifty-one samples from food, food contact and non-food contact surfaces, water, and workers' hands were collected from cage to finished products over a 1-yr period. In plant A, 20.1% of the samples were positive for L. monocytogenes, whereas in plant M, 16.4% was found. The greatest incidence of contamination with the pathogen in plant A was found in non-food contact surfaces (27.3%), while in plant M, it was found in products (19.4%). The most prevalent serovars were 1/2a or 3a (plant M) and 4b, 4d, or 4e (plant A). Despite having proper hygiene and good manufacturing practices, controlling the entry and persistence of L. monocytogenes in processing facilities remains a formidable task. PMID:19276422

  18. Utilization of iron-catecholamine complexes involving ferric reductase activity in Listeria monocytogenes.

    PubMed Central

    Coulanges, V; Andre, P; Ziegler, O; Buchheit, L; Vidon, D J

    1997-01-01

    Listeria monocytogenes is a ubiquitous potentially pathogenic organism requiring iron for growth and virulence. Although it does not produce siderophores, L. monocytogenes is able to obtain iron by using either exogenous siderophores produced by various microorganisms or natural catechol compounds widespread in the environment. In the presence of tropolone, an iron-chelating agent, growth of L. monocytogenes is completely inhibited. However, the growth inhibition can be relieved by the addition of dopamine or norepinephrine under their different isomeric forms, while the catecholamine derivatives 4-hydroxy-3-methoxyphenylglycol and normetanephrine did not relieve the inhibitory effect of tropolone. Preincubation of L. monocytogenes with chlorpromazine and yohimbine did not antagonize the growth-promoting effect of catecholamines in iron-complexed medium. In addition, norepinephrine stimulated the growth-promoting effect induced by human transferrin in iron-limited medium. Furthermore, dopamine and norepinephrine allowed 55Fe uptake by iron-deprived bacterial cells. The uptake of iron was energy dependent, as indicated by inhibition of 55Fe uptake at 0 degrees C as well as by preincubating the bacteria with KCN. Inhibition of 55Fe uptake by L. monocytogenes was also observed in the presence of Pt(II). Moreover, when assessed by a whole-cell ferric reductase assay, reductase activity of L. monocytogenes was inhibited by Pt(II). These data demonstrate that dopamine and norepinephrine can function as siderophore-like compounds in L. monocytogenes owing to their ortho-diphenol function and that catecholamine-mediated iron acquisition does not involve specific catecholamine receptors but acts through a cell-bound ferrireductase activity. PMID:9199450

  19. Evolution and Diversity of Listeria monocytogenes from Clinical and Food Samples in Shanghai, China

    PubMed Central

    Zhang, Jianmin; Cao, Guojie; Xu, Xuebin; Allard, Marc; Li, Peng; Brown, Eric; Yang, Xiaowei; Pan, Haijian; Meng, Jianghong

    2016-01-01

    Listeria monocytogenes is a significant foodborne pathogen causing severe systemic infections in humans with high mortality rates. The objectives of this work were to establish a phylogenetic framework of L. monocytogenes from China and to investigate sequence diversity among different serotypes. We selected 17 L. monocytogenes strains recovered from patients and foods in China representing serotypes 1/2a, 1/2b, and 1/2c. Draft genome sequences were determined using Illumina MiSeq technique and associated protocols. Open reading frames were assigned using prokaryotic genome annotation pipeline by NCBI. Twenty-four published genomes were included for comparative genomic and phylogenetic analysis. More than 154,000 single nucleotide polymorphisms (SNPs) were identified from multiple genome alignment and used to reconstruct maximum likelihood phylogenetic tree. The 41 genomes were differentiated into lineages I and II, which consisted of 4 and 11 subgroups, respectively. A clinical strain from China (SHL009) contained significant SNP differences compared to the rest genomes, whereas clinical strain SHL001 shared most recent common ancestor with strain SHL017 from food. Moreover, clinical strains SHL004 and SHL015 clustered together with two strains (08-5578 and 08-5923) recovered from an outbreak in Canada. Partial sequences of a plasmid found in the Canadian strain were also present in SHL004. We investigated the presence of various genes and gene clusters associated with virulence and subgroup-specific genes, including internalins, L. monocytogenes pathogenicity islands (LIPIs), L. monocytogenes genomic islands (LGIs), stress survival islet 1 (SSI-1), and clustered regularly interspaced short palindromic repeats (CRISPR)/cas system. A novel genomic island, denoted as LGI-2 was identified. Comparative sequence analysis revealed differences among the L. monocytogenes strains related to virulence, survival abilities, and attributes against foreign genetic elements. L

  20. Evolution and Diversity of Listeria monocytogenes from Clinical and Food Samples in Shanghai, China.

    PubMed

    Zhang, Jianmin; Cao, Guojie; Xu, Xuebin; Allard, Marc; Li, Peng; Brown, Eric; Yang, Xiaowei; Pan, Haijian; Meng, Jianghong

    2016-01-01

    Listeria monocytogenes is a significant foodborne pathogen causing severe systemic infections in humans with high mortality rates. The objectives of this work were to establish a phylogenetic framework of L. monocytogenes from China and to investigate sequence diversity among different serotypes. We selected 17 L. monocytogenes strains recovered from patients and foods in China representing serotypes 1/2a, 1/2b, and 1/2c. Draft genome sequences were determined using Illumina MiSeq technique and associated protocols. Open reading frames were assigned using prokaryotic genome annotation pipeline by NCBI. Twenty-four published genomes were included for comparative genomic and phylogenetic analysis. More than 154,000 single nucleotide polymorphisms (SNPs) were identified from multiple genome alignment and used to reconstruct maximum likelihood phylogenetic tree. The 41 genomes were differentiated into lineages I and II, which consisted of 4 and 11 subgroups, respectively. A clinical strain from China (SHL009) contained significant SNP differences compared to the rest genomes, whereas clinical strain SHL001 shared most recent common ancestor with strain SHL017 from food. Moreover, clinical strains SHL004 and SHL015 clustered together with two strains (08-5578 and 08-5923) recovered from an outbreak in Canada. Partial sequences of a plasmid found in the Canadian strain were also present in SHL004. We investigated the presence of various genes and gene clusters associated with virulence and subgroup-specific genes, including internalins, L. monocytogenes pathogenicity islands (LIPIs), L. monocytogenes genomic islands (LGIs), stress survival islet 1 (SSI-1), and clustered regularly interspaced short palindromic repeats (CRISPR)/cas system. A novel genomic island, denoted as LGI-2 was identified. Comparative sequence analysis revealed differences among the L. monocytogenes strains related to virulence, survival abilities, and attributes against foreign genetic elements. L

  1. Listeria monocytogenes in Different Specimens from Healthy Red Deer and Wild Boars.

    PubMed

    Weindl, Lucia; Frank, Elisabeth; Ullrich, Ulrike; Heurich, Marco; Kleta, Sylvia; Ellerbroek, Lüppo; Gareis, Manfred

    2016-07-01

    In the past, Listeria monocytogenes has been isolated from game feces and meat. However, less information is available on the occurrence of L. monocytogenes in other specimens originating from game animals. Hence, the aim of this study was to get an overview of the occurrence and distribution of L. monocytogenes in game animals by characterization of isolates from different matrices. For that purpose, samples were collected from red deer (Cervus elaphus), wild boars (Sus scrofa), and feed during the hunting season 2011-2012 in three different regions of Germany and Austria. Six samples from each animal were examined: tonsils, content of the rumen or the stomach, liver, intestinal lymph nodes, cecum content, and feces. Nineteen of 45 red deer and 12 of 49 wild boars were found to be positive for L. monocytogenes as well as 4 of 22 pooled feed samples. L. monocytogenes was isolated most frequently from the rumen of red deer (14 of 19) and the tonsils of wild boars (7 of 12). Serotypes 1/2a, 1/2b, 4a, and 4b were detected in samples of game animals and feed, and serotypes 1/2a and 4b were the most prevalent serotypes. The presence of L. monocytogenes serotype 4a had not yet been described in red deer. This might be due to the fact that it was only isolated from the content of rumen and that no other study has yet examined ruminal content. Pulsed-field gel electrophoresis showed a wide variety of strains. Some strains occurred in both species and feed samples, but one strain was dominant in one region. The results show that red deer and wild boars can be carriers of L. monocytogenes in different matrices, although the feces samples can be negative. PMID:27159352

  2. Examination of Listeria monocytogenes in Seafood Processing Facilities and Smoked Salmon in the Republic of Ireland.

    PubMed

    Leong, Dara; Alvarez-Ordóñez, Avelino; Zaouali, Sarah; Jordan, Kieran

    2015-12-01

    Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a relatively rare but life-threatening disease primarily affecting immunocompromised individuals. The aim of this study was to determine the prevalence of L. monocytogenes in the seafood processing industry in the Republic of Ireland. The occurrence of L. monocytogenes was determined by regular sampling of both food samples and processing environment swabs at eight seafood processing facilities over two calendar years. All samples were analyzed by the International Organization for Standardization 11290-1 standard method, and the isolates were characterized by PCR, pulsed-field gel electrophoresis, serotyping, and the occurrence of some genes related to survival under stress (SSI-1, Tn6188, and bcrABC). A prevalence of 2.5% in 508 samples (433 environmental swabs and 75 food samples) was found. From the isolates obtained, eight different pulsed-field gel electrophoresis profiles were identified, two occurring in more than one facility and one occurring in food and the environment. Five of the eight pulsotypes identified contained at least one of the three stress survival-related genes tested. The tolerance of the isolates to benzalkonium chloride, a representative quaternary ammonium compound, was also examined and ranged from 5.5 ± 0.5 to 8.5 ± 0.5 ppm of benzalkonium chloride. To evaluate the ability of smoked salmon to support the growth of L. monocytogenes, including the T4 widespread pulsotype that was isolated, a challenge test was performed on cold-smoked salmon obtained from two separate producers. The results showed clearly that both types of smoked salmon supported the growth of L. monocytogenes. Although occurrence of L. monocytogenes on seafood was low, this study showed that the smoked salmon used in this study can support the growth of L. monocytogenes; therefore, vigilance is required in the processing facilities to reduce the associated risk. PMID:26613913

  3. Inhibition of Listeria monocytogenes on bologna sausages by an antimicrobial film containing mustard extract or sinigrin.

    PubMed

    Lara-Lledó, Marta; Olaimat, Amin; Holley, Richard A

    2012-05-01

    The ability of Listeria (L.) monocytogenes to convert glucosinolates into antimicrobial isothiocyanates was investigated. Mustard glucosinolates in pure (sinigrin) or extract forms (sinigrin, oriental; sinalbin, yellow mustard) were used in broth media and in a polyvinyl polyethylene glycol graft copolymer (PPG) packaging film with bologna to examine their value as antimicrobial precursors for the control of L. monocytogenes viability and extension of bologna shelf-life at 4 °C. During broth tests with deodorized (myrosinase-inactivated) mustard extracts (10 d at 20 °C) or with purified sinigrin (21 d at 20 °C) L. monocytogenes was only inhibited when exogenous myrosinase was added. None the less, the organism was able to hydrolyze almost half the pure sinigrin by 21 d in tests without added enzyme. Reductions in sinigrin levels were measured by reversed-phase liquid chromatography, and in the absence of L. monocytogenes or added myrosinase the glucosinolate was stable. When pure sinigrin, oriental or yellow mustard extracts were incorporated in PPG films containing 3, 5 and 6% (w/w) of the corresponding glucosinolate and used to package bologna inoculated with 4 log CFU/g L. monocytogenes, the pathogen became undetectable in bologna packed with the oriental mustard extract at 52 d storage and remained undetectable at 70 d. The yellow mustard extract was less inhibitory and the pure sinigrin was not antimicrobial. L. monocytogenes numbers reached >7 log CFU/g in the film and untreated controls at 17 d storage. At 35 d storage, samples packed with control film contained sufficient numbers of lactic acid bacteria (LAB) (>7 log CFU/g) to be considered spoiled, whereas treatments containing mustard or sinigrin remained <7 log CFU/g LAB for ≤ 70 d. L. monocytogenes played a key role in exerting control over its own viability in bologna by hydrolysis of the glucosinolate in the oriental mustard film, but other antimicrobials in treatments may have contributed. PMID

  4. Investigation of the Mechanisms by Which Listeria monocytogenes Grows in Porcine Gallbladder Bile▿ †

    PubMed Central

    Dowd, Georgina C.; Joyce, Susan A.; Hill, Colin; Gahan, Cormac G. M.

    2011-01-01

    The food-borne pathogen Listeria monocytogenes is known to colonize the lumen of the gallbladder in infected mice and to grow rapidly in this environment (J. Hardy et al., Science 303:851-853, 2004). However, relatively little is known about the mechanisms utilized by the pathogen to survive and grow in this location. We utilized gallbladder bile (GB bile) isolated directly from porcine gallbladders as an ex vivo model of gallbladder growth. We demonstrate that GB bile is generally nontoxic for bacteria and can readily support growth of a variety of bacterial species including L. monocytogenes, Lactococcus lactis, Salmonella enterica serovar Typhimurium, and Escherichia coli. Significantly, L. monocytogenes grew at the same rate as the nonpathogenic species Listeria innocua, indicating that the pathogen does not possess specialized mechanisms that enable growth in this environment. However, when we reduced the pH of GB bile to pH 5.5 in order to mimic the release of bile within the small intestine, the toxicity of GB bile increased significantly and specific resistance mechanisms (Sigma B, BSH, and BilE) were essential for survival of the pathogen under these conditions. In order to identify genetic loci that are necessary for growth of L. monocytogenes in the gallbladder, a mariner transposon bank was created and screened for mutants unable to replicate in GB bile. This led to the identification of mutants in six loci, including genes encoding enzymes involved in purine metabolism, amino acid biosynthesis, and biotin uptake. Although GB bile does not represent a significant impediment to bacterial growth, specific metabolic processes are required by L. monocytogenes in order to grow in this environment. PMID:20937762

  5. Optical immunosensors for detection of Listeria monocytogenes and Salmonella enteritidis from food

    NASA Astrophysics Data System (ADS)

    Bhunia, Arun K.; Geng, Tao; Lathrop, Amanda; Valadez, Angela; Morgan, Mark T.

    2004-03-01

    Listeria monocytogenes and Salmonella are two major foodborne pathogens of significant concern. Two optical evanescent wave immunosensors were evaluated for detection: Antibody-coupled fiber-optic biosensor and a surface plasmon resonant (SPR) immunosensor. In the fiber-optic sensor, polyclonal antibodies for the test organisms were immobilized on polystyrene fiber wave -guides using streptavidin - biotin chemistry. Cyanine 5 -labeled monoclonal antibodies C11E9 (for L. monocytogenes) and SF-11 (for Salmonella Enteritidis) were used to generate a specific fluorescent signal. Signal acquisition was performed by launching a laser-light (635 nm) from an Analyte-2000. This immunosensor was able to detect 103 - 109 cfu/ml of L. monocytogenes or 106-109 cfu/ml of Salmonella Enteritidis and the assays were conducted at near real-time with results obtained within one hour of sampling. The assays were specific and showed signal even in the presence of other microorganisms such as E. coli, Enterococcus faecalis or Salmonella Typhimurium. In the SPR system, IAsys instrument (resonant mirror sensor) was used. Monoclonal antibody-C11E9 was directly immobilized onto a carboxylate cuvette. Whole Listeria cells at various concentrations did not yield any signal while surface protein extracts did. Crude protein extracts from L. monocytogenes and L. innocua had average binding responses of around 150 arc sec (0.25 ng/mm2), which was significantly different from L. grayi, L. ivanovii, or L. welshimeri with average responses of <48 arc sec. Both fiber-optic and SPR sensors show promise in near real-time detection of foodborne L. monocytogenes and Salmonella Enteritidis.

  6. Hygiene and Safety in the Meat Processing Environment from Butcher Shops: Microbiological Contamination and Listeria monocytogenes.

    PubMed

    da Silva, Danilo Augusto Lopes; Dias, Mariane Rezende; Cossi, Marcus Vinícius Coutinho; de Castilho, Natália Parma Augusto; Camargo, Anderson Carlos; Nero, Lúis Augusto

    2016-04-01

    The quality and safety of meat products can be estimated by assessing their contamination by hygiene indicator microorganisms and some foodborne pathogens, with Listeria monocytogenes as a major concern. To identify the main sources of microbiological contamination in the processing environment of three butcher shops, surface samples were obtained from the hands of employees, tables, knives, inside butcher displays, grinders, and meat tenderizers (24 samples per point). All samples were subjected to enumeration of hygiene indicator microorganisms and detection of L. monocytogenes, and the obtained isolates were characterized by their serogroups and virulence genes. The results demonstrated the absence of relevant differences in the levels of microbiological contamination among butcher shops; samples with counts higher than reference values indicated inefficiency in adopted hygiene procedures. A total of 87 samples were positive for Listeria spp. (60.4%): 22 from tables, 20 from grinders, 16 from knives, 13 from hands, 9 from meat tenderizers, and 7 from butcher shop displays. Thirty-one samples (21.5%) were positive for L. monocytogenes, indicating the presence of the pathogen in meat processing environments. Seventy-four L. monocytogenes isolates were identified, with 52 from serogroups 1/2c or 3c and 22 from serogroups 4b, 4d, 4a, or 4c. All 74 isolates were positive for hlyA, iap, plcA, actA, and internalins (inlA, inlB, inlC, and inlJ). The establishment of appropriate procedures to reduce microbial counts and control the spread of L. monocytogenes in the final steps of the meat production chain is of utmost importance, with obvious effects on the quality and safety of meat products for human consumption. PMID:27052868

  7. Listeriaphages and coagulin C23 act synergistically to kill Listeria monocytogenes in milk under refrigeration conditions.

    PubMed

    Rodríguez-Rubio, Lorena; García, Pilar; Rodríguez, Ana; Billington, Craig; Hudson, J Andrew; Martínez, Beatriz

    2015-07-16

    Bacteriophages and bacteriocins are promising biocontrol tools in food. In this work, two Listeria bacteriophages, FWLLm1 and FWLLm3, were assessed in combination with the bacteriocin coagulin C23 to inhibit Listeria monocytogenes. Preliminary results under laboratory conditions demonstrated that both antimicrobials act synergistically when they were applied in suboptimal concentrations. The combined approach was further assessed in milk contaminated with 5×10(4) CFU/ml L. monocytogenes 2000/47 and stored at 4 °C for 10 days. When used alone, phage FWLLm1 added at 5×10(6) PFU/ml, FWLLm3 at 5×10(5) PFU/ml and coagulin C23 at 584 AU/ml kept L. monocytogenes 2000/47 counts lower than the untreated control throughout storage. However, when used in combination, inhibition was enhanced and in the presence of FWLLm1 and coagulin C23, L. monocytogenes 2000/47 counts were under the detection limits (less than 10 CFU/ml) from day 4 until the end of the experiment. Resistant mutants towards phages and coagulin C23 could be obtained, but cross-resistance was not detected. Mutants resistant to FWLLm3 and coagulin C23 were also recovered from surviving colonies after cold storage in milk which may explain the failure of this combination to inhibit L. monocytogenes. Remarkably, the fraction of resistant mutants isolated from the combined treatment was lower than that from each antimicrobial alone, suggesting that synergy between bacteriocins and phages could be due to a lower rate of resistance development and the absence of cross-resistance. PMID:25897991

  8. A novel method to detect Listeria monocytogenes via superparamagnetic lateral flow immunoassay.

    PubMed

    Shi, Lei; Wu, Feng; Wen, Yiming; Zhao, Fang; Xiang, Junjian; Ma, Lan

    2015-01-01

    A novel strip test system combining immunomagnetic separation with lateral flow immunoassay (LFIA) was established for the accurate detection of Listeria monocytogenes. In this system, a pair of matched monoclonal antibodies was used to construct a sandwich immunoassay, in which superparamagnetic particles were coupled with one of the antibodies as a labeled antibody to capture the target bacteria, while the other antibody was immobilized on the detection zone. After a 20-min reaction, the strips were analyzed by a novel instrument which could detect the magnetic signal of the immunocomplex in a magnetic field. Sensitivity evaluation showed that the limit of detection (LOD) of the superparamagnetic LFIA system for L. monocytogenes was 10(4) CFU/mL, which was at least one log lower than conventional LFIA. No cross-reaction was observed when Salmonella, Escherichia coli O157:H7, or three types of harmless Listeria strains were tested. Further evaluation with actual food samples indicated that the superparamagnetic LFIA system showed 100 % concordance with real-time PCR. Therefore, this novel superparamagnetic LFIA system could be used as a rapid, sensitive, and specific method for the detection of L. monocytogenes. PMID:25486917

  9. Inhibition of multidrug resistant Listeria monocytogenes by peptides isolated from combinatorial phage display libraries.

    PubMed

    Flachbartova, Z; Pulzova, L; Bencurova, E; Potocnakova, L; Comor, L; Bednarikova, Z; Bhide, M

    2016-01-01

    The aim of the study was to isolate and characterize novel antimicrobial peptides from peptide phage library with antimicrobial activity against multidrug resistant Listeria monocytogenes. Combinatorial phage-display library was used to affinity select peptides binding to the cell surface of multidrug resistant L. monocytogenes. After several rounds of affinity selection followed by sequencing, three peptides were revealed as the most promising candidates. Peptide L2 exhibited features common to antimicrobial peptides (AMPs), and was rich in Asp, His and Lys residues. Peptide L3 (NSWIQAPDTKSI), like peptide L2, inhibited bacterial growth in vitro, without any hemolytic or cytotoxic effects on eukaryotic cells. L1 peptide showed no inhibitory effect on Listeria. Structurally, peptides L2 and L3 formed random coils composed of α-helix and β-sheet units. Peptides L2 and L3 exhibited antimicrobial activity against multidrug resistant isolates of L. monocytogenes with no haemolytic or toxic effects. Both peptides identified in this study have the potential to be beneficial in human and veterinary medicine. PMID:27296960

  10. Single cell swimming dynamics of Listeria monocytogenes using a nanoporous microfluidic platform

    SciTech Connect

    Wright, Evan; Neethirajan, Suresh; Warriner, Keith; Retterer, Scott T; Srijanto, Bernadeta R

    2014-01-01

    Listeria monocytogenes remains a significant foodborne pathogen due to its virulence and ability to become established in food processing facilities. The pathogen is characterized by its ability to grow over a wide temperature range and withstand a broad range of stresses. The following reports on the chemotaxis and motility of the L. monocytogenes when exposed to relatively small concentrations of acetic acid. Using the developed nanoporous microfluidic device to precisely modulate the cellular environment, we exposed the individual Listeria cells to acetic acid and, in real time and with high resolution, observed how the cells reacted to the change in their surroundings. Our results showed that concentrations of acetic acid below 10 mM had very little, if any, effect on the motility. However, when exposed to 100 mM acetic acid, the cells exhibited a sharp drop in velocity and displayed a more random pattern of motion. These results indicate that at appropriate concentrations, acetic acid has the ability to disable the flagellum of the cells, thus impairing their motility. This drop in motility has numerous effects on the cell; its main effects being the obstruction of the cell's ability to properly form biofilms and a reduction in the overall infectivity of the cells. Since these characteristics are especially useful in controlling the proliferation of L. monocytogenes, acetic acid shows potential for application in the food industry as an active compound in designing a food packaging environment and as an antimicrobial agent.

  11. Survival of bioluminescent Listeria monocytogenes and Escherichia coli O157:H7 in soft cheeses.

    PubMed

    Ramsaran, H; Chen, J; Brunke, B; Hill, A; Griffiths, M W

    1998-07-01

    Pasteurized and raw milks that had been inoculated at 10(4) cfu/ml with bioluminescent strains of Listeria monocytogenes and Escherichia coli O157:H7 were used in the manufacture of Camembert and Feta cheeses with or without nisin-producing starter culture. Survival of both organisms was determined during the manufacture and storage of Camembert and Feta cheeses at 2 +/- 1 degree C for 65 and 75 d, respectively. Bacterial bioluminescence was used as an indicator to enumerate the colonies plated on selective Listeria agar and on MacConkey agar. Escherichia coli O157:H7 survived the manufacturing process of both cheeses and was present at the end of the storage period in greater numbers than in the initial inoculum. At the end of 75 d of storage, E. coli O157:H7 was found in the brine of Feta cheese. The counts of L. monocytogenes increased as the pH of the Camembert cheese increased, and there were significant differences between the counts from samples taken from the inside and the counts from samples obtained near the surface of the cheese. The Feta cheese that contained nisin was the only cheese in which L. monocytogenes was at the level of the initial inoculum after 75 d of storage. PMID:9710748

  12. An Internalin A Probe-Based Genosensor for Listeria monocytogenes Detection and Differentiation

    PubMed Central

    Ingianni, Angela

    2013-01-01

    Internalin A (InlA), a protein required for Listeria monocytogenes virulence, is encoded by the inlA gene, which is only found in pathogenic strains of this genus. One of the best ways to detect and confirm the pathogenicity of the strain is the detection of one of the virulence factors produced by the microorganism. This paper focuses on the design of an electrochemical genosensor used to detect the inlA gene in Listeria strains without labelling the target DNA. The electrochemical sensor was obtained by immobilising an inlA gene probe (single-stranded oligonucleotide) on the surfaces of screen-printed gold electrodes (Au-SPEs) by means of a mercaptan-activated self-assembled monolayer (SAM). The hybridisation reaction occurring on the electrode surface was electrochemically transduced by differential pulse voltammetry (DPV) using methylene blue (MB) as an indicator. The covalently immobilised single-stranded DNA was able to selectively hybridise to its complementary DNA sequences in solution to form double-stranded DNA on the gold surface. A significant decrease of the peak current of the voltammogram (DPV) upon hybridisation of immobilised ssDNA was recorded. Whole DNA samples of L. monocytogenes strains could be discriminated from other nonpathogenic Listeria species DNA with the inlA gene DNA probe genosensor. PMID:23586053

  13. Listeria monocytogenes-associated biliary tract infections: a study of 12 consecutive cases and review.

    PubMed

    Charlier, Caroline; Fevre, Cindy; Travier, Laetitia; Cazenave, Benoît; Bracq-Dieye, Hélène; Podevin, Juliette; Assomany, Daher; Guilbert, Lydie; Bossard, Céline; Carpentier, Françoise; Cales, Valérie; Leclercq, Alexandre; Lecuit, Marc

    2014-10-01

    At present, little is known regarding Listeria monocytogenes-associated biliary tract infection, a rare form of listeriosis.In this article, we will study 12 culture-proven cases reported to the French National Reference Center for Listeria from 1996 to 2013 and review the 8 previously published cases.Twenty cases were studied: 17 cholecystitis, 2 cholangitis, and 1 biliary cyst infection. Half were men with a median age of 69 years (32-85). Comorbidities were present in 80%, including cirrhosis, rheumatoid arthritis, and diabetes. Five patients received immunosuppressive therapy, including corticosteroids and anti-tumor necrosis factor biotherapies. Half were afebrile. Blood cultures were positive in 60% (3/5). Gallbladder histological lesions were analyzed in 3 patients and evidenced acute, chronic, or necrotic exacerbation of chronic infection. Genoserogroup of the 12 available strains were IVb (n=6), IIb (n=5), and IIa (n=1). Their survival in the bile was not enhanced when compared with isolates from other listeriosis cases. Adverse outcome was reported in 33% (5/15): 3 deaths, 1 recurrence; 75% of the patients with adverse outcome received inadequate antimicrobial therapy (P=0.033).Biliary tract listeriosis is a severe infection associated with high mortality in patients not treated with appropriate therapy. This study provides medical relevance to in vitro and animal studies that had shown Listeria monocytogenes ability to survive in bile and induce overt biliary infections. PMID:25319439

  14. Determination of the presence of Listeria monocytogenes in milk and dairy products: IDF collaborative study.

    PubMed

    Twedt, R M; Hitchins, A D; Prentice, G A

    1994-01-01

    A collaborative study was conducted on the recovery of viable Listeria monocytogenes from milk and dairy products (Camembert cheese, Limburger cheese, skim milk powder, and ice cream). Test portions were homogenized with Listeria-selective liquid enrichment medium and cultured at 30 degrees C for 48 h. The enrichment culture was then subcultured onto a solid isolation medium at 37 degrees C for 48 h. Suspected Listeria colonies were identified by appropriate conventional morphological, physiological, and biochemical tests. Five kinds of dairy matrixes were spiked with L. monocytogenes at 2 levels: 12 and 120 colony forming units (cfu)/25 g. Each of the 18 collaborating laboratories analyzed 15 blind test portions from each matrix, comprising 5 replicates at each spiking level and 5 uninoculated controls, for a total of 1350 analyses. The specificity of the method was 100%; its sensitivity was 94-100% at the high spiking level and 89-98% at the low spiking level, except for Limburger cheese, which was only 68%. No specificity or sensitivity differences were observed between laboratories for all matrixes at the high spiking level and for all except Limburger cheese at the low spiking level. The calculated 50% detection limit for all products except Limburger cheese was 1.6 cfu/25 g; the 50% detection limit for Limburger cheese itself was 4.1 cfu/25 g. The method was adopted first action by AOAC INTERNATIONAL. PMID:8199474

  15. Inhibition of Listeria monocytogenes by piscicolin 126 in milk and Camembert cheese manufactured with a thermophilic starter.

    PubMed

    Wan, J; Harmark, K; Davidson, B E; Hillier, A J; Gordon, J B; Wilcock, A; Hickey, M W; Coventry, M J

    1997-03-01

    The effect of bacteriocin, piscicolin 126, on the growth of Listeria monocytogenes and cheese starter bacteria was investigated in milk and in Camembert cheese manufactured from milk challenged with 10(2) cfu ml(-1) L. monocytogenes. In milk incubated at 30 degrees C, piscicolin 126 added in the range of 512-2,048 AU ml(-1) effectively inhibited growth of L. monocytogenes for more than 20 d when challenged with approximately 10(2) cfu ml(-1) L. monocytogenes. At higher challenge levels (10(4) and 10(6) cfu ml(-1)), piscicolin 126 reduced the viable count of L. monocytogenes by 4-5 log units immediately after addition of the bacteriocin; however, growth of Listeria occurred within 24 h. The minimum inhibitory concentration (MIC) of piscicolin 126 against lactic acid cheese starter bacteria was generally greater than 204,800 AU ml(-1) , and the viable count and acid production of these starter cultures in milk were not affected by the addition of 2,048 AU ml(-1) piscicolin 126. Camembert cheeses made from milk challenged with L. monocytogenes and with added piscicolin 126 showed a viable count of L. monocytogenes 3-4 log units lower than those without piscicolin 126. Inactivation of piscicolin 126 by proteolytic enzymes from cheese starter bacteria and mould together with the emergence of piscicolin 126-resistant isolates was responsible for the recovery of L. monocytogenes in the cheeses during ripening. PMID:12455889

  16. Occurrence of Listeria sp and L monocytogenes in sewage sludge used for land application: effect of dewatering, liming and storage in tank on survival of Listeria species.

    PubMed

    Garrec, N; Picard-Bonnaud, F; Pourcher, A M

    2003-04-01

    The application of sewage sludge to agricultural land is widely used in France. To determine the impact of sludge treatments, concentrations of Listeria sp., Listeria monocytogenes and faecal indicators were monitored in five types of sludge from three sewage treatment plants in Angers (France) and its suburbs over a 1-year period. On the whole, bacteria were reduced in numbers through sludge treatments. Apart from liming, which leads to reduced levels of bacteria below detection limits, other sludge treatments did not eliminate Listeria sp. and faecal indicators. Listeria sp. and L. monocytogenes were found respectively in 87% and 73% of dewatered sludges and in 96% and 80% of sludges stored in tanks. Concentrations of L. monocytogenes, ranging from 0.15 to 20 MPN g(-1) dry matter in dewatered sludge and from 1 to 240 MPN g(-1) dry matter in sludge stored in tanks, did not show seasonal variations. Spreading of sanitised sludge onto agricultural land results in the addition of 10(6)-10(8) L. monocytogenes per hectare per year, which may contribute to the increase in the dissemination of this pathogenic species in the environment. PMID:12648847

  17. Phylogenetic analysis of the Listeria monocytogenes based on sequencing of 16S rRNA and hlyA genes.

    PubMed

    Soni, Dharmendra Kumar; Dubey, Suresh Kumar

    2014-12-01

    The discrimination between Listeria monocytogenes and Listeria species has been detected. The 16S rRNA and hlyA were PCR amplified with set of oligonucleotide primers with flank 1,500 and 456 bp fragments, respectively. Based on the differences in 16S rRNA and hlyA genes, a total 80 isolates from different environmental, food and clinical samples confirmed it to be L. monocytogenes. The 16S rRNA sequence similarity suggested that the isolates were similar to the previously reported ones from different habitats by others. The phylogenetic interrelationships of the genus Listeria were investigated by sequencing of 16S rRNA and hlyA gene. The 16S rRNA sequence indicated that genus Listeria is comprised of following closely related but distinct lines of descent, one is the L. monocytogenes species group (including L. innocua, L. ivanovii, L. seeligeri and L. welshimeri) and other, the species L. grayi, L. rocourtiae and L. fleischmannii. The phylogenetic tree based on hlyA gene sequence clearly differentiates between the L. monocytogenes, L. ivanovii and L. seeligeri. In the present study, we identified 80 isolates of L. monocytogenes originating from different clinical, food and environmental samples based on 16S rRNA and hlyA gene sequence similarity. PMID:25205124

  18. Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State

    PubMed Central

    Weller, Daniel; Wiedmann, Martin

    2015-01-01

    While rain and irrigation events have been associated with an increased prevalence of foodborne pathogens in produce production environments, quantitative data are needed to determine the effects of various spatial and temporal factors on the risk of produce contamination following these events. This study was performed to quantify these effects and to determine the impact of rain and irrigation events on the detection frequency and diversity of Listeria species (including L. monocytogenes) and L. monocytogenes in produce fields. Two spinach fields, with high and low predicted risks of L. monocytogenes isolation, were sampled 24, 48, 72, and 144 to 192 h following irrigation and rain events. Predicted risk was a function of the field's proximity to water and roads. Factors were evaluated for their association with Listeria species and L. monocytogenes isolation by using generalized linear mixed models (GLMMs). In total, 1,492 (1,092 soil, 334 leaf, 14 fecal, and 52 water) samples were collected. According to the GLMM, the likelihood of Listeria species and L. monocytogenes isolation from soil samples was highest during the 24 h immediately following an event (odds ratios [ORs] of 7.7 and 25, respectively). Additionally, Listeria species and L. monocytogenes isolates associated with irrigation events showed significantly lower sigB allele type diversity than did isolates associated with precipitation events (P = <0.001), suggesting that irrigation water may be a point source of L. monocytogenes contamination. Small changes in management practices (e.g., not irrigating fields before harvest) may therefore reduce the risk of L. monocytogenes contamination of fresh produce. PMID:26116668

  19. Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State.

    PubMed

    Weller, Daniel; Wiedmann, Martin; Strawn, Laura K

    2015-09-01

    While rain and irrigation events have been associated with an increased prevalence of foodborne pathogens in produce production environments, quantitative data are needed to determine the effects of various spatial and temporal factors on the risk of produce contamination following these events. This study was performed to quantify these effects and to determine the impact of rain and irrigation events on the detection frequency and diversity of Listeria species (including L. monocytogenes) and L. monocytogenes in produce fields. Two spinach fields, with high and low predicted risks of L. monocytogenes isolation, were sampled 24, 48, 72, and 144 to 192 h following irrigation and rain events. Predicted risk was a function of the field's proximity to water and roads. Factors were evaluated for their association with Listeria species and L. monocytogenes isolation by using generalized linear mixed models (GLMMs). In total, 1,492 (1,092 soil, 334 leaf, 14 fecal, and 52 water) samples were collected. According to the GLMM, the likelihood of Listeria species and L. monocytogenes isolation from soil samples was highest during the 24 h immediately following an event (odds ratios [ORs] of 7.7 and 25, respectively). Additionally, Listeria species and L. monocytogenes isolates associated with irrigation events showed significantly lower sigB allele type diversity than did isolates associated with precipitation events (P = <0.001), suggesting that irrigation water may be a point source of L. monocytogenes contamination. Small changes in management practices (e.g., not irrigating fields before harvest) may therefore reduce the risk of L. monocytogenes contamination of fresh produce. PMID:26116668

  20. Molecular Serotyping and Pathogenic Potential of Listeria monocytogenes Isolated from Milk and Milk Products in Tamil Nadu, India.

    PubMed

    Karthikeyan, Raman; Gunasekaran, Paramasamy; Rajendhran, Jeyaprakash

    2015-06-01

    Listeria monocytogenes, an important bacterial pathogen, is responsible for foodborne illnesses worldwide. Examination of food samples for the presence of L. monocytogenes and assessment of their pathogenicity is usually an effective strategy in the prevention of listeriosis. In the present study, we have tested 307 samples of milk and milk products from various places in Tamil Nadu, India for the presence of L. monocytogenes using ISO 11290 and U.S. Food and Drug Administration Bacteriological Analytical Manual methods. 16S rDNA sequencing and duplex polymerase chain reaction (PCR) analysis for prs and iap genes were used to identify L. monocytogenes at the species level. Fifteen of the 307 samples screen tested positive for L. monocytogenes. Molecular serotyping of the L. monocytogenes isolates by multiplex PCR revealed the predominance of the serogroups 1/2a and 4b. Fourteen of the 15 isolates contained all the virulence genes (inlA, inlB, hlyA, and plcA) screened for using multiplex PCR. Only one isolate of L. monocytogenes was negative for the plcA gene and in vitro phosphatidylinositol-phospholipase C activity. L. monocytogenes strains that belong to the serogroup 4b exhibited higher nematocidal activity against Caenorhabditis elegans than the serogroup 1/2a. Worms infected with L. monocytogenes were symptomatic with aberrant contraction of body muscles, loss of pharyngeal pumping, and decreased locomotion, which highlights the pathogenic potential of the L. monocytogenes isolates. PMID:25793931

  1. Survival kinetics of Listeria monocytogenes on raw sheep milk cured cheese under different storage temperatures.

    PubMed

    Valero, Antonio; Hernandez, Marta; De Cesare, Alessandra; Manfreda, Gerardo; González-García, Patricia; Rodríguez-Lázaro, David

    2014-08-01

    Raw sheep milk cured cheese produced in the Castilla y Leon region (Spain) constitutes a traditional semi-hard aromatic cheese typically aged for three to six months. This product is catalogued as ready-to-eat since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens such as Listeria monocytogenes can represent a health concern for susceptible consumers. This study was aimed at evaluating the survival of L. monocytogenes on raw sheep milk cured cheese under different storage temperatures. Log-linear+shoulder and Weibull type models were fitted to data observed in order to estimate kinetic parameters. The Arrhenius relationship was further used to predict the impact of temperature on L. monocytogenes behavior during storage at 4, 12 and 22°C. Additionally, growth of lactic acid bacteria (LAB) as a representative group of the indigenous microbiota was evaluated. Results obtained indicated that the time to eradication (time when absence of L. monocytogenes in the analyzed samples was observed) was 114, 104, and 77 days for cheese samples stored at 4, 12 and 22°C, respectively. The LAB population showed an increase at 12 and 22°C during storage. However, an increase of 1 log CFU/g was observed during the first 2 weeks irrespectively of the storage temperature. The log-linear+shoulder model indicated a good fit to observed data. Likewise, the Arrhenius relationship explained sufficiently the dependency of temperature on L. monocytogenes behavior. This study demonstrated that cheese storage at ambient temperatures could lead to the preservation of its quality properties as well as its safety against L. monocytogenes. PMID:24630556

  2. Strain-Specific Interactions of Listeria monocytogenes with the Autophagy System in Host Cells

    PubMed Central

    Stöckli, Martina; Higgins, Darren E.; Brumell, John H.

    2015-01-01

    Listeria monocytogenes is an intracellular bacterial pathogen that can replicate in the cytosol of host cells. These bacteria undergo actin-based motility in the cytosol via expression of ActA, which recruits host actin-regulatory proteins to the bacterial surface. L. monocytogenes is thought to evade killing by autophagy using ActA-dependent mechanisms. ActA-independent mechanisms of autophagy evasion have also been proposed, but remain poorly understood. Here we examined autophagy of non-motile (ΔactA) mutants of L. monocytogenes strains 10403S and EGD-e, two commonly studied strains of this pathogen. The ΔactA mutants displayed accumulation of ubiquitinated proteins and p62/SQSTM1 on their surface. However, only strain EGD-e ΔactA displayed colocalization with the autophagy marker LC3 at 8 hours post infection. A bacteriostatic agent (chloramphenicol) was required for LC3 recruitment to 10403S ΔactA, suggesting that these bacteria produce a factor for autophagy evasion. Internalin K was proposed to block autophagy of L. monocytogenes in the cytosol of host cells. However, deletion of inlK in either the wild-type or ΔactA background of strain 10403S had no impact on autophagy evasion by bacteria, indicating it does not play an essential role in evading autophagy. Replication of ΔactA mutants of strain EGD-e and 10403S was comparable to their parent wild-type strain in macrophages. Thus, ΔactA mutants of L. monocytogenes can block killing by autophagy at a step downstream of protein ubiquitination and, in the case of strain EGD-e, downstream of LC3 recruitment to bacteria. Our findings highlight the strain-specific differences in the mechanisms that L. monocytogenes uses to evade killing by autophagy in host cells. PMID:25970638

  3. Evaluation of enrichment procedures for recovering Listeria monocytogenes from dairy products.

    PubMed

    Lammerding, A M; Doyle, M P

    1989-11-01

    Six different enrichment media and five selective plating media were compared for their suitability for the recovery of Listeria monocytogenes from dairy products. These included media used to test milk products by the U.S. Food and Drug Administration (FDA) and the U.S. Centers for Disease Control (CDC), and media developed by the U.S. Department of Agriculture (USDA) for testing meat and poultry products. Test samples included naturally contaminated goat's milk, cultured milk products and ice cream manufactured with L. monocytogenes, and unpasteurized milk inoculated with heat- and freeze-injured cells of L. monocytogenes. Generally, the media and two-stage enrichment protocol developed by the USDA, with plating of samples after two consecutive 24-h incubation periods, yielded better recoveries than all other enrichment media incubated for 24 h. A modified USDA procedure, incorporating nonselective pre-enrichment of samples by omitting acriflavine and nalidixic acid from the primary USDA enrichment broth, and transfer of a larger volume of the initial culture broth to the secondary enrichment media, significantly increased recoveries of low numbers of sublethally stressed L. monocytogenes. Prolonged incubation of samples in the FDA enrichment broth, for 7 days, did not consistently improve recoveries over the initial 24-h incubation time of the medium. The selective plating medium developed by the USDA, lithium chloride-phenylethanol-moxalactam agar, was the most effective plating agar for isolation of L. monocytogenes following enrichment of samples in any broth culture, and increased recoveries of L. monocytogenes by 19-40% compared with other selective agar media tested. PMID:2518230

  4. Inactivation of Listeria monocytogenes on hams shortly after vacuum packaging by spray application of lauric arginate.

    PubMed

    Taormina, P J; Dorsa, W J

    2009-12-01

    This study measured and compared the short-term efficacy levels of lauric arginate (LAE) as a postlethality treatment against Listeria monocytogenes present on varied surfaces of large-diameter hams. Preliminary in vitro work demonstrated a 5-log inactivation of L. monocytogenes in 5,000- and 9,090-ppm LAE solutions within 180 min at 4.4 and 23 degrees C. Six different whole-muscle ham types were inoculated with L. monocytogenes at ca. 7-log CFU per ham and spray treated with between 15 and 29 ml of a 9,090-ppm LAE solution, or an equal volume of water (control), prior to vacuum packaging. After 48 h at 4.4 degrees C, populations were recovered from ham and interior packaging surfaces by using a surface rinse method with Dey-Engley neutralizing broth followed by plating on modified Oxford medium. Logarithmic reductions of L. monocytogenes exceeding 2 log CFU/cm(2) of ham surfaces were achieved by LAE treatment on all ham types. Hams with 1,129 cm(2) of surface area that had been processed by drenching in liquid smoke had 3.84 and 2.67 CFU/cm(2) 48 h following treatment with 18 ml of water or LAE, respectively, but increasing treatment volumes to 22 ml significantly reduced (P < 0.05) L. monocytogenes levels to 0.65 log CFU/cm(2). This study demonstrated the efficacy of LAE against L. monocytogenes on several ham types, thereby validating it as a postlethality treatment for inactivation of the pathogen. PMID:20003733

  5. Plasmid-borne cadmium resistant determinants are associated with the susceptibility of Listeria monocytogenes to bacteriophage.

    PubMed

    Zhang, Hui; Zhou, Yan; Bao, Hongduo; Zhang, Lili; Wang, Ran; Zhou, Xiaohui

    2015-03-01

    Listeria monocytogenes is an intracellular pathogen causing gastroenteritis, central nervous system infections and abortions. Chromosomal virulence determinants have been extensively investigated. However, the function of genes encoded by plasmids in L. monocytogenes has not been fully understood. In this study, we determined the prevalence and molecular profile of plasmids in food isolates of L. monocytogenes and examined the contribution of four plasmid-borne cadmium-resistant genes to the susceptibility of L. monocytogenes to bacteriophage infection. The results showed that plasmids were isolated from 55% (11/20) of the isolates and the plasmids exhibited 10 molecular types as determined by restriction enzyme digestion. Furthermore, 65% and 15% of the isolates were tolerant to cadmium and benzalkonium chloride (BC), respectively. All the BC-resistant isolates were resistant to cadmium. The prevalence of predicted cadmium resistance determinants (cadA1, cadA2, cadA3 and cadC) was determined and the results showed that cadA1 (35%) in isolates of serotypes 1/2a and 1/2b was much more prevalent than cadC (15%). As expected, both cadA and cadC mutants had reduced resistance to cadmium, while the resistance to BC was not significantly affected. Interestingly, both cadA and cadC mutants showed significantly higher susceptibility against L. monocytogenes phage LipG2-5 and FWLLm3 compared with the wide-type strain. Based on these results, we concluded that plasmids from L. monocytogenes encoded important functional determinants that are not only associated with cadmium resistance, but also phage susceptibility. PMID:25721472

  6. Antibacterial activity of hen egg white lysozyme against Listeria monocytogenes Scott A in foods.

    PubMed

    Hughey, V L; Wilger, P A; Johnson, E A

    1989-03-01

    Egg white lysozyme killed or prevented growth of Listeria monocytogenes Scott A in several foods. Lysozyme was more active in vegetables than in animal-derived foods that we tested. For maximum activity in certain foods, EDTA was required in addition to lysozyme. Lysozyme with EDTA effectively killed inoculated populations of 10(4) L. monocytogenes per g in fresh corn, fresh green beans, shredded cabbage, shredded lettuce, and carrots during storage at 5 degrees C. Control incubations without lysozyme supported growth of L. monocytogenes to 10(6) to 10(7)/g. Lysozyme had less activity in animal-derived foods, including fresh pork sausage (bratwurst) and Camembert cheese. In bratwurst, lysozyme with EDTA prevented L. monocytogenes from growing for 2 to 3 weeks but did not kill significant numbers of cells and did not prevent eventual growth. The control sausages not containing lysozyme supported rapid and heavy growth, which indicated that lysozyme was bacteriostatic for 2 to 3 weeks in fresh pork sausage. We also prepared Camembert cheese containing 10(4) L. monocytogenes cells per g and investigated the changes during ripening in cheeses supplemented with lysozyme and EDTA. Cheeses with lysozyme by itself or together with EDTA reduced the L. monocytogenes population by approximately 10-fold over the first 3 to 4 weeks of ripening. In the same period, the control cheese wheels without added lysozyme with and without chelator slowly started to grown and eventually reached 10(6) to 10(7) CFU/g after 55 days of ripening.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2494938

  7. Isolation and characterization of Listeria monocytogenes from commercial asazuke (Japanese light pickles).

    PubMed

    Maklon, Khuanwalai; Minami, Atsuka; Kusumoto, Akiko; Takeshi, Koichi; Nguyen, Thi Bich Thuy; Makino, Sou-ichi; Kawamoto, Keiko

    2010-05-15

    Asazuke is a ready-to-eat Japanese light pickle, mainly made of vegetables which are known to be one of the sources of Listeria monocytogenes contamination. Although asazuke is a popular side-dish in Japan, the hazard of bacterial contamination has not been evaluated yet. In this study, we investigated the prevalence of L. monocytogenes, Salmonella spp., verotoxigenic E. coli (VTEC) and coliforms in 108 asazuke samples that randomly collected from supermarkets in Obihiro (Hokkaido prefecture, Japan) during the period of June to November 2007. Twelve (11.11%) L. monocytogenes were isolated with predominant serotype 4b (seven isolates) followed by 1/2a (two isolates), 1/2b, 3b and 4c (one isolate each) while Salmonella spp., VTEC and coliforms were not detected. All L. monocytogenes isolates demonstrated hemolytic activity by CAMP test and possessed all the virulence-associated genes (prfA, actA, mpl, inlA, inlC, plcA, plcB, hly, iap, clpC and opuCA) as resulted in PCR, thus revealed their potential pathogenicity. Moreover, 7 out of 12 isolates were from asazuke samples produced by the same factory and their pulsed-field gel electrophoresis (PFGE) profiles suggested that 6 of them were indistinguishable and one was different. L. monocytogenes contamination in the asazuke factory environment was further investigated and 23 out of 60 environmental swabs (38.33%) contained the bacterium. Comparison of PFGE profiles showed relatedness between food and environmental isolates indicating that contamination probably occurred in the asazuke factory during manufacturing. Interestingly, after HACCP training course conducted to the factory workers, 20 samples collected during the period of November to December 2008 were negative to L. monocytogenes revealing that the hygienic status has improved. PMID:20388574

  8. Structural and biochemical analysis of the essential diadenylate cyclase CdaA from Listeria monocytogenes.

    PubMed

    Rosenberg, Jonathan; Dickmanns, Achim; Neumann, Piotr; Gunka, Katrin; Arens, Johannes; Kaever, Volkhard; Stülke, Jörg; Ficner, Ralf; Commichau, Fabian M

    2015-03-01

    The recently identified second messenger cyclic di-AMP (c-di-AMP) is involved in several important cellular processes, such as cell wall metabolism, maintenance of DNA integrity, ion transport, transcription regulation, and allosteric regulation of enzyme function. Interestingly, c-di-AMP is essential for growth of the Gram-positive model bacterium Bacillus subtilis. Although the genome of B. subtilis encodes three c-di-AMP-producing diadenlyate cyclases that can functionally replace each other, the phylogenetically related human pathogens like Listeria monocytogenes and Staphylococcus aureus possess only one enzyme, the diadenlyate cyclase CdaA. Because CdaA is also essential for growth of these bacteria, the enzyme is a promising target for the development of novel antibiotics. Here we present the first crystal structure of the L. monocytogenes CdaA diadenylate cyclase domain that is conserved in many human pathogens. Moreover, biochemical characterization of the cyclase revealed an unusual metal cofactor requirement. PMID:25605729

  9. Adhesion of Salmonella Enteritidis and Listeria monocytogenes on stainless steel welds.

    PubMed

    Casarin, Letícia Sopeña; Brandelli, Adriano; de Oliveira Casarin, Fabrício; Soave, Paulo Azevedo; Wanke, Cesar Henrique; Tondo, Eduardo Cesar

    2014-11-17

    Pathogenic microorganisms are able to adhere on equipment surfaces, being possible to contaminate food during processing. Salmonella spp. and Listeria monocytogenes are important pathogens that can be transmitted by food, causing severe foodborne diseases. Most surfaces of food processing industry are made of stainless steel joined by welds. However currently, there are few studies evaluating the influence of welds in the microorganism's adhesion. Therefore the purpose of the present study was to investigate the adhesion of Salmonella Enteritidis and L. monocytogenes on surface of metal inert gas (MIG), and tungsten inert gas (TIG) welding, as well as to evaluate the cell and surface hydrophobicities. Results demonstrated that both bacteria adhered to the surface of welds and stainless steel at same levels. Despite this, bacteria and surfaces demonstrated different levels of hydrophobicity/hydrophilicity, results indicated that there was no correlation between adhesion to welds and stainless steel and the hydrophobicity. PMID:25261827

  10. Detection of Listeria monocytogenes with a nonisotopic polymerase chain reaction-coupled ligase chain reaction assay.

    PubMed Central

    Wiedmann, M; Barany, F; Batt, C A

    1993-01-01

    A polymerase chain reaction (PCR)-coupled ligase chain reaction (LCR) assay for the specific detection of Listeria monocytogenes (M. Wiedmann, J. Czajka, F. Barany, and C. A. Batt, Appl. Environ. Microbiol. 58:3443-3447, 1992) has been modified for detection of the LCR products with a nonisotopic readout. When a chemiluminescent or a colorimetric substrate for the nonisotopic detection of the LCR products was used, the PCR-coupled LCR gave a sensitivity of 10 CFU of L. monocytogenes. The detection method with the chemiluminescent substrate Lumi-Phos 530 permitted detection of the LCR products in less than 3 h, so that the whole assay can be completed within 10 h. Images PMID:8368859

  11. Structural and Biochemical Analysis of the Essential Diadenylate Cyclase CdaA from Listeria monocytogenes*

    PubMed Central

    Rosenberg, Jonathan; Dickmanns, Achim; Neumann, Piotr; Gunka, Katrin; Arens, Johannes; Kaever, Volkhard; Stülke, Jörg; Ficner, Ralf; Commichau, Fabian M.

    2015-01-01

    The recently identified second messenger cyclic di-AMP (c-di-AMP) is involved in several important cellular processes, such as cell wall metabolism, maintenance of DNA integrity, ion transport, transcription regulation, and allosteric regulation of enzyme function. Interestingly, c-di-AMP is essential for growth of the Gram-positive model bacterium Bacillus subtilis. Although the genome of B. subtilis encodes three c-di-AMP-producing diadenlyate cyclases that can functionally replace each other, the phylogenetically related human pathogens like Listeria monocytogenes and Staphylococcus aureus possess only one enzyme, the diadenlyate cyclase CdaA. Because CdaA is also essential for growth of these bacteria, the enzyme is a promising target for the development of novel antibiotics. Here we present the first crystal structure of the L. monocytogenes CdaA diadenylate cyclase domain that is conserved in many human pathogens. Moreover, biochemical characterization of the cyclase revealed an unusual metal cofactor requirement. PMID:25605729

  12. Influence of Catalase and Superoxide Dismutase on Ozone Inactivation of Listeria monocytogenes

    PubMed Central

    Fisher, Christopher W.; Lee, Dongha; Dodge, Beth-Anne; Hamman, Kristen M.; Robbins, Justin B.; Martin, Scott E.

    2000-01-01

    The effects of ozone at 0.25, 0.40, and 1.00 ppm on Listeria monocytogenes were evaluated in distilled water and phosphate-buffered saline. Differences in sensitivity to ozone were found to exist among the six strains examined. Greater cell death was found following exposure at lower temperatures. Early stationary-phase cells were less sensitive to ozone than mid-exponential- and late stationary-phase cells. Ozonation at 1.00 ppm of cabbage inoculated with L. monocytogenes effectively inactivated all cells after 5 min. The abilities of in vivo catalase and superoxide dismutase to protect the cells from ozone were also examined. Three listerial test strains were inactivated rapidly upon exposure to ozone. Both catalase and superoxide dismutase were found to protect listerial cells from ozone attack, with superoxide dismutase being more important than catalase in this protection. PMID:10742219

  13. Characterization of human invasive isolates of Listeria monocytogenes in Sweden 1986-2007.

    PubMed

    Parihar, Vishal Singh; Lopez-Valladares, Gloria; Danielsson-Tham, Marie-Louise; Peiris, Inoka; Helmersson, Seved; Unemo, Magnus; Andersson, Birgitta; Arneborn, Malin; Bannerman, Elizabeth; Barbuddhe, Sukdevo; Bille, Jacques; Hajdu, Lajos; Jacquet, Christine; Johansson, Christina; Löfdahl, Margareta; Möllerberg, Gunnel; Ringberg, Håkan; Rocourt, Jocelyne; Tjernberg, Ingela; Ursing, Jan; Henriques-Normark, Birgitta; Tham, Wilhelm

    2008-12-01

    Since 1986, 68% of the Listeria monocytogenes isolates from human cases of invasive listeriosis in Sweden are available for retrospective studies. The aim of the present study was to characterize 601 human invasive isolates of L. monocytogenes in Sweden from 1986 to 2007 by using serotyping and pulsed-field gel electrophoresis. Since 1996, serovar 4b was permanently reduced to the second or third most common serovar in human cases in Sweden. During the latter period, 2000-2007, only 13% belonged to serovar 4b and 71% to 1/2a. The dendrogram, based on pulsovars, reveals two clusters with different serovars. Cluster 1 exhibits serovars 4b and 1/2b, whereas cluster 2 consists of serovar 1/2a. Serovar 1/2a seems to be more heterogeneous than serovar 4b. PMID:18847381

  14. Activities of ABT-773 against Listeria monocytogenes and Coryneform Bacteria of Clinical Interest

    PubMed Central

    Conejo, María del Carmen; Martínez-Martínez, Luis; Pascual, Álvaro; Suárez, Ana Isabel; Perea, Evelio J.

    2003-01-01

    The in vitro activities of ABT-773 were evaluated against 15 Listeria monocytogenes strains and 196 coryneform bacteria isolated from clinical samples. One hundred percent of the L. monocytogenes strains were inhibited by ≤0.015 μg of ABT-773/ml. MICs of ABT-773 (μg/ml) at which 50% of the isolates tested were inhibited (MIC50s) and MIC90s for other organisms were 0.125 and 0.5 (Corynebacterium amycolatum), 1 and >32 (Corynebacterium jeikeium), 0.03 and >32 (Corynebacterium minutissimum), >32 and >32 (Corynebacterium pseudodiphtheriticum and Corynebacterium urealyticum), 0.125 and >32 (Corynebacterium striatum), and 0.03 and 0.5 (Rhodococcus equi), respectively. PMID:12654678

  15. Activities of ABT-773 against Listeria monocytogenes and coryneform bacteria of clinical interest.

    PubMed

    Conejo, María del Carmen; Martínez-Martínez, Luis; Pascual, Alvaro; Suárez, Ana Isabel; Perea, Evelio J

    2003-04-01

    The in vitro activities of ABT-773 were evaluated against 15 Listeria monocytogenes strains and 196 coryneform bacteria isolated from clinical samples. One hundred percent of the L. monocytogenes strains were inhibited by 32 (Corynebacterium jeikeium), 0.03 and >32 (Corynebacterium minutissimum), >32 and >32 (Corynebacterium pseudodiphtheriticum and Corynebacterium urealyticum), 0.125 and >32 (Corynebacterium striatum), and 0.03 and 0.5 (Rhodococcus equi), respectively. PMID:12654678

  16. Growth of Listeria monocytogenes in Camembert and other soft cheeses at refrigeration temperatures.

    PubMed

    Back, J P; Langford, S A; Kroll, R G

    1993-08-01

    Listeria monocytogenes survived and, under most conditions, multiplied when inoculated directly into the cheese milk of laboratory made Camembert cheeses. The rate and extent of growth was reduced at lower storage temperatures. Significantly higher rates of growth occurred at the surface compared with the centre of the cheeses, and these were probably associated with increased pH and proteolysis at the cheese surface due to the mould ripening process. Similar results were obtained with Camenbert cheeses surface inoculated after manufacture. There was also temperature-dependent growth of List. monocytogenes on a range of inoculated commercially manufactured soft cheeses. Significant growth occurred in Cambazola, French and English Brie, blue and white Lymeswold, French Camembert and Brie with garlic. Little if any growth occurred in blue and white Stilton, Mycella, Chaume and full fat soft cheese with garlic and herbs at the temperatures examined. PMID:8376636

  17. The Essential Role of Neutrophils during Infection with the Intracellular Bacterial Pathogen Listeria monocytogenes.

    PubMed

    Witter, Alexandra R; Okunnu, Busola M; Berg, Rance E

    2016-09-01

    Neutrophils have historically been characterized as first responder cells vital to host survival because of their ability to contain and eliminate bacterial and fungal pathogens. However, recent studies have shown that neutrophils participate in both protective and detrimental responses to a diverse array of inflammatory and infectious diseases. Although the contribution of neutrophils to extracellular infections has been investigated for decades, their specific role during intracellular bacterial infections has only recently been appreciated. During infection with the Gram-positive intracellular pathogen Listeria monocytogenes, neutrophils are recruited from the bone marrow to sites of infection where they use novel bacterial-sensing pathways leading to phagocytosis and production of bactericidal factors. This review summarizes the requirement of neutrophils during L. monocytogenes infection by examining both neutrophil trafficking and function during primary and secondary infection. PMID:27543669

  18. Effect of monolaurin and lactic acid on Listeria monocytogenes attached to catfish fillets.

    PubMed

    Verhaegh, E G; Marshall, D L; Oh, D H

    1996-04-01

    The purpose of this study was to determine the effects of monolaurin and lactic acid, singly or combined, on Listeria monocytogenes attached to catfish fillets. Skinless catfish fillets were inoculated with L. monocytogenes and dip treated in monolaurin and/or lactic acid solution for various time periods. Results showed that monolaurin up to 400 micrograms/ml had no influence on counts. Conversely, lactic acid-treated fillets had reduced counts compared to controls. Dipping in 0.85, 1.70, or 2.55% lactic acid for 30 min reduced counts by 0.9, 1.4, or 1.3 logs, respectively. Extending the dipping time to 60 min resulted in little additional decrease in counts. Combining monolaurin with lactic acid yielded results similar to lactic acid alone. Hence, population reduction ability resides with lactic acid and not monolaurin. PMID:8796441

  19. Efficacy of ultraviolet light exposure against survival of Listeria monocytogenes on conveyor belts.

    PubMed

    Morey, Amit; McKee, Shelly R; Dickson, James S; Singh, Manpreet

    2010-06-01

    Listeria monocytogenes has been repeatedly isolated from foods and food-processing facilities including food contact surfaces such as conveyor belts (CB). CBs are often difficult to clean and require rigorous sanitation programs for decontamination. Ultraviolet (UV) light has exhibited microbicidal properties on food contact surfaces and this study was conducted to determine the efficacy of UV against L. monocytogenes on CB made of different materials. A four-strain cocktail of L. monocytogenes (serotypes 3A, 4A, 4B, and 4C) was made to give a suspension of approximately 10(7) CFU/mL. CBs made from four different types of materials, (1) Ropanyl DM 8/2 A2 + 04 (belt 1), (2) Volta FRMW-3.0 (belt 2), (3) Volta FRMB-3.0 (belt 3), and (4) Ropanyl DM (belt 4), were inoculated with 1 mL of the four-strain cocktail (approximately 10(7) CFU/mL) of the bacterial suspension. CBs were treated with UV light (254 nm) for 1 and 3 sec at 5.53 and 5.95 mW/cm(2). Three replications of the experiments were conducted. Two-way analysis of variance of survival populations of L. monocytogenes showed that bacterial counts were significantly reduced (p < 0.05) on all belt types irrespective of UV light intensities and times of exposure. L. monocytogenes populations were reduced (p < 0.05) to below detection limits on belts 1, 2, and 3 after exposure to 5.95 mW/cm(2) UV light intensity for 3 sec. L. monocytogenes-inoculated CBs that were exposed to 5.53 mW/cm(2) showed higher (p < 0.05) survival populations of L. monocytogenes compared with 5.95 mW/cm(2) on all the four CBs. Belt 4 showed survival populations of L. monocytogenes ranging from 1.42 to 1.73 log(10) CFU/cm(2) after UV light treatment for 1 and 3 sec. UV light can be effectively used to reduce L. monocytogenes contamination on CBs. PMID:20113207

  20. Tetracycline-resistant L-forms isolated from an antibiotic-susceptible strain of Listeria monocytogenes.

    PubMed Central

    Schmitt-Slomska, J; Marmouset, M C; Louis, C; Bally, R; Starka, G; Madoff, S

    1982-01-01

    A tetracycline-susceptible strain of Listeria monocytogenes type 4b was converted to stable L-forms by penicillin. L-form variants resistant to tetracycline were then selected from a predominantly tetracycline-susceptible L-form population on plates containing penicillin and increasing concentrations of tetracycline. The origin of tetracycline-resistant L-forms from the parent Listeria strain was confirmed biochemically, by immunofluorescence, and by polyacrylamide gel electrophoresis. Scanning and transmission electron microscopy confirmed the typical L-form structure and the complete lack of cell wall in both L-form strains. The level of [3H]tetracycline uptake was lower in tetracycline-resistant than in susceptible cells. Images PMID:6817706

  1. Prospective Whole-Genome Sequencing Enhances National Surveillance of Listeria monocytogenes.

    PubMed

    Kwong, Jason C; Mercoulia, Karolina; Tomita, Takehiro; Easton, Marion; Li, Hua Y; Bulach, Dieter M; Stinear, Timothy P; Seemann, Torsten; Howden, Benjamin P

    2016-02-01

    Whole-genome sequencing (WGS) has emerged as a powerful tool for comparing bacterial isolates in outbreak detection and investigation. Here we demonstrate that WGS performed prospectively for national epidemiologic surveillance of Listeria monocytogenes has the capacity to be superior to our current approaches using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), multilocus variable-number tandem-repeat analysis (MLVA), binary typing, and serotyping. Initially 423 L. monocytogenes isolates underwent WGS, and comparisons uncovered a diverse genetic population structure derived from three distinct lineages. MLST, binary typing, and serotyping results inferred in silico from the WGS data were highly concordant (>99%) with laboratory typing performed in parallel. However, WGS was able to identify distinct nested clusters within groups of isolates that were otherwise indistinguishable using our current typing methods. Routine WGS was then used for prospective epidemiologic surveillance on a further 97 L. monocytogenes isolates over a 12-month period, which provided a greater level of discrimination than that of conventional typing for inferring linkage to point source outbreaks. A risk-based alert system based on WGS similarity was used to inform epidemiologists required to act on the data. Our experience shows that WGS can be adopted for prospective L. monocytogenes surveillance and investigated for other pathogens relevant to public health. PMID:26607978

  2. Selective pharmacologic inhibition of a PASTA kinase increases Listeria monocytogenes susceptibility to β-lactam antibiotics.

    PubMed

    Pensinger, Daniel A; Aliota, Matthew T; Schaenzer, Adam J; Boldon, Kyle M; Ansari, Israr-ul H; Vincent, William J B; Knight, Benjamin; Reniere, Michelle L; Striker, Rob; Sauer, John-Demian

    2014-08-01

    While β-lactam antibiotics are a critical part of the antimicrobial arsenal, they are frequently compromised by various resistance mechanisms, including changes in penicillin binding proteins of the bacterial cell wall. Genetic deletion of the penicillin binding protein and serine/threonine kinase-associated protein (PASTA) kinase in methicillin-resistant Staphylococcus aureus (MRSA) has been shown to restore β-lactam susceptibility. However, the mechanism remains unclear, and whether pharmacologic inhibition would have the same effect is unknown. In this study, we found that deletion or pharmacologic inhibition of the PASTA kinase in Listeria monocytogenes by the nonselective kinase inhibitor staurosporine results in enhanced susceptibility to both aminopenicillin and cephalosporin antibiotics. Resistance to vancomycin, another class of cell wall synthesis inhibitors, or antibiotics that inhibit protein synthesis was unaffected by staurosporine treatment. Phosphorylation assays with purified kinases revealed that staurosporine selectively inhibited the PASTA kinase of L. monocytogenes (PrkA). Importantly, staurosporine did not inhibit a L. monocytogenes kinase without a PASTA domain (Lmo0618) or the PASTA kinase from MRSA (Stk1). Finally, inhibition of PrkA with a more selective kinase inhibitor, AZD5438, similarly led to sensitization of L. monocytogenes to β-lactam antibiotics. Overall, these results suggest that pharmacologic targeting of PASTA kinases can increase the efficacy of β-lactam antibiotics. PMID:24867981

  3. The human P-glycoprotein transporter enhances the type I interferon response to Listeria monocytogenes infection.

    PubMed

    Sigal, Nadejda; Kaplan Zeevi, Millie; Weinstein, Shiri; Peer, Dan; Herskovits, Anat A

    2015-06-01

    Human multidrug efflux transporters are known for their ability to extrude antibiotics and toxic compounds out of cells, yet accumulating data indicate they have additional functions in diverse physiological processes not related to drug efflux. Here, we show that the human multidrug transporter P-glycoprotein (P-gp) (also named MDR1 and ABCB1) is transcriptionally induced in the monocytic cell line THP-1 upon infection with the human intracellular bacterial pathogen Listeria monocytogenes. Notably, we found that P-gp is important for full activation of the type I interferon response elicited against L. monocytogenes bacteria. Both inhibition of P-gp function by verapamil and inhibition of its transcription using mRNA silencing led to a reduction in the magnitude of the type I response in infected cells. This function of P-gp was specific to type I interferon cytokines elicited against cytosolic replicating bacteria and was not observed in response to cyclic di-AMP (c-di-AMP), a molecule that was shown to be secreted by L. monocytogenes during infection and to trigger type I interferons. Moreover, P-gp was not involved in activation of other proinflammatory cytokines, such as those triggered by vacuolar-restricted L. monocytogenes or lipopolysaccharide (LPS). Taken together, these findings demonstrate a role for P-gp in proper development of an innate immune response against intracellular pathogens, highlighting the complexity in employing therapeutic strategies that involve inhibition of multidrug resistance (MDR) efflux pumps. PMID:25824830

  4. The Human P-Glycoprotein Transporter Enhances the Type I Interferon Response to Listeria monocytogenes Infection

    PubMed Central

    Sigal, Nadejda; Kaplan Zeevi, Millie; Weinstein, Shiri; Peer, Dan

    2015-01-01

    Human multidrug efflux transporters are known for their ability to extrude antibiotics and toxic compounds out of cells, yet accumulating data indicate they have additional functions in diverse physiological processes not related to drug efflux. Here, we show that the human multidrug transporter P-glycoprotein (P-gp) (also named MDR1 and ABCB1) is transcriptionally induced in the monocytic cell line THP-1 upon infection with the human intracellular bacterial pathogen Listeria monocytogenes. Notably, we found that P-gp is important for full activation of the type I interferon response elicited against L. monocytogenes bacteria. Both inhibition of P-gp function by verapamil and inhibition of its transcription using mRNA silencing led to a reduction in the magnitude of the type I response in infected cells. This function of P-gp was specific to type I interferon cytokines elicited against cytosolic replicating bacteria and was not observed in response to cyclic di-AMP (c-di-AMP), a molecule that was shown to be secreted by L. monocytogenes during infection and to trigger type I interferons. Moreover, P-gp was not involved in activation of other proinflammatory cytokines, such as those triggered by vacuolar-restricted L. monocytogenes or lipopolysaccharide (LPS). Taken together, these findings demonstrate a role for P-gp in proper development of an innate immune response against intracellular pathogens, highlighting the complexity in employing therapeutic strategies that involve inhibition of multidrug resistance (MDR) efflux pumps. PMID:25824830

  5. Rapid enumeration of Listeria monocytogenes in artificially contaminated cabbage using real-time polymerase chain reaction.

    PubMed

    Hough, Angela J; Harbison, Sally-Ann; Savill, Marion G; Melton, Laurence D; Fletcher, Graham

    2002-08-01

    A quantitative real-time polymerase chain reaction (PCR) detection method specific for Listeria monocytogenes was developed, and studies involving pure culture showed that the response of the assay was linear over 7 log10 (log) cycles. The method was then applied to the detection of L. monocytogenes artificially inoculated onto cabbage, a vegetable chosen because it is a major component of coleslaw, which has been associated with an outbreak of listeriosis. After being allowed to attach to the food, cells were washed from the cabbage leaf surface and recovered by centrifugation. The DNA was purified by an organic solvent extraction technique and analyzed by real-time PCR. In this matrix, the method again produced a linear response over 7 log cycles from 1.4 x 10(2) to 1.4 x 10(9) CFU of L. monocytogenes in 25 g of cabbage, and analysis of the reproducibility of the system showed that log differences in L. monocytogenes numbers added to cabbage could be reliably distinguished. The system allowed quantitative results to be obtained within 8 h and was relatively inexpensive, showing good potential for routine analytical use. PMID:12182489

  6. Effectiveness of a bacteriophage in reducing Listeria monocytogenes on fresh-cut fruits and fruit juices.

    PubMed

    Oliveira, M; Viñas, I; Colàs, P; Anguera, M; Usall, J; Abadias, M

    2014-04-01

    Listeria monocytogenes is a serious foodborne pathogen and new strategies to control it in food are needed. Among them, bacteriophages hold attributes that appear to be attractive. The objective of this study was to investigate the efficacy of the bacteriophage Listex P100 to control L. monocytogenes growth on melon, pear and apple products (juices and slices) stored at 10 °C. L. monocytogenes grew well in untreated fruit slices. In juices, the pathogen grew in untreated melon, survived in untreated pear and decreased in untreated apple. Phage treatment was more effective on melon followed by pear, but no effect on apple products was observed. Reductions of about 1.50 and 1.00 log cfu plug(-1) for melon and pear slices were found, respectively. In juices, higher reductions were obtained in melon (8.00 log cfu mL(-1)) followed by pear (2.10 log cfu mL(-1)) after 8 days of storage. L. monocytogenes in apple juice was unaffected by phage treatment in which the phage decreased to almost undetectable numbers. These results highlight that Listex P100 could avoid pathogen growth on fresh-cut and in fruit juices with high pH during storage at 10 °C. The combination with other technologies may be required to improve the phage application on high acidity fruits. PMID:24290636

  7. Modeling the Growth of Listeria monocytogenes in Soft Blue-White Cheese

    PubMed Central

    Detmer, Ann; Ingmer, Hanne; Larsen, Marianne Halberg

    2012-01-01

    The aim of this study was to develop a predictive model simulating growth over time of the pathogenic bacterium Listeria monocytogenes in a soft blue-white cheese. The physicochemical properties in a matrix such as cheese are essential controlling factors influencing the growth of L. monocytogenes. We developed a predictive tertiary model of the bacterial growth of L. monocytogenes as a function of temperature, pH, NaCl, and lactic acid. We measured the variations over time of the physicochemical properties in the cheese. Our predictive model was developed based on broth data produced in previous studies. New growth data sets were produced to independently calibrate and validate the developed model. A characteristic of this tertiary model is that it handles dynamic growth conditions described in time series of temperature, pH, NaCl, and lactic acid. Supplying the model with realistic production and retail conditions showed that the number of L. monocytogenes cells increases 3 to 3.5 log within the shelf life of the cheese. PMID:22983971

  8. Selective Pharmacologic Inhibition of a PASTA Kinase Increases Listeria monocytogenes Susceptibility to β-Lactam Antibiotics

    PubMed Central

    Pensinger, Daniel A.; Aliota, Matthew T.; Schaenzer, Adam J.; Boldon, Kyle M.; Ansari, Israr-ul H.; Vincent, William J. B.; Knight, Benjamin; Reniere, Michelle L.; Striker, Rob

    2014-01-01

    While β-lactam antibiotics are a critical part of the antimicrobial arsenal, they are frequently compromised by various resistance mechanisms, including changes in penicillin binding proteins of the bacterial cell wall. Genetic deletion of the penicillin binding protein and serine/threonine kinase-associated protein (PASTA) kinase in methicillin-resistant Staphylococcus aureus (MRSA) has been shown to restore β-lactam susceptibility. However, the mechanism remains unclear, and whether pharmacologic inhibition would have the same effect is unknown. In this study, we found that deletion or pharmacologic inhibition of the PASTA kinase in Listeria monocytogenes by the nonselective kinase inhibitor staurosporine results in enhanced susceptibility to both aminopenicillin and cephalosporin antibiotics. Resistance to vancomycin, another class of cell wall synthesis inhibitors, or antibiotics that inhibit protein synthesis was unaffected by staurosporine treatment. Phosphorylation assays with purified kinases revealed that staurosporine selectively inhibited the PASTA kinase of L. monocytogenes (PrkA). Importantly, staurosporine did not inhibit a L. monocytogenes kinase without a PASTA domain (Lmo0618) or the PASTA kinase from MRSA (Stk1). Finally, inhibition of PrkA with a more selective kinase inhibitor, AZD5438, similarly led to sensitization of L. monocytogenes to β-lactam antibiotics. Overall, these results suggest that pharmacologic targeting of PASTA kinases can increase the efficacy of β-lactam antibiotics. PMID:24867981

  9. Photodynamic inactivation of methylene blue and tungsten-halogen lamp light against food pathogen Listeria monocytogenes.

    PubMed

    Lin, Shao-ling; Hu, Jia-miao; Tang, Shu-shu; Wu, Xi-yang; Chen, Zhen-qiang; Tang, Shu-ze

    2012-01-01

    The aim of this study was to verify the bactericidal effect and the damage of photodynamic inactivation (PDI) using methylene blue (MB) and tungsten-halogen lamp over Listeria monocytogenes via atomic force microscopy, absorption spectrophotometry, agarose gel electrophoresis, real-time PCR and SDS-PAGE. The obtained data indicated that the viability of L. monocytogenes was ca 7-log reduced by illumination with 10 min tungsten-halogen lamp light under the presence of 0.5 μg mL(-1) MB, and this bactericidal activity against L. monocytogenes of PDI increased proportionally to the concentration of MB and the duration of irradiation. Moreover, after irradiation with MB and visible light, the leakage of intracellular contents was estimated by spectrophotometer at OD(260) and OD(280), which correlated with morphological alterations. Furthermore, genomic DNA cleavage and protein degradation were also detected after PDI treatment. Consequently, breakage of the membrane, damage of the genomic DNA and degradation of bacterial proteins may play an important role in the mechanisms involved in PDI-MB bactericidal activity on L. monocytogenes. PMID:22469298

  10. Inhibition of Listeria monocytogenes using natural antimicrobials in no-nitrate-or-nitrite-added ham.

    PubMed

    Sullivan, Gary A; Jackson-Davis, Armitra L; Niebuhr, Steven E; Xi, Yuan; Schrader, Kohl D; Sebranek, Joseph G; Dickson, James S

    2012-06-01

    Consumer demand for foods manufactured without the direct addition of chemical preservatives, such as sodium nitrite and organic acid salts, has resulted in a unique class of "naturally" cured meat products. Formulation with a natural nitrate source and nitrate-reducing bacteria results in naturally cured processed meats that possess traits similar to conventionally cured meats. However, previous research has shown that the naturally cured products are more susceptible to pathogen growth. This study evaluated Listeria monocytogenes growth on ham manufactured with natural curing methods and with commercially available clean-label antimicrobials (cultured sugar and vinegar blend; lemon, cherry, and vinegar powder blend) and assessed impacts on physicochemical characteristics of the product. Hams made with either of the antimicrobials supported L. monocytogenes growth similar to that in the traditionally cured control (P > 0.05). Hams made with prefermented celery juice powder had the lowest residual nitrite concentrations (P < 0.05), and when no antimicrobial was added, L. monocytogenes growth was similar to that of the uncured control (P > 0.05). Aside from residual nitrite and nitrate concentrations, few physicochemical differences were identified. These findings show that ham can be produced with natural curing methods and antimicrobials to provide similar L. monocytogenes inhibition and physicochemical traits as in traditionally cured ham. PMID:22691474

  11. Effect of chitosan on spoilage bacteria, Escherichia coli and Listeria monocytogenes in cured chicken meat.

    PubMed

    Shekarforoush, Seyed Shahram; Basiri, Sara; Ebrahimnejad, Hadi; Hosseinzadeh, Saeid

    2015-05-01

    The effects of essential oil (EO) of oregano and chitosan on the microbial quality and growth inhibition of Listeria monocytogenes and Escherichia coli O157:H7 in the Iranian traditional ready-to-barbecue chicken was evaluated. Thus, three groups of samples were prepared. One of them was considered to evaluate for aerobic plate count (APC), lactic acid bacteria (LAB), psychrophilic and enterobacteriacae counts and the other two groups were inoculated with E. coli O157:H7 and L. monocytogenes 4b to investigate the effect of oregano EO and chitosan on pathogenic bacteria. All groups were stored at 3, 8 and 20°C. Oregano showed antibacterial effects against APC, LAB, psychrophilics, enterobacteriacae and E. coli O157:H7, whereas, such an effect was not observed against L. monocytogenes. Chitosan individually did not show an inhibitory effect on the spoilage-inducing bacteria and E. coli, but was effective against L. monocytogenes. Using chitosan and oregano EO in combination can reduce the number of spoilage and safety indicators and also the two food-borne pathogens in ready-to-barbecue chicken meat. PMID:25735728

  12. A novel gene, lstC, of Listeria monocytogenes is implicated in high salt tolerance.

    PubMed

    Burall, Laurel S; Simpson, Alexandra C; Chou, Luoth; Laksanalamai, Pongpan; Datta, Atin R

    2015-06-01

    Listeria monocytogenes, causative agent of human listeriosis, has been isolated from a wide variety of foods including deli meats, soft cheeses, cantaloupes, sprouts and canned mushrooms. Standard control measures for restricting microbial growth such as refrigeration and high salt are often inadequate as L. monocytogenes grows quite well in these environments. In an effort to better understand the genetic and physiological basis by which L. monocytogenes circumvents these controls, a transposon library of L. monocytogenes was screened for changes in their ability to grow in 7% NaCl and/ or at 5 °C. This work identified a transposon insertion upstream of an operon, here named lstABC, that led to a reduction in growth in 7% NaCl. In-frame deletion studies identified lstC which codes for a GNAT-acetyltransferase being responsible for the phenotype. Transcriptomic and RT-PCR analyses identified nine genes that were upregulated in the presence of high salt in the ΔlstC mutant. Further analysis of lstC and the genes affected by ΔlstC is needed to understand LstC's role in salt tolerance. PMID:25790994

  13. Effect of temperature history on the growth of Listeria monocytogenes Scott A at refrigeration temperatures.

    PubMed

    Buchanan, R L; Klawitter, L A

    1991-02-01

    The effect of pre-inoculation temperature on the subsequent growth of Listeria monocytogenes Scott A at 5 degrees C was examined in microbiological medium, UHT milk, canned dog food, and raw ground beef (untreated and irradiation-sterilized). In microbiological medium, the duration of the lag phase was decreased when aerobic and anaerobic cultures were initially grown at less than or equal to 28 and less than or equal to 13 degrees C, respectively. Subsequent exponential growth rates and maximum population densities of the 5 degrees C cultures were not affected by temperature history. Differences in lag phase durations were also observed when L. monocytogenes initially cultured at 19 and 37 degrees C were grown at 5 degrees C in UHT milk and some of the canned dog food varieties. Growth of L. monocytogenes was not observed in either untreated or irradiation-sterilized raw ground beef. While temperature history can affect the growth kinetics of L. monocytogenes at 5 degrees C, it did not account for the lack of growth in raw meat, suggesting that there is an inhibitory condition or component in ground beef that is lost upon cooking. PMID:1904762

  14. Sensitization of heat-treated Listeria monocytogenes to added lysozyme in milk.

    PubMed Central

    Kihm, D J; Leyer, G J; An, G H; Johnson, E A

    1994-01-01

    Listeria monocytogenes was highly resistant to hen egg white lysozyme in whole milk but was sensitive in media and in phosphate buffer. Methods to sensitize the pathogen to lysozyme in milk were investigated. Treatment of whole milk by cation exchange to remove minerals, particularly Ca2+ and Mg2+, slightly promoted inactivation of L. monocytogenes by lysozyme at 4 degrees C over a period of 6 days. Heat treatment (62.5 degrees C for 15 s) strongly sensitized L. monocytogenes to lysozyme in demineralized milk and in MES [2-(N-morpholino)ethanesulfonic acid] buffer. Addition of Ca2+ or Mg2+ to the demineralized milk restored resistance to lysozyme. Cells were more rapidly heat inactivated at 55 degrees C in demineralized milk containing lysozyme, and addition of Ca2+ to the demineralized milk restored the resistance to heat. The results indicate that minerals or mineral-associated components protect L. monocytogenes from inactivation by lysozyme and heat in milk, probably by increasing cell surface stability. The heat treatment of foods containing added lysozyme can probably play a significant role in producing microbiologically safe foods. Images PMID:7986052

  15. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

    PubMed Central

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Alves, Eduardo; Piccoli, Roberta Hilsdorf

    2010-01-01

    An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 °C and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential. PMID:24031469

  16. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential.

    PubMed

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Alves, Eduardo; Piccoli, Roberta Hilsdorf

    2010-01-01

    An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 °C and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential. PMID:24031469

  17. Inactivation of Listeria monocytogenes on agar and processed meat surfaces by atmospheric pressure plasma jets.

    PubMed

    Lee, Hyun Jung; Jung, Heesoo; Choe, Wonho; Ham, Jun Sang; Lee, Jun Heon; Jo, Cheorun

    2011-12-01

    An apparatus for generating atmospheric pressure plasma (APP) jet was used to investigate the inactivation of Listeria monocytogenes on the surface of agar plates and slices of cooked chicken breast and ham. He, N₂ (both 7 L/min), and mixtures of each with O₂ (0.07 L/min) were used to produce the plasma jets. After treatment for 2 min with APP jets of He, He + O₂, N₂, or N₂ + O₂, the numbers of L. monocytogenes on agar plates were reduced by 0.87, 4.19, 4.26, and 7.59 log units, respectively. Similar treatments reduced the L. monocytogenes inoculated onto sliced chicken breast and ham by 1.37 to 4.73 and 1.94 to 6.52 log units, respectively, according to the input gas used with the N₂ + O₂ mixture being the most effective. Most APP jets reduced the numbers of aerobic bacteria on the meat surfaces to <10² CFU/g, and the numbers remained below that level of detection after storage at 10 °C for 7 days. The results indicate that APP jets are effective for the inactivation of L. monocytogenes on sliced meats and for prolonging the shelf-life of such foods. PMID:21925030

  18. Antimicrobial activity of hop extracts against Listeria monocytogenes in media and in food.

    PubMed

    Larson, A E; Yu, R R; Lee, O A; Price, S; Haas, G J; Johnson, E A

    1996-12-01

    Growth of Listeria monocytogenes was inhibited in culture media and in certain foods by four hop extracts (I-IV) containing varying concentrations of alpha-and beta-acids. Extracts (II and III) containing the highest concentrations of beta-acids were inhibitory at 0.01 mg/l in trypticase soy broth. In food, these hop extracts showed varying magnitudes of inhibition. In coleslaw, hop extract III at 1 mg/g enhanced the rate of inactivation of L. monocytogenes Scott A. Hop extract II was inhibitory at 0.1 and 1 mg/ml in skim and 2% milk, and was inhibitory at 1 mg/ml in whole milk. Hop extract II was listericidal in cottage cheese at 0.1 to 3 g/kg. No inhibition of L. monocytogenes by hop extract III was observed in Camembert cheese. Overall, the antimicrobial activity of hop extracts in food appeared to increase with acidity and lower fat content. Our results indicate that hop extracts could be used to control L. monocytogenes in minimally processed food with low fat content. PMID:8930705

  19. Prospective Whole-Genome Sequencing Enhances National Surveillance of Listeria monocytogenes

    PubMed Central

    Kwong, Jason C.; Mercoulia, Karolina; Tomita, Takehiro; Easton, Marion; Li, Hua Y.; Bulach, Dieter M.; Stinear, Timothy P.; Seemann, Torsten

    2015-01-01

    Whole-genome sequencing (WGS) has emerged as a powerful tool for comparing bacterial isolates in outbreak detection and investigation. Here we demonstrate that WGS performed prospectively for national epidemiologic surveillance of Listeria monocytogenes has the capacity to be superior to our current approaches using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), multilocus variable-number tandem-repeat analysis (MLVA), binary typing, and serotyping. Initially 423 L. monocytogenes isolates underwent WGS, and comparisons uncovered a diverse genetic population structure derived from three distinct lineages. MLST, binary typing, and serotyping results inferred in silico from the WGS data were highly concordant (>99%) with laboratory typing performed in parallel. However, WGS was able to identify distinct nested clusters within groups of isolates that were otherwise indistinguishable using our current typing methods. Routine WGS was then used for prospective epidemiologic surveillance on a further 97 L. monocytogenes isolates over a 12-month period, which provided a greater level of discrimination than that of conventional typing for inferring linkage to point source outbreaks. A risk-based alert system based on WGS similarity was used to inform epidemiologists required to act on the data. Our experience shows that WGS can be adopted for prospective L. monocytogenes surveillance and investigated for other pathogens relevant to public health. PMID:26607978

  20. Organic acid dipping of catfish fillets: effect on color, microbial load, and Listeria monocytogenes.

    PubMed

    Bal'a, M F; Marshall, D L

    1998-11-01

    Microbiological and color changes of catfish fillets were determined following dip treatment in solutions at 4 degrees C of 2% acetic, citric, hydrochloric, lactic, malic, or tartaric acid. Fillets were inoculated with an eight-strain mixture of Listeria monocytogenes prior to dipping. L. monocytogenes, coliform, and aerobic plate counts and surface pH and Hunter color were measured at 0, 2, 5, and 8 days of storage at 4 degrees C. Acid dipping reduced surface pH and L. monocytogenes, coliform, and aerobic microbial loads. Little microbial proliferation was observed on acid-treated fillets, however, controls had a distinct foul odor and microbial loads in excess of 10(6) CFU/g by day 8. On untreated fillets, L. monocytogenes counts did not increase during storage, perhaps due to competitive inhibition by normal catfish microflora. Hunter color analysis revealed lighter and yellower acid-treated fillets than untreated controls, with malic acid producing the least bleaching. The shelf life of refrigerated fillets increased when fillets were acid dipped. It remains to be established if this enhanced microbial quality also parallels sensory acceptability. PMID:9829187

  1. Temperature- and nitrogen source-dependent regulation of GlnR target genes in Listeria monocytogenes.

    PubMed

    Kaspar, Daniela; Auer, Franziska; Schardt, Jakob; Schindele, Franziska; Ospina, Alberto; Held, Claudia; Ehrenreich, Armin; Scherer, Siegfried; Müller-Herbst, Stefanie

    2014-06-01

    The ubiquitous pathogen Listeria monocytogenes lives either saprophytically in the environment or within cells in a vertebrate host, thus adapting its lifestyle to its ecological niche. Growth experiments at 24 and 37 °C (environmental and host temperature) with ammonium or glutamine as nitrogen sources revealed that ammonium is the preferred nitrogen source of L. monocytogenes. Reduced growth on glutamine is more obvious at 24 °C. Global transcriptional microarray analyses showed that the most striking difference in temperature-dependent transcription was observed for central nitrogen metabolism genes, glnR (glutamine synthetase repressor GlnR), glnA (glutamine synthetase GlnA), amtB (ammonium transporter AmtB), glnK (PII regulatory protein GlnK), and gdh (glutamate dehydrogenase) when cells were grown on glutamine. When grown on ammonium, both at 24 and 37 °C, the transcriptional level of these genes resembles that of cells grown with glutamine at 37 °C. Electrophoretic mobility shift assay studies and qPCR analyses in the wild-type L. monocytogenes and the deletion mutant L. monocytogenes ∆glnR revealed that the transcriptional regulator GlnR is directly involved in temperature- and nitrogen source-dependent regulation of the respective genes. Glutamine, a metabolite known to influence GlnR activity, seems unlikely to be the (sole) intracellular signal mediating this temperature-and nitrogen source-dependent metabolic adaptation. PMID:24801548

  2. Vaccination against the intracellular bacterium Listeria monocytogenes with a clonotypic antiserum.

    PubMed

    Kaufmann, S H; Eichmann, K; Müller, I; Wrazel, L J

    1985-06-01

    The T cell clone 26.1.1, which confers specific protection against the intracellular bacterium Listeria monocytogenes, was fused to BW 5147. The resulting T cell hybridoma, TLm1, could be stimulated to secret interleukin 2 by antigen plus accessory cells or concanavalin A. Stimulation was specific for an epitope expressed by L. monocytogenes EGD but not ATCC 19114 and was H-2I-A restricted. Antisera against TLm1 were raised in syngeneic mice and tested for their capacity to block TLm1 responses. Two antisera were identified that blocked antigen but not concanavalin A stimulation of TLm1 and did not affect antigen stimulation of similar but not identical L. monocytogenes-specific T cell hybridomas. Hence, these antisera had clonotypic activity. When these antisera were administered subcutaneously in complete Freund's adjuvant, mice were protected against a subsequent L. monocytogenes infection. Protection was antigen specific and H-2 nonrestricted. These findings suggest the feasibility of clonotypic antibodies for vaccination against intracellular bacterial infections. PMID:2580906

  3. An updated review of Listeria monocytogenes in the pork meat industry and its products.

    PubMed

    Thévenot, D; Dernburg, A; Vernozy-Rozand, C

    2006-07-01

    Pork meat and processed pork products have been the sources of outbreaks of listeriosis in France and in other European countries during the last decade. The aim of this review is to understand how contamination, survival and growth of Listeria monocytogenes can occur in pork meat products. This study discusses the presence of L. monocytogenes in raw pork meat, in the processing environment and in finished products. The prevalence of L. monocytogenes generally increases from the farm to the manufacturing plants and this mainly due to cross-contamination. In many cases, this pathogen is present in raw pork meat at low or moderate levels, but foods involved in listeriosis outbreaks are those in which the organism has multiplied to reach levels significantly higher than 1000 CFU g(-1). In such cases, L. monocytogenes has been able to survive and/or to grow despite the hurdles encountered during the manufacturing and conservation processes. Accordingly, attention must be paid to the design of food-processing equipment and to the effectiveness of the cleaning and disinfecting procedures in factories. Finally, the production of safe pork meat products is based on the implementation of general preventive measures such as Good Hygiene Practices, Good Manufacturing and the Hazard Analysis Critical Control Point. PMID:16834586

  4. Host resistance of CD18 knockout mice against systemic infection with Listeria monocytogenes

    NASA Technical Reports Server (NTRS)

    Wu, Huaizhu; Prince, Joseph E.; Brayton, Cory F.; Shah, Chirayu; Zeve, Daniel; Gregory, Stephen H.; Smith, C. Wayne; Ballantyne, Christie M.

    2003-01-01

    Mice with targeted mutations of CD18, the common beta2 subunit of CD11/CD18 integrins, have leukocytosis, impaired transendothelial neutrophil emigration, and reduced host defense to Streptococcus pneumoniae, a gram-positive extracellular bacterium. Previous studies using blocking monoclonal antibodies suggested roles for CD18 and CD11b in hepatic neutrophil recruitment and host innate response to Listeria monocytogenes, a gram-positive intracellular bacterium. We induced systemic listeriosis in CD18 knockout (CD18-ko) and wild-type (WT) mice by tail vein injection with Listeria. By 14 days postinjection (dpi), 8 of 10 WT mice died, compared with 2 of 10 CD18-ko mice (P < 0.01). Quantitative organ culture showed that numbers of Listeria organisms in livers and spleens were similar in both groups at 20 min postinfection. By 3, 5, and 7 dpi, however, numbers of Listeria organisms were significantly lower in livers and spleens of CD18-ko mice than in WT mice. Histopathology showed that following Listeria infection, CD18-ko mice had milder inflammatory and necrotizing lesions in both spleens and livers than did WT mice. Cytokine assays indicated that baseline interleukin-1beta and granulocyte colony-stimulating factor (G-CSF) levels were higher in CD18-ko mice than in WT mice and that CD18-ko splenocytes produced higher levels of interleukin-1beta and G-CSF than WT splenocytes under the same amount of Listeria stimulation. These findings show that CD18 is not an absolute requirement for antilisterial innate immunity or hepatic neutrophil recruitment. We propose that the absence of CD18 in the mice results in the priming of innate immunity, as evidenced by elevated cytokine expression, and neutrophilic leukocytosis, which augments antilisterial defense.

  5. Host Resistance of CD18 Knockout Mice against Systemic Infection with Listeria monocytogenes

    PubMed Central

    Wu, Huaizhu; Prince, Joseph E.; Brayton, Cory F.; Shah, Chirayu; Zeve, Daniel; Gregory, Stephen H.; Smith, C. Wayne; Ballantyne, Christie M.

    2003-01-01

    Mice with targeted mutations of CD18, the common β2 subunit of CD11/CD18 integrins, have leukocytosis, impaired transendothelial neutrophil emigration, and reduced host defense to Streptococcus pneumoniae, a gram-positive extracellular bacterium. Previous studies using blocking monoclonal antibodies suggested roles for CD18 and CD11b in hepatic neutrophil recruitment and host innate response to Listeria monocytogenes, a gram-positive intracellular bacterium. We induced systemic listeriosis in CD18 knockout (CD18-ko) and wild-type (WT) mice by tail vein injection with Listeria. By 14 days postinjection (dpi), 8 of 10 WT mice died, compared with 2 of 10 CD18-ko mice (P < 0.01). Quantitative organ culture showed that numbers of Listeria organisms in livers and spleens were similar in both groups at 20 min postinfection. By 3, 5, and 7 dpi, however, numbers of Listeria organisms were significantly lower in livers and spleens of CD18-ko mice than in WT mice. Histopathology showed that following Listeria infection, CD18-ko mice had milder inflammatory and necrotizing lesions in both spleens and livers than did WT mice. Cytokine assays indicated that baseline interleukin-1β and granulocyte colony-stimulating factor (G-CSF) levels were higher in CD18-ko mice than in WT mice and that CD18-ko splenocytes produced higher levels of interleukin-1β and G-CSF than WT splenocytes under the same amount of Listeria stimulation. These findings show that CD18 is not an absolute requirement for antilisterial innate immunity or hepatic neutrophil recruitment. We propose that the absence of CD18 in the mice results in the priming of innate immunity, as evidenced by elevated cytokine expression, and neutrophilic leukocytosis, which augments antilisterial defense. PMID:14500519

  6. Transfer of surface-dried Listeria monocytogenes from stainless steel knife blades to roast turkey breast.

    PubMed

    Keskinen, Lindsey A; Todd, Ewen C D; Ryser, Elliot T

    2008-01-01

    Listeria contamination of food contact surfaces can lead to cross-contamination of ready-to-eat foods in delicatessens. Recognizing that variations in Listeria biofilm-forming ability exist, the goal of this study was to determine whether these differences in biofilm formation would affect the Listeria transfer rate during slicing of delicatessen turkey meat. In this study, six previously identified strong and weak biofilm-forming strains of Listeria monocytogenes were grown at 22 degrees C for 48 h on Trypticase soy agar containing 0.6% yeast extract and harvested in 0.1% peptone. Thereafter, the strains were combined to obtain two 3-strain cocktails, resuspended in turkey slurry, and inoculated onto flame-sterilized AISI grade 304 stainless steel knife blades that were subjected to 6 and 24 h of ambient storage at approximately 78% relative humidity. After mounting on an Instron Universal Testing Machine, these blades were used to obtain 16 slices of retail roast turkey breast. Based on an analysis of the slices by direct plating, Listeria populations decreased 3 to 5 log CFU per slice after 16 slices. Overall, total transfer to turkey was significantly greater for strong (4.4 log CFU total) as opposed to weak (3.5 log CFU total; P < 0.05) biofilm formers. In addition, significantly more cells were transferred at 6 (4.6 log CFU total) than at 24 h (3.3 log CFU total; P < 0.05) with Listeria quantifiable to the 16th slice, regardless of the inoculation level. Increased survival by the strong biofilm formers, as evidenced by viability staining, suggests that these strains are better adapted to survive stressful conditions than their weak biofilm-forming counterparts. PMID:18236680

  7. Use of E-beam radiation to eliminate Listeria monocytogenes from surface mould cheese.

    PubMed

    Velasco, Raquel; Ordóñez, Juan A; Cambero, M Isabel; Cabeza, M Concepción

    2015-03-01

    Camembert and Brie soft cheese varieties were subjected to E-beam irradiation as a sanitation treatment. The effects of treatments on microbiota and selected physicochemical properties were also studied. The absorbed doses required to meet the food safety objective (FSO) according to EU and USDA criteria for Listeria monocytogenes were 1.27 and 2.59 kGy, respectively. The bacterial load, mainly lactic acid bacteria, was reduced by the treatment but injured cells were recovered during storage at 14°C. The radiation treatment gave rise to negligible changes in the pH and water activity at doses required to achieve microbial safety. PMID:26415665

  8. Illuminating the landscape of host–pathogen interactions with the bacterium Listeria monocytogenes

    PubMed Central

    Cossart, Pascale

    2011-01-01

    Listeria monocytogenes has, in 25 y, become a model in infection biology. Through the analysis of both its saprophytic life and infectious process, new concepts in microbiology, cell biology, and pathogenesis have been discovered. This review will update our knowledge on this intracellular pathogen and highlight the most recent breakthroughs. Promising areas of investigation such as the increasingly recognized relevance for the infectious process, of RNA-mediated regulations in the bacterium, and the role of bacterially controlled posttranslational and epigenetic modifications in the host will also be discussed. PMID:22114192

  9. Listeria monocytogenes' Step-Like Response to Sub-Lethal Concentrations of Nisin.

    PubMed

    Takhistov, Paul; George, Bernice; Chikindas, Michael L

    2009-12-01

    Microbial safety of food products is often accomplished by the formulation of food-grade preservatives into the product. Because of the growing consumer demand for natural substances (including preservatives) in the composition of consumed foods, there is also a growing interest in the natural antimicrobial nisin, which has generally recognized as safe (GRAS) status for certain applications. During the products storage time, concentrations of preservative(s) are decreasing, which may eventually cause a serious problem in the food's microbial safety. Here, for the first time we report on the non-linear response of a foodborne pathogen, Listeria monocytogenes, to sub-lethal concentrations of nisin. PMID:26783172

  10. Oleanolic acid and ursolic acid affect peptidoglycan metabolism in Listeria monocytogenes.

    PubMed

    Kurek, Anna; Grudniak, Anna M; Szwed, Magdalena; Klicka, Anna; Samluk, Lukasz; Wolska, Krystyna I; Janiszowska, Wirginia; Popowska, Magdalena

    2010-01-01

    The plant pentacyclic triterpenoids, oleanolic and ursolic acids, inhibit the growth and survival of many bacteria, particularly Gram-positive species, including pathogenic ones. The effect of these compounds on the facultative human pathogen Listeria monocytogenes was examined. Both acids affected cell morphology and enhanced autolysis of the bacterial cells. Autolysis of isolated cell walls was inhibited by oleanolic acid, but the inhibitory activity of ursolic acid was less pronounced. Both compounds inhibited peptidoglycan turnover and quantitatively affected the profile of muropeptides obtained after digestion of peptidoglycan with mutanolysin. These results suggest that peptidoglycan metabolism is a cellular target of oleanolic and ursolic acids. PMID:19894138

  11. Interleukin-1-induced promotion of T-cell differentiation in mice immunized with killed Listeria monocytogenes.

    PubMed Central

    Igarashi, K; Mitsuyama, M; Muramori, K; Tsukada, H; Nomoto, K

    1990-01-01

    We studied the effects of administration of recombinant interleukin-1 alpha (rIL-1 alpha) to mice after immunization with killed Listeria monocytogenes cells on the promotion of the functional differentiation of T cells in vivo. Mice immunized with killed L. monocytogenes were unable to express cell-mediated immunity to specific antigen in vivo, as determined by delayed-type hypersensitivity (DTH) and acquired cellular resistance (ACR), and splenic T cells obtained from such mice were unable to respond to rIL-2 and specific antigen and to produce IL-2 after antigenic restimulation in vitro. When rIL-1 alpha was given to mice after immunization with killed bacteria. T cells became capable of responding to rIL-2 and specific antigen in vitro. These functions of T cells were similar to those from mice immunized with viable listeriae. Moreover, using a local passive transfer system, it was found that effector T cells mediating DTH but not ACR to L. monocytogenes were generated in mice treated with rIL-1 alpha after immunization with killed bacteria. These T cells were able to produce macrophage chemotactic factor but not macrophage-activating factor or gamma interferon in vitro in response to stimulation with specific antigen. These results suggest that in vivo administration of rIL-1 alpha facilitates the maturation of antigen-specific T cells mediating DTH and that different effector T cells mediating DTH or ACR are involved in cell-mediated immunity to L. monocytogenes. PMID:2123829

  12. Serovar 4b complex predominates among Listeria monocytogenes isolates from imported aquatic products in China.

    PubMed

    Chen, Jianshun; Chen, Qiaomiao; Jiang, Jianjun; Hu, Hongxia; Ye, Jiangbo; Fang, Weihuan

    2010-01-01

    Listeria monocytogenes, the causative organism of listeriosis, is primarily transmitted to humans through contaminated food. In this study, we examined 1275 batches of aquatic products imported from 29 countries and found that 36 batches from 8 countries were contaminated by Listeria (2.8%), with L. monocytogenes accounting for 2.6% (33/1275) and L. innocua for 0.2% (3/1275). Of the 23 selected L. monocytogenes isolates (from the 33 identified), 15 (65.2%) were of serovar 4b complex (4b, 4d, or 4e), three (13.0%) of 1/2a or 3a, four (17.4%) of 1/2b or 3b, and one (4.4%) of 1/2c or 3c. Notably, four of the 23 isolates belonged to epidemic clone I (ECI) and another four were associated with epidemic clone II (ECII), two highly clonal 4b clusters responsible for most of the documented listeriosis outbreaks. In the multilocus sequence typing scheme based on the concatenated genes gyrB-dapE-hisJ-sigB-ribC-purM-betL-gap-tuf, serovar 4b complex isolates from imported aquatic products exhibited significant genetic diversity. While the four ECI isolates were genetically related to those from Chinese diseased animals, both lacking one proline-rich repeat of ActA, the four ECII isolates were located between 1/2b or 3b strains. As the L. monocytogenes isolates from imported aquatic products possessed a nearly complete set of major infection-related genes, they demonstrated virulence potential in mouse model. PMID:19735205

  13. Role of proapoptotic BH3-only proteins in Listeria monocytogenes infection.

    PubMed

    Margaroli, Camilla; Oberle, Susanne; Lavanchy, Christine; Scherer, Stefanie; Rosa, Muriel; Strasser, Andreas; Pellegrini, Marc; Zehn, Dietmar; Acha-Orbea, Hans; Ehirchiou, Driss

    2016-06-01

    The ability of pathogens to influence host cell survival is a crucial virulence factor. Listeria monocytogenes (Lm) infection is known to be associated with severe apoptosis of hepatocytes and spleen cells. This impairs host defense mechanisms and thereby facilitates the spread of intracellular pathogens. The general mechanisms of apoptosis elicited by Lm infection are understood, however, the roles of BH3-only proteins during primary Lm infection have not been examined. To explore the roles of BH3-only proteins in Lm-induced apoptosis, we studied Listeria infections in mice deficient in Bim, Bid, Noxa or double deficient in BimBid or BimNoxa. We found that BimNoxa double knockout mice were highly resistant to high-dose challenge with Listeria. Decreased bacterial burden and decreased host cell apoptosis were found in the spleens of these mice. The ability of the BH3-deficient mice to clear bacterial infection more efficiently than WT was correlated with increased concentrations of ROS, neutrophil extracellular DNA trap release and downregulation of TNF-α. Our data show a novel pathway of infection-induced apoptosis that enhances our understanding of the mechanism by which BH3-only proteins control apoptotic host cell death during Listeria infection. PMID:27064265

  14. LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes ▿ †

    PubMed Central

    Kastner, Renate; Dussurget, Olivier; Archambaud, Cristel; Kernbauer, Elisabeth; Soulat, Didier; Cossart, Pascale; Decker, Thomas

    2011-01-01

    Intracellular bacterial pathogens manipulate host cell functions by producing enzymes that stimulate or antagonize signal transduction. The Listeria monocytogenes genome contains a gene, lmo1800, encoding a protein with a conserved motif of conventional tyrosine phosphatases. Here, we report that the lmo1800-encoded protein LipA is secreted by Listeria and displays tyrosine as well as lipid phosphatase activity in vitro. Bacteria lacking LipA are severely attenuated in virulence in vivo, thus revealing a so-far-undescribed enzymatic activity involved in Listeria infection. PMID:21444667

  15. Important vectors for Listeria monocytogenes transmission at farm dairies manufacturing fresh sheep and goat cheese from raw milk.

    PubMed

    Schoder, Dagmar; Melzner, Daniela; Schmalwieser, Alois; Zangana, Abdoulla; Winter, Petra; Wagner, Martin

    2011-06-01

    The aim of this study was to determine the transmission routs of Listeria spp. in dairy farms manufacturing fresh cheese made from ovine and caprine raw milk and to evaluate the impact of Listeria monocytogenes mastitis on raw milk contamination. Overall, 5,799 samples, including 835 environmental samples, 230 milk and milk product samples, and 4,734 aseptic half-udder foremilk samples were collected from 53 dairy farms in the dairy intensive area of Lower Austria. Farms were selected for the study because raw milk was processed to cheese that was sold directly to consumers. A total of 153 samples were positive for Listeria spp., yielding an overall prevalence of 2.6%; L. monocytogenes was found in 0.9% of the samples. Bulk tank milk, cheese, and half-udder samples were negative for Listeria spp. Because none of the sheep and goats tested positive from udder samples, L. monocytogenes mastitis was excluded as a significant source of raw milk contamination. L. monocytogenes was detected at 30.2% of all inspected farms. Swab samples from working boots and fecal samples had a significantly higher overall prevalence (P < 0.001) of L. monocytogenes (15.7 and 13.0%, respectively) than did swab samples from the milk processing environment (7.9%). A significant correlation was found between the prevalence of L. monocytogenes in the animal and in the milk processing environment and the silage feeding practices. Isolation of L. monocytogenes was three to seven times more likely from farms where silage was fed to animals throughout the year than from farms where silage was not fed to the animals. PMID:21669068

  16. Effect of nisin (Nisaplin) on the growth of Listeria monocytogenes in Karashi-mentaiko (Red-pepper Seasoned Cod Roe).

    PubMed

    Hara, Hiroyoshi; Ohashi, Yuji; Sakurai, Toshio; Yagi, Kazuhiro; Fujisawa, Tomohiko; Igimi, Shizunobu

    2009-08-01

    The influence of Nisaplin, which contains 2.5% nisin, on the growth of Listeria monocytogenes in Karashi-mentaiko (red-pepper seasoned cod roe) was investigated. The MICs of Nisaplin for L. monocytogenes (10(8) CFU/mL) were measured; seven isolates showed a value of 1,600 microg/mL and one isolate showed a value of 800 microg/mL. All L. monocytogenes isolates had a MIC of 800 microg/mL at 10(6) CFU/mL. The number of L. monocytogenes in Karashi-mentaiko stored at 4 degrees C was decreased by Nisaplin added at 60 and 600 microg/g. These results indicated that Nisaplin effectively inhibits the growth of L. monocytogenes in Karashi-mentaiko. PMID:19745585

  17. Investigating the control of Listeria monocytogenes on alternatively-cured frankfurters using natural antimicrobial ingredients or post-lethality interventions.

    PubMed

    Lavieri, Nicolas A; Sebranek, Joseph G; Brehm-Stecher, Byron F; Cordray, Joseph C; Dickson, James S; Horsch, Ashley M; Jung, Stephanie; Larson, Elaine M; Manu, David K; Mendonca, Aubrey F

    2014-08-01

    The objective of this study was to investigate natural antimicrobials including cranberry powder, dried vinegar and lemon juice/vinegar concentrate, and post-lethality interventions (lauric arginate, octanoic acid, thermal treatment and high hydrostatic pressure) for the control of Listeria monocytogenes on alternatively-cured frankfurters. Lauric arginate, octanoic acid, and high hydrostatic pressure (400 MPa) reduced L. monocytogenes populations by 2.28, 2.03, and 1.88 log 10 CFU per g compared to the control. L. monocytogenes grew in all post-lethality intervention treatments, except after a 600 MPa high hydrostatic pressure treatment for 4 min. Cranberry powder did not inhibit the growth of L. monocytogenes, while a dried vinegar and a vinegar/lemon juice concentrate did. This study demonstrated the bactericidal properties of high hydrostatic pressure, octanoic acid and lauric arginate, and the bacteriostatic potential of natural antimicrobial ingredients such as dried vinegar and vinegar/lemon juice concentrate against L. monocytogenes. PMID:24769878

  18. Survival of Listeria monocytogenes in sea water and effect of exposure on thermal resistance.

    PubMed

    Bremer, P J; Osborne, C M; Kemp, R A; Smith, J J

    1998-09-01

    Survival, recoverability and sublethal injury of two strains of Listeria monocytogenes, Scott A and an environmental strain KM, on exposure to sea water at 12.8 or 20.8 degrees C was determined using in situ diffusion chambers. Plate counts were used to assess recoverability and injury while 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was used to determine respiratory activity. T90 values (times for 10-fold decreases in numbers of recoverable cells) on non-selective medium (trypticase soya agar with 0.6% yeast extract) at 12.8 and 20.8 degrees C were 61.7 and 69.2 h for L. monocytogenes Scott A, and 103.0 and 67.0 h for L. monocytogenes KM, respectively. On selective medium (Oxford agar), T90 values at 12.8 and 20.8 degrees C were 60.6 and 56.9 h for L. monocytogenes Scott A, and 83.0 and 65.9 h for L. monocytogenes KM, respectively. With Scott A, the percentage of sublethally injured cells at 12.8 and 20.8 degrees C was 1.7 and 17.7%, respectively, while for KM the values were 19.0 and 1.6%, respectively. The fraction of cells reducing CTC but which were not recoverable on plating progressively increased on exposure to sea water. Listeria monocytogenes KM challenged at 58 degrees C showed an apparent increase in heat resistance after exposure to sea water at 20.8 degrees C for 7 d (D58 = 2.64 min) compared with before exposure (D58 = 1.24). This increase in thermal resistance was not apparent at temperatures greater than 63 degrees C, and analysis of the best-fit regression lines fitted to the thermal data obtained from the two cell populations indicated that their thermal resistance was not significantly different (P > 0.05) over the temperature range tested (58-62 degrees C). PMID:9750285

  19. In Vitro Evaluation of Bacteriocins Activity Against Listeria monocytogenes Biofilm Formation.

    PubMed

    Camargo, Anderson Carlos; de Paula, Otávio Almeida Lino; Todorov, Svetoslav Dimitrov; Nero, Luís Augusto

    2016-03-01

    The present study aimed to assess the activity of cell-free supernatant (CFS) containing bacteriocins on the formation and maintenance of biofilms developed by Listeria monocytogenes, and the associated effect of bacteriocins and ethylene-diamine-tetra-acetic acid (EDTA) on the formed biofilm. CFS from 9 lactic acid bacteria (LAB) strains was tested for inhibitory activity against 85 L. monocytogenes isolates and 21 LAB strains. Then, 12 L. monocytogenes strains were selected based on genetic profiles and sensitivity to CFS and were subjected to an in vitro assay to assess biofilm formation in microtiter plates, considering different culture media and incubation conditions. Based on these results, 6 L. monocytogenes strains were subjected to the same in vitro procedure to assess biofilm formation, being co-inoculated with CFS. In addition, these strains were subjected to the same in vitro procedure, modified by adding the CFS after biofilm formation. Relevant decrease in biofilm formation was observed in the first experiment, but CFS added after biofilm formation did not eliminate them. CFS from Lactobacillus curvatus ET31 were selected due to its anti-biofilm activity, being associated to EDTA at different concentrations and tested for biofilm control of three strains of L. monocytogenes, using the same in vitro procedure described previously. Concentrated bacteriocin presented poor performance in eliminating formed biofilms, and EDTA concentration presented no evident interference on biofilm elimination. Twelve selected L. monocytogenes strains were positive for investigated virulence makers and negative for luxS gene, recognized as being involved in biofilm formation. Selected L. monocytogenes strains were able to produce biofilms under different conditions. CFSs have the potential to prevent biofilm formation, but they were not able to destroy already formed biofilms. Nevertheless, low concentrations of CFS combined with EDTA caused a relevant reduction in

  20. Tackling the true prevalence and levels of listeria monocytogenes: market basket surveys of ready-to-eat retail foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes remains a serious threat to public health due to its prevalence, persistence, and pathogenicity in our food supply, particularly when associated with ready-to-eat (RTE) foods. For the past decade or so, considerable resources have been directed to reduce human illness attribut...

  1. Prevalence and sources of Listeria monocytogenes in blue crab (Callinectus sapidus) meat and blue crab processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and L. monocytogenes for two years (2006-2007). A total of 488 raw crab, 624 crab meat, and 624 environmental samples were tested by molecular and culture-based standard methods. Presumptive Liste...

  2. Inactivation of Listeria monocytogenes, Salmonella spp. and Escherichia coli O157:H7 on cantaloupes by octenidine hydrochloride

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the efficacy of a new generation disinfectant, namely octenidine dihydrochloride (OH) as wash and coating treatments for reducing Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 on cantaloupe surface. Cantaloupe rind plugs inoculated separately with L. m...

  3. Inactivation of Listeria monocytogenes in Skim Milk and Liquid Egg White by Antimicrobial Bottle Coating with Polylactic Acid and Nisin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was to develop an antimicrobial bottle coating method to reduce the risk of outbreaks of human listeriosis caused by contaminated liquid foods. Liquid egg white and skim milk were inoculated with Listeria monocytogenes Scott A and stored in glass jars that were coated with a mixture of po...

  4. Survival and growth of Listeria monocytogenes on whole cantaloupes is dependent on site of contamination and storage temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole cantaloupes (Cucumis melo L), marketed as ‘Rocky Ford’, were implicated in a large multi-state outbreak of listeriosis in the United States in 2011; however, survival and growth of Listeria monocytogenes on whole cantaloupes remains relatively unexplored. The research presented here evaluated ...

  5. Sodium lactate, sodium diacetate and pediocin: effects and interactions on the thermal inactivation of Listeria monocytogenes on bologna

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects and interactions of temperature (56.3C-60C), sodium lactate (SL; 0-4.8%), sodium diacetate (SD; 0-0.25%) and pediocin (0-10,000 AU) on Listeria monocytogenes inoculated on bologna were studied and a predictive inactivation model was developed. Bologna was manufactured with different SL ...

  6. The use of Flagella and Motility for plant colonization and fitness by different strains of the foodborne pathogen Listeria monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The role of flagella and motility in the attachment of the foodborne pathogen Listeria monocytogenes to various surfaces is mixed with some systems requiring flagella for an interaction and others needing only motility for cells to get to the surface. In nature this bacterium is a saprophyte and co...

  7. Co-infection of Market-age Turkeys with Escherichia coli and Listeria monocytogenes in Two Stress Models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have hypothesized that stress-induced subclinical infection of turkeys with Listeria monocytogenes (Lm) may be an overlooked source of processing plant contamination and we have shown that concurrent Escherichia coli challenge can increase Lm colonization. The objective of this study was to deter...

  8. Inactivation of Salmonella enterica and Listeria monocytogenes in cantaloupe puree by high hydrostatic pressure with/without added ascorbic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to evaluate and develop a method for inactivation of Salmonella enterica and Listeria monocytogenes in cantaloupe puree (CP) by high hydrostatic pressure (HHP). Cantaloupe being the most netted varieties of melons presents a greater risk of pathogen transmission. ...

  9. EFFICACY OF OZONE IN KILLING LISTERIA MONOCYTOGENES ON ALFALFA SEEDS AND SPROUTS, AND EFFECTS ON SENSORY QUALITY OF SPROUTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was done to determine the efficacy of aqueous ozone treatment in killing Listeria monocytogenes on inoculated alfalfa seeds and sprouts. Reduction in populations of naturally occurring aerobic microorganisms on sprouts and changes in sensory quality of sprouts were also determined. Treatme...

  10. Reduction of Listeria monocytogenes on the surface of fresh channel catfish fillets by bacteriophage listex P100

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteriophage Listex P100 (phage P100) was approved by the U.S. Food and Drug Administration and U.S. Department of Agriculture's Food Safety and Inspection Service for Listeria monocytogenes control on both raw and ready-to-eat food products. In this article, we present the proof of concept on the ...

  11. The role of Listeria monocytogenes cell wall surface anchor protein LapB in virulence, adherence, and intracellular replication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lmof2365_2117 is a Listeria monocytogenes putative cell wall surface anchor protein with a conserved domain found in collagen binding proteins. We constructed a deletion mutation in lmof2365_2117 in serotype 4b strain F2365, evaluated its virulence, and determined its ability to adhere and invade co...

  12. Genetic determinants for cadmium and arsenic resistance among Listeria monocytogenes serotype 4b isolates from sporadic human listeriosis patients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Listeria monocytogenes serotype 4b from sporadic listeriosis, heavy metal resistance was primarily encountered in certain clonal groups (ECI, ECII, ECIa). All arsenic-resistant isolates harbored the arsenic resistance cassette previously identified in pLI100; ECIa harbored additional arsenic resi...

  13. Effect of chemical sanitizers with and without ultra-sonication on Listeria monocytogenes as a biofilm within PVC drain pipes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes (LM) can colonize poultry cooking plants becoming a long term resident. Once a processing plant is contaminated, LM can be readily detected in floor drains where it becomes part of a complex biofilm community. As part of this biofilm, LM is exceedingly difficult to eradicate...

  14. Modeling the impact of chlorine on the behavior of Listeria monocytogenes on ready-to-eat meats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes (Lm) continues to pose a food safety hazard in ready-to-eat (RTE) meat due to potential cross-contamination. Chlorine is commonly used to sanitize processing equipment and utensils. However, Lm may survive the treatment and then contaminate food products. The objective of t...

  15. Diverse genomic location and sequence content of a Listeria monocytogenes chromosomal island harboring heavy metal resistance and other genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes remains a major foodborne pathogen with three serotype 4b clonal groups (ECI, ECII, ECIa) repeatedly implicated in human listeriosis. For reasons that are unknown, many of these strains are also resistant to heavy metals, i.e. cadmium and arsenic. The acquisition and fitness i...

  16. Transmission electron microscopy study of Listeria monocytogenes serotype 1/2a cells exposed to sublethal heat stress and carvacrol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to investigate the morphological changes that occurred in Listeria monocytogenes serotype 1/2a cells as visualized by transmission electron microscopy (TEM) after exposure to sublethal heat stress at 48°C for 60 min and in combination with lethal concentration of carv...

  17. Impact of chlorine and temperature on Listeria monocytogenes survival growth behavior on ready-to-eat meats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes (Lm) continues to pose a food safety hazard in ready-to-eat (RTE) meat due to potential cross-contamination. Chlorine is commonly used to sanitize processing equipment. However, Lm may survive on processing equipment surfaces, which then contaminate food products. The objec...

  18. Development of a multiplex PCR detection kit for Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multiplex PCR method was developed for simultaneous detection of Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7 in food samples, and the detection sensitivity for this method was 103 CFU/ml for each pathogen. When this method was used for the detection of each of pathogens ...

  19. Efficacy of a surface spray application of lauric arginate derivatives to control Listeria monocytogenes on roast beef and pastrami

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Post-processing contamination of the surface and/or purge of vacuum-packaged ready-to-eat (RTE) meats with Listeria monocytogenes (Lm) poses a significant risk to consumers. Because some RTE meats provide a suitable environment for growth/survival of Lm, a post-processing intervention ...

  20. Radiation D10-Values on Thawed and Frozen Catfish and Tilapia for Finfish Isolates of Listeria Monocytogenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With the popularity of catfish and tilapia in the healthy diet, the consumption and harvesting of farm raised finfish has increased. Since 1987 the bacterial pathogen, Listeria monocytogenes, has been isolated from seafood, particularly farm raised catfish in the United States. Seafood isolates of...

  1. Survival of Listeria monocytogenes on slices of turkey bacon during extended storage at 4 Degrees and 10 Degrees C

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the fate of Listeria monocytogenes (Lm) on the surface of fully-cooked, cured turkey bacon, an increasingly popular product that on a per ounce (28 g) basis is generally lower in fat (ca. 1.0 g), sodium (ca. 200 mg), and calories (40 calories) than its traditional counterpart, that bein...

  2. Antimicrobial Efficacy of Zinc Oxide Quantum Dots Against Listeria Monocytogenes, Salmonella Enteritidis and Escherichia coli O157:H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Zinc oxide quantum dots (ZnO QDs) in a powder form, a ZnO-polystyrene (PS) film form and a polyvinylprolidone capped ZnO (ZnO-PVP) gel form were prepared and their antibacterial activities against foodborne pathogenic Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli O157:H7 in cul...

  3. Recipes for Antimicrobial Wine Marinades against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated bactericidal activities of several antimicrobial wine recipes consisting of red and white wine extracts of oregano leaves with added garlic juice and oregano oil against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica. Dose-response plots were...

  4. Multiple abscesses of the left brain hemisphere due to Listeria monocytogenes in an immunocompromised patient: a case report.

    PubMed

    Matera, Giovanni; Puccio, Rossana; Giancotti, Aida; Quirino, Angela; Guadagnino, Vincenzo; Pardatscher, Kurt; Caroleo, Santo; De Rose, Marisa; Amorosi, Andrea; Liberto, Maria Carla; Focà, Alfredo

    2012-12-01

    We describe a case of brain abscesses in a cirrhotic and diabetic 57-year-old woman showing fever, aphasia, right hemiparesis and seizures. Neuroradiological investigation revealed unilateral cerebritis evolving in multiple abscesses. From blood and surgical drainage samples Listeria monocytogenes grew in pure culture. Despite decompressive craniotomy, the patient died two months after hospital admission. PMID:23299068

  5. Dynamic kinetic analysis of growth of Listeria monocytogenes in a simulated comminuted, non-cured cooked pork product

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to directly construct a tertiary growth model for Listeria monocytogenes in cooked pork and simultaneously determine the kinetic parameters using a combination of dynamic and isothermal growth curves. Growth studies were conducted using a cocktail of 5 strains of L. ...

  6. Draft Genome Sequences of 15 Isolates of Listeria monocytogenes Serotype 1/2a, Subgroup ST204.

    PubMed

    Allnutt, Theodore R; Bradbury, Mark I; Fanning, Séamus; Chandry, P Scott; Fox, Edward M

    2016-01-01

    Listeria monocytogenes sequence type 204 (ST204) strains have been isolated from a range of food, environmental, and clinical sources in Australia. This study describes the draft genome sequences of 15 isolates collected from meat and dairy associated sources. PMID:27609916

  7. Tannin-rich fraction from pomegranate rind damages membrane of Listeria monocytogenes.

    PubMed

    Li, Guanghui; Xu, Yunfeng; Wang, Xin; Zhang, Baigang; Shi, Chao; Zhang, Weisong; Xia, Xiaodong

    2014-04-01

    Pomegranate rind has been reported to inhibit several foodborne pathogens, and its antimicrobial activity has been attributed mainly to its tannin fraction. This study aimed to investigate the antimicrobial activity of the tannin-rich fraction from pomegranate rind (TFPR) against Listeria monocytogenes and its mechanism of action. The tannin-related components of TFPR were analyzed by high-performance liquid chromatography and liquid chromatography-mass spectrometry, and the minimum inhibitory concentration (MIC) of TFPR was determined using the agar dilution method. Extracellular potassium concentration, the release of cell constituents, intra- and extracellular ATP concentrations, membrane potential, and intracellular pH (pHin) were measured to elucidate a possible antibacterial mechanism. Punicalagin (64.2%, g/g) and ellagic acid (3.1%, g/g) were detected in TFPR, and the MICs of TFPR were determined to be 1.25-5.0 mg/mL for different L. monocytogenes strains. Treatment with TFPR induced a decrease of the intracellular ATP concentration, an increase of the extracellular concentrations of potassium and ATP, and the release of cell constituents. A reduction of pHin and cell membrane hyperpolarization were observed after treatment. Electron microscopic observations showed that the cell membrane structures of L. monocytogenes were apparently impaired by TFPR. It is concluded that TFPR could destroy the integrity of the cell membrane of L. monocytogenes, leading to a loss of cell homeostasis. These findings indicate that TFPR has the potential to be used as a food preservative in order to control L. monocytogenes contamination in food and reduce the risk of listeriosis. PMID:24447173

  8. Differential internalin A levels in biofilms of Listeria monocytogenes grown on different surfaces and nutrient conditions.

    PubMed

    Gilmartin, Niamh; Gião, Maria S; Keevil, Charles W; O'Kennedy, Richard

    2016-02-16

    Listeria monoctyogenes is a foodborne pathogen containing the surface protein, internalin A (InlA). The expression of this protein permits the invasion of L. monocytogenes into intestinal epithelial cells expressing the receptor E-cadherin, thus crossing the intestinal barrier and resulting in listerosis. The main aim of this work was to investigate InlA levels in different L. monocytogenes strains in both planktonic and sessile states using an anti-InlA antibody. Biofilms were grown in high and low nutrient environments on glass, stainless steel and polytetrafluoroethylene (PTFE). This study demonstrated that InlA levels varied greatly between strains and serotypes of L. monocytogenes. However, the serotypes 1/2a, 1/2b and 4b, associated with the largest number of outbreaks of listerosis consistently showed the highest InlA levels, regardless of nutrient content or planktonic or sessile state. Differences in InlA levels were also observed in biofilms grown on different surfaces such as glass, stainless steel and PTFE, with a significant reduction in InlA levels observed in biofilms on PTFE. Interestingly, although a large number of the total cells observed in biofilms formed in tap-water were non-cultivable, the virulence factor, InlA, was expressed at levels between 78 and 85%, thus indicating that these cells may still be virulent. A greater understanding of the factors that affect the levels of InlA on the surface of L. monocytogenes, is essential in the appreciation of the role of InlA in the persistence of biofilms containing L. monocytogenes and their potential to cause food borne disease. PMID:26724402

  9. Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition

    PubMed Central

    Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.

    2015-01-01

    Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential. PMID:26529510

  10. Multifaceted Activity of Listeriolysin O, the Cholesterol-Dependent Cytolysin of Listeria monocytogenes

    PubMed Central

    2014-01-01

    The cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins that are produced by numerous Gram-positive bacterial pathogens. These toxins are released in the extracellular environment as water-soluble monomers or dimers that bind to cholesterol-rich membranes and assemble into large pore complexes. Depending upon their concentration, the nature of the host cell and membrane (cytoplasmic or intracellular) they target, the CDCs can elicit many different cellular responses. Among the CDCs, listeriolysin O (LLO), which is a major virulence factor of the facultative intracellular pathogen Listeria monocytogenes, is involved in several stages of the intracellular lifecycle of the bacterium and displays unique characteristics. It has long been known that following L. monocytogenes internalization into host cells, LLO disrupts the internalization vacuole, enabling the bacterium to replicate into the host cell cytosol. LLO is then used by cytosolic bacteria to spread from cell to cell, avoiding bacterial exposure to the extracellular environment. Although LLO is continuously produced during the intracellular lifecycle of L. monocytogenes, several processes limit its toxicity to ensure the survival of infected cells. It was previously thought that LLO activity was limited to mediating vacuolar escape during bacterial entry and cell to cell spreading. This concept has been challenged by compelling evidence suggesting that LLO secreted by extracellular L. monocytogenes perforates the host cell plasma membrane, triggering important host cell responses. This chapter provides an overview of the well-established intracellular activity of LLO and the multiple roles attributed to LLO secreted by extracellular L. monocytogenes. PMID:24798012

  11. Type I IFN Does Not Promote Susceptibility to Foodborne Listeria monocytogenes.

    PubMed

    Pitts, Michelle G; Myers-Morales, Tanya; D'Orazio, Sarah E F

    2016-04-01

    Type I IFN (IFN-α/β) is thought to enhance growth of the foodborne intracellular pathogen Listeria monocytogenes by promoting mechanisms that dampen innate immunity to infection. However, the type I IFN response has been studied primarily using methods that bypass the stomach and, therefore, fail to replicate the natural course of L. monocytogenes infection. In this study, we compared i.v. and foodborne transmission of L. monocytogenes in mice lacking the common type I IFN receptor (IFNAR1(-/-)). Contrary to what was observed using i.v. infection, IFNAR1(-/-) and wild-type mice had similar bacterial burdens in the liver and spleen following foodborne infection. Splenocytes from wild-type mice infected i.v. produced significantly more IFN-β than did those infected by the foodborne route. Consequently, the immunosuppressive effects of type I IFN signaling, which included T cell death, increased IL-10 secretion, and repression of neutrophil recruitment to the spleen, were all observed following i.v. but not foodborne transmission of L. monocytogenes. Type I IFN was also previously shown to cause a loss of responsiveness to IFN-γ through downregulation of the IFN-γ receptor α-chain on macrophages and dendritic cells. However, we detected a decrease in surface expression of IFN-γ receptor α-chain even in the absence of IFN-α/β signaling, suggesting that in vivo, this infection-induced phenotype is not type I IFN-dependent. These results highlight the importance of using the natural route of infection for studies of host-pathogen interactions and suggest that the detrimental effects of IFN-α/β signaling on the innate immune response to L. monocytogenes may be an artifact of the i.v. infection model. PMID:26895837

  12. Essential oils of thyme and Rosemary in the control of Listeria monocytogenes in raw beef

    PubMed Central

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Piccoli, Roberta Hilsdorf

    2013-01-01

    This study was developed in order to evaluate two alternatives for the control of Listeria monocytogenes in raw bovine meat pieces, both based on the use of Thymus vulgaris and Rosmarinus officinalis essential oils (EOs). The antilisterial activity of different concentrations of the EOs was tested in vitro using agar dilution and disk volatilization techniques. In addition, L. monocytogenes was inoculated in meat pieces, which were submerged in edible gelatin coatings containing 2% (v/v) EOs or submitted to the vapor of EOs (0.74 μL.cm−3). L. monocytogenes was quantified after one, 48 and 96 hours of storage (7 °C). In the in vitro tests, the EO of T. vulgaris presented higher activity. The two options used (edible gelatin coating and vapor activity), in spite of exercising effects with differentiated behaviors, presented antibacterial activity against L. monocytogenes inoculated in raw bovine meat (p < 0.05). Greatest antibacterial activity were obtained in the experiment that used edible coatings containing EOs, at 48 hours of storage reductions in bacterial counts between 1.09 and 1.25 Log CFU.g−1 were obtained. In the vapor effect experiment, the EO of T. vulgaris caused the highest reduction in the population of bacteria inoculated in raw bovine meat (p < 0.05), 0.40 Log CFU.g−1 at 96 hours of storage. This study supplied important information regarding new and promising natural alternatives, based on the concept of active packaging, for the control of L. monocytogenes in the meat industry. PMID:24688509

  13. Control of Listeria monocytogenes growth in soft cheeses by bacteriophage P100.

    PubMed

    Silva, Elaine Nóbrega Gibson; Figueiredo, Ana Cláudia Leite; Miranda, Fernanda Araújo; de Castro Almeida, Rogeria Comastri

    2014-01-01

    The purpose of this study was to determine the effect of bacteriophage P100 on strains of Listeria monocytogenes in artificially inoculated soft cheeses. A mix of L. monocytogenes 1/2a and Scott A was inoculated in Minas Frescal and Coalho cheeses (approximately 10(5) cfu/g) with the bacteriophage added thereafter (8.3 × 10(7) PFU/g). Samples were analyzed immediately, and then stored at 10 °C for seven days. At time zero, 30 min post-infection, the bacteriophage P100 reduced L. monocytogenes counts by 2.3 log units in Minas Frescal cheese and by 2.1 log units in Coalho cheese, compared to controls without bacteriophage. However, in samples stored under refrigeration for seven days, the bacteriophage P100 was only weakly antilisterial, with the lowest decimal reduction (DR) for the cheeses: 1.0 log unit for Minas Frescal and 0.8 log units for Coalho cheese. The treatment produced a statistically significant decrease in the counts of viable cells (p < 0.05) and in all assays performed, we observed an increase of approximately one log cycle in the number of viable cells of L. monocytogenes in the samples under refrigeration for seven days. Moreover, a smaller effect of phages was observed. These results, along with other published data, indicate that the effectiveness of the phage treatment depends on the initial concentration of L. monocytogenes, and that a high concentration of phages per unit area is required to ensure sustained inactivation of target pathogens on food surfaces. PMID:24948908

  14. Listeria monocytogenes can grow in macrophages without the aid of proteins induced by environmental stresses.

    PubMed

    Hanawa, T; Yamamoto, T; Kamiya, S

    1995-12-01

    Listeria monocytogenes is a facultative intracellular pathogen which is able to survive and grow within phagocytic cells. Some facultative intracellular bacteria have been shown to respond to the hostile environment within phagocytic cells by producing a set of stress proteins. Since L. monocytogenes has a mechanism for intracellular survival that is distinct from those of other bacteria, we studied the phenotypic response of the bacterium to phagocytosis by macrophages. After phagocytosis of L. monocytogenes EGD by J774-1 macrophage cells, the microorganism rapidly increased in numbers about 20-fold during an incubation period of 5 h. In this phase of phagocytosis, the selective induction of 32 proteins was observed by two-dimensional gel electrophoresis. The responses to the environmental stresses of heat and hydrogen peroxide were also studied, and it was found that 14 heat shock proteins and 13 oxidative stress proteins were induced. Five of the induced proteins were common to both heat and oxidative stresses. By amino acid sequencing analysis, homologs of DnaK and GroEL were confirmed among the heat shock proteins. A comparison of the autoradiograms of the two-dimensional gels revealed that none of these stress proteins were among the proteins induced by L. monocytogenes within the macrophages. This behavior is entirely different from that shown by other facultative intracellular pathogens. Stress proteins known to be induced by environmental stresses were absent in intracellularly grown L. monocytogenes in the present study. This absence could be due to the mechanism by which the microorganisms rapidly escape from this stressful environment at a very early phase of phagocytosis. PMID:7591111

  15. Listeria monocytogenes EGD-e Biofilms: No Mushrooms but a Network of Knitted Chains▿

    PubMed Central

    Rieu, Aurélie; Briandet, Romain; Habimana, Olivier; Garmyn, Dominique; Guzzo, Jean; Piveteau, Pascal

    2008-01-01

    Listeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L. monocytogenes biofilm formation and its regulation. The aims of this study were, by combining genetics and time-lapse laser-scanning confocal microscopy (LSCM), (i) to characterize the structural dynamics of L. monocytogenes EGD-e sessile growth in two nutritional environments (with or without a nutrient flow), and (ii) to evaluate the possible role of the L. monocytogenes agr system during biofilm formation by tracking the spatiotemporal fluorescence expression of a green fluorescent protein (GFP) reporter system. In the absence of nutrient flow (static conditions), unstructured biofilms composed of a few layers of cells that covered the substratum were observed. In contrast, when grown under dynamic conditions, L. monocytogenes EGD-e biofilms were highly organized. Indeed, ball-shaped microcolonies were surrounded by a network of knitted chains. The spatiotemporal tracking of fluorescence emitted by the GFP reporter system revealed that agr expression was barely detectable under static conditions, but it progressively increased during 40 h under dynamic conditions. Moreover, spatial analysis revealed that agr was expressed preferentially in cells located outside the microcolonies. Finally, the in-frame deletion of agrA, which encodes a transcriptional regulator, resulted in a decrease in initial adherence without affecting the subsequent biofilm development. PMID:18502930

  16. Molecular methods to assess Listeria monocytogenes route of contamination in a dairy processing plant.

    PubMed

    Alessandria, Valentina; Rantsiou, Kalliopi; Dolci, Paola; Cocolin, Luca

    2010-07-31

    In this study we investigated the occurrence of Listeria monocytogenes in a dairy processing plant during two sampling campaigns in 2007 and 2008. Samples represented by semifinished and finished cheeses, swabs from the equipment and brines from the salting step, were subjected to analysis by using traditional and molecular methods, represented mainly by quantitative PCR. Comparing the results obtained by the application of the two approaches used, it became evident how traditional microbiological analysis underestimated the presence of L. monocytogenes in the dairy plant. Especially samples of the brines and the equipment swabs were positive only with qPCR. For some equipment swabs it was possible to detect a load of 10(4)-10(5) cfu/cm(2), while the modified ISO method employed gave negative results both before and after the enrichment step. The evidences collected during the first sampling year, highlighting a heavy contamination of the brines and of the equipment, lead to the implementation of specific actions that decreased the contamination in these samples during the 2008 campaign. However, no reduction in the number of L. monocytogenes positive final products was observed, suggesting that a more strict control is necessary to avoid the presence of the pathogen. All the isolates of L. monocytogenes were able to attach to abiotic surfaces, and, interestingly, considering the results obtained from their molecular characterization it became evident how strains present in the brines, were genetically connected with isolates from the equipment and from the final product, suggesting a clear route of contamination of the pathogen in the dairy plant. This study underlines the necessity to use appropriate analytical tools, such as molecular methods, to fully understand the spread and persistence of L. monocytogenes in food producing companies. PMID:20193970

  17. Acid adaptation of Listeria monocytogenes can enhance survival in acidic foods and during milk fermentation.

    PubMed Central

    Gahan, C G; O'Driscoll, B; Hill, C

    1996-01-01

    We have previously shown that tolerance to severe acid stress (pH 3.5) can be induced in Listeria monocytogenes following a 1-h adaptation to mild acid (pH 5.5), a phenomenon termed the acid tolerance response (ATR) (B. O'Driscoll, C. G. M. Gahan, and C. Hill, Appl. Environ. Microbiol. 62:1693-1698, 1966). In an attempt to determine the industrial significance of the ATR, we have examined the survival of adapted and nonadapted cells in a variety of acidic foods. Acid adaptation enhanced the survival of L. monocytogenes in acidified dairy products, including cottage cheese, yogurt, and whole-fat cheddar cheese. Acid-adapted L. monocytogenes cultures also demonstrated increased survival during active milk fermentation by a lactic acid culture. Similarly, acid-adapted cells showed greatly improved survival in low-pH foods (orange juice and salad dressing) containing acids other than lactic acid. However, in foods with a marginally higher pH, such as mozzarella cheese, a commercial cottage cheese, or low-fat cheddar cheese, acid adaptation did not appear to enhance survival. We have previously isolated mutants of L. monocytogenes that are constitutively acid tolerant in the absence of an induction step (O'Driscoll et al., Appl. Environ. Microbiol. 62:1693-1698, 1996). In the present study, one such mutant, ATM56, demonstrated an increased ability to survive in low-pH foods and during milk fermentation when compared with the wild-type strain. Significant numbers of ATM56 could be recovered even after 70 days in both whole-fat and low-fat cheddar cheese. Collectively, the data suggest that ATR mechanisms, whether constitutive or induced, can greatly influence the survival of L. monocytogenes in low-pH food environments. PMID:8795199

  18. Listeria monocytogenes exploits efferocytosis to promote cell-to-cell spread.

    PubMed

    Czuczman, Mark A; Fattouh, Ramzi; van Rijn, Jorik M; Canadien, Veronica; Osborne, Suzanne; Muise, Aleixo M; Kuchroo, Vijay K; Higgins, Darren E; Brumell, John H

    2014-05-01

    Efferocytosis, the process by which dying or dead cells are removed by phagocytosis, has an important role in development, tissue homeostasis and innate immunity. Efferocytosis is mediated, in part, by receptors that bind to exofacial phosphatidylserine (PS) on cells or cellular debris after loss of plasma membrane asymmetry. Here we show that a bacterial pathogen, Listeria monocytogenes, can exploit efferocytosis to promote cell-to-cell spread during infection. These bacteria can escape the phagosome in host cells by using the pore-forming toxin listeriolysin O (LLO) and two phospholipase C enzymes. Expression of the cell surface protein ActA allows L. monocytogenes to activate host actin regulatory factors and undergo actin-based motility in the cytosol, eventually leading to formation of actin-rich protrusions at the cell surface. Here we show that protrusion formation is associated with plasma membrane damage due to LLO's pore-forming activity. LLO also promotes the release of bacteria-containing protrusions from the host cell, generating membrane-derived vesicles with exofacial PS. The PS-binding receptor TIM-4 (encoded by the Timd4 gene) contributes to efficient cell-to-cell spread by L. monocytogenes in macrophages in vitro and growth of these bacteria is impaired in Timd4(-/-) mice. Thus, L. monocytogenes promotes its dissemination in a host by exploiting efferocytosis. Our results indicate that PS-targeted therapeutics may be useful in the fight against infections by L. monocytogenes and other bacteria that use similar strategies of cell-to-cell spread during infection. PMID:24739967

  19. Microwave oven heating for inactivation of Listeria monocytogenes on frankfurters before consumption.

    PubMed

    Rodríguez-Marval, Mawill; Geornaras, Ifigenia; Kendall, Patricia A; Scanga, John A; Belk, Keith E; Sofos, John N

    2009-10-01

    Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (<-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between > 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of <-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination. PMID:19799673

  20. Essential oils of thyme and Rosemary in the control of Listeria monocytogenes in raw beef.

    PubMed

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Piccoli, Roberta Hilsdorf

    2013-12-01

    This study was developed in order to evaluate two alternatives for the control of Listeria monocytogenes in raw bovine meat pieces, both based on the use of Thymus vulgaris and Rosmarinus officinalis essential oils (EOs). The antilisterial activity of different concentrations of the EOs was tested in vitro using agar dilution and disk volatilization techniques. In addition, L. monocytogenes was inoculated in meat pieces, which were submerged in edible gelatin coatings containing 2% (v/v) EOs or submitted to the vapor of EOs (0.74 μL.cm(-3)). L. monocytogenes was quantified after one, 48 and 96 hours of storage (7 °C). In the in vitro tests, the EO of T. vulgaris presented higher activity. The two options used (edible gelatin coating and vapor activity), in spite of exercising effects with differentiated behaviors, presented antibacterial activity against L. monocytogenes inoculated in raw bovine meat (p < 0.05). Greatest antibacterial activity were obtained in the experiment that used edible coatings containing EOs, at 48 hours of storage reductions in bacterial counts between 1.09 and 1.25 Log CFU.g(-1) were obtained. In the vapor effect experiment, the EO of T. vulgaris caused the highest reduction in the population of bacteria inoculated in raw bovine meat (p < 0.05), 0.40 Log CFU.g(-1) at 96 hours of storage. This study supplied important information regarding new and promising natural alternatives, based on the concept of active packaging, for the control of L. monocytogenes in the meat industry. PMID:24688509

  1. Influence of antiorthostatic suspension on resistance to murine Listeria monocytogenes infection

    NASA Technical Reports Server (NTRS)

    Miller, E. S.; Sonnenfeld, G.

    1994-01-01

    The present study was designed to evaluate the influence of antiorthostatic suspension, a ground-based modeling system employed to simulate certain aspects of weightlessness that occur during space flight, on the capacity of mice to resist infection with the facultative intracellular bacterial pathogen Listeria monocytogenes. Female BDF1 mice were suspended by the tail in the orthostatic or antiorthostatic position and were infected with a sublethal dose of virulent L. monocytogenes at various times during the suspension. It was found that suspension did not influence the kinetics of bacterial growth in vivo if the infection was started concurrently with the suspension. However, mice that were antiorthostatically suspended 2, 4, or 7 days before the onset of infection exhibited an enhanced capacity to eliminate the challenge infection. Suspending mice on day 2 of the infection did not alter the kinetics of bacterial growth. Finally, the enhancement of resistance to the primary Listeria infection was accompanied by failure of the mice to generate long-term protective immunological memory to the challenge organism. Collectively, these results indicate that the stress of antiorthostatic suspension can influence the capacity of mice to resist bacterial infection.

  2. Acanthamoeba feature a unique backpacking strategy to trap and feed on Listeria monocytogenes and other motile bacteria.

    PubMed

    Doyscher, Dominik; Fieseler, Lars; Dons, Lone; Loessner, Martin J; Schuppler, Markus

    2013-02-01

    Despite its prominent role as an intracellular human pathogen, Listeria monocytogenes normally features a saprophytic lifestyle, and shares many environmental habitats with predatory protozoa. Earlier studies claimed that Acanthamoeba may act as environmental reservoirs for L. monocytogenes, whereas others failed to confirm this hypothesis. Our findings support the latter and provide clear evidence that L. monocytogenes is unable to persist in Acanthamoeba castellanii and A. polyphaga. Instead, external Listeria cells are rapidly immobilized on the surface of Acanthamoeba trophozoites, forming large aggregates of densely packed bacteria that we termed backpacks. While the assembly of backpacks is dependent on bacterial motility, flagellation alone is not sufficient. Electron micrographs showed that the aggregates are held together by filaments of likely amoebal origin. Time-lapse microscopy revealed that shortly after the bacteria are collected, the amoeba can change direction of movement, phagocytose the backpack and continue to repeat the process. The phenomenon was also observed with avirulent L. monocytogenes mutants, non-pathogenic Listeria, and other motile bacteria, indicating that formation of backpacks is not specific for L. monocytogenes, and independent of bacterial pathogenicity or virulence. Hence, backpacking appears to represent a unique and highly effective strategy of Acanthamoeba to trap and feed on motile bacteria. PMID:22925311

  3. Optimized, one-step, recovery-enrichment broth for enhanced detection of Listeria monocytogenes in pasteurized milk and hot dogs.

    PubMed

    Knabel, Stephen J

    2002-01-01

    A one-step, recovery-enrichment broth, optimized Penn State University (oPSU) broth, was developed to consistently detect low levels of injured and uninjured Listeria monocytogenes cells in ready-to-eat foods. The oPSU broth contains special selective agents that inhibit growth of background flora without inhibiting recovery of injured Listeria cells. After recovery in the anaerobic section of oPSU broth, Listeria cells migrated to the surface, forming a black zone. This migration separated viable from nonviable cells and the food matrix, thereby reducing inhibitors that prevent detection by molecular methods. The high Listeria-to-background ratio in the black zone resulted in consistent detection of low levels of L. monocytogenes in pasteurized foods by both cultural and molecular methods, and greatly reduced both false-negative and false-positive results. oPSU broth does not require transfer to a secondary enrichment broth, making it less laborious and less subject to external contamination than 2-step enrichment protocols. Addition of 150mM D-serine prevented germination of Bacillus spores, but not the growth of vegetative cells. Replacement of D-serine with 12 mg/L acriflavin inhibited growth of vegetative cells of Bacillus spp. without inhibiting recovery of injured Listeria cells. oPSU broth may allow consistent detection of low levels of injured and uninjured cells of L. monocytogenes in pasteurized foods containing various background microflora. PMID:11990038

  4. Host range and in vitro lysis of Listeria monocytogenes seafood isolates by bacteriophages.

    PubMed

    Arachchi, Geevika J Ganegama; Cruz, Cristina D; Dias-Wanigasekera, Beatrice M; McIntyre, Lynn; Billington, Craig; Hudson, Andrew; Flint, Steve H; Mutukumira, Anthony N

    2014-12-01

    Listeria-infecting bacteriophages (listeriaphages) can be used to control Listeria monocytogenes in the food industry. However, the sensitivity of many of seafood-borne Listeria strains to phages has not been reported. This research investigated the host ranges of three listeriaphages (FWLLm1, FWLLm3 and FWLLm5) by the formation of lytic zones and plaques on host lawns and in vitro lysis kinetics of listeriaphage FWLLm3. The study also predicted the phage titres required to lyse host cells. The host ranges of the phages were determined using 50 L. monocytogenes strains, of which 48 were isolated from the seafood industry and two from clinical cases. Of the 50 strains, 36 were tested at 25 and 30 ℃ and the remainder (14) at 15 and 25 ℃. Based on the formation of either discrete plaques or lytic zones (host kill zones), the host ranges of FWLLm1, FWLLm3 and FWLLm5 were about 87%, 81% and 87%, respectively, at 25 ℃. Six L. monocytogenes strains from the seafood environment were insensitive to all three phages, while the other seafood strains (42) were phage-sensitive. The adsorption rate constant (k value) of listeriaphage FWLLm3 was between 1.2 × 10(-9) and 1.6 × 10(-9 )ml/min across four host strains in tryptic soy broth at 25 ℃. The cultures (at 3-4 log colony-forming unit (CFU/ml) were completely lysed (<1 log CFU/ml) when cultures were infected with FWLLm3 at > 8.7 log phage-forming units (PFU/ml) for 30 min. Re-growth of phage-infected cultures was not detected after 24 h. The effective empirical phage titre was similar to the calculated titre using a kinetic model. Results indicate the potential use of the three phages for controlling L. monocytogenes strains in seafood processing environments. PMID:23908393

  5. Interleukin-22-Induced Antimicrobial Phospholipase A2 Group IIA Mediates Protective Innate Immunity of Nonhematopoietic Cells against Listeria monocytogenes.

    PubMed

    Okita, Yamato; Shiono, Takeru; Yahagi, Ayano; Hamada, Satoru; Umemura, Masayuki; Matsuzaki, Goro

    2016-02-01

    Listeria monocytogenes is a bacterial pathogen which establishes intracellular parasitism in various cells, including macrophages and nonhematopoietic cells, such as hepatocytes. It has been reported that several proinflammatory cytokines have pivotal roles in innate protection against L. monocytogenes infection. We found that a proinflammatory cytokine, interleukin 22 (IL-22), was expressed by CD3(+) CD4(+) T cells at an early stage of L. monocytogenes infection in mice. To assess the influence of IL-22 on L. monocytogenes infection in hepatocytes, cells of a human hepatocellular carcinoma line, HepG2, were treated with IL-22 before L. monocytogenes infection in vitro. Gene expression analysis of the IL-22-treated HepG2 cells identified phospholipase A2 group IIA (PLA2G2A) as an upregulated antimicrobial molecule. Addition of recombinant PLA2G2A to the HepG2 culture significantly suppressed L. monocytogenes infection. Culture supernatant of the IL-22-treated HepG2 cells contained bactericidal activity against L. monocytogenes, and the activity was abrogated by a specific PLA2G2A inhibitor, demonstrating that HepG2 cells secreted PLA2G2A, which killed extracellular L. monocytogenes. Furthermore, colocalization of PLA2G2A and L. monocytogenes was detected in the IL-22-treated infected HepG2 cells, which suggests involvement of PLA2G2A in the mechanism of intracellular killing of L. monocytogenes by HepG2 cells. These results suggest that IL-22 induced at an early stage of L. monocytogenes infection enhances innate immunity against L. monocytogenes in the liver by stimulating hepatocytes to produce an antimicrobial molecule, PLA2G2A. PMID:26644377

  6. Interleukin-22-Induced Antimicrobial Phospholipase A2 Group IIA Mediates Protective Innate Immunity of Nonhematopoietic Cells against Listeria monocytogenes

    PubMed Central

    Okita, Yamato; Shiono, Takeru; Yahagi, Ayano; Hamada, Satoru; Umemura, Masayuki

    2015-01-01

    Listeria monocytogenes is a bacterial pathogen which establishes intracellular parasitism in various cells, including macrophages and nonhematopoietic cells, such as hepatocytes. It has been reported that several proinflammatory cytokines have pivotal roles in innate protection against L. monocytogenes infection. We found that a proinflammatory cytokine, interleukin 22 (IL-22), was expressed by CD3+ CD4+ T cells at an early stage of L. monocytogenes infection in mice. To assess the influence of IL-22 on L. monocytogenes infection in hepatocytes, cells of a human hepatocellular carcinoma line, HepG2, were treated with IL-22 before L. monocytogenes infection in vitro. Gene expression analysis of the IL-22-treated HepG2 cells identified phospholipase A2 group IIA (PLA2G2A) as an upregulated antimicrobial molecule. Addition of recombinant PLA2G2A to the HepG2 culture significantly suppressed L. monocytogenes infection. Culture supernatant of the IL-22-treated HepG2 cells contained bactericidal activity against L. monocytogenes, and the activity was abrogated by a specific PLA2G2A inhibitor, demonstrating that HepG2 cells secreted PLA2G2A, which killed extracellular L. monocytogenes. Furthermore, colocalization of PLA2G2A and L. monocytogenes was detected in the IL-22-treated infected HepG2 cells, which suggests involvement of PLA2G2A in the mechanism of intracellular killing of L. monocytogenes by HepG2 cells. These results suggest that IL-22 induced at an early stage of L. monocytogenes infection enhances innate immunity against L. monocytogenes in the liver by stimulating hepatocytes to produce an antimicrobial molecule, PLA2G2A. PMID:26644377

  7. Evaluation of the Thermo Scientific SureTect Listeria monocytogenes Assay.

    PubMed

    Cloke, Jonathan; Leon-Velarde, Carlos; Larson, Nathan; Dave, Keron; Evans, Katharine; Crabtree, David; Hughes, Annette; Hopper, Craig; Simpson, Helen; Withey, Sophie; Oleksiuk, Milena; Holopainen, Jani; Wickstrand, Nina; Kauppinen, Mikko

    2014-01-01

    The Thermo Scientific SureTect Listeria monocytogenes Assay is a new real-time PCR assay for the detection of Listeria monocytogenes in food and environmental samples. This assay was validated using the AOAC Research Institute (AOAC-RI) Performance Tested Methods program in comparison to the reference method detailed in International Organization for Standardization 11290-1:1996, including Amendment 1:2004 with the following foods and food contact surfaces: smoked salmon, processed cheese, fresh bagged spinach, fresh cantaloupe, cooked prawns (chilled product), cooked sliced turkey meat (chilled product), ice cream, pork frankfurters, salami, ground raw beef meat (12% fat), plastic, and stainless steel. All matrixes were tested by Thermo Fisher Scientific, Microbiology Division, Basingstoke, UK. In addition, three matrixes (pork frankfurters, bagged lettuce, and stainless steel) were analyzed independently as part of the AOAC-RI controlled laboratory study by the University of Guelph, Canada. Using probability of detection (POD) statistical analysis, a significant difference was demonstrated between the candidate and reference methods for salami, cooked sliced turkey and ice cream in favor of the SureTect assay. For all other matrixes, no significant difference by POD was seen between the two methods during the study. Inclusivity and exclusivity testing was also conducted with 53 and 30 isolates, respectively, which demonstrated that the SureTect assay was able to detect all serotypes of L. monocytogenes. None of the exclusivity isolates analyzed were detected by the SureTect assay. Ruggedness testing was conducted to evaluate the performance of the assay with specific method deviations outside the recommended parameters open to variation, i.e., enrichment time and temperature and lysis temperature, which demonstrated that the assay gave reliable performance. Accelerated stability testing was also conducted, validating the assay shelf life. PMID:24672870

  8. Attachment of Salmonella serovars and Listeria monocytogenes to stainless steel and plastic conveyor belts.

    PubMed

    Veluz, G A; Pitchiah, S; Alvarado, C Z

    2012-08-01

    In poultry industry, cross-contamination due to processing equipment and contact surfaces is very common. This study examined the extent of bacterial attachment to 6 different types and design of conveyor belts: stainless steel-single loop, stainless steel-balance weave, polyurethane with mono-polyester fabric, acetal, polypropylene mesh top, and polypropylene. Clean conveyor belts were immersed separately in either a cocktail of Salmonella serovars (Salmonella Typhimurium and Salmonella Enteritidis) or Listeria monocytogenes strains (Scott A, Brie 1, ATCC 6744) for 1 h at room temperature. Soiled conveyor chips were dipped in poultry rinses contaminated with Salmonella or Listeria cocktail and incubated at 10°C for 48 h. The polyurethane with mono-polyester fabric conveyor belt and chip exhibited a higher (P<0.05) mean number of attached Salmonella serovars (clean: 1.6 to 3.6 cfu/cm2; soiled: 0.8 to 2.4 cfu/cm2) and L. monocytogenes (clean: 4.0 to 4.3 cfu/cm2; soiled: 0.3 to 2.1 cfu/cm2) in both clean and soiled conditions. The stainless steel conveyor belt attached a lower (P<0.05) number of Salmonella serovars (clean: 0 to 2.6 cfu/cm2; soiled: 0.4 to 1.3 cfu/cm2) and L. monocytogenes (clean: 0.4 to 2.9 cfu/cm2; soiled: 0 to 0.7 cfu/cm2) than the polymeric materials, indicating weaker adhesion properties. Plastic conveyor belts exhibited stronger bacterial adhesion compared with stainless steel. The result suggests the importance of selecting the design and finishes of conveyor belt materials that are most resistant to bacterial attachment. PMID:22802197

  9. Characterization of a spontaneous, pressure-tolerant Listeria monocytogenes Scott A ctsR deletion mutant.

    PubMed

    Joerger, Rolf D; Chen, Haiqiang; Kniel, Kalmia E

    2006-01-01

    A spontaneous, pressure-tolerant mutant of Listeria monocytogenes Scott A, designated 2-1, was isolated after several rounds of pressure treatments at 500 MPa for 10 min. Mutant 2-1 was almost 100,000-fold more resistant than the wild type to a pressure of 350 MPa, and about 100-fold more resistant to 450 MPa when pressurized in growth medium. Approximately ten times more mutant cells than wild-type cells survived a 20-min exposure to 55 degrees C, and the mutant appears also to be more resistant to 0.2% H(2)O(2), although the difference could not be confirmed statistically. About 10 times more wild-type than mutant cells survived exposure to growth medium adjusted to pH 2.5 with HCl. The mutant is about 16-fold more sensitive to nisin than the wild type. Mutant 2-1 is non-motile, produces hemolytic activity, is able to grow in fetal calf serum as well as the wild type, and exhibits a lower level of invasiveness of human ileocecal adenocarcinoma cells than the wild type. The mutation in strain 2-1 is a deletion in the ctsR gene that results in the predicted production of truncated CtsR of 20 amino acids compared to a CtsR of 152 amino acids in the wild type. With the exception of its response to pH and possibly also to H(2)O(2), mutant 2-1 shares most of the phenotypes of the previously described ctsR mutant, AK01. The isolation of another spontaneous, pressure-resistant ctsR mutant confirms the central role of this regulatory gene in pressure tolerance of L. monocytogenes. Although such mutants appear of lesser concern to human health then the wild type, current detection methods for Listeria monocytogenes are not able to distinguish between these mutants and wildtype cells. PMID:16761946

  10. Role of the twin-arginine translocase (tat) system in iron uptake in Listeria monocytogenes.

    PubMed

    Tiwari, Kiran B; Birlingmair, Jacob; Wilkinson, Brian J; Jayaswal, Radheshyam K

    2015-02-01

    The twin-arginine translocase (Tat) complex is a unique system that translocates folded proteins across the cytoplasmic membrane. In this study, the Tat transporter system in Listeria monocytogenes was characterized to determine the role of Tat in the iron uptake pathway. A putative tatAC operon, containing conserved Fur-binding sequences in the promoter region, has been predicted to encode Tat-translocase components. Another operon, fepCAB, with a putative Fur-binding sequence in the promoter, close to TatAC, was identified in the complementary strands of L. monocytogenes. Electrophoretic mobility shift assay showed that the listerial Fur-repressor binds to the promoter of the tatAC operon, suggesting that tat is under Fur regulation. Using a heterologous system in a reporter assay, FepB was translocated across the membrane. Mutations in tatC and fepB were constructed to determine the roles of Tat and FepB, respectively. In a whole-cell ferric reductase assay, the fepB and tatC mutants were found to have reduced levels of ferric reductase activities compared with those of the isogenic parent strain. Although ferric reductase activity has been demonstrated in Listeria, a conventional ferric reductase encoding sequence does not appear to be present in its genome. Hence, we propose that fepB encodes a ferric reductase enzyme, which is translocated by the Tat-translocase system onto the bacterial cell surface, and plays an important role in the reductive iron uptake process in L. monocytogenes. PMID:25416690

  11. Modeling the growth of Listeria monocytogenes on the surface of smear- or mold-ripened cheese

    PubMed Central

    Schvartzman, M. Sol; Gonzalez-Barron, Ursula; Butler, Francis; Jordan, Kieran

    2014-01-01

    Surface-ripened cheeses are matured by means of manual or mechanical technologies posing a risk of cross-contamination, if any cheeses are contaminated with Listeria monocytogenes. In predictive microbiology, primary models are used to describe microbial responses, such as growth rate over time and secondary models explain how those responses change with environmental factors. In this way, primary models were used to assess the growth rate of L. monocytogenes during ripening of the cheeses and the secondary models to test how much the growth rate was affected by either the pH and/or the water activity (aw) of the cheeses. The two models combined can be used to predict outcomes. The purpose of these experiments was to test three primary (the modified Gompertz equation, the Baranyi and Roberts model, and the Logistic model) and three secondary (the Cardinal model, the Ratowski model, and the Presser model) mathematical models in order to define which combination of models would best predict the growth of L. monocytogenes on the surface of artificially contaminated surface-ripened cheeses. Growth on the surface of the cheese was assessed and modeled. The primary models were firstly fitted to the data and the effects of pH and aw on the growth rate (μmax) were incorporated and assessed one by one with the secondary models. The Logistic primary model by itself did not show a better fit of the data among the other primary models tested, but the inclusion of the Cardinal secondary model improved the final fit. The aw was not related to the growth of Listeria. This study suggests that surface-ripened cheese should be separately regulated within EU microbiological food legislation and results expressed as counts per surface area rather than per gram. PMID:25072033

  12. Detection, quantification and vitality of Listeria monocytogenes in food as determined by quantitative PCR.

    PubMed

    Rantsiou, Kalliopi; Alessandria, Valentina; Urso, Rosalinda; Dolci, Paola; Cocolin, Luca

    2008-01-15

    In this paper we describe the development of a quantitative PCR (qPCR) technique to detect, quantify and determine the vitality of Listeria monocytogenes in foods. The method was based on the amplification of the intergenic region spacer (IGS) between the 16S and 23S rRNA genes. A panel of more than 100 strains of Listeria spp. and non-Listeria was used in order to verify the specificity of the primers and Taqman probe and amplification signals were obtained only when L. monocytogenes DNA and RNA were loaded in the qPCR mix. Standard curves were constructed in several food matrices (milk, meat, soft cheese, fermented sausage, cured ham and ready-to-eat salad). The quantification limit was of 10(3)-10(4) cfu/g or ml, while for the determination of vitality it was 10(4)-10(5) cfu/g or ml. After an overnight enrichment in BHI at 37 degrees C also 10 cfu/g or ml could be detected in all the matrices used in this study. When we applied the protocol to food samples collected from the market or from small food processing plants, on a total number of 66 samples, 4 fresh cheeses from raw milk gave positive results prior to the overnight incubation, while 9 samples, of which only one represented by fresh meat and the others by cheeses from raw milk, were positive after the enrichment. Out of the 4 positive samples, only one could be quantified and it was determined to contain 4x10(3) cfu/g. PMID:18061295

  13. Development and validation of qualitative SYBR®Green real-time PCR for detection and discrimination of Listeria spp. and Listeria monocytogenes.

    PubMed

    Barbau-Piednoir, Elodie; Botteldoorn, Nadine; Yde, Marc; Mahillon, Jacques; Roosens, Nancy H

    2013-05-01

    A combination of four qualitative SYBR®Green qPCR screening assays targeting two levels of discrimination: Listeria genus (except Listeria grayi) and Listeria monocytogenes, is presented. These assays have been developed to be run simultaneously using the same polymerase chain reaction (PCR) programme. The paper also proposes a new validation procedure to specifically validate qPCR assays applied to food microbiology according to two guidelines: the ISO 22118 norm and the "Definition of minimum performance requirements for analytical methods of GMO testing". The developed assays target the iap, prs and hlyA genes that belong to or neighbour the virulence cluster of Listeria spp. The selected primers were designed to amplify short fragments (60 to 103 bp) in order to obtain optimal PCR efficiency (between 97 and 107 % efficiency). The limit of detection of the SYBR®Green qPCR assays is two to five copies of target genes per qPCR reaction. These assays are highly accurate (98.08 and 100 % accuracy for the Listeria spp. and L. monocytogenes assays, respectively). PMID:23086339

  14. Fate of Viable but Non-culturable Listeria monocytogenes in Pig Manure Microcosms.

    PubMed

    Desneux, Jérémy; Biscuit, Audrey; Picard, Sylvie; Pourcher, Anne-Marie

    2016-01-01

    The fate of two strains of Listeria monocytogenes and their ability to become viable but non-culturable (VBNC) was investigated in microcosms containing piggery effluents (two raw manures and two biologically treated manures) stored for 2 months at 8 and 20°C. Levels of L. monocytogenes were estimated using the culture method, qPCR, and propidium monoazide treatment combined with qPCR (qPCRPMA). The chemical composition and the microbial community structure of the manures were also analyzed. The strains showed similar decline rates and persisted up to 63 days. At day zero, the percentage of VBNC cells among viable cells was higher in raw manures (81.5-94.8%) than in treated manures (67.8-79.2%). The changes in their proportion over time depended on the temperature and on the type of effluent: the biggest increase was observed in treated manures at 20°C and the smallest increase in raw manures at 8°C. The chemical parameters had no influence on the behavior of the strains, but decrease of the persistence of viable cells was associated with an increase in the microbial richness of the manures. This study demonstrated that storing manure altered the culturability of L. monocytogenes, which rapidly entered the VBNC state, and underlines the importance of including VBNC cells when estimating the persistence of the pathogens in farm effluents. PMID:26973623

  15. Combined effect of ultrasound and essential oils to reduce Listeria monocytogenes on fresh produce.

    PubMed

    Özcan, Gülçin; Demirel Zorba, Nükhet Nilüfer

    2016-06-01

    Salads prepared from contaminated fresh produce have a high risk of causing food-borne illnesses. Essential oils obtained from plants have antimicrobial activity and may provide a natural approach to reduce the pathogens on fresh produce. Additionally, ultrasound treatments have been shown to reduce the microbial counts on different foods. The objective of this study was to investigate the antimicrobial activities of cinnamon and lemon essential oils in vitro and in food applications. Mixtures of lettuce, parsley and dill were inoculated with Listeria monocytogenes and then dip-treated for 5 min in one of the following treatments: sterile tap water, chlorinated water, 1% lemon essential oil, 2% cinnamon essential oil or 2% cinnamon essential oil + ultrasound. The samples were stored at 4 ℃ and collected at d 0, 1, 3, 5, 7 and 9 post inoculation. The 1% lemon (4 log) and 2% cinnamon (2 log) essential oil washes provided partial inhibition against L. monocytogenes by d 1. The combined application of 2% cinnamon oil and ultrasound resulted in only 0.85 log inhibition by d 1; however, the number of L. monocytogenes increased during storage and became nearly equal to the control at d 9. Therefore, different combinations of essential oils with other antimicrobials or novel technologies are required. PMID:26377335

  16. Effect of anolyte on background microflora, Salmonella, and Listeria monocytogenes on catfish fillets.

    PubMed

    Rajkowski, Kathleen T; Sommers, Christopher H

    2012-04-01

    Near-neutral electrolyzed water (anolyte), having a pH of 6.0 to 6.5 ± 0.02, oxidation reduction potential of greater than 700 mV, and a residual chlorine level of 10 to 200 ppm, was reported to have a potential use to decontaminate food surfaces. An electrolyzing cell was developed that is capable of producing neutral electrolyzed water containing a chlorine level of greater than 700 ppm in the form of hypochlorous acid (anolyte). Anolyte with a chlorine level of 300 ppm was used to determine its effect on Salmonella and Listeria monocytogenes cells after a 3-min contact. Transmission electron micrograph results showed disruption of the outer cellular membrane for both bacteria. The anolyte (300 ppm) was used as a washing solution to decontaminate catfish fillets inoculated with either Salmonella or L. monocytogenes. After a 3-min contact time with the anolyte, there was a 1-log reduction for Salmonella, and after 8 days of refrigerated storage (4°C), this bacterial reduction was maintained. There was no reduction of L. monocytogenes on the catfish fillet surfaces. The anolyte was an effective wash solution for Salmonella reduction on the catfish fillet surfaces. PMID:22488069

  17. Proteomic analysis of cross protection provided between cold and osmotic stress in Listeria monocytogenes.

    PubMed

    Pittman, Joseph R; Buntyn, Joe O; Posadas, Gabriel; Nanduri, Bindu; Pendarvis, Ken; Donaldson, Janet R

    2014-04-01

    Listeria monocytogenes is a Gram-positive, foodborne pathogen responsible for approximately 28% of all food-related deaths each year in the United States. L. monocytogenes infections are linked to the consumption of minimally processed ready-to-eat (RTE) products such as cheese, deli meats, and cold-smoked finfish products. L. monocytogenes is resistant to stresses commonly encountered in the food-processing environment, including low pH, high salinity, oxygen content, and various temperatures. The purpose of this study was to determine if cells habituated at low temperatures would result in cross-protective effects against osmotic stress. We found that cells exposed to refrigerated temperatures prior to a mild salt stress treatment had increased survival in NaCl concentrations of 3%. Additionally, the longer the cells were pre-exposed to cold temperatures, the greater the increase in survival in 3% NaCl. A proteomics analysis was performed in triplicate in order to elucidate mechanisms involved in cold-stress induced cross protection against osmotic stress. Proteins involved in maintenance of the cell wall and cellular processes, such as penicillin binding proteins and osmolyte transporters, and processes involving amino acid metabolism, such as osmolyte synthesis, transport, and lipid biosynthesis, had the greatest increase in expression when cells were exposed to cold temperatures prior to salt. By gaining a better understanding of how this pathogen adapts physiologically to various environmental conditions, improvements can be made in detection and mitigation strategies. PMID:24564473

  18. Food safety objectives for Listeria monocytogenes in Spanish food sampled in cafeterias and restaurants.

    PubMed

    Doménech, E; Amorós, J A; Escriche, I

    2011-09-01

    To gain more insight into the context of food safety management by public administrations, food safety objectives must be studied. The Valencian administration quantified the prevalence of Listeria monocytogenes in cafeterias and restaurants in this region of Spain between 2002 and 2010. The results obtained from this survey are presented here for 2,262 samples of fish, salad, egg, cold meat, and mayonnaise dishes. Microbiological criteria defined for L. monocytogenes were used to differentiate acceptable and unacceptable samples; more than 99.9% of the samples were acceptable. These findings indicate that established food safety objectives are achievable, consumer health at the time of consumption can be safeguarded, and food safety management systems such as hazard analysis critical control point plans or good manufacturing practices implemented in food establishments are effective. Monitoring of foods and food safety is an important task that must continue to reduce the current L. monocytogenes prevalence of 0.1% in restaurant or cafeteria dishes, which could adversely affect consumer health. PMID:21902930

  19. Elimination of Listeria monocytogenes in sausage meat by combination treatment: Radiation and radiation-resistant bacteriocins

    NASA Astrophysics Data System (ADS)

    Turgis, Mélanie; Stotz, Viviane; Dupont, Claude; Salmieri, Stéphane; Khan, Ruhul A.; Lacroix, Monique

    2012-08-01

    Two new bacteria were isolated from human feces and were designated MT 104 and MT 162. They were able to produce bacteriocins that are active against five strains of Listeria monocytogenes. Bacteriocins produced by these isolated strains had 100% and 82.35% residual activity when they were treated by gamma radiation at doses of 4 and 40 kGy, respectively. A reduction of 1.0, 1.5 and 3 log CFU/g of L. monocytogenes was observed in sausage meat when treated with bacteriocins from MT 104, MT 162, and nisin, respectively. For synergic effect, the D10 value in presence of the bacteriocins produced by MT 104 showed a 1.08 fold increased relative sensitivity of L. monocytogenes as compared to control after 5 days. The highest synergic effect was observed in presence of nisin which led to 1.61 fold increased relative sensitivity. Combined treatments with nisin and γ-irradiation showed a synergic antimicrobial effect in meat after 24 h and 5 days of storage. A synergic effect was observed only after 5 days at 4 °C for the bacteriocin from MT 104, as compared to the bacteriocin produced by MT 162 that had only an additive antimicrobial effect in all conditions.

  20. Influence of immunomodulation on the development of Listeria monocytogenes infection in aged guinea pigs.

    PubMed

    Pang, Hoan-Jen E; Lo, Chih-Yu; Matthews, Karl R

    2007-04-01

    We investigated the impact of immunomodulation on the development of listeriosis within an aged population of guinea pigs after an intragastric challenge with Listeria monocytogenes. Supplementation with vitamin E for 35 days significantly increased the level of cytotoxic T cells (CD8(+)), while treatment with cyclosporin A resulted in a 25% decrease of CD8(+) T cells. In the animals receiving the low dose (10(2) CFU) of L. monocytogenes, 50% of the control-group animals became infected. Only 22% of animals receiving the orthomolecular dose of vitamin E became infected, whereas animals that were immunosuppressed had an infection rate of 89%. In the immunosuppressed group three animals (16%) developed listerial infection with a quantifiable bacterial level of 0.3-3 log CFU g(-1) of organ in the spleen and liver. In the high-dose study, the population of L. monocytogenes was consistently 1 log CFU g(-1) lower in the spleen or liver of the vitamin E-supplemented group, compared with the control and cyclosporin A-treated animals. At day 4, a significant increase in the levels of CD8(+) during listerial infection occurred in vitamin E-supplemented animals, suggesting an increased ability to produce CD8(+) T cells. The results suggest that immunomodulation of the host can influence listerial infection within an aged population of guinea pigs. PMID:17378902

  1. Internalin must be on the bacterial surface to mediate entry of Listeria monocytogenes into epithelial cells.

    PubMed

    Lebrun, M; Mengaud, J; Ohayon, H; Nato, F; Cossart, P

    1996-08-01

    Entry of Listeria monocytogenes into cultured epithelial cells requires production of internalin, a protein with features characteristic of some Gram-positive bacterial surface proteins, in particular an LPXTG motif preceding a hydrophobic sequence and a few basic residues at its C-terminal end. By immunofluorescence and immunogold labelling, we show that in wild-type L. monocytogenes, internalin is present on the cell surface and has a polarized distribution similar to that of ActA, another surface protein of L. monocytogenes involved in actin assembly. Through a genetic analysis, we establish that the C-terminal region of internalin is necessary for cell-surface association, and that although internalin is partially released in the culture medium, its location on the bacterial surface is required to promote entry. Finally, using a 'domain-swapping' strategy-replacement of the cell wall anchor of IniA by the membrane anchor of ActA- we show that the reduced ability to adhere and enter cells of strains expressing IniA-ActA correlates with a lower amount of surface-exposed internalin. Taken together, these results suggest that internalin exposed on the bacterial surface mediates direct contact between the bacterium and the host cell. PMID:8866480

  2. Effects of several factors on the heat-shock-induced thermotolerance of Listeria monocytogenes.

    PubMed Central

    Pagán, R; Condón, S; Sala, F J

    1997-01-01

    The influence of the temperature at which Listeria monocytogenes had been grown (4 or 37 degrees C) on the response to heat shocks of different durations at different temperatures was investigated. For cells grown at 4 degrees C, the effect of storage, prior to and after heat shock, on the induced thermotolerance was also studied. Death kinetics of heat-shocked cells is also discussed. For L. monocytogenes grown at 37 degrees C, the greatest response to heat shock was a fourfold increase in thermotolerance. For L. monocytogenes grown at 4 degrees C, the greatest response to heat shock was a sevenfold increase in thermotolerance. The only survival curves of cells to have shoulders were those for cells that had been heat shocked. A 3% concentration of sodium chloride added to the recovery medium made these shoulders disappear and decreased decimal reduction times. The percentage of cells for which thermotolerance increased after a heat shock was smaller the milder the heat shock and the longer the prior storage. PMID:9251209

  3. Genetic diversity, virulence potential and antimicrobial susceptibility of Listeria monocytogenes recovered from different sources in India.

    PubMed

    Negi, Mamta; Vergis, Jess; Vijay, Deepthi; Dhaka, Pankaj; Malik, S V S; Kumar, Ashok; Poharkar, Krupali V; Doijad, Swapnil P; Barbuddhe, Sukhadeo B; Ramteke, Pramod W; Rawool, Deepak B

    2015-12-01

    Listeria monocytogenes isolates (n = 36) recovered from human and animal clinical cases and foods from different geographical regions of India were characterized using multiplex PCR-based serotyping, pulsed field gel electrophoresis (PFGE), in vitro and in vivo pathogenicity tests and antibiogram profiling. Multiplex PCR-based serotyping distributed L. monocytogenes isolates into 3 serogroups, of which 91.67% belonged to 4b, 4d, 4e serogroup, followed by 5.56% to 1/2a, 3a and 2.78% to 1/2b, 3b serogroups. PFGE analysis using ApaI and AscI restriction enzymes revealed 17 pulsotypes among 36 L. monocytogenes isolates with 6 major clusters having similar fingerprint profile within their cluster and 11 unique fingerprint profiles. Interestingly, PFGE analysis inferred that foods of animal origin could be a significant source of infection for spread of listeriosis among human populations. Furthermore, on comparison of in vitro and in vivo pathogenicity tests, an overall good correlation was observed between hemolytic titer assay and chick embryo inoculation test as most of the isolates with a hemolytic titer of ≥ 16 were found to be lethal to chick embryo. All the isolates were found to be susceptible to tested antimicrobials except for one animal isolate which showed resistance towards co-trimoxazole. PMID:26476275

  4. Environmental and biological factors influencing the UV-C resistance of Listeria monocytogenes.

    PubMed

    Gayán, E; Serrano, M J; Pagán, R; Álvarez, I; Condón, S

    2015-04-01

    In this investigation, the effect of microbiological factors (strain, growth phase, exposition to sublethal stresses, and photorepair ability), treatment medium characteristics (pH, water activity, and absorption coefficient), and processing parameters (dose and temperature) on the UV resistance of Listeria monocytogenes was studied. The dose to inactivate 99.99% of the initial population of the five strains tested ranged from 21.84 J/mL (STCC 5672) to 14.66 J/mL (STCC 4031). The UV inactivation of the most resistant strain did not change in different growth phases and after exposure to sublethal heat, acid, basic, and oxidative shocks. The pH and water activity of the treatment medium did not affect the UV resistance of L. monocytogenes, whereas the inactivation rate decreased exponentially with the absorption coefficient. The lethal effect of UV radiation increased synergistically with temperature between 50 and 60 °C (UV-H treatment). A UV-H treatment of 27.10 J/mL at 55 °C reached 2.99 and 3.69 Log10 inactivation cycles of L. monocytogenes in orange juice and vegetable broth, and more than 5 Log10 cycles in apple juice and chicken broth. This synergistic effect opens the possibility to design UV combined processes for the pasteurization of liquid foods with high absorptivity. PMID:25475293

  5. Listeriolysin S, a Novel Peptide Haemolysin Associated with a Subset of Lineage I Listeria monocytogenes

    PubMed Central

    Cotter, Paul D.; Draper, Lorraine A.; Lawton, Elaine M.; Daly, Karen M.; Groeger, David S.; Casey, Pat G.; Ross, R. Paul; Hill, Colin

    2008-01-01

    Streptolysin S (SLS) is a bacteriocin-like haemolytic and cytotoxic virulence factor that plays a key role in the virulence of Group A Streptococcus (GAS), the causative agent of pharyngitis, impetigo, necrotizing fasciitis and streptococcal toxic shock syndrome. Although it has long been thought that SLS and related peptides are produced by GAS and related streptococci only, there is evidence to suggest that a number of the most notorious Gram-positive pathogenic bacteria, including Listeria monocytogenes, Clostridium botulinum and Staphylococcus aureus, produce related peptides. The distribution of the L. monocytogenes cluster is particularly noteworthy in that it is found exclusively among a subset of lineage I strains; i.e., those responsible for the majority of outbreaks of listeriosis. Expression of these genes results in the production of a haemolytic and cytotoxic factor, designated Listeriolysin S, which contributes to virulence of the pathogen as assessed by murine- and human polymorphonuclear neutrophil–based studies. Thus, in the process of establishing the existence of an extended family of SLS-like modified virulence peptides (MVPs), the genetic basis for the enhanced virulence of a proportion of lineage I L. monocytogenes may have been revealed. PMID:18787690

  6. Deciphering Host Genotype-Specific Impacts on the Metabolic Fingerprint of Listeria monocytogenes by FTIR Spectroscopy

    PubMed Central

    Grunert, Tom; Monahan, Avril; Lassnig, Caroline; Vogl, Claus; Müller, Mathias; Ehling-Schulz, Monika

    2014-01-01

    Bacterial pathogens are known for their wide range of strategies to specifically adapt to host environments and infection sites. An in-depth understanding of these adaptation mechanisms is crucial for the development of effective therapeutics and new prevention measures. In this study, we assessed the suitability of Fourier Transform Infrared (FTIR) spectroscopy for monitoring metabolic adaptations of the bacterial pathogen Listeria monocytogenes to specific host genotypes and for exploring the potential of FTIR spectroscopy to gain novel insights into the host-pathogen interaction. Three different mouse genotypes, showing different susceptibility to L. monocytogenes infections, were challenged with L. monocytogenes and re-isolated bacteria were subjected to FTIR spectroscopy. The bacteria from mice with different survival characteristics showed distinct IR spectral patterns, reflecting specific changes in the backbone conformation and the hydrogen-bonding pattern of the protein secondary structure in the bacterial cell. Coupling FTIR spectroscopy with chemometrics allowed us to link bacterial metabolic fingerprints with host infection susceptibility and to decipher longtime memory effects of the host on the bacteria. After prolonged cultivation of host-passaged bacteria under standard laboratory conditions, the host's imprint on bacterial metabolism vanished, which suggests a revertible metabolic adaptation of bacteria to host environment and loss of host environment triggered memory effects over time. In summary, our work demonstrates the potential and power of FTIR spectroscopy to be used as a fast, simple and highly discriminatory tool to investigate the mechanism of bacterial host adaptation on a macromolar and metabolic level. PMID:25541972

  7. Exendin-4 improves resistance to Listeria monocytogenes infection in diabetic db/db mice

    PubMed Central

    Liu, Hsien Yueh; Chung, Chih-Yao; Yang, Wen-Chin; Liang, Chih-Lung; Wang, Chi-Young; Chang, Chih-Yu

    2012-01-01

    The incidence of diabetes mellitus is increasing among companion animals. This disease has similar characteristics in both humans and animals. Diabetes is frequently identified as an independent risk factor for infections associated with increased mortality. In the present study, homozygous diabetic (db/db) mice were infected with Listeria (L.) monocytogenes and then treated with the anti-diabetic drug exendin-4, a glucagon-like peptide 1 analogue. In aged db/db mice, decreased CD11b+ macrophage populations with higher lipid content and lower phagocytic activity were observed. Exendin-4 lowered high lipid levels and enhanced phagocytosis in macrophages from db/db mice infected with L. monocytogenes. Exendin-4 also ameliorated obesity and hyperglycemia, and improved ex vivo bacteria clearance by macrophages in the animals. Liver histology examined during L. monocytogenes infection indicated that abscess formation was much milder in exendin-4-treated db/db mice than in the control animals. Moreover, mechanistic studies demonstrated that expression of ATP binding cassette transporter 1, a sterol transporter, was higher in macrophages isolated from the exendin-4-treated db/db mice. Overall, our results suggest that exendin-4 decreases the risk of infection in diabetic animals by modifying the interaction between intracellular lipids and phagocytic macrophages. PMID:23000581

  8. Modelling inactivation of Listeria monocytogenes by pulsed electric fields in media of different pH.

    PubMed

    Gómez, N; García, D; Alvarez, I; Condón, S; Raso, J

    2005-08-25

    A study of the effect of square-wave pulsed electric fields (PEF) on the inactivation of Listeria monocytogenes in McIlvaine buffer of different pH (3.5-7.0) was conducted. L. monocytoges was more PEF sensitive at higher electric field strengths (E) and in media of low pH. A treatment at 28 kV/cm for 400 mus that inactivated 1.5, 2.3 and 3.0 Log10 cycles at pH 7.0, 6.5 and 5.0 respectively destroyed almost 6.0 Log10 cycles at pH 3.5. The general shape of survival curves of L. monocytogenes PEF treated at different pH was convex/concave upwards. A mathematical model based on the Weibull distribution accurately described these survival curves. At each pH, the shape parameter (n value) did not depend on E. The relationship between n value of the Weibull model and the pH of the treatment medium was described by the Gompertz equation. A multiple linear regression model using three predictor variables (E, E2, pH2) related the Log10 of the scale paramenter (b value) of the Weibull model with E and pH of the treatment medium. A tertiary model developed using McIlvaine buffer as treatment medium predicted satisfactorily the inactivation of L. monocytogenes in apple juice. PMID:16083822

  9. Previous Homologous and Heterologous Stress Exposure Induces Tolerance Development to Pulsed Light in Listeria monocytogenes.

    PubMed

    Heinrich, Victoria; Zunabovic, Marija; Petschnig, Alice; Müller, Horst; Lassenberger, Andrea; Reimhult, Erik; Kneifel, Wolfgang

    2016-01-01

    As one of the emerging non-thermal technologies, pulsed light (PL) facilitates rapid, mild and residue-free microbial surface decontamination of food and food contact materials. While notable progress has been made in the characterization of the inactivation potential of PL, experimental data available on the tolerance development to the same (homologous) stress or to different (heterologous) stresses commonly applied in food manufacturing (e.g., acid, heat, salt) is rather controversial. The findings of the present study clearly indicate that both the homologous tolerance development against PL as well as the heterologous tolerance development from heat to PL can be triggered in Listeria monocytogenes. Further, conducted kinetic analysis confirmed that the conventionally applied log-linear model is not well suited to describe the inactivation of L. monocytogenes, when exposed to PL. Instead, the Weibull model as well as the log-linear + tail model were identified as suitable models. Transmission electron microscopic (TEM) approaches allow suggestions on the morphological alterations in L. monocytogenes cells after being subjected to PL. PMID:27092137

  10. CXCR3 blockade protects against Listeria monocytogenes infection-induced fetal wastage.

    PubMed

    Chaturvedi, Vandana; Ertelt, James M; Jiang, Tony T; Kinder, Jeremy M; Xin, Lijun; Owens, Kathryn J; Jones, Helen N; Way, Sing Sing

    2015-04-01

    Mammalian pregnancy requires protection against immunological rejection of the developing fetus bearing discordant paternal antigens. Immune evasion in this developmental context entails silenced expression of chemoattractant proteins (chemokines), thereby preventing harmful immune cells from penetrating the maternal-fetal interface. Here, we demonstrate that fetal wastage triggered by prenatal Listeria monocytogenes infection is driven by placental recruitment of CXCL9-producing inflammatory neutrophils and macrophages that promote infiltration of fetal-specific T cells into the decidua. Maternal CD8+ T cells with fetal specificity upregulated expression of the chemokine receptor CXCR3 and, together with neutrophils and macrophages, were essential for L. monocytogenes-induced fetal resorption. Conversely, decidual accumulation of maternal T cells with fetal specificity and fetal wastage were extinguished by CXCR3 blockade or in CXCR3-deficient mice. Remarkably, protection against fetal wastage and in utero L. monocytogenes invasion was maintained even when CXCR3 neutralization was initiated after infection, and this protective effect extended to fetal resorption triggered by partial ablation of immune-suppressive maternal Tregs, which expand during pregnancy to sustain fetal tolerance. Together, our results indicate that functionally overriding chemokine silencing at the maternal-fetal interface promotes the pathogenesis of prenatal infection and suggest that therapeutically reinforcing this pathway represents a universal approach for mitigating immune-mediated pregnancy complications. PMID:25751061

  11. Listeria monocytogenes Traffics from Maternal Organs to the Placenta and Back

    PubMed Central

    Bakardjiev, Anna I; Theriot, Julie A; Portnoy, Daniel A

    2006-01-01

    Infection with Listeria monocytogenes is a significant health problem during pregnancy. This study evaluates the role of trafficking between maternal organs and placenta in a pregnant guinea pig model of listeriosis. After intravenous inoculation of guinea pigs, the initial ratio of bacteria in maternal organs to placenta was 103–104:1. Rapid increase of bacteria in the placenta changed the ratio to 1:1 after 24 h. Utilizing two wild-type strains, differentially marked by their susceptibility to erythromycin, we found that only a single bacterium was necessary to cause placental infection, and that L. monocytogenes trafficked from maternal organs to the placenta in small numbers. Surprisingly, bacteria trafficked in large numbers from the placenta to maternal organs. Bacterial growth, clearance, and transport between organs were simulated with a mathematical model showing that the rate of bacterial clearance relative to the rate of bacterial replication in the placenta was sufficient to explain the difference in the course of listeriosis in pregnant versus nonpregnant animals. These results provide the basis for a new model where the placenta is relatively protected from infection. Once colonized, the placenta becomes a nidus of infection resulting in massive reseeding of maternal organs, where L. monocytogenes cannot be cleared until trafficking is interrupted by expulsion of the infected placental tissues. PMID:16846254

  12. Ultrasonic cleaning of conveyor belt materials using Listeria monocytogenes as a model organism.

    PubMed

    Tolvanén, Riina; Lunden, Janne; Korkeala, Hannu; Wirtanen, Gun

    2007-03-01

    Persistent Listeria monocytogenes contamination of food industry equipment is a difficult problem to solve. Ultrasonic cleaning offers new possibilities for cleaning conveyors and other equipment that are not easy to clean. Ultrasonic cleaning was tested on three conveyor belt materials: polypropylene, acetal, and stainless steel (cold-rolled, AISI 304). Cleaning efficiency was tested at two temperatures (30 and 45 degrees C) and two cleaning times (30 and 60 s) with two cleaning detergents (KOH, and NaOH combined with KOH). Conveyor belt materials were soiled with milk-based soil and L. monocytogenes strains V1, V3, and B9, and then incubated for 72 h to attach bacteria to surfaces. Ultrasonic cleaning treatments reduced L. monocytogenes counts on stainless steel 4.61 to 5.90 log units; on acetal, 3.37 to 5.55 log units; and on polypropylene, 2.31 to 4.40 log units. The logarithmic reduction differences were statistically analyzed by analysis of variance using Statistical Package for the Social Sciences software. The logarithmic reduction was significantly greater in stainless steel than in plastic materials (P < 0.001 for polypropylene, P = 0.023 for acetal). Higher temperatures enhanced the cleaning efficiency in tested materials. No significant difference occurred between cleaning times. The logarithmic reduction was significantly higher (P = 0.013) in cleaning treatments with potassium hydroxide detergent. In this study, ultrasonic cleaning was efficient for cleaning conveyor belt materials. PMID:17388072

  13. Pregnancy - associated human listeriosis: Virulence and genotypic analysis of Listeria monocytogenes from clinical samples.

    PubMed

    Soni, Dharmendra Kumar; Singh, Durg Vijai; Dubey, Suresh Kumar

    2015-09-01

    Listeria monocytogenes, a life-threatening pathogen, poses severe risk during pregnancy, may cause abortion, fetal death or neonatal morbidity in terms of septicemia and meningitis. The present study aimed at characterizing L. monocytogenes isolated from pregnant women based on serotyping, antibiotic susceptibility, virulence genes, in vivo pathogenicity test and ERIC- and REP-PCR fingerprint analyses. The results revealed that out of 3700 human clinical samples, a total of 30 (0.81%) isolates [12 (0.80%) from placental bit (1500), 18 (0.81%) from vaginal swab (2200)] were positive for L. monocytogenes. All the isolates belonged to serogroup 4b, and were + ve for virulence genes tested i.e. inlA, inlC, inlJ, plcA, prfA, actA, hlyA, and iap. Based on the mice inoculation tests, 20 isolates showed 100% and 4 isolates 60% relative virulence while 6 isolates were non-pathogenic. Moreover, 2 and 10 isolates were resistant to ciprofloxacin and cefoxitin, respectively, while the rest susceptible to other antibiotics used in this study. ERIC- and REP-PCR collectively depicted that the isolates from placental bit and vaginal swab had distinct PCR fingerprints except a few isolates with identical patterns. This study demonstrates prevalence of pathogenic strains mostly resistant to cefoxitin and/or ciprofloxacin. The results indicate the importance of isolating and characterizing the pathogen from human clinical samples as the pre-requisite for accurate epidemiological investigations. PMID:26231373

  14. Inhibition of Listeria monocytogenes in minas frescal cheese by free and nanovesicle-encapsulated nisin.

    PubMed

    Malheiros, Patrícia da Silva; Daroit, Daniel Joner; Brandelli, Adriano

    2012-10-01

    The effectiveness of free and nanovesicle-encapsulated nisin to control Listeria monocytogenes in Minas Frescal cheese was investigated. Commercial nisin was encapsulated into liposomes of partially purified soy lecithin. Free (0.1 mg/mL and 0.25 mg/mL) and nanovesicle-encapsulated nisin (0.25 mg/mL) were applied onto the surface of cheese samples, and L. monocytogenes was inoculated before incubation at 6-8°C for 28 days. A bactericidal effect was observed with 0.25 mg/mL free nisin; a bacteriostatic effect was observed for liposome-encapsulated nisin and 0.1 mg/mL free nisin. Free nisin was more efficient than nisin-loaded liposomes in controlling L. monocytogenes. Possible reasons for this behavior, and also the significance of nisin to soft cheeses are discussed. Nisin acted as a suitable barrier within hurdle technology, potentially extending the shelf-life and safety of fresh cheeses. PMID:24031971

  15. Inhibition of Listeria monocytogenes in minas frescal cheese by free and nanovesicle-encapsulated nisin

    PubMed Central

    Malheiros, Patrícia da Silva; Daroit, Daniel Joner; Brandelli, Adriano

    2012-01-01

    The effectiveness of free and nanovesicle-encapsulated nisin to control Listeria monocytogenes in Minas Frescal cheese was investigated. Commercial nisin was encapsulated into liposomes of partially purified soy lecithin. Free (0.1 mg/mL and 0.25 mg/mL) and nanovesicle-encapsulated nisin (0.25 mg/mL) were applied onto the surface of cheese samples, and L. monocytogenes was inoculated before incubation at 6–8°C for 28 days. A bactericidal effect was observed with 0.25 mg/mL free nisin; a bacteriostatic effect was observed for liposome-encapsulated nisin and 0.1 mg/mL free nisin. Free nisin was more efficient than nisin-loaded liposomes in controlling L. monocytogenes. Possible reasons for this behavior, and also the significance of nisin to soft cheeses are discussed. Nisin acted as a suitable barrier within hurdle technology, potentially extending the shelf-life and safety of fresh cheeses. PMID:24031971

  16. Proteomics analysis of Listeria monocytogenes ATCC 19115 in response to simultaneous triple stresses.

    PubMed

    He, Lei; Deng, Qing-Li; Chen, Mou-Tong; Wu, Qing-Ping; Lu, Yong-Jun

    2015-08-01

    Listeria monocytogenes can cause listeriosis in humans through consumption of contaminated food. L. monocytogenes can adapt and grow in a vast array of physiochemical stresses in the food production environment. In this study, we performed a proteomics strategy in order to investigate how L. monocytogenes survives with a simultaneous exposure to low pH, high salinity and low temperature. The results showed that the adaptation processes mainly affected the biochemical pathways related to protein synthesis, oxidative stress, cell wall and nucleotide metabolism. Interestingly, enzymes involved in the carbohydrate metabolism of energy, such as glycolysis and pentose phosphate pathway, were derepressed due to the down-regulation of CodY, a global transcriptional repressor. The down-regulation of CodY, together with the up-regulation of carbohydrate metabolism enzymes, likely leads to the accumulation of pyruvate and further to the activation of fatty acid synthesis pathway. Proteomics profiling offered a better understanding of the physiological responses of this pathogen to adapt to harsh environment and would hopefully contribute to improving the food-processing and storage methods. PMID:25990453

  17. Fate of Viable but Non-culturable Listeria monocytogenes in Pig Manure Microcosms

    PubMed Central

    Desneux, Jérémy; Biscuit, Audrey; Picard, Sylvie; Pourcher, Anne-Marie

    2016-01-01

    The fate of two strains of Listeria monocytogenes and their ability to become viable but non-culturable (VBNC) was investigated in microcosms containing piggery effluents (two raw manures and two biologically treated manures) stored for 2 months at 8 and 20°C. Levels of L. monocytogenes were estimated using the culture method, qPCR, and propidium monoazide treatment combined with qPCR (qPCRPMA). The chemical composition and the microbial community structure of the manures were also analyzed. The strains showed similar decline rates and persisted up to 63 days. At day zero, the percentage of VBNC cells among viable cells was higher in raw manures (81.5–94.8%) than in treated manures (67.8–79.2%). The changes in their proportion over time depended on the temperature and on the type of effluent: the biggest increase was observed in treated manures at 20°C and the smallest increase in raw manures at 8°C. The chemical parameters had no influence on the behavior of the strains, but decrease of the persistence of viable cells was associated with an increase in the microbial richness of the manures. This study demonstrated that storing manure altered the culturability of L. monocytogenes, which rapidly entered the VBNC state, and underlines the importance of including VBNC cells when estimating the persistence of the pathogens in farm effluents. PMID:26973623

  18. Previous Homologous and Heterologous Stress Exposure Induces Tolerance Development to Pulsed Light in Listeria monocytogenes

    PubMed Central

    Heinrich, Victoria; Zunabovic, Marija; Petschnig, Alice; Müller, Horst; Lassenberger, Andrea; Reimhult, Erik; Kneifel, Wolfgang

    2016-01-01

    As one of the emerging non-thermal technologies, pulsed light (PL) facilitates rapid, mild and residue-free microbial surface decontamination of food and food contact materials. While notable progress has been made in the characterization of the inactivation potential of PL, experimental data available on the tolerance development to the same (homologous) stress or to different (heterologous) stresses commonly applied in food manufacturing (e.g., acid, heat, salt) is rather controversial. The findings of the present study clearly indicate that both the homologous tolerance development against PL as well as the heterologous tolerance development from heat to PL can be triggered in Listeria monocytogenes. Further, conducted kinetic analysis confirmed that the conventionally applied log-linear model is not well suited to describe the inactivation of L. monocytogenes, when exposed to PL. Instead, the Weibull model as well as the log-linear + tail model were identified as suitable models. Transmission electron microscopic (TEM) approaches allow suggestions on the morphological alterations in L. monocytogenes cells after being subjected to PL. PMID:27092137

  19. Attenuating Listeria monocytogenes Virulence by Targeting the Regulatory Protein PrfA

    PubMed Central

    Good, James A.D.; Andersson, Christopher; Hansen, Sabine; Wall, Jessica; Krishnan, K. Syam; Begum, Afshan; Grundström, Christin; Niemiec, Moritz S.; Vaitkevicius, Karolis; Chorell, Erik; Wittung-Stafshede, Pernilla; Sauer, Uwe H.; Sauer-Eriksson, A. Elisabeth; Almqvist, Fredrik; Johansson, Jörgen

    2016-01-01

    Summary The transcriptional activator PrfA, a member of the Crp/Fnr family, controls the expression of some key virulence factors necessary for infection by the human bacterial pathogen Listeria monocytogenes. Phenotypic screening identified ring-fused 2-pyridone molecules that at low micromolar concentrations attenuate L. monocytogenes cellular uptake by reducing the expression of virulence genes. These inhibitors bind the transcriptional regulator PrfA and decrease its affinity for the consensus DNA-binding site. Structural characterization of this interaction revealed that one of the ring-fused 2-pyridones, compound 1, binds at two separate sites on the protein: one within a hydrophobic pocket or tunnel, located between the C- and N-terminal domains of PrfA, and the second in the vicinity of the DNA-binding helix-turn-helix motif. At both sites the compound interacts with residues important for PrfA activation and helix-turn-helix formation. Ring-fused 2-pyridones represent a new class of chemical probes for studying virulence in L. monocytogenes. PMID:26991105

  20. Inactivation of the MAPK signaling pathway by Listeria monocytogenes infection promotes trophoblast giant cell death

    PubMed Central

    Hashino, Masanori; Tachibana, Masato; Nishida, Takashi; Hara, Hideki; Tsuchiya, Kohsuke; Mitsuyama, Masao; Watanabe, Kenta; Shimizu, Takashi; Watarai, Masahisa

    2015-01-01

    Listeria monocytogenes has a well-characterized ability to cross the placental barrier, resulting in spontaneous abortion and fetal infections. However, the mechanisms resulting in infection-associated abortion are not fully understood. In this study, we demonstrate that the dephosphorylation of MAPK family proteins caused by L. monocytogenes infection of trophoblast giant (TG) cells, which are placental immune cells, contributes to infectious abortion. Dephosphorylation of c-Jun, p38, and ERK1/2 was observed in infected TG cells, causing the downregulation of cytoprotective heme oxygenase (HO)-1. Blocking the dephosphorylation of proteins, including MAPK family proteins, inhibited the decrease in HO-1 expression. Treatment with MAPK inhibitors inhibited bacterial internalization into TG cells. Moreover, Toll-like receptor 2 involved in the expression of MAPK family proteins. Infection with a listeriolysin O-deleted mutant impaired dephosphorylation of MAPK family proteins in TG cells and did not induce infectious abortion in a mouse model. These results suggest that inactivation of the MAPK pathway by L. monocytogenes induces TG cell death and causes infectious abortion. PMID:26528279