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Sample records for listeria monocytogenes durante

  1. [Listeria monocytogenes in food].

    PubMed

    Mícková, V

    1992-12-01

    As in recent years laboratory diagnostics of listeria has become part of food microbiology, the frequency of occurrence of the bacteria Listeria monocytogenes has been followed in various kinds of foods for a year. A total of 51 strains of L. monocytogenes (7.2%) was isolated from 700 kinds of samples (raw milk, pasteurized milk, meat surface, poultry, cheeses, thermally not treated meat products, food--industry machinery). As can be seen in Tab. I, the highest number of strains was isolated from meat surfaces (13.5%), followed by meat--industry machinery (12.72%), poultry (10%) and cheeses (5%). The lower numbers of strains were found out in thermally not treated meat products (3.8%) and in raw milk (3.3%). Pasteurized milk did not contain any strains. Our findings in raw milk (3.3%) and in pasteurized milk (0) are in agreement with the data cited e. g. by authors from the USA (Lovett et al., 1987), who mention the value of 4.2% in raw milk and the zero value in pasteurized milk. The percentage of strains monitored in cheeses (5%) can be evaluated as low as the assortment of investigated cheeses was small (all strains were isolated from soft ripening cheeses). German authors (Tham et al., 1988) speak about the 2.5% percentage of L. monocytogenes strains; this is in keeping with our findings. The findings in thermally not treated meat products (3.8%) can be evaluated as low although the number of strains found in raw meat was high.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. [Hematometra & Listeria monocytogenes].

    PubMed

    Gómez Arzapalo, E; Pérez Mendizábal, A; Herrera Avalos, I; Gorozpe Calvillo, J I

    2001-05-01

    The hematometra is a nosological entity that may not always be attributed to an embryonic defect of the paramesonefros; cervical-vaginal infections such as etiological possibilities due to Listeria monocytogenes (Lm), cervix malignant neoplasias, iatrogenias due to endometrial ablation with Lasser, traumatic bloody uterine curetage and because of cervical cryocoagulation or electrocoagulation are also mentioned. The case to be reported is from a woman in reproductive stage, who is 32 years old, and had menarca at the age of 13, starting her sexual life at 31, not using any method to control her fertility. When having an eight-week amenorrhea after 8 months of marriage, she visited the doctor for assumed pregnancy, within the prenatal analysis a pelvic echographic study was requested, finding out images that we concluded as hematometra, having been drained and demonstrated the presence of LM by anti-Lm antibodies, being administered Azitromicina and Espiramicina.

  3. 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

  4. Neuroinfections due to Listeria monocytogenes.

    PubMed

    Streharova, A; Babjakova, A; Moravcikova, A; Harnicarova, A; Holeckova, K; Lesnakova, A; Sladeckova, V; Seckova, S; Kisac, P; Beno, P

    2007-11-01

    Listeria monocytogenes is not a rare pathogen causing meningitis, mainly in small children and in close contacts to livestock. The pathogen is naturally resistant to cephalosporins and some glycopeptides as well, therefore despite of syndromologic diagnosis of meningitis and initial therapy with 3rd generation cephalosporins according to the guidelines therapeutic failures with clinical consequences may occur.

  5. Lipoteichoic acid from Listeria monocytogenes.

    PubMed Central

    Hether, N W; Jackson, L L

    1983-01-01

    A lipoteichoic acid (LTA) was extracted from Listeria monocytogenes (serotype 1) by phenol-water partition and isolated by gel-filtration chromatography. The LTA exhibited amphiphilic properties by changes in gel-filtration mobility in the presence of detergent buffers and after mild base hydrolysis. In a hemagglutination assay, Listeria LTA bound antibody prepared against a known LTA from Streptococcus spp. Listeria LTA inhibited the binding of anti-LTA antibody to a Lactobacillus LTA in a hemagglutination inhibition assay. The Listeria LTA contained glucose, galactose, fatty acids, glycerol, and phosphate with molar ratios of 0.05, 0.07, 0.21, 0.94, and 1.0 to phosphate, respectively. Adjacent glycerols were linked between the C-1 and C-3 positions by phosphodiesters (structural type 1). The average chain length was 19 +/- 2 (standard deviation) glycerol-phosphate repeating units. Approximately one glycosyl side chain was present per LTA molecule. The side chain was a galactose-containing disaccharide. The lipid portion of the LTA was a galactose- and glucose-containing glycolipid which may have been a phosphoglycolipid, but the structure was not confirmed. Major fatty acids of LTA and the glycolipid were 17:anteiso, 15:anteiso, 16:iso, 16:n, and 18:n. L. monocytogenes contained cell wall products typical of gram-positive bacteria which is in contrast to the reports by others of the presence of lipopolysaccharides from L. monocytogenes. PMID:6415040

  6. Biodiversity of the species Listeria monocytogenes and the genus Listeria.

    PubMed

    Buchrieser, Carmen

    2007-08-01

    This review describes the Listeria monocytogenes genome sequences available today and their comparison with that of Listeria innocua and Listeria welshimeri by highlighting their characteristic features and common traits. The diversity present among them is analysed with emphasis on putative virulence and host-pathogen interaction related functions. Then large-scale studies comparing gene content of Listeria and how these studies contributed to typing applications will be discussed. Finally, evolutionary conclusions and future perspectives in Listeria genomics are presented.

  7. Listeria monocytogenes and hemolytic Listeria innocua in poultry.

    PubMed

    Milillo, S R; Stout, J C; Hanning, I B; Clement, A; Fortes, E D; den Bakker, H C; Wiedmann, M; Ricke, S C

    2012-09-01

    Listeria monocytogenes is a ubiquitous, saprophytic, Gram-positive bacterium and occasional food-borne pathogen, often associated with ready-to-eat meat products. Because of the increased consumer interest in organic, all natural, and free range poultry products, it is important to understand L. monocytogenes in the context of such systems. Pasture-reared poultry were surveyed over the course of two 8-wk rearing periods. Cecal, soil, and grass samples were collected for Listeria isolation and characterization. Seven of 399 cecal samples (or 1.75%) were Listeria-positive. All positive cecal samples were obtained from broilers sampled at 2 wk of age. Grass and soil samples were collected from the pasture both before and after introduction of the poultry. Environmental samples collected after introduction of poultry were significantly more likely to contain Listeria (P < 0.001). The results of analytical profile index Listeria, sigB allelic typing, and hlyA PCR tests found that both L. monocytogenes and L. innocua, including hemolytic L. innocua, were recovered from the cecal and environmental (grass/soil) samples. The sigB allelic typing also revealed that (1) positive samples could be composed of 2 or more allelic types; (2) allelic types found in cecal samples could also be found in the environment; and (3) allelic types could persist through the 2 rearing periods. Our data indicate that both pasture-reared poultry and their environment can be contaminated with L. monocytogenes and hemolytic L. innocua.

  8. Listeria monocytogenes infections in Canada.

    PubMed

    Davies, J W; Ewan, E P; Varughese, P; Acres, S E

    1984-01-01

    Since its first isolation by Murray in 1926 Listeria monocytogenes has become recognized as a significant pathogen occurring worldwide and involving a wide range of wild and domestic animals including man. The first confirmed human listeriosis case in Canada was published by Stoot in 1951. A later survey based on records maintained at the Laboratory Centre for Disease Control, Ottawa showed 101 cases detected over a 21 year period in nine provinces. The overall mortality was 30%. The most frequently isolated serotype was 4b followed by 1 and 1b. Prior to the Nova Scotia epidemic (41 cases) of 1981, fewer than 15 cases per annum had been diagnosed based on hospital discharge records. The Nova Scotia epidemic was unique in that the source and mode of transmission of the organism were determined. Sixty-three strains isolated from this outbreak were typed, and with the exception of one 1a strain, were identified as 4b. These were subsequently classified mainly as phage type 00 042 0000 and 00 002 0000. Listeriosis appears to be a common infection in the animal population in Canada primarily in cattle, sheep, chinchillas, chickens and goats. Outbreaks have been described in rabbits, goats, and chinchillas. Chinchilla farms were affected in one outbreak (serotype 1) in Nova Scotia which was attributed to feeding a new batch of meal containing beet pulp. Many aspects of the epidemiology of listeriosis are obscure. A cycle involving contaminated soil and consumption of raw vegetables has been confirmed as the cause of the Nova Scotia epidemic and could explain a proportion of the sporadic cases.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6442654

  9. 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.

  10. [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

  11. Biodiversity and hypervirulence of Listeria monocytogenes.

    PubMed

    Grad, Yonatan H; Fortune, Sarah M

    2016-03-01

    The integration of large, well-sampled collections of bacterial isolates with genomics and experimental methods provides opportunities for 'top-down' discovery of the genetic basis of phenotypes of interest. In a new report, the authors apply this approach to investigate the heterogeneity in manifestations of disease caused by Listeria monocytogenes and demonstrate that a previously uncharacterized cellobiose PTS system is involved in central nervous system infection.

  12. 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.

  13. 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

  14. 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.

  15. 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...

  16. 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.

  17. Relationship between Listeria monocytogenes and Listeria spp. in seafood processing plants.

    PubMed

    Alali, Walid Q; Schaffner, Donald W

    2013-07-01

    The objective of this study was to evaluate the relationship between prevalence of Listeria monocytogenes as an outcome and Listeria spp. as an explanatory variable by food products, food contact surfaces, and nonfood contact surfaces in seafood processing plants by using peer-reviewed published data. Nine sets of prevalence data of L. monocytogenes and Listeria spp. were collected from published studies and used for the analyses. Based on our analysis, the relationship between L. monocytogenes prevalence and Listeria spp. prevalence in food products (incoming raw materials and finish products) was significant (P = 0.04) with (low) R² = 0.36. Furthermore, Listeria spp. were not a good indicator for L. monocytogenes when testing food contact surfaces (R² = 0.10). Listeria spp. were a good indicator for L. monocytogenes only on nonfood contact surfaces (R² = 0.90). On the other hand, the presence of Listeria spp. on food contact surfaces (R² = 0.002) and nonfood contact surfaces (R² = 0.03) was not a good indicator for L. monocytogenes presence in food products. In general, prevalence of Listeria spp. does not seem to be a good indicator for L. monocytogenes prevalence in seafood processing plants.

  18. 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.

  19. 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...

  20. Resistance of Listeria monocytogenes biofilms to sanitizing agents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is notorious for its capacity to colonize the environment and equipment of food processing facilities and to persist in the processing plant ecosystem, sometimes for decades. Such persistence is mediated by multiple attributes of L. monocytogenes, including the pathogen’s capa...

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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

  6. A New Perspective on Listeria monocytogenes Evolution

    PubMed Central

    Ragon, Marie; Wirth, Thierry; Hollandt, Florian; Lavenir, Rachel; Lecuit, Marc; Le Monnier, Alban; Brisse, Sylvain

    2008-01-01

    Listeria monocytogenes is a model organism for cellular microbiology and host–pathogen interaction studies and an important food-borne pathogen widespread in the environment, thus representing an attractive model to study the evolution of virulence. The phylogenetic structure of L. monocytogenes was determined by sequencing internal portions of seven housekeeping genes (3,288 nucleotides) in 360 representative isolates. Fifty-eight of the 126 disclosed sequence types were grouped into seven well-demarcated clonal complexes (clones) that comprised almost 75% of clinical isolates. Each clone had a unique or dominant serotype (4b for clones 1, 2 and 4, 1/2b for clones 3 and 5, 1/2a for clone 7, and 1/2c for clone 9), with no association of clones with clinical forms of human listeriosis. Homologous recombination was extremely limited (r/m<1 for nucleotides), implying long-term genetic stability of multilocus genotypes over time. Bayesian analysis based on 438 SNPs recovered the three previously defined lineages, plus one unclassified isolate of mixed ancestry. The phylogenetic distribution of serotypes indicated that serotype 4b evolved once from 1/2b, the likely ancestral serotype of lineage I. Serotype 1/2c derived once from 1/2a, with reference strain EGDe (1/2a) likely representing an intermediate evolutionary state. In contrast to housekeeping genes, the virulence factor internalin (InlA) evolved by localized recombination resulting in a mosaic pattern, with convergent evolution indicative of natural selection towards a truncation of InlA protein. This work provides a reference evolutionary framework for future studies on L. monocytogenes epidemiology, ecology, and virulence. PMID:18773117

  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. 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.

  10. Assessment of Listeria sp. Interference Using a Molecular Assay To Detect Listeria monocytogenes in Food.

    PubMed

    Zittermann, Sandra I; Stanghini, Brenda; See, Ryan Soo; Melano, Roberto G; Boleszczuk, Peter; Murphy, Allana; Maki, Anne; Mallo, Gustavo V

    2016-01-01

    Detection of Listeria monocytogenes in food is currently based on enrichment methods. When L. monocytogenes is present with other Listeria species in food, the species compete during the enrichment process. Overgrowth competition of the nonpathogenic Listeria species might result in false-negative results obtained with the current reference methods. This potential issue was noted when 50 food samples artificially spiked with L. monocytogenes were tested with a real-time PCR assay and Canada's current reference method, MFHPB-30. Eleven of the samples studied were from foods naturally contaminated with Listeria species other than those used for spiking. The real-time PCR assay detected L. monocytogenes in all 11 of these samples; however, only 6 of these samples were positive by the MFHPB-30 method. To determine whether L. monocytogenes detection can be affected by other species of the same genus due to competition, an L. monocytogenes strain and a Listeria innocua strain with a faster rate of growth in the enrichment broth were artificially coinoculated at different ratios into ground pork meat samples and cultured according to the MFHPB-30 method. L. monocytogenes was detected only by the MFHPB-30 method when L. monocytogenes/L. innocua ratios were 6.0 or higher. In contrast, using the same enrichments, the real-time PCR assay detected L. monocytogenes at ratios as low as 0.6. Taken together, these findings support the hypothesis that L. monocytogenes can be outcompeted by L. innocua during the MFHPB-30 enrichment phase. However, more reliable detection of L. monocytogenes in this situation can be achieved by a PCR-based method mainly because of its sensitivity.

  11. Listeria Monocytogenes Infections in Metropolitan Toronto

    PubMed Central

    Sepp, A. H.; Roy, T. E.

    1963-01-01

    The clinical and laboratory findings in 21 patients with listeriosis are described and the subject is reviewed. Eleven of the infections were septicemias of newborns, eight were meningitis in infants or adults, and two other children had unusual manifestations. Neonatal septicemia was rapidly fatal; one of 11 infants survived. The disease often seemed traceable to mild maternal infection during the third trimester usually leading to premature delivery of critically ill babies. Only awareness of the possible presence of listeriosis and early antibiotic therapy seem capable of reducing this high mortality. Tissues from autopsies showed characteristic microscopic necrotic foci with mononuclear infiltration progressing to microabscesses containing small Gram-positive rods. Lesions were found in the one placenta examined. Five infants with meningitis recovered, and one of three affected adults. Specific diagnosis depends on demonstrating Listeria monocytogenes; differentiation from other forms of acute meningitis cannot be made clinically. One older child had septicemia and another had listerial pharyngitis. Both recovered. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14 PMID:13987999

  12. Phage display-derived binders able to distinguish Listeria monocytogenes from other Listeria species.

    PubMed

    Morton, Josephine; Karoonuthaisiri, Nitsara; Charlermroj, Ratthaphol; Stewart, Linda D; Elliott, Christopher T; Grant, Irene R

    2013-01-01

    The objective of this study was to produce phage display-derived binders with the ability to distinguish Listeria monocytogenes from other Listeria spp., which may have potential utility to enhance detection of Listeria monocytogenes. To obtain binders with the desired binding specificity a series of surface and solution phage-display biopannings were performed. Initially, three rounds of surface biopanning against gamma-irradiated L. monocytogenes serovar 4b cells were performed followed by an additional surface biopanning round against L. monocytogenes 4b which included prior subtraction biopanning against gamma-irradiated L. innocua cells. In an attempt to further enhance binder specificity for L. monocytogenes 4b two rounds of solution biopanning were performed, both rounds included initial subtraction solution biopanning against L. innocua. Subsequent evaluations were performed on the phage clones by phage binding ELISA. All phage clones tested from the second round of solution biopanning had higher specificity for L. monocytogenes 4b than for L. innocua and three other foodborne pathogens (Salmonella spp., Escherichia coli and Campylobacter jejuni). Further evaluation with five other Listeria spp. revealed that one phage clone in particular, expressing peptide GRIADLPPLKPN, was highly specific for L. monocytogenes with at least 43-fold more binding capability to L. monocytogenes 4b than to any other Listeria sp. This proof-of-principle study demonstrates how a combination of surface, solution and subtractive biopanning was used to maximise binder specificity. L. monocytogenes-specific binders were obtained which could have potential application in novel detection tests for L. monocytogenes, benefiting both the food and medical industries. PMID:24040227

  13. Phage display-derived binders able to distinguish Listeria monocytogenes from other Listeria species.

    PubMed

    Morton, Josephine; Karoonuthaisiri, Nitsara; Charlermroj, Ratthaphol; Stewart, Linda D; Elliott, Christopher T; Grant, Irene R

    2013-01-01

    The objective of this study was to produce phage display-derived binders with the ability to distinguish Listeria monocytogenes from other Listeria spp., which may have potential utility to enhance detection of Listeria monocytogenes. To obtain binders with the desired binding specificity a series of surface and solution phage-display biopannings were performed. Initially, three rounds of surface biopanning against gamma-irradiated L. monocytogenes serovar 4b cells were performed followed by an additional surface biopanning round against L. monocytogenes 4b which included prior subtraction biopanning against gamma-irradiated L. innocua cells. In an attempt to further enhance binder specificity for L. monocytogenes 4b two rounds of solution biopanning were performed, both rounds included initial subtraction solution biopanning against L. innocua. Subsequent evaluations were performed on the phage clones by phage binding ELISA. All phage clones tested from the second round of solution biopanning had higher specificity for L. monocytogenes 4b than for L. innocua and three other foodborne pathogens (Salmonella spp., Escherichia coli and Campylobacter jejuni). Further evaluation with five other Listeria spp. revealed that one phage clone in particular, expressing peptide GRIADLPPLKPN, was highly specific for L. monocytogenes with at least 43-fold more binding capability to L. monocytogenes 4b than to any other Listeria sp. This proof-of-principle study demonstrates how a combination of surface, solution and subtractive biopanning was used to maximise binder specificity. L. monocytogenes-specific binders were obtained which could have potential application in novel detection tests for L. monocytogenes, benefiting both the food and medical industries.

  14. Peptide nucleic acid fluorescence in situ hybridization for identification of Listeria genus, Listeria monocytogenes and Listeria ivanovii.

    PubMed

    Zhang, Xiaofeng; Wu, Shan; Li, Ke; Shuai, Jiangbing; Dong, Qiang; Fang, Weihuan

    2012-07-01

    A fluorescent in situ hybridization (FISH) method in conjunction with fluorescin-labeled peptide nucleic acid (PNA) probes (PNA-FISH) for detection of Listeria species was developed. In silico analysis showed that three PNA probes Lis-16S-1, Lm-16S-2 and Liv-16S-5 were suitable for specific identification of Listeria genus, Listeria monocytogenes and Listeria ivanovii, respectively. These probes were experimentally verified by their reactivity against 19 strains of six Listeria species (excluding newly described species Listeria marthii and Listeria rocourtiae) and eight other bacterial species. The PNA-FISH method was optimized as 30 min of hybridization with 0.2% Triton X-100 in the solution and used to identify 85 Listeria strains from individual putative Listeria colonies on PALCAM agar plates streaked from selectively enriched cultures of 780 food or food-related samples. Of the 85 Listeria strains, thirty-seven were identified as L. monocytogenes with the probe Lm-16S-2 and two as L. ivanovii with the probe Liv-16S-5 which was in agreement with the results obtained by the API LISTERIA method. Thus, the PNA-FISH protocol has the potential for identification of pathogenic Listeria spp. from food or food-related samples.

  15. Listeria monocytogenes in retailed raw chicken meat in Malaysia.

    PubMed

    Goh, S G; Kuan, C H; Loo, Y Y; Chang, W S; Lye, Y L; Soopna, P; Tang, J Y H; Nakaguchi, Y; Nishibuchi, M; Afsah-Hejri, L; Son, R

    2012-10-01

    This study aimed to determine the prevalence Listeria monocytogenes in raw chicken meat samples at hypermarkets and wet markets. Chicken drumsticks, breasts, and thighs were randomly selected. The most probable number (MPN) PCR method was used to quantify the L. monocytogenes in the samples. Listeria monocytogenes was detected in 20% of the samples. Occurrence of L. monocytogenes was highest in breast (42.03%) followed by drumstick (11.27%) and thigh (7.14%). Samples from hypermarkets showed higher occurrence (25.71%) of L. monocytogenes compared with wet markets (14.29%). The density of L. monocytogenes found in samples ranged from <3.0 to 16 MPN•g(-1). The presence of L. monocytogenes in raw chicken meat is unwanted but unpreventable. Thus, further research on the processing method to reduce and eliminate this kind of bacteria in chicken meat before consumption is necessary. The presence of L. monocytogenes in chicken samples suggests the importance of this pathogen in chicken. Thus, more study is needed to find ways to eliminate this pathogen from poultry. PMID:22991558

  16. 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.

  17. In vitro activities of trimethoprim and sulfamethoxazole against Listeria monocytogenes.

    PubMed Central

    Winslow, D L; Pankey, G A

    1982-01-01

    The in vitro activities of trimethoprim and sulfamethoxyazole against clinical isolates of Listeria monocytogenes were examined separately and in combination with a microtiter broth dilution system. Sulfamethoxazole demonstrated variable activity and was generally bacteriostatic. Trimethoprim alone was bactericidal against 96% of isolates at less than 0.5 microgram/ml. The bactericidal action of trimethoprim against L. monocytogenes was generally potentiated by sulfamethoxyazole even when isolates were relatively resistant to sulfamethoxyazole alone. PMID:6812496

  18. Toward an improved laboratory definition of Listeria monocytogenes virulence.

    PubMed

    Liu, Dongyou; Lawrence, Mark L; Ainsworth, A Jerald; Austin, Frank W

    2007-09-15

    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 assessing L. monocytogenes virulence include in vivo bioassays and in vitro cell assays. While in vivo bioassays provide a measurement of all virulence determinants of L. monocytogenes, they are not applied routinely due to their reliance on experimental animals whose costs have become increasingly prohibitive. As a low cost alternative, in vitro cell assays are useful for estimating the virulence of L. monocytogenes strains. However, these assays are often slow, and at times variable. Prior attempts to ascertain L. monocytogenes virulence by targeting virulence-associated proteins and genes have been largely unsuccessful, since many of the assay targets are present in both virulent and avirulent strains. Recent identification of novel virulence-specific genes (particularly internalin gene inlJ) has opened a new avenue for rapid, sensitive, and precise differentiation of virulent L. monocytogenes strains from avirulent strains. The application of DNA sequencing technique also offers an additional tool for assessing L. monocytogenes virulence potential. By providing an update on the laboratory methods that have been reported for the determination of L. monocytogenes pathogenicity, this review discusses future research needs that may help achieve an improved laboratory definition of L. monocytogenes virulence.

  19. Recombinant Probiotic Expressing Listeria Adhesion Protein Attenuates Listeria monocytogenes Virulence In Vitro

    PubMed Central

    Koo, Ok Kyung; Amalaradjou, Mary Anne Roshni; Bhunia, Arun K.

    2012-01-01

    Background Listeria monocytogenes, an intracellular foodborne pathogen, infects immunocompromised hosts. The primary route of transmission is through contaminated food. In the gastrointestinal tract, it traverses the epithelial barrier through intracellular or paracellular routes. Strategies to prevent L. monocytogenes entry can potentially minimize infection in high-risk populations. Listeria adhesion protein (LAP) aids L. monocytogenes in crossing epithelial barriers via the paracellular route. The use of recombinant probiotic bacteria expressing LAP would aid targeted clearance of Listeria from the gut and protect high-risk populations from infection. Methodology/Principal Findings The objective was to investigate the ability of probiotic bacteria or LAP-expressing recombinant probiotic Lactobacillus paracasei (LbpLAP) to prevent L. monocytogenes adhesion, invasion, and transwell-based transepithelial translocation in a Caco-2 cell culture model. Several wild type probiotic bacteria showed strong adhesion to Caco-2 cells but none effectively prevented L. monocytogenes infection. Pre-exposure to LbpLAP for 1, 4, 15, or 24 h significantly (P<0.05) reduced adhesion, invasion, and transepithelial translocation of L. monocytogenes in Caco-2 cells, whereas pre-exposure to parental Lb. paracasei had no significant effect. Similarly, LbpLAP pre-exposure reduced L. monocytogenes translocation by as much as 46% after 24 h. LbpLAP also prevented L. monocytogenes-mediated cell damage and compromise of tight junction integrity. Furthermore, LbpLAP cells reduced L. monocytogenes-mediated cell cytotoxicity by 99.8% after 1 h and 79% after 24 h. Conclusions/Significance Wild type probiotic bacteria were unable to prevent L. monocytogenes infection in vitro. In contrast, LbpLAP blocked adhesion, invasion, and translocation of L. monocytogenes by interacting with host cell receptor Hsp60, thereby protecting cells from infection. These data show promise for the use of recombinant

  20. 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

  1. 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

  2. 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.

  3. Antimicrobial resistance of Listeria monocytogenes and Listeria innocua from meat products and meat-processing environment.

    PubMed

    Gómez, Diego; Azón, Ester; Marco, Noelia; Carramiñana, Juan J; Rota, Carmina; Ariño, Agustín; Yangüela, Javier

    2014-09-01

    A total of 336 Listeria isolates from ready-to-eat (RTE) meat products and meat-processing environments, consisting of 206 Listeria monocytogenes, and 130 Listeria innocua isolates, were characterized by disc diffusion assay and minimum inhibitory concentration (MIC) values for antimicrobial susceptibility against twenty antimicrobials. Resistance to one or two antimicrobials was observed in 71 L. monocytogenes isolates (34.5%), and 56 L. innocua isolates (43.1%). Multidrug resistance was identified in 24 Listeria isolates, 18 belonging to L. innocua (13.9%) and 6 to L. monocytogenes (2.9%). Oxacillin resistance was the most common resistance phenotype and was identified in 100% Listeria isolates. A medium prevalence of resistance to clindamycin (39.3% isolates) and low incidence of resistance to tetracycline (3.9% isolates) were also detected. Listeria isolates from RTE meat products displayed higher overall antimicrobial resistance (31.3%) than those from the environment (13.4%). All the strains assayed were sensitive to the preferred antibiotics used to treat listeriosis. Results showed that although antimicrobial resistance in L. monocytogenes still occurs at a low prevalence, L. innocua can form a reservoir of resistance genes which may transfer between bacterial species, including transference to organisms capable of causing disease in humans.

  4. 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...

  5. 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...

  6. 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...

  7. 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

  8. 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

  9. Case of Contamination by Listeria Monocytogenes in Mozzarella Cheese

    PubMed Central

    Tolli, Rita; Bossù, Teresa; Rodas, Eda Maria Flores; Di Giamberardino, Fabiola; Di Sirio, Alessandro; Vita, Silvia; De Angelis, Veronica; Bilei, Stefano; Sonnessa, Michele; Gattuso, Antonietta; Lanni, Luigi

    2014-01-01

    Following a Listeria monocytogenes detection in a mozzarella cheese sampled at a dairy plant in Lazio Region, further investigations have been conducted both by the competent Authority and the food business operatordairy factory (as a part of dairy factory HACCP control). In total, 90 dairy products, 7 brine and 64 environmental samples have been tested. The prevalence of Listeria monocytogenes was 24.4% in mozzarella cheese, and 9.4% in environmental samples, while brines were all negatives. Forty-seven strains of L. monocytogenes have been isolated, all belonging to 4b/4e serotype. In 12 of these, the macrorestriction profile has been determined by means of pulsed field gel electrophoresis. The profiles obtained with AscI enzyme showed a 100% similarity while those obtained with ApaI a 96.78% similarity. These characteristics of the isolated strains jointly with the production process of mozzarella cheese has allowed to hypothesise an environmental contamination. PMID:27800317

  10. Incidence of Listeria monocytogenes and Listeria spp. in a small-scale mushroom production facility.

    PubMed

    Viswanath, Prema; Murugesan, Latha; Knabel, Stephen J; Verghese, Bindhu; Chikthimmah, Naveen; Laborde, Luke F

    2013-04-01

    Listeria monocytogenes is a foodborne pathogen of significant concern to the agricultural and food processing industry because of its ability to grow and persist in cool and moist environments and its association with listeriosis, a disease with a very high mortality rate. Although there have been no listeriosis outbreaks attributed to fresh mushrooms in the United States, retail surveys and recalls are evidence that L. monocytogenes contamination of mushrooms (Agaricus bisporus) can occur. The objective of this study was to determine the prevalence of Listeria spp., including L. monocytogenes, in a small-scale mushroom production facility on the campus of the Pennsylvania State University in the United States. Of 184 samples taken from five production zones within the facility, 29 (15.8%) samples were positive for Listeria spp. Among the Listeria spp. isolates, L. innocua was most prevalent (10.3%) followed by L. welshimeri (3.3%), L. monocytogenes (1.6%), and L. grayi (0.5%). L. monocytogenes was recovered only from the phase I raw material composting area. Isolates of L. monocytogenes were confirmed and serotyped by multiplex PCR. The epidemiological relatedness of the three L. monocytogenes isolates to those serotypes or lineages frequently encountered in listeriosis infections was determined by multi-virulence-locus sequence typing using six virulence genes, namely, prfA, inlB, inlC, dal, clpP, and lisR. The phylogenetic positions of the three isolates in the dendrogram prepared with data from other isolates of L. monocytogenes showed that all isolates were grouped with serotype 4a, lineage IIIA. To date, this serotype has rarely been reported in foodborne disease outbreaks.

  11. A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix.

    PubMed

    Colagiorgi, Angelo; Di Ciccio, Pierluigi; Zanardi, Emanuela; Ghidini, Sergio; Ianieri, Adriana

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen able to persist in food industry and is responsible for a severe illness called listeriosis. The ability of L. monocytogenes to persist in environments is due to its capacity to form biofilms that are a sessile community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances (EPS's). In this review, we summarized recent efforts performed in order to better characterize the polymeric substances that compose the extracellular matrix (ECM) of L. monocytogenes biofilms. EPS extraction and analysis led to the identification of polysaccharides, proteins, extracellular DNA, and other molecules within the listerial ECM. All this knowledge will be useful for increasing food protection, suggesting effective strategies for the minimization of persistence of L. monocytogenes in food industry environments. PMID:27681916

  12. A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix

    PubMed Central

    Colagiorgi, Angelo; Di Ciccio, Pierluigi; Zanardi, Emanuela; Ghidini, Sergio; Ianieri, Adriana

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen able to persist in food industry and is responsible for a severe illness called listeriosis. The ability of L. monocytogenes to persist in environments is due to its capacity to form biofilms that are a sessile community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances (EPS’s). In this review, we summarized recent efforts performed in order to better characterize the polymeric substances that compose the extracellular matrix (ECM) of L. monocytogenes biofilms. EPS extraction and analysis led to the identification of polysaccharides, proteins, extracellular DNA, and other molecules within the listerial ECM. All this knowledge will be useful for increasing food protection, suggesting effective strategies for the minimization of persistence of L. monocytogenes in food industry environments.

  13. A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix

    PubMed Central

    Colagiorgi, Angelo; Di Ciccio, Pierluigi; Zanardi, Emanuela; Ghidini, Sergio; Ianieri, Adriana

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen able to persist in food industry and is responsible for a severe illness called listeriosis. The ability of L. monocytogenes to persist in environments is due to its capacity to form biofilms that are a sessile community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances (EPS’s). In this review, we summarized recent efforts performed in order to better characterize the polymeric substances that compose the extracellular matrix (ECM) of L. monocytogenes biofilms. EPS extraction and analysis led to the identification of polysaccharides, proteins, extracellular DNA, and other molecules within the listerial ECM. All this knowledge will be useful for increasing food protection, suggesting effective strategies for the minimization of persistence of L. monocytogenes in food industry environments. PMID:27681916

  14. 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...

  15. [Listeria monocytogenes meningitis in immunocompetent children: unpasteurized cheese likely cause of infection].

    PubMed

    Valdivia-Tapia, María Del C; Pinelo-Chumbe, Elizabeth; Carreazo, Nilton Y

    2015-08-01

    Listeria meningoencephalitis is a rare condition, occurring mainly in immunocompromised patients. We present two cases of Listeria monocytogenes meningoencephalitis in immunocompetent children, with successful treatment with betalactam/aminoglycoside combination. Unpasteurized cheese was postulated as the source of infection.

  16. Listeria Spp. and Listeria Monocytogenes Contamination in Ready-To-Eat Sandwiches Collected from Vending Machines

    PubMed Central

    Cossu, Francesca; Spanu, Carlo; Deidda, Silvia; Mura, Erica; Casti, Daniele; Pala, Carlo; Lamon, Sonia; Spanu, Vincenzo; Ibba, Michela; Marrocu, Elena; Piana, Andrea; De Santis, Enrico Pietro Luigi

    2016-01-01

    Ready-to-eat (RTE) food is characterised by a long shelf-life at refrigerated temperature and can be consumed as such, without any treatment. The aim of the work was to evaluate the presence of Listeria spp. and Listeria monocytogenes in RTEs collected from refrigerated vending machines placed in hospital environment and accessible to the hospitalised patients. In 4 different sampling, 55 RTEs were collected from vending machines of six hospitals located in different areas of Sardinia region. All the samples were characterised by similar manufacturing process, such as the use of modified atmosphere packaging and belonged to 5 different producers. Listeria spp. was not countable using the enumeration method in all of the analysed samples. Using the detection method, Listeria spp. was recovered from 9 sandwich samples. Interestingly, 3 of these samples (5.5%) made by the manufacturer, were positive for L. monocytogenes contamination. The risk related to the L. monocytogenes presence in RTEs proportionally increases when food is introduced in susceptible environments, such as hospitals and consumed by susceptible people. Although the RTEs analysed showed values that complied with the European microbiological criteria for foodstuffs, the availability of these products in a susceptible environment should be carefully checked. Therefore, in order to limit the possible exposition to L. monocytogenes, more information on the risk related to RTE consumption should be provided to the hospitalised patients. PMID:27800439

  17. RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells.

    PubMed

    Sigal, Nadejda; Pasechnek, Anna; Herskovits, Anat A

    2016-01-01

    Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. However, isolating bacterial RNA from infected cells or tissues is a challenging task, since mammalian RNA mostly dominates the lysates of infected cells. Here we describe an optimized method for RNA isolation of Listeria monocytogenes bacteria growing within bone marrow derived macrophage cells. Upon infection, cells are mildly lysed and rapidly filtered to discard most of the host proteins and RNA, while retaining intact bacteria. Next, bacterial RNA is isolated using hot phenol-SDS extraction followed by DNase treatment. The extracted RNA is suitable for gene transcription analysis by multiple techniques. This method is successfully employed in our studies of Listeria monocytogenes gene regulation during infection of macrophage cells (1-4). The protocol can be easily modified to study other bacterial pathogens and cell types. PMID:27341521

  18. 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

  19. Two Outbreaks of Listeria monocytogenes Infection, Northern Spain

    PubMed Central

    Zigorraga, Carmen; Artieda, Junkal; Alkorta, Miriam; Marimón, José M.

    2014-01-01

    In the province of Gipuzkoa, Spain (≈700,000 inhabitants), 7–12 episodes of human listeriosis were recorded annually during 2009–2012. However, during January 2013–February 2014, 27 episodes were detected, including 11 pregnancy-associated cases. Fifteen cases in 2 epidemiologically unrelated outbreaks were caused by a rare type of Listeria monocytogenes, sequence type 87 serotype 1/2b. PMID:25418800

  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. 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

  2. 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

  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.

  4. Inhibition of Listeria monocytogenes infection by neurological drugs

    PubMed Central

    Lieberman, Linda A.; Higgins, Darren E.

    2009-01-01

    To gain insights into the cellular processes required for intracellular bacterial pathogenesis, we previously developed a generalisable screening approach to identify small molecule compounds that alter Listeria monocytogenes infection. In this report, a small molecule library enriched for compounds affecting neurological functions was screened and 68 compounds that disrupted L. monocytogenes infection of macrophages were identified. Many of these compounds were known antimicrobial agents, however 26 compounds were novel inhibitors of intracellular infection. Two of the compounds chosen for further study, the antipsychotic drug thioridazine and the calcium channel blocker bepridil, exhibited dose-dependent inhibition of vacuolar escape and intracellular replication of L. monocytogenes during infection of murine macrophages. These results suggest that clinically approved neurological drugs may provide a novel source of anti-infective agents that are suitable for development as therapeutics against intracellular bacterial infections. PMID:20031379

  5. Whole genome sequence-based serogrouping of Listeria monocytogenes isolates.

    PubMed

    Hyden, Patrick; Pietzka, Ariane; Lennkh, Anna; Murer, Andrea; Springer, Burkhard; Blaschitz, Marion; Indra, Alexander; Huhulescu, Steliana; Allerberger, Franz; Ruppitsch, Werner; Sensen, Christoph W

    2016-10-10

    Whole genome sequencing (WGS) is currently becoming the method of choice for characterization of Listeria monocytogenes isolates in national reference laboratories (NRLs). WGS is superior with regards to accuracy, resolution and analysis speed in comparison to several other methods including serotyping, PCR, pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), multilocus variable number tandem repeat analysis (MLVA), and multivirulence-locus sequence typing (MVLST), which have been used thus far for the characterization of bacterial isolates (and are still important tools in reference laboratories today) to control and prevent listeriosis, one of the major sources of foodborne diseases for humans. Backward compatibility of WGS to former methods can be maintained by extraction of the respective information from WGS data. Serotyping was the first subtyping method for L. monocytogenes capable of differentiating 12 serovars and national reference laboratories still perform serotyping and PCR-based serogrouping as a first level classification method for Listeria monocytogenes surveillance. Whole genome sequence based core genome MLST analysis of a L. monocytogenes collection comprising 172 isolates spanning all 12 serotypes was performed for serogroup determination. These isolates clustered according to their serotypes and it was possible to group them either into the IIa, IIc, IVb or IIb clusters, respectively, which were generated by minimum spanning tree (MST) and neighbor joining (NJ) tree data analysis, demonstrating the power of the new approach.

  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. 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...

  8. 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

  9. 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

  10. Identification of Listeria monocytogenes Determinants Required for Biofilm Formation

    PubMed Central

    Regeimbal, James M.; Regan, Patrick M.; Higgins, Darren E.

    2014-01-01

    Listeria monocytogenes is a Gram-positive, food-borne pathogen of humans and animals. L. monocytogenes is considered to be a potential public health risk by the U.S. Food and Drug Administration (FDA), as this bacterium can easily contaminate ready-to-eat (RTE) foods and cause an invasive, life-threatening disease (listeriosis). Bacteria can adhere and grow on multiple surfaces and persist within biofilms in food processing plants, providing resistance to sanitizers and other antimicrobial agents. While whole genome sequencing has led to the identification of biofilm synthesis gene clusters in many bacterial species, bioinformatics has not identified the biofilm synthesis genes within the L. monocytogenes genome. To identify genes necessary for L. monocytogenes biofilm formation, we performed a transposon mutagenesis library screen using a recently constructed Himar1 mariner transposon. Approximately 10,000 transposon mutants within L. monocytogenes strain 10403S were screened for biofilm formation in 96-well polyvinyl chloride (PVC) microtiter plates with 70 Himar1 insertion mutants identified that produced significantly less biofilms. DNA sequencing of the transposon insertion sites within the isolated mutants revealed transposon insertions within 38 distinct genetic loci. The identification of mutants bearing insertions within several flagellar motility genes previously known to be required for the initial stages of biofilm formation validated the ability of the mutagenesis screen to identify L. monocytogenes biofilm-defective mutants. Two newly identified genetic loci, dltABCD and phoPR, were selected for deletion analysis and both ΔdltABCD and ΔphoPR bacterial strains displayed biofilm formation defects in the PVC microtiter plate assay, confirming these loci contribute to biofilm formation by L. monocytogenes. PMID:25517120

  11. 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

  12. 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

  13. 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...

  14. Quantitative detection of Listeria monocytogenes in biofilms by real-time PCR.

    PubMed

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

    2005-04-01

    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 x 10(2) CFU/cm2.

  15. 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

  16. Characterization of Listeria monocytogenes from three countries and antibiotic resistance differences among countries and Listeria monocytogenes serogroups.

    PubMed

    Obaidat, M M; Bani Salman, A E; Lafi, S Q; Al-Abboodi, A R

    2015-06-01

    A total of 104 Listeria monocytogenes isolates from 330 fish samples from three countries were characterized by multiplex PCR for serogrouping and virulence markers determination and tested for antibiotics resistance. A 53·8% of the isolates belonged to serogroup 1/2a, 3a; 32% belonged to 1/2b, 3b, 7; 14·4% belonged to 4b, 4d, 4e and 1% belonged to 1/2c, 3c. All isolates exhibited resistance to at least one antibiotic but the resistance rates varied among countries. The isolates exhibited high resistance to penicillin, rifampicin, clindamycin, erythromycin and tetracycline, but low resistance to amoxicillin-clavulanic acid, streptomycin, sulfamethoxazole-trimethoprim, gentamicin, chloramphenicol and kanamycin. When comparing countries, the resistance rate for rifampicin, clindamycin, erythromycin, tetracycline, amoxicillin-clavulanic acid varied among countries. When comparing serogroup, 1/2a, 3a exhibited the highest resistance to clindamycin, erythromycin, tetracycline and vancomycin while serogroup 4b, 4d, 4e exhibited the highest resistance to amoxicillin-clavulanic acid. All isolates carried inlA, inlC, inlJ and lmo2672. Listeriolysin S was carried by 42 and 30% of 4b and 1/2b isolates respectively. Significance and impact of the study: This is one of few studies to correlate antibiotic resistance with Listeria monocytogenes serogroups. The study also compared the antibiotic resistance and serogroups of L. monocytogenes isolates from three countries in one single study. The findings of this study will be helpful in improving data on the antibiotics resistance of L. monocytogenes in developing countries and enriches the epidemiological and public health studies of L. monocytogenes.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Occurrence and distribution of Listeria monocytogenes and other Listeria species in ready-to-eat and raw meat products.

    PubMed

    Mengesha, Desalegn; Zewde, Bayleyegn Molla; Toquin, Marie-Thérèse; Kleer, Josef; Hildebrandt, Goetz; Gebreyes, Wondwossen A

    2009-01-01

    The present study was undertaken to estimate the occurrence and distribution of Listeria monocytogenes and other Listeria species in ready-to-eat food items (pasteurized milk, cheese, ice cream, and cakes) and raw meat products (minced beef, pork, and chicken carcasses). A total of 711 randomly selected samples were collected from supermarkets and pastry shops in Addis Ababa, Ethiopia. Listeria monocytogenes and other Listeria species were isolated and identified according to the techniques recommended by the International Organization for Standardization (ISO 11290-1). Serotyping of L. monocytogenes strains was carried out at the French Food Safety Agency (AFSSA), Ploufragan, France. Of the 711 food samples examined, 189 (26.6%) were Listeria positive of which 34 (4.8%) were L. monocytogenes. Pork was the most contaminated with Listeria species (62.5%) followed by minced beef (47.7%), ice cream (42.7%), soft cheese (16.8%), chicken carcasses (16.0%), and cakes (12.1%). All pasteurized milk and cottage cheese samples examined were Listeria negative. Listeria monocytogenes strains were isolated in ready-to-eat food items consisting of ice cream (11.7%), cakes (6.5%), and soft cheese (3.9%) and in meat products ranging from 3.7% to 5.1%. Among the 34 isolates of L. monocytogenes serotyped, serotypes 4b/4e (n = 32), 4c, and 4e (n = 2) were identified. The presence of L. monocytogenes in some ready-to-eat food items could pose public health hazards to the consumer, particularly to the high-risk group of the population.

  6. 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.

  7. Cold shock induction of thermal sensitivity in Listeria monocytogenes.

    PubMed

    Miller, A J; Bayles, D O; Eblen, B S

    2000-10-01

    Cold shock at 0 to 15 degrees C for 1 to 3 h increased the thermal sensitivity of Listeria monocytogenes. In a model broth system, thermal death time at 60 degrees C was reduced by up to 45% after L. monocytogenes Scott A was cold shocked for 3 h. The duration of the cold shock affected thermal tolerance more than did the magnitude of the temperature downshift. The Z values were 8.8 degrees C for controls and 7.7 degrees C for cold-shocked cells. The D values of cold-shocked cells did not return to control levels after incubation for 3 h at 28 degrees C followed by heating at 60 degrees C. Nine L. monocytogenes strains that were cold shocked for 3 h exhibited D(60) values that were reduced by 13 to 37%. The D-value reduction was greatest in cold-shocked stationary-phase cells compared to cells from cultures in either the lag or exponential phases of growth. In addition, cold-shocked cells were more likely to be inactivated by a given heat treatment than nonshocked cells, which were more likely to experience sublethal injury. The D values of chloramphenicol-treated control cells and chloramphenicol-treated cold-shocked cells were no different from those of untreated cold-shocked cells, suggesting that cold shock suppresses synthesis of proteins responsible for heat protection. In related experiments, the D values of L. monocytogenes Scott A were decreased 25% on frankfurter skins and 15% in ultra-high temperature milk if the inoculated products were first cold shocked. Induction of increased thermal sensitivity in L. monocytogenes by thermal flux shows potential to become a practical and efficacious preventative control method.

  8. Sepsis and Meningitis due to Listeria Monocytogenes

    PubMed Central

    Aygen, Bilgehan; Esel, Duygu; Kayabas, Uner; Alp, Emine; Sumerkan, Bulent; Doganay, Mehmet

    2007-01-01

    Purpose This study focused on the effect of immuno-compromising conditions on the clinical presentation of severe listerial infection. Patients and Methods Nine human listeriosis cases seen from 1991-2002 were reviewed. All adult patients, from whose blood, peritoneal fluid or cerebrospinal fluid (CSF) the L. monocytogenes was isolated, were included in this retrospective study. Results Listeriosis presented as primary sepsis with positive blood cultures in 5 cases and meningitis with positive CSF cultures in 4 cases. All of these patients had at least one underlying disease, most commonly, hematologic malignancy, diabetes mellitus, amyloidosis and hepatic cirrhosis; 55.6% had received immunosuppressive or corticosteroid therapy within a week before the onset of listeriosis. The patients were adults with a mean age of 60 years. Fever, night sweats, chills and lethargy were the most common symptoms; high temperature (> 38℃), tachycardia, meningeal signs and poor conditions in general were the most common findings on admission. The mortality rate was 33.3% and was strictly associated with the severity of the underlying disease. Mortality differences were significant between sepsis (20%) and meningitis (50%) patients. Conclusion Listeriosis as an uncommon infection in our region and that immuno-suppressive therapy is an important pre-disposing factor of listeriosis. Sepsis and meningitis were more common in this group of patients and had the highest case-fatality rate for food-borne illnesses. PMID:17594151

  9. Prevalence of Listeria spp. and Molecular Characterization of Listeria monocytogenes Isolates from Broilers at the Abattoir.

    PubMed

    Bouayad, Leila; Hamdi, Taha M; Naim, Malek; Leclercq, Alexandre; Lecuit, Marc

    2015-07-01

    Products from three broiler abattoirs were sampled for Listeria species to evaluate the changes in the prevalence and contamination rates at two stages of processing. Sampling was performed at the evisceration stage and at the end of processing after packaging and refrigerating at 4°C for 24 h. A total of 212 samples were collected; 52 were from abattoir A, and 80 samples each were collected from abattoirs B and C. Among all samples, 99 (46.7%) tested positive for Listeria, including L. monocytogenes 19 (8.9%), L. innocua 69 (32.5%), L. grayi 10 (4.7%), and L. welshimeri 1 (0.5%). The L. monocytogenes contamination rate varied from 5% to 11.5% in the 3 abattoirs. L. innocua was the most common species identified and was found in 8.8% of the samples from abattoir A and 33.7% of the samples from both abattoirs B and C. Twenty-six of the L. monocytogenes isolates obtained from positive samples were subjected to serotyping by multiplex polymerase chain reaction and characterization by the pulsed-field gel electrophoresis (PFGE) method using two cutting enzymes, ApaI and AscI. Three molecular serogroups were identified: IIa, IIb, and IVb. Serogroup IIa was common to all abattoirs, and serogroups IIb and IVb were found only in abattoir C. The 10 different obtained PFGE profiles were grouped into 7 clusters; some of these clusters were common to the 3 abattoirs, and others were specific to the abattoirs in which they were identified. This study revealed a high prevalence of Listeria spp., particularly L. monocytogenes, in raw broilers. This high incidence presents a risk to consumers due to the potential occurrence of cross-contamination with other foods in domestic refrigerators and the ability of these microorganisms to survive in undercooked products.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. Postenrichment population differentials using buffered Listeria enrichment broth: implications of the presence of Listeria innocua on Listeria monocytogenes in food test samples.

    PubMed

    Keys, Ashley L; Dailey, Rachel C; Hitchins, Anthony D; Smiley, R Derike

    2013-11-01

    The recovery of low levels of Listeria monocytogenes from foods is complicated by the presence of competing microorganisms. Nonpathogenic species of Listeria pose a particular problem because variation in growth rate during the enrichment step can produce more colonies of these nontarget cells on selective and/or differential media, resulting in a preferential recovery of nonpathogens, especially Listeria innocua. To gauge the extent of this statistical barrier to pathogen recovery, 10 isolates each of L. monocytogenes and L. innocua were propagated together from approximately equal initial levels using the current U. S. Food and Drug Administration's enrichment procedure. In the 100 isolate pairs, an average 1.3-log decrease was found in the 48-h enrichment L. monocytogenes population when L. innocua was present. In 98 of the 100 isolate pairs, L. innocua reached higher levels at 48 h than did L. monocytogenes, with a difference of 0.2 to 2.4 log CFU/ml. The significance of these population differences was apparent by an increase in the difficulty of isolating L. monocytogenes by the streak plating method. L. monocytogenes went completely undetected in 18 of 30 enrichment cultures even after colony isolation was attempted on Oxoid chromogenic Listeria agar. This finding suggests that although both Listeria species were present on the plate, the population differential between them restricted L. monocytogenes to areas of the plate with confluent growth and that isolated individual colonies were only L. innocua.

  15. 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...

  16. Variation in biofilm formation among strains of Listeria monocytogenes.

    PubMed

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

    2003-12-01

    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.

  17. 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

  18. How Listeria monocytogenes organizes its surface for virulence.

    PubMed

    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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. Development and characterization of a monoclonal antibody specific for Listeria monocytogenes and Listeria innocua.

    PubMed Central

    Bhunia, A K; Ball, P H; Fuad, A T; Kurz, B W; Emerson, J W; Johnson, M G

    1991-01-01

    BALB/c mice were immunized with crude cell surface proteins of Listeria monocytogenes V7. Approximately 1,680 hybridomas were generated after two fusions, and the monoclone C11E9 was selected and used for further characterization. The monoclonal antibody (MAb) produced by C11E9 was immunoglobulin subclass G2b with kappa light chains. Dot and colony blot results indicated that MAb C11E9 was reactive to all the L. monocytogenes (34 of 34) and Listeria innocua (6 of 6) isolates without any cross-reaction to other organisms tested. Western blot (immunoblot) analysis of crude cell surface proteins in native polyacrylamide gel electrophoresis (PAGE) indicated that MAb C11E9 reacts with a single band in each species, with a molecular mass of 174 kDa for L. monocytogenes and 182 kDa for L. innocua. The MAb reacted with one major protein band in Western blot from acid-urea PAGE for both L. monocytogenes and L. innocua. Isoelectric focusing results indicated two immunoreactive protein bands with pIs of 8.1 and 7.4 for L. monocytogenes. Sodium dodecyl sulfate (SDS)-PAGE and Western blot analysis indicated several proteins with molecular masses of 76, 66, 56, and 52 kDa for L. monocytogenes and 66, 56, and 52 kDa for L. innocua. Reaction of MAb C11E9 to washed live cells indicated the possible binding of antibody to cell surface antigen. These cell surface antigens could be removed by 1 N HCl plus 9 M urea, 2% SDS-0.5% beta-mercaptoethanol, or 4 M guanidine-HCl. The epitope of MAb C11E9 binding site was shown to be protein in nature. Periodic acid-Schiff staining and glycoprotein immunoassay indicated that carbohydrate was absent in the epitope. The cellular locations of the MAb C11E9-reactive antigens were calculated to be 76 and 90% outside and 24 and 10% inside the cell membranes of L. monocytogenes and L. innocua, respectively, for 12- to 14-h cultures. Images PMID:1715321

  4. 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, ...

  5. Quantifying Translocation of Listeria monocytogenes in Rats by Using Urinary Nitric Oxide-Derived Metabolites

    PubMed Central

    Sprong, R. Corinne; Hulstein, Marco F. E.; van der Meer, Roelof

    2000-01-01

    The urinary nitric oxide metabolites NO2− and NO3− (summed as NOx) are a noninvasive, quantitative biomarker of translocation of salmonella from the intestinal lumen to systemic organs. Listeria monocytogenes is a food-borne gram-positive pathogen that can also cross the intestinal epithelium. In this study, we tested the efficacy of urinary NOx as a marker of listeria translocation. Rats (eight per group) were orally infected with increasing doses of L. monocytogenes; control rats received heat-killed listeria. The kinetics of urinary NOx and population levels of listeria in feces were determined for 7 days. Another group of rats was killed 1 day after infection to verify translocation by culturing viable listeria from systemic organs. Oral administration of increasing doses of L. monocytogenes resulted in a time- and dose-dependent increase in urinary NOx excretion. Translocation was a prerequisite for inducing a NOx response, since heat-killed L. monocytogenes did not elevate NOx excretion in urine. Fecal counts of listeria also showed dose and time dependency. Moreover, the number of viable L. monocytogenes cells in mesenteric lymph nodes also increased in a dose-dependent manner and correlated with urinary NOx. In conclusion, urinary NOx is a quantitative, noninvasive biomarker of listeria translocation. PMID:11097905

  6. 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.

  7. Behaviour of Listeria Monocytogenes in Artisanal Raw Milk Pecorino Umbro Cheese: A Microbiological Challenge Test

    PubMed Central

    Ortenzi, Roberta; Branciari, Raffaella; Primavilla, Sara; Valiani, Andrea

    2015-01-01

    In the present study, a microbiological challenge test in artificially contaminated raw milk Pecorino Umbro cheese during cheese-making was carried out. Raw ewe milk was contaminated by a suspension of particular Listeria monocytogenes strains. The number of L. monocytogenes and L. monocytogenes dynamic growth were evaluated during cheese-making and storage. A significant decrease of the viable count of L. monocytogenes was observed during ripening and L. monocytogenes viable count was below the limit of quantification during storage. The results show that the product is unable to support the growth of the pathogen. PMID:27800412

  8. Detection of Listeria monocytogenes in CSF from Three Patients with Meningoencephalitis by Next-Generation Sequencing

    PubMed Central

    Yao, Ming; Zhou, Jiali; Zhu, Yicheng; Zhang, Yinxin; Lv, Xia; Sun, Ruixue; Shen, Ao; Ren, Haitao; Cui, Liying

    2016-01-01

    Background and Purpose Encephalitis caused by Listeria monocytogenes (L. monocytogenes) is rare but sometimes fatal. Early diagnosis is difficult using routine cerebrospinal fluid (CSF) tests, while next-generation sequencing (NGS) is increasingly being used for the detection and characterization of pathogens. Methods This study set up and applied unbiased NGS to detect L. monocytogenes in CSF collected from three cases of clinically suspected listeria meningoencephalitis. Results Three cases of patients with acute/subacute meningoencephalitis are reported. Magnetic resonance imaging and blood cultures led to a suspected diagnosis of L. monocytogenes, while the CSF cultures were negative. Unbiased NGS of CSF identified and sequenced reads corresponding to L. monocytogenes in all three cases. Conclusions This is the first report highlighting the feasibility of applying NGS of CSF as a diagnostic method for central nervous system (CNS) L. monocytogenes infection. Routine application of this technology in clinical microbiology will significantly improve diagnostic methods for CNS infectious diseases.

  9. 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...

  10. 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...

  11. 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...

  12. Effects of lactic acid on the growth characteristics of Listeria monocytogenes on cooked ham surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surfaces of ready-to-eat meats are susceptible to post-processing contamination by Listeria monocytogenes. This study examined and modeled the growth characteristics of L. monocytogenes on the surface of cooked ham treated with lactic acid solutions (LA). Pieces of cooked ham inoculated with a...

  13. 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...

  14. Genome Sequence of the Listeria monocytogenes Food Isolate HPB913, Collected in Canada in 1993.

    PubMed

    Pightling, Arthur W; Rand, Hugh; Strain, Errol; Pagotto, Franco

    2016-09-15

    Listeria monocytogenes is a pathogenic bacterium of importance to public health and food safety agencies. We present the genome sequence of the serotype 1/2a L. monocytogenes food isolate HPB913, which was collected in Canada in 1993 as part of an investigation into a sporadic case of foodborne illness.

  15. 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...

  16. 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...

  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. 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...

  19. 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...

  20. 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...

  1. Genome Sequence of the Listeria monocytogenes Food Isolate HPB913, Collected in Canada in 1993.

    PubMed

    Pightling, Arthur W; Rand, Hugh; Strain, Errol; Pagotto, Franco

    2016-01-01

    Listeria monocytogenes is a pathogenic bacterium of importance to public health and food safety agencies. We present the genome sequence of the serotype 1/2a L. monocytogenes food isolate HPB913, which was collected in Canada in 1993 as part of an investigation into a sporadic case of foodborne illness. PMID:27634991

  2. Genome Sequence of the Listeria monocytogenes Food Isolate HPB913, Collected in Canada in 1993

    PubMed Central

    Pightling, Arthur W.; Rand, Hugh; Strain, Errol

    2016-01-01

    Listeria monocytogenes is a pathogenic bacterium of importance to public health and food safety agencies. We present the genome sequence of the serotype 1/2a L. monocytogenes food isolate HPB913, which was collected in Canada in 1993 as part of an investigation into a sporadic case of foodborne illness. PMID:27634991

  3. Pathogenic capacity of Listeria monocytogenes isolated from various food types in Mexico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Mexico, although Listeria monocytogenes is not a mandatory diagnostic pathogen, neither in food nor in suspected clinical cases, the bacterium has been recovered from food. The latter highlights the importance of further characterizing the comparative virulence properties L. monocytogenes recover...

  4. 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...

  5. 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

  6. Listeria monocytogenes: a rare complication of ventriculoperitoneal shunt in children.

    PubMed

    Le Monnier, Alban; Blanot, Stéphane; Abachin, Eric; Beretti, Jean-Luc; Berche, Patrick; Kayal, Samer

    2011-11-01

    We report a case of ventriculoperitoneal (VP) shunt infection in a 3-year-old boy caused by the food-borne pathogen Listeria monocytogenes, subsequent to acute peritonitis. This unusual presentation of central nervous system (CNS) listeriosis underlines the ability of the bacteria to form and survive within biofilms on indwelling medical devices. Bacterial persistence may lead to treatment failure and spreading. We highlight the helpfulness of specific quantitative real-time PCR for the hly gene (PCR-hly) for the diagnosis and follow-up of such infections in detecting bacterial persistence within medical devices despite effective antibiotic treatment. Only the surgical replacement of the VP shunt will resolve the infection.

  7. Inhibition of intracellular growth of Listeria monocytogenes by antibiotics.

    PubMed Central

    Michelet, C; Avril, J L; Cartier, F; Berche, P

    1994-01-01

    We studied the activities of 15 antibiotics on the intracellular growth of Listeria monocytogenes in a HeLa cell line. After 24 h of contact with the infected cells, the antibiotics most effective against the intracellular growth of the 10 strains tested were amoxicillin, temafloxacin, and sparfloxacin, which nevertheless failed to totally eliminate the intracellular bacteria. Rifampin and co-trimoxazole had variable effects, depending on the isolates studied. The most active combinations were amoxicillin-sparfloxacin, co-trimoxazole-gentamicin, and sparfloxacin-co-trimoxazole. The results suggest the value of using a cell culture technique to study the activities of antibiotics against certain bacteria with intracellular sites of multiplication. PMID:8203836

  8. Incidence and contamination level of Listeria monocytogenes and other Listeria spp. in ready-to-eat meat products in Jordan.

    PubMed

    Awaisheh, S S

    2010-03-01

    The objective of the present study was to investigate the incidence and contamination levels of different Listeria monocytogenes serovars in ready-to-eat meat products (RTE-MP) collected from different outlets and processing plants in Jordan in order (i) to provide information to Jordanian health authorities on the incidence of L. monocytogenes in RTE-MP sold and consumed in Jordan and (ii) to ascertain the risks of these products for consumers. Two hundred forty RTE-MP samples, 120 beef and 120 poultry, were analyzed. European International Organization for Standardization (EN ISO) 11290-1 and -2 standard protocols were used for detection and enumeration of L. monocytogenes. The identity of suspected L. monocytogenes was confirmed using PCR. Three Listeria spp., L. monocytogenes, L. innocua, and L. welshimeri, were isolated. L. innocua and L. welshimeri were the most and least frequently isolated with 56 and 36 samples, respectively. L. monocytogenes was isolated from 41 samples (17.1%): 23 from beef and 18 from poultry samples. The contamination levels of L. monocytogenes were 100 CFU/g was found. The L. monocytogenes strains isolated fell into two serotypes (1 and 4) and four different serovars (1/2a, 1/2b, 1/2c, and 4b).

  9. Phenotypic and genotypic characterization of atypical Listeria monocytogenes and Listeria innocua isolated from swine slaughterhouses and meat markets.

    PubMed

    Moreno, Luisa Zanolli; Paixão, Renata; de Gobbi, Debora Dirani Sena; 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.

  10. 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

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

    PubMed

    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.

  12. Sensitive enumeration of Listeria monocytogenes and other Listeria species in various naturally contaminated matrices using a membrane filtration method.

    PubMed

    Barre, Léna; Brasseur, Emilie; Doux, Camille; Lombard, Bertrand; Besse, Nathalie Gnanou

    2015-06-01

    For the enumeration of Listeria monocytogenes (L. monocytogenes) in food, a sensitive enumeration method has been recently developed. This method is based on a membrane filtration of the food suspension followed by transfer of the filter on a selective medium to enumerate L. monocytogenes. An evaluation of this method was performed with several categories of foods naturally contaminated with L. monocytogenes. The results obtained with this technique were compared with those obtained from the modified reference EN ISO 11290-2 method for the enumeration of L. monocytogenes in food, and are found to provide more precise results. In most cases, the filtration method enabled to examine a greater quantity of food thus greatly improving the sensitivity of the enumeration. However, it was hardly applicable to some food categories because of filtration problems and background microbiota interference.

  13. 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...

  14. 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 ...

  15. A nucleic acid sequence-based amplification system for detection of Listeria monocytogenes hlyA sequences.

    PubMed Central

    Blais, B W; Turner, G; Sooknanan, R; Malek, L T

    1997-01-01

    A nucleic acid sequence-based amplification system primarily targeting mRNA from the Listeria monocytogenes hlyA gene was developed. This system enabled the detection of low numbers (< 10 CFU/g) of L. monocytogenes cells inoculated into a variety of dairy and egg products after 48 h of enrichment in modified listeria enrichment broth. PMID:8979357

  16. Genome Sequence of Listeria monocytogenes Scott A, a Clinical Isolate from a Food-Borne Listeriosis Outbreak▿

    PubMed Central

    Briers, Yves; Klumpp, Jochen; Schuppler, Markus; Loessner, Martin J.

    2011-01-01

    Listeria monocytogenes is an opportunistic food-borne pathogen and the causative agent of listeriosis in animals and humans. We present the genome sequence of Listeria monocytogenes Scott A, a widely distributed and frequently used serovar 4b clinical isolate from the 1983 listeriosis outbreak in Massachusetts. PMID:21685277

  17. 9 CFR 430.4 - Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... documentation that the establishment is required to maintain under 9 CFR 417.5. (7) The establishment must make... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Control of Listeria monocytogenes in... Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products. (a)...

  18. 9 CFR 430.4 - Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... documentation that the establishment is required to maintain under 9 CFR 417.5. (7) The establishment must make... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Control of Listeria monocytogenes in... Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products. (a)...

  19. 9 CFR 430.4 - Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... documentation that the establishment is required to maintain under 9 CFR 417.5. (7) The establishment must make... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Control of Listeria monocytogenes in... Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products. (a)...

  20. 9 CFR 430.4 - Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... documentation that the establishment is required to maintain under 9 CFR 417.5. (7) The establishment must make... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Control of Listeria monocytogenes in... Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products. (a)...

  1. 9 CFR 430.4 - Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... documentation that the establishment is required to maintain under 9 CFR 417.5. (7) The establishment must make... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Control of Listeria monocytogenes in... Control of Listeria monocytogenes in post-lethality exposed ready-to-eat products. (a)...

  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.

  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.

  5. 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

  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. Antimicrobial susceptibility and antibiotic resistance gene transfer analysis of foodborne, clinical, and environmental Listeria spp. isolates including Listeria monocytogenes.

    PubMed

    Bertsch, David; Muelli, Mirjam; Weller, Monika; Uruty, Anaïs; Lacroix, Christophe; Meile, Leo

    2014-02-01

    The aims of this study were to assess antibiotic resistance pheno- and genotypes in foodborne, clinical, and environmental Listeria isolates, as well as to elucidate the horizontal gene transfer potential of detected resistance genes. A small fraction of in total 524 Listeria spp. isolates (3.1%) displayed acquired antibiotic resistance mainly to tetracycline (n = 11), but also to clindamycin (n = 4) and trimethoprim (n = 3), which was genotypically confirmed. In two cases, a tetracycline resistance phenotype was observed together with a trimethoprim resistance phenotype, namely in a clinical L. monocytogenes strain and in a foodborne L. innocua isolate. Depending on the applied guidelines, a differing number of isolates (n = 2 or n = 20) showed values for ampicillin that are on the edge between intermediate susceptibility and resistance. Transferability of the antibiotic resistance genes from the Listeria donors, elucidated in vitro by filter matings, was demonstrated for genes located on transposons of the Tn916 family and for an unknown clindamycin resistance determinant. Transfer rates of up to 10(-5) transconjugants per donor were obtained with a L. monocytogenes recipient and up to 10(-7) with an Enterococcus faecalis recipient, respectively. Although the prevalence of acquired antibiotic resistance in Listeria isolates from this study was rather low, the transferability of these resistances enables further spread in the future. This endorses the importance of surveillance of L. monocytogenes and other Listeria spp. in terms of antibiotic susceptibility.

  8. [Immunomodulatory role of dietary lipids in an immunosuppressed mouse model and infected with listeria monocytogenes].

    PubMed

    Cerón Rodríguez, José María; Puertollano Vacas, M Ángeles; Puertollano Vacas, M Elena; Alvarez de Cienfuegos López, Gerardo

    2014-10-01

    Introducción: La capacidad inmunomoduladora de los ácidos grasos de la dieta en situaciones de inmunosupresión puede diferir de acuerdo con el tipo de ácido graso presente. Objetivo: Analizar el efecto de diferentes tipos de dietas lipídicas, en la resistencia de animales inmunosuprimidos o no, frente a una infección experimental con Listeria monocytogenes. Métodos: Ratones Balb/c fueron divididos en cuatro grupos experimentales, según su tratamiento inmunosupresor: control (PBS), Ciclofosfamida (CPA), GK 1.5 y RB6-8C5. Cada grupo fue subdividido en cuatro subgrupos según la dieta lipídica utilizada: control con aceite de maíz 5% (BG); aceite de oliva 20% (AO); aceite de pescado 20% (AP) y aceite de girasol 20% (AG). Los animales se alimentaron durante un mes antes del tratamiento y posteriormente infectados con L. monocytogenes. Resultados: Mostramos incrementos en el número de bacterias viables en bazo e hígado, y bajos porcentajes de supervivencia en todos los grupos de ratones inmunosuprimidos y también en el grupo PBS alimentado con AP. Además, se observaron incrementos en la linfoproliferación, de bazos de ratones alimentados con AO y tratados con CPA. Discusión: La dieta AP, produce una disminución en la resistencia del hospedador en situaciones de inmunosupresión. Por el contrario, las dietas AO y AG muestran mayor eficacia en la eliminación de L. monocytogenes y mayores ventajas en animales inmunosuprimidos. El tratamiento con RB6-8C5, produce una reducción en la supervivencia de los ratones de los grupos estudiados, lo que induce a establecer que los granulocitos juegan un papel fundamental en el control de la infección.

  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.

  10. 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

  11. Comparison of media and sampling locations for isolation of Listeria monocytogenes in queso fresco cheese.

    PubMed

    Lin, Chia-Min; Zhang, Lei; Doyle, Michael P; Swaminathan, Bala

    2006-09-01

    Listeriosis associated with Hispanic-style soft cheese is an ongoing public health concern. Although rapid detection methods based on molecular and immunological technologies have been applied successfully for detecting Listeria monocytogenes in foods, obtaining isolates of the pathogen is a critical procedure for epidemiologic studies and regulatory analysis. Oxford agar, a medium recommended by the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) to isolate L. monocytogenes from cheese, is unable to differentiate L. monocytogenes from other Listeria species. Hence, two selective isolation media, L. monocytogenes blood agar (LMBA) and Rapid 'L. mono agar (RLMA), were compared with Oxford agar for isolating L. monocytogenes from cheese. Queso fresco cheese was inoculated at 10(0) or 10(1) CFU/g with a five-strain mixture of L. monocytogenes or with the five-strain L. monocytogenes mixture and Listeria innocua. Cheese samples were stored at 21, 12, and 4 degrees C and Listeria counts were determined at 3, 7, and 10 days; 7, 10, 14, 21 days; and 2, 4, 8, and 12 weeks postinoculation, respectively. Surface and interior cheese samples as well as liquid exudate produced during storage were assayed individually to determine differences in Listeria contamination at different sampling locations. L. monocytogenes was more easily differentiated from L. innocua on RLMA than LMBA and Oxford agar. Similar L. monocytogenes counts (ca. 10(4) CFU/g) were obtained on the last sampling day on the surface and interior of cheese samples (P > 0.05) for all storage temperatures and both initial inoculation levels, but smaller cell numbers were detected in the exudate produced during storage. In addition, simultaneous inoculation of L. innocua with L. monocytogenes did not affect the final L. monocytogenes counts in the cheese. The amount of exudate released from the cheese and decrease of pH correlated with storage temperature. More exudate was produced and a

  12. 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.

  13. 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

  14. Listeria monocytogenes Meningitis in Adults: The Czech Republic Experience

    PubMed Central

    Rozsypal, Hanus; Smiskova, Dita; Benes, Jiri

    2013-01-01

    Background. Listeria monocytogenes (LM) is currently the third most frequent pathogen of bacterial meningitis in adults. Methods. A prospective study of patients with LM meningitis in a Czech tertiary care hospital, carried out from 1997 to 2012. Results. Thirty-one patients were diagnosed with LM meningitis, which was 7% of a total of 440 adult patients with acute bacterial meningitis (ABM) over a 16-year period. Their median age was 63 years, range 26–80 years. Nineteen patients (61%) had underlying immunocompromising comorbidity; 15 patients (48%) were older than 65 years. Fourteen patients (45%) had arterial hypertension. The typical triad of fever, neck stiffness, and altered mental status was present in 21 patients (68%). The median count of cerebrospinal fluid (CSF) leukocytes was 680/μL, protein level 2.6 g/L, and glucose ratio 0.28. Four patients (13%) died, and nine (29%) survived with moderate to severe sequelae. Conclusion. LM meningitis is known to affect immunosuppressed and elderly patients. Arterial hypertension seems to be another important predisposing factor. Clinical symptoms, CSF findings, and disease outcomes, did not significantly differ from other community-acquired ABM in our study, although the CSF leukocyte count was lower. Ampicillin showed good clinical and bacteriological efficacy in the majority of patients. PMID:24106719

  15. Tumor suppressor p53 protects mice against Listeria monocytogenes infection.

    PubMed

    Wang, Shaohui; Liu, Pingping; Wei, Jianchao; Zhu, Zixiang; Shi, Zixue; Shao, Donghua; Ma, Zhiyong

    2016-01-01

    Tumor suppressor p53 is involved in regulating immune responses, which contribute to antitumor and antiviral activity. However, whether p53 has anti-bacterial functions remains unclear. Listeria monocytogenes (LM) causes listeriosis in humans and animals, and it is a powerful model for studying innate and adaptive immunity. In the present study, we illustrate an important regulatory role of p53 during LM infection. p53 knockout (p53KO) mice were more susceptible to LM infection, which was manifested by a shorter survival time and lower survival rate. p53KO mice showed significant impairments in LM eradication. Knockdown of p53 in RAW264.7 and HeLa cells resulted in increased invasion and intracellular survival of LM. Furthermore, the invasion and intracellular survival of LM was inhibited in p53-overexpressing RAW264.7 and HeLa cells. LM-infected p53KO mice exhibited severe clinical symptoms and organ injury, presumably because of the abnormal production of the pro-inflammatory cytokines TNF-α, IL-6, IL-12, and IL-18. Decreased IFN-γ and GBP1 productions were observed in LM-infected p53-deficient mice or cells. The combination of these defects likely resulted in the overwhelming LM infection in the p53KO mice. These observations indicate that p53 serves as an important regulator of the host innate immune that protects against LM infection. PMID:27644341

  16. Tumor suppressor p53 protects mice against Listeria monocytogenes infection

    PubMed Central

    Wang, Shaohui; Liu, Pingping; Wei, Jianchao; Zhu, Zixiang; Shi, Zixue; Shao, Donghua; Ma, Zhiyong

    2016-01-01

    Tumor suppressor p53 is involved in regulating immune responses, which contribute to antitumor and antiviral activity. However, whether p53 has anti-bacterial functions remains unclear. Listeria monocytogenes (LM) causes listeriosis in humans and animals, and it is a powerful model for studying innate and adaptive immunity. In the present study, we illustrate an important regulatory role of p53 during LM infection. p53 knockout (p53KO) mice were more susceptible to LM infection, which was manifested by a shorter survival time and lower survival rate. p53KO mice showed significant impairments in LM eradication. Knockdown of p53 in RAW264.7 and HeLa cells resulted in increased invasion and intracellular survival of LM. Furthermore, the invasion and intracellular survival of LM was inhibited in p53-overexpressing RAW264.7 and HeLa cells. LM-infected p53KO mice exhibited severe clinical symptoms and organ injury, presumably because of the abnormal production of the pro-inflammatory cytokines TNF-α, IL-6, IL-12, and IL-18. Decreased IFN-γ and GBP1 productions were observed in LM-infected p53-deficient mice or cells. The combination of these defects likely resulted in the overwhelming LM infection in the p53KO mice. These observations indicate that p53 serves as an important regulator of the host innate immune that protects against LM infection. PMID:27644341

  17. Tumor suppressor p53 protects mice against Listeria monocytogenes infection.

    PubMed

    Wang, Shaohui; Liu, Pingping; Wei, Jianchao; Zhu, Zixiang; Shi, Zixue; Shao, Donghua; Ma, Zhiyong

    2016-01-01

    Tumor suppressor p53 is involved in regulating immune responses, which contribute to antitumor and antiviral activity. However, whether p53 has anti-bacterial functions remains unclear. Listeria monocytogenes (LM) causes listeriosis in humans and animals, and it is a powerful model for studying innate and adaptive immunity. In the present study, we illustrate an important regulatory role of p53 during LM infection. p53 knockout (p53KO) mice were more susceptible to LM infection, which was manifested by a shorter survival time and lower survival rate. p53KO mice showed significant impairments in LM eradication. Knockdown of p53 in RAW264.7 and HeLa cells resulted in increased invasion and intracellular survival of LM. Furthermore, the invasion and intracellular survival of LM was inhibited in p53-overexpressing RAW264.7 and HeLa cells. LM-infected p53KO mice exhibited severe clinical symptoms and organ injury, presumably because of the abnormal production of the pro-inflammatory cytokines TNF-α, IL-6, IL-12, and IL-18. Decreased IFN-γ and GBP1 productions were observed in LM-infected p53-deficient mice or cells. The combination of these defects likely resulted in the overwhelming LM infection in the p53KO mice. These observations indicate that p53 serves as an important regulator of the host innate immune that protects against LM infection.

  18. 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

  19. Enterocin 226NWC, a bacteriocin produced by Enterococcus faecalis 226, active against Listeria monocytogenes.

    PubMed

    Villani, F; Salzano, G; Sorrentino, E; Pepe, O; Marino, P; Coppola, S

    1993-04-01

    Enterococcus faecalis 226, isolated from natural whey cultures utilized as starters in the manufacture of mozzarella cheese from water-buffalo milk, produces a bacteriocin designated enterocin 226NWC. The bacteriocin was isolated from culture supernatant fluids of the producer strain and was active against strains of the same species and Listeria monocytogenes, but not against useful lactic acid bacteria. Enterocin 226NWC is a protein with an apparent molecular weight of about 5800; it is relatively heat-stable and has a bactericidal mode of action. Listeria monocytogenes, growing in the presence of the enterocin 226NWC producer strain in broth and in reconstituted skim milk, was inhibited.

  20. 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.

  1. Listeria monocytogenes-induced bacterial peritonitis caused by contaminated cheese in a patient with haemochromatosis.

    PubMed

    Galan, S R; Kann, P H; Gress, T M; Michl, P

    2011-07-01

    Infections with Listeria monocytogenes can present clinically with a wide range of different organ manifestations such as gastroenteritis, meningoencephalitis or osteomyelitis, posing a serious threat, particularly to immunocompromised patients. We present the case of a 76-year-old female patient with advanced liver disease due to underlying haemochromatosis, who was admitted to the hospital with increasing abdominal pain. She was diagnosed with spontaneous bacterial peritonitis caused by infection with Listeria monocytogenes, which she had acquired after consuming contaminated cheese from a local supermarket chain. To the best of our knowledge, this is the first case to describe Listeria-induced spontaneous bacterial peritonitis in a patient with haemochromatosis. Both end-stage liver disease and hereditary haemochromatosis on their own impair the local and systemic immune response, thereby representing predisposing factors for acquiring Listeria monocytogenes infection. This case demonstrates a rare organ manifestation of Listeria monocytogenes infection, which can be life-threatening if not diagnosed and treated adequately, and underlines the need to identify possible sources of infection in order to apply measures to prevent the further spread of the contaminated food.

  2. Amplified fragment length polymorphism analysis of Listeria monocytogenes by Experion™ automated microfluidic electrophoresis.

    PubMed

    Sammarco, Michela Lucia; Vitullo, Monia; Tamburro, Manuela; Pontello, Mirella; Ripabelli, Giancarlo

    2011-10-01

    Fifty Listeria monocytogenes strains were genotyped by sAFLP and PCR products were separated by agarose gel and automated chip-based microfluidic electrophoresis. A high congruency of results was observed comparing the two techniques, although for some cultures a better separation of sAFLP fragments was achieved with microfluidic system, which proved to be a highly reliable and reproducible tool to improve the molecular typing of L. monocytogenes, requiring lower volumes of samples and reducing significantly analysis time.

  3. 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.

  4. Subtyping Listeria monocytogenes from bulk tank milk using automated repetitive element-based PCR.

    PubMed

    Van Kessel, J S; Karns, J S; Gorski, L; Perdue, M L

    2005-12-01

    Sixty-one Listeria monocytogenes strains from raw milk were analyzed with an automated repetitive element-based PCR (rep-PCR) system to examine the utility of this system for serotype grouping and to determine whether specific regional relationships could be identified. Results of the similarity analysis revealed two primary clusters of L. monocytogenes isolates. Cluster 2 exclusively contained serogroup 1/2a isolates; however, two 1/2a isolates were also found in cluster 1. Isolates of serogroups 1/2b, 4b, 3b, and 4c were also in cluster 1. Clusters 1 and 2 were separated at a relative similarity of 86%. Listeria species other than L. monocytogenes (L. ivanovii, L. seeligeri, L. welshimeri, L. grayi, and L. innocua) had similarity scores of less than 80% in pairwise comparisons with the L. monocytogenes isolates. Thus, this method may be useful for species identification once an isolate is characterized as Listeria. When rep-PCR fingerprints of the L. monocytogenes 1/2a isolates were compared, there was no apparent regional grouping. However, discrimination between isolates suggests that the rep-PCR assay might be useful for tracking L. monocytogenes 1/2a and for tracking isolates across regions or within smaller ecological niches. The automated rep-PCR method could not discriminate between serotypes 1/2b and 4b but may be useful for discriminating between 1/2a and other serotypes and for tracking isolates within serotype 1/2a.

  5. Deletion of the membrane protein Lmo0412 increases the virulence of Listeria monocytogenes.

    PubMed

    Quereda, Juan José; Pucciarelli, María Graciela

    2014-08-01

    Listeria monocytogenes is a facultative intracellular pathogen that causes gastroenteritis, meningitis, encephalitis and maternofetal infections. 20-30% of eubacterial ORFs are predicted to encode membrane proteins. The bacterial cytoplasmic membrane is a macromolecular structure, which plays a key role for the pathogenesis. Despite this, little knowledge exists regarding the function of cytoplasmic membrane proteins of Listeria during infection. Here, we investigated a predicted membrane protein of the pathogen L. monocytogenes, Lmo0412, of unknown function. Lmo0412 is only present in the Listeria genus and low conserved in the non-pathogenic species L. innocua. Bacterial fractionation and western blot analyses showed that Lmo0412 was only detectable in the membrane of L. monocytogenes EGDe during logarithmic growth phase. lmo0412 expression in L. monocytogenes was down-regulated during in vitro infection of JEG-3 epithelial cells. An L. monocytogenes mutant deficient in this membrane protein showed increased invasion of Caco-2 and NRK-49F host cells using in vitro infection models. Moreover, the lack of Lmo0412 in this deletion mutant increased the viable bacteria counts in the spleen and liver of mice compared to the wild type strain. Taken together, these data suggest a selective advantage conferred by the absence of Lmo0412 for the virulence of L. monocytogenes.

  6. 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).

  7. 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

  8. Sublethal injury and virulence changes in Listeria monocytogenes and Listeria innocua treated with antimicrobials carvacrol and citral.

    PubMed

    Silva, A; Genovés, S; Martorell, P; Zanini, S F; Rodrigo, D; Martinez, A

    2015-09-01

    The aim of this study was to evaluate the effect of two antimicrobial substances, carvacrol and citral, on Listeria monocytogenes and Listeria innocua cells, as well as possible virulence changes in injured cells, using Caenorhabditis elegans as a model test. The results indicated that the percentage of sublethal damage was higher in L. monocytogenes than in L. innocua. The results of the study carried out by using C. elegans indicated that C. elegans fed in a lawn of L. monocytogenes previously treated with carvacrol showed a loss in life span (p ≤ 0.05) as compared with L. monocytogenes treated with citral, Escherichia coli OP50 as a negative control, and treated and untreated L. innocua. Egg laying was also affected: worms fed in a lawn of treated and untreated L. monocytogenes laid fewer eggs than those fed in a lawn of treated and untreated L. innocua or fed with OP50 as a negative control. Worms fed in a lawn of treated and untreated L. innocua also laid fewer eggs than those fed with OP50 as a negative control. A phenotype named bag of worms and an undescribed new one, "vulva inflammation", were also observed.

  9. 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

  10. Listeria monocytogenes Infection in a Sugar Glider (Petaurus breviceps) - New Mexico, 2011.

    PubMed

    Nichols, M; Takacs, N; Ragsdale, J; Levenson, D; Marquez, C; Roache, K; Tarr, C L

    2015-06-01

    Listeria monocytogenes is a Gram-positive, facultative anaerobic, rod-shaped bacterium that can infect and cause disease in many species. In this case report, we describe a case of L. monocytogenes infection causing sepsis in a sugar glider (Petaurus breviceps). The sugar glider consumed a varied diet consisting of human food items, including cantaloupe. A nationwide outbreak of L. monocytogenes foodborne illness associated with cantaloupes occurred simultaneously with this incident case. In this case, the bacterial strains from the outbreak and glider were genetically distinct. Although rare, veterinarians should be aware of the emergence of foodborne pathogens' ability to infect exotic animals residing in domestic environments.

  11. InstantLabs Listeria monocytogenes food safety kit. Performance tested method 051304.

    PubMed

    Sharma, Neil; Bambusch, Lauren; Le, Thu; Morey, Amit

    2014-01-01

    The InstantLabs Listeria monocytogenes Food Safety Kit was validated against the International Organization for Standardization (ISO) reference method 11290-1 for the detection of Listeria monocytogenes and other Listeria species. The matrixes (stainless steel, sealed concrete, ice cream, whole milk, cheddar cheese, raw shrimp, hot dogs, deli turkey, and lettuce) were inoculated with approximately 1 CFU/test portion of L. monocytogenes to generate fractional positives (5-15) in 20 inoculated samples. Enrichments were also fractionally inoculated with L. grayii for side-by-side testing of the Listeria Species Food Safety Kit. Stainless steel and sealed concrete samples were validated using 4 x 4" and 1 x 1 " test areas, respectively, and enriched in Buffered Listeria Enrichment Broth (BLEB) at 35 +/- 1degreesC for 22-28 h. All food samples were tested at 25 g and enriched in BLEB at 35 +/- 1 degreesC for 24-28 h. All samples were confirmed using the ISO reference method, regardless of initial screen result. The InstantLabs test method performed as well as or better than the reference method for the detection of L. monocytogenes on stainless steel and sealed concrete and in ice cream, whole milk, cheddar cheese, raw shrimp, hot dogs, deli turkey, and lettuce. Inclusivity and exclusivity testing revealed no false negatives and no false positives among the 50 L. monocytogenes serovars and 30 non-L. monocytogenes species examined. The method was shown to be robust when the enrichment times, volumes for DNA extraction, and heat block times were varied. PMID:25051634

  12. 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

  13. 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

  14. Listeria monocytogenes associated kerato-conjunctivitis in four horses in Norway.

    PubMed

    Revold, Tobias; Abayneh, Takele; Brun-Hansen, Hege; Kleppe, Signe L; Ropstad, Ernst-Otto; Hellings, Robert A; Sørum, Henning

    2015-11-09

    Listeria monocytogenes has been reported to cause various infectious diseases in both humans and animals. More rarely, ocular infections have been reported. To our knowledge, only two cases of Listeria keratitis have been described in horses. We report kerato-conjunctivitis in four Norwegian horses associated with L. monocytogenes. Clinically, all cases were presented with recurrent unilateral kerato-conjunctivitis. L. monocytogenes bacteria were isolated from swab samples from all cases, and cytology carried out in 3 cases was indicative of L. monocytogenes infection. The present report describes the first known cases in which L. monocytogenes has been isolated from keratitic lesions in horses in Norway. A potential risk factor may be feeding of silage or haylage, but other sources of infection cannot be ruled out. The phenotypic features including antimicrobial susceptibility and serotype of the isolates are described. Laboratory detection of L. monocytogenes demands extra caution since only low numbers of bacteria were detected in the eye-swabs, probably due to the low volume of sample material and the intracellular niche of the bacterium. A general poor response to treatment in all these cases indicates that clinicians should pay extra attention to intensity and duration of treatment if L. monocytogenes is identified in connection with equine kerato-conjunctivitis.

  15. Modeling the effect of temperature on survival rate of Listeria monocytogenes in yogurt.

    PubMed

    Szczawiński, J; Szczawińska, M E; Łobacz, A; Jackowska-Tracz, A

    2016-01-01

    The aim of the study was to (i) evaluate the behavior of Listeria monocytogenes in a commercially produced yogurt, (ii) determine the survival/inactivation rates of L. monocytogenes during cold storage of yogurt and (iii) to generate primary and secondary mathematical models to predict the behavior of these bacteria during storage at different temperatures. The samples of yogurt were inoculated with the mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12 and 15°C for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14 and 16 days of storage. From each sample a series of decimal dilutions were prepared and plated onto ALOA agar (agar for Listeria according to Ottaviani and Agosti). It was found that applied temperature and storage time significantly influenced the survival rate of listeriae (p<0.01). The number of L. monocytogenes in all the samples decreased linearly with storage time. The slowest decrease in the number of the bacteria was found in the samples stored at 6°C (D-10 value = 243.9 h), whereas the highest reduction in the number of the bacteria was observed in the samples stored at 15°C (D-10 value = 87.0 h). The number of L. monocytogenes was correlated with the pH value of the samples (p<0.01). The natural logarithm of the mean survival/inactivation rates of L. monocytogenes calculated from the primary model was fitted to two secondary models, namely linear and polynomial. Mathematical equations obtained from both secondary models can be applied as a tool for the prediction of the survival/inactivation rate of L. monocytogenes in yogurt stored under temperature range from 3 to 15°C, however, the polynomial model gave a better fit to the experimental data. PMID:27487505

  16. Molecular typing by pulsed-field gel electrophoresis of Spanish animal and human Listeria monocytogenes isolates.

    PubMed

    Vela, A I; Fernandez-Garayzabal, J F; Vazquez, J A; Latre, M V; Blanco, M M; Moreno, M A; de La Fuente, L; Marco, J; Franco, C; Cepeda, A; Rodriguez Moure, A A; Suarez, G; Dominguez, L

    2001-12-01

    A total of 153 strains of Listeria monocytogenes isolated from different sources (72 from sheep, 12 from cattle, 18 from feedstuffs, and 51 from humans) in Spain from 1989 to 2000 were characterized by pulsed-field gel electrophoresis. The strains of L. monocytogenes displayed 55 pulsotypes. The 84 animal, 51 human, and 18 feedstuff strains displayed 31, 29, and 7 different pulsotypes, respectively, indicating a great genetic diversity among the Spanish L. monocytogenes isolates studied. L. monocytogenes isolates from clinical samples and feedstuffs consumed by the diseased animals were analyzed in 21 flocks. In most cases, clinical strains from different animals of the same flock had identical pulsotypes, confirming the existence of a listeriosis outbreak. L. monocytogenes strains with pulsotypes identical to those of clinical strains were isolated from silage, potatoes, and maize stalks. This is the first study wherein potatoes and maize stalks are epidemiologically linked with clinical listeriosis.

  17. Incidence and characteristics of Staphylococcus aureus and Listeria monocytogenes from the Japan and South China seas.

    PubMed

    Beleneva, Irina A

    2011-02-01

    The distribution of Staphylococcus aureus and Listeria monocytogenes in the sea water and marine organisms of Peter the Great and Nha Trang bays, the phenotypic properties and antibiotic sensitivity of the isolates were studied. S. aureus was recorded from 9.3% samples in the Sea of Japan and from 20.4% samples in the South China Sea, L. monocytogenes respectively from 5.9 % and 5.8 % samples. S. aureus and L. monocytogenes found in the tropics differed in their phenotypic properties from those found in the temperate zone. Antibiotic resistance was detected in 81.8% and 71.8% of S. aureus strains and in 19% and 71.4% of L. monocytogenes strains respectively from Peter the Great Bay and from Vietnam. The results show that multiresistant strains of S. aureus and L. monocytogenes are widespread throughout Peter the Great and Nha Trang bays and present a hazard to the health of humans and marine animals.

  18. 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

  19. 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

  20. 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

  1. 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...

  2. 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 ...

  3. 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

  4. 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...

  5. 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...

  6. Draft Genome Sequences of Historical Listeria monocytogenes from Human Listeriosis, 1933

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report here the draft genome sequences of two Listeria monocytogenes strains from some of the earliest reported cases of human listeriosis in North America. The strains were isolated in 1933 from patients in Massachusetts and Connecticut, USA, and belong to the widely disseminated hypervirulent c...

  7. 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...

  8. 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...

  9. 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 ...

  10. 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...

  11. 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 ...

  12. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 mo...

  14. 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...

  15. 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...

  16. 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...

  17. 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 ...

  18. 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.

  19. 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

  20. Genome comparison of Listeria monocytogenes serotype 4a strain HCC23 with selected lineage I and lineage II L. monocytogenes strains and other Listeria strains

    PubMed Central

    Paul, Debarati; Steele, Chelsea; Donaldson, Janet R.; Banes, Michelle M.; Kumar, Ranjit; Bridges, Susan M.; Arick, Mark; Lawrence, Mark L.

    2014-01-01

    More than 98% of reported human listeriosis cases are caused by specific serotypes within genetic lineages I and II. The genome sequence of Listeria monocytogenes lineage III strain HCC23 (serotype 4a) enables whole genomic comparisons across all three L. monocytogenes lineages. Protein cluster analysis indicated that strain HCC23 has the most unique protein pairs with nonpathogenic species Listeria innocua. Orthology analysis of the genome sequences of representative strains from the three L. monocytogenes genetic lineages and L. innocua (CLIP11262) identified 319 proteins unique to nonpathogenic strains HCC23 and CLIP11262 and 58 proteins unique to pathogenic strains F2365 and EGD-e. BLAST comparison of these proteins with all the sequenced L. monocytogenes and L. innocua revealed 126 proteins unique to serotype 4a and/or L. innocua; 14 proteins were only found in pathogenic serotypes. Some of the 58 proteins unique to pathogenic strains F2365 and EGD-e were previously published and are already known to contribute to listerial virulence. PMID:26484097

  1. An outbreak of an unusual strain of Listeria monocytogenes infection in North-East Scotland.

    PubMed

    Okpo, Emmanuel; Leith, Jayne; Smith-Palmer, Alison; Bell, John; Parks, Duncan; Browning, Fiona; Byers, Lynn; Corrigan, Helen; Webster, Diana; Karcher, Anne M; Murray, Andrew; Storey, Tom

    2015-01-01

    Listeria monocytogenes infection is an important cause of illness and hospitalization in vulnerable individuals. In the present study, we describe a community outbreak of Listeria monocytogenes in the North-East region of Scotland, which was epidemiologically, environmentally and microbiologically linked to a local meat product and ready-to-eat product manufacturer. Infected individuals were interviewed, and an environmental investigation was conducted. Clinical and environmental samples were tested by culture, and isolates were typed by fluorescent amplified fragment length polymorphism (fAFLP). Three cases of Listeria monocytogenes were linked geographically, had the same serotype (1/2a) and were indistinguishable by fAFLP type XII.6. The human, food and environmental isolates were of the same serotype and were indistinguishable by molecular typing. This is the first community outbreak of L. monocytogenes reported in Scotland since the current outbreak surveillance was established in 1996. Epidemiological and laboratory evidence indicated poor hand hygiene, unhygienic practices and cross-contamination throughout the manufacturing process of ready-to-eat foods as a possible cause of the outbreak. More stringent control of commercial food establishments that provide ready-to-eat food and the need to advise specifically vulnerable groups, e.g., pregnant women, of the risk of L. monocytogenes in ready-to-eat food is urgently needed.

  2. Efficiency of four secondary enrichment protocols in differentiation and isolation of Listeria spp. and Listeria monocytogenes from smoked fish processing chains.

    PubMed

    Duarte, G; Vaz-Velho, M; Capell, C; Gibbs, P

    1999-11-15

    Four secondary enrichment protocols (conventional methods: UVM II, Fraser 24 h and Fraser 48 h: Impedimetric method: Listeria electrical detection medium) were studied for their ability to isolate Listeria spp. and Listeria monocytogenes from fish and environmental samples collected along the processing chain of cold-smoked fish. From all methods, Listeria spp. and L. monocytogenes were respectively present in 56 and 34 of 315 samples analysed. Fraser broth incubated for 48 h gave the fewest false negative Listeria spp. results [4/56; (7.1%)], but concurrently only 15/34 (44.1%) samples were correctly identified as containing L. monocytogenes, Listeria electrical detection (LED) medium detected only 36/56 (64.3%) Listeria spp. positive samples. Despite this lower isolation rate, LED identified 20/34 (58.8%) L. monocytogenes positive samples correctly and gave fewer false positive results. The overall conclusion was that more than one isolation method is needed to accurately estimate L. monocytogenes contamination rates. PMID:10733247

  3. A simple RNA probe system for analysis of Listeria monocytogenes polymerase chain reaction products.

    PubMed Central

    Blais, B W; Phillippe, L M

    1993-01-01

    The synthesis of an RNA probe specific for the hlyA gene of Listeria monocytogenes by in vitro transcription from a polymerase chain reaction (PCR)-generated template incorporating bacteriophage T7 promoter sequences is described. This simple method produced a high yield of RNA which hybridized specifically with hlyA PCR products on a membrane, resulting in RNA-DNA hybrids which were detected by an immunoenzymatic assay with an anti-RNA-DNA hybrid antibody. The RNA probe hybridization system was more sensitive in the analysis of the PCR products than was the conventional agarose gel electrophoresis method. When applied to the analysis of PCR samples from cultures of various Listeria and non-Listeria organisms, the RNA probe was reactive in the assay of 62 different L. monocytogenes isolates but not other Listeria species. Among the non-Listeria organisms tested, only Enterococcus faecalis gave a weak positive reaction with more than 10(9) cells per ml. This reactivity disappeared at lower cell densities. This strategy for the synthesis and application of RNA probes should facilitate the analysis of PCR products in the detection of L. monocytogenes and possibly other food pathogens. Images PMID:8215354

  4. Teichoic acid is the major polysaccharide present in the Listeria monocytogenes biofilm matrix.

    PubMed

    Brauge, Thomas; Sadovskaya, Irina; Faille, Christine; Benezech, Thierry; Maes, Emmanuel; Guerardel, Yann; Midelet-Bourdin, Graziella

    2016-01-01

    The aim of this study was to characterize the Listeria monocytogenes biofilm and particularly the nature of the carbohydrates in the biofilm extracellular matrix and culture supernatant versus to cell wall carbohydrates. Listeria monocytogenes serotype 1/2a and 4b strains were able to form complex biofilms embedded in an extracellular matrix. The soluble carbohydrates from biofilm extracellular matrix and culture supernatant were identified as teichoic acids, structurally identical to cell wall teichoic acids. In addition, the DSS 1130 BFA2 strain had a serotype 1/2a teichoic acid lacking N-acetyl glucosamine glycosylation due to a mutation in the lmo2550 gene. Consequently, we hypothesized that the extracellular teichoic acids in L. monocytogenes biofilms have the same origin as cell wall teichoic acid.

  5. Replica plating of colonies from Listeria-selective agars to blood agar to improve the isolation of Listeria monocytogenes from foods.

    PubMed

    Cassiday, P K; Graves, L M; Swaminathan, B

    1990-07-01

    Bacterial colonies from Listeria-selective agars were replica plated to sheep blood agar to screen for beta-hemolysis. By using the replica plating method to test for the beta-hemolytic characteristic of all the colonies growing on Listeria-selective agars instead of picking 3 to 10 suspected colonies for further testing, we recovered Listeria monocytogenes from 59 of 142 Listeria-selective agar plates which contained colonies of hemolytic and nonhemolytic Listeria species and were negative when tested by conventional colony picks.

  6. 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

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

    PubMed

    Vallim, Deyse Christina; Barroso Hofer, Cristina; Lisbôa, Rodrigo de Castro; Barbosa, André Victor; 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.

  8. 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...

  9. Efficiency of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing gloves.

    PubMed

    Liu, Chengchu; Su, Yi-Cheng

    2006-07-15

    Food processing gloves are typically used to prevent cross-contamination during food preparation. However, gloves can be contaminated with microorganisms and become a source of contamination. This study investigated the survival of Listeria monocytogenes on gloves and determined the efficacy of electrolyzed oxidizing (EO) water for reducing L. monocytogenes contamination on seafood processing gloves. Three types of reusable gloves (natural rubber latex, natural latex, and nitrile) and two types of disposable gloves (latex and nitrile) were cut into small pieces (4 x 4 cm(2)) and inoculated with 5-strain L. monocytogenes cocktail (5.1 x 10(7) CFU/cm(2)) with and without shrimp meat residue attached to surfaces. L. monocytogenes did not survive well on clean reusable gloves and its populations decreased rapidly to non-detectable levels within 30 min at room temperature. However, high levels of Listeria cells were recovered from clean disposable gloves after 30 min of inoculation. Presence of shrimp meat residue on gloves enhanced the survival of L. monocytogenes. Cells of L. monocytogenes were detected on both reusable and disposal gloves even after 2 h at room temperature. Soaking inoculated gloves in EO water at room temperature for 5 min completely eliminated L. monocytogenes on clean gloves (>4.46 log CFU/cm(2) reductions) and significantly (p<0.05) reduced the contamination on soil-containing gloves when compared with tap water treatment. EO water could be used as a sanitizer to reduce L. monocytogenes contamination on gloves and reduce the possibility of transferring L. monocytogenes from gloves to RTE seafoods. PMID:16690154

  10. 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.

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

    PubMed Central

    Winkelströter, Lizziane Kretli; Martinis, Elaine C.P. De

    2015-01-01

    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. 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.

  13. 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

  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. Modeling the growth of Listeria monocytogenes on cut cantaloupe, honeydew and watermelon.

    PubMed

    Danyluk, Michelle D; Friedrich, Loretta M; Schaffner, Donald W

    2014-04-01

    A recent outbreak linked to whole cantaloupes underscores the importance of understanding growth kinetics of Listeria monocytogenes in cut melons at different temperatures. Whole cantaloupe, watermelon, and honeydew purchased from a local supermarket were cut into 10 ± 1 g cubes. A four-strain cocktail of L. monocytogenes from food related outbreaks was used to inoculate fruit, resulting in ~10(3) CFU/10 g. Samples were stored at 4, 10, 15, 20, or 25 °C and L. monocytogenes were enumerated at appropriate time intervals. The square root model was used to describe L. monocytogenes growth rate as a function of temperature. The model was compared to prior models for Salmonella and Escherichia coli O157:H7 growth on cut melon, as well as models for L. monocytogenes on cantaloupe and L. monocytogenes ComBase models. The current model predicts faster growth of L. monocytogenes vs. Salmonella and E. coli O157:H7 at temperatures below 20 °C, and agrees with estimates from ComBase Predictor, and a corrected published model for L. monocytogenes on cut cantaloupe. The model predicts ~4 log CFU increase following 15 days at 5 °C, and ∼1 log CFU increase following 6 days at 4 °C. The model can also be used in subsequent quantitative microbial risk assessments.

  16. Listeria monocytogenes Inhibits Serotonin Transporter in Human Intestinal Caco-2 Cells.

    PubMed

    Latorre, E; Pradilla, A; Chueca, B; Pagán, R; Layunta, E; Alcalde, A I; Mesonero, J E

    2016-10-01

    Listeria monocytogenes is a Gram-positive bacterium that can cause a serious infection. Intestinal microorganisms have been demonstrated to contribute to intestinal physiology not only through immunological responses but also by modulating the intestinal serotonergic system. Serotonin (5-HT) is a neuromodulator that is synthesized in the intestinal epithelium and regulates the whole intestinal physiology. The serotonin transporter (SERT), located in enterocytes, controls intestinal 5-HT availability and therefore serotonin's effects. Infections caused by L. monocytogenes are well described as being due to the invasion of intestinal epithelial cells; however, the effect of L. monocytogenes on the intestinal epithelium remains unknown. The main aim of this work, therefore, was to study the effect of L. monocytogenes on SERT. Caco2/TC7 cell line was used as an enterocyte-like in vitro model, and SERT functional and molecular expression assays were performed. Our results demonstrate that living L. monocytogenes inhibits serotonin uptake by reducing SERT expression at the brush border membrane. However, neither inactivated L. monocytogenes nor soluble metabolites were able to affect SERT. The results also demonstrate that L. monocytogenes yields TLR2 and TLR10 transcriptional changes in intestinal epithelial cells and suggest that TLR10 is potentially involved in the inhibitory effect observed on SERT. Therefore, L. monocytogenes, through TLR10-mediated SERT inhibition, may induce increased intestinal serotonin availability and potentially contributing to intestinal physiological changes and the initiation of the inflammatory response.

  17. Listeria monocytogenes Inhibits Serotonin Transporter in Human Intestinal Caco-2 Cells.

    PubMed

    Latorre, E; Pradilla, A; Chueca, B; Pagán, R; Layunta, E; Alcalde, A I; Mesonero, J E

    2016-10-01

    Listeria monocytogenes is a Gram-positive bacterium that can cause a serious infection. Intestinal microorganisms have been demonstrated to contribute to intestinal physiology not only through immunological responses but also by modulating the intestinal serotonergic system. Serotonin (5-HT) is a neuromodulator that is synthesized in the intestinal epithelium and regulates the whole intestinal physiology. The serotonin transporter (SERT), located in enterocytes, controls intestinal 5-HT availability and therefore serotonin's effects. Infections caused by L. monocytogenes are well described as being due to the invasion of intestinal epithelial cells; however, the effect of L. monocytogenes on the intestinal epithelium remains unknown. The main aim of this work, therefore, was to study the effect of L. monocytogenes on SERT. Caco2/TC7 cell line was used as an enterocyte-like in vitro model, and SERT functional and molecular expression assays were performed. Our results demonstrate that living L. monocytogenes inhibits serotonin uptake by reducing SERT expression at the brush border membrane. However, neither inactivated L. monocytogenes nor soluble metabolites were able to affect SERT. The results also demonstrate that L. monocytogenes yields TLR2 and TLR10 transcriptional changes in intestinal epithelial cells and suggest that TLR10 is potentially involved in the inhibitory effect observed on SERT. Therefore, L. monocytogenes, through TLR10-mediated SERT inhibition, may induce increased intestinal serotonin availability and potentially contributing to intestinal physiological changes and the initiation of the inflammatory response. PMID:27488594

  18. 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

  19. Detection of Listeria monocytogenes in ready-to-eat food by Step One real-time polymerase chain reaction.

    PubMed

    Pochop, Jaroslav; Kačániová, Miroslava; Hleba, Lukáš; Lopasovský, L'ubomír; Bobková, Alica; Zeleňáková, Lucia; Stričík, Michal

    2012-01-01

    The aim of this study was to follow contamination of ready-to-eat food with Listeria monocytogenes by using the Step One real time polymerase chain reaction (PCR). We used the PrepSEQ Rapid Spin Sample Preparation Kit for isolation of DNA and MicroSEQ® Listeria monocytogenes Detection Kit for the real-time PCR performance. In 30 samples of ready-to-eat milk and meat products without incubation we detected strains of Listeria monocytogenes in five samples (swabs). Internal positive control (IPC) was positive in all samples. Our results indicated that the real-time PCR assay developed in this study could sensitively detect Listeria monocytogenes in ready-to-eat food without incubation.

  20. 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.

  1. Identification of the agr Peptide of Listeria monocytogenes.

    PubMed

    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

  2. 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

  3. International Life Sciences Institute North America Listeria monocytogenes strain collection: development of standard Listeria monocytogenes strain sets for research and validation studies.

    PubMed

    Fugett, Eric; Fortes, Esther; Nnoka, Catherine; Wiedmann, Martin

    2006-12-01

    Research and development efforts on bacterial foodborne pathogens, including the development of novel detection and subtyping methods, as well as validation studies for intervention strategies can greatly be enhanced through the availability and use of standardized strain collections. These types of strain collections are available for some foodborne pathogens, such as Salmonella and Escherichia coli. We have developed a standard Listeria monocytogenes strain collection that has not been previously available. The strain collection includes (i) a diversity set of 25 isolates chosen to represent a genetically diverse set of L. monocytogenes isolates as well as a single hemolytic Listeria innocua strain and (ii) an outbreak set, which includes 21 human and food isolates from nine major human listeriosis outbreaks that occurred between 1981 and 2002. The diversity set represents all three genetic L. monocytogenes lineages (I, n = 9; II, n = 9; and III, n = 6) as well as nine different serotypes. Molecular subtyping by EcoRI automated ribotyping and pulsed-field gel electrophoresis (PFGE) with AscI and ApaI separated the 25 isolates in the diversity set into 23 ribotypes and 25 PFGE types, confirming that this isolate set represents considerable genetic diversity. Molecular subtyping of isolates in the outbreak set confirmed that human and food isolates were identical by ribotype and PFGE, except for human and food isolates for two outbreaks, which displayed related but distinct PFGE patterns. Subtype and source data for all isolates in this strain collection are available on the Internet and are linked to the PathogenTracker database (www.pathogentracker.com), which allows the addition of new, relevant information on these isolates, including links to publications that have used isolates from this collection. We have thus developed a core L. monocytogenes strain collection, which will provide a resource for L. monocytogenes research and development efforts with

  4. Post-parturient shedding of Listeria monocytogenes in breast milk of infected mice

    PubMed Central

    Poulsen, Keith P; Pillers, DeAnn M; Conway, James H; Faith, Nancy G; Czuprynski, Charles J

    2014-01-01

    The objectives of this study were to develop an animal model to study Listeria monocytogenes infection during the peri-parturient period and identify sources of maternal shedding of the pathogen. Peri-parturient mice were infected intragastrically with L. monocytogenes that expressed bacterial luciferase. Mice were then imaged in vivo over time. Secreted breast milk samples from mice infected after parturition were enriched and plated for culture and imaging. Bioluminescence imaging technology was able to detect luciferase emitting L. monocytogenes in vaginal secretions and maternal and fetal organs at 72 and 96 h post infection in mice infected prior to, or just after, parturition. The results from this study clearly show that L. monocytogenes is shed in vaginal secretions and disseminates to the mammary chain, from which it can be shed in the milk of peri-parturient mice. PMID:24246517

  5. Thermal inactivation of Listeria monocytogenes during rapid and slow heating in sous vide cooked beef.

    PubMed

    Hansen, T B; Knøchel, S

    1996-06-01

    Heating at slowly rising temperatures is suspected to enhance thermotolerance in Listeria monocytogenes and, since anaerobic environments have been shown to facilitate resuscitation of heat-injured cells of this micro-organism, concern may arise about the possibility of L. monocytogenes surviving in minimally preserved products. The effect of rapid ( > 10 degrees C min-1) and slow (0.3 and 0.6 degrees C min-1) heating on survival of L. monocytogenes in sous vide cooked beef was therefore examined at mild processing temperatures of 56 degrees, 60 degrees and 64 degrees C. No statistically significant difference (P = 0.70) was observed between the tested heating regimes. Since the average pH of beef was low (5.6), and little or no effect was observed, a pH-dependency of heat shock-induced thermotolerance in L. monocytogenes is suggested to account for this result. PMID:8695067

  6. Heat resistance of an outbreak strain of Listeria monocytogenes in hot dog batter.

    PubMed

    Mazzotta, A S; Gombas, D E

    2001-03-01

    The heat resistance of a strain of Listeria monocytogenes responsible for a listeriosis outbreak in hot dogs was not higher than the heat resistance of other L. monocytogenes strains when tested in tryptic soy broth and in laboratory-prepared hot dog batter. For the thermal death time experiments, the cells were grown to stationary phase or were starved in phosphate-buffered saline, pH 7, for 6 h at 30 degrees C. Starvation increased the heat resistance of L. monocytogenes in broth but not in hot dog batter. D-values in hot dog batter were higher than in broth. For the hot dog formulation used in this study, cooking the hot dog batter for 30 s at 71.1 degrees C (160 degrees F), or its equivalent using a z-value of 6 degrees C (11 degrees F), would inactivate 5 logs of L. monocytogenes.

  7. 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

  8. 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

  9. Prevalence and quantification of Listeria monocytogenes in chicken offal at the retail level in Malaysia.

    PubMed

    Kuan, C H; Goh, S G; Loo, Y Y; Chang, W S; Lye, Y L; Puspanadan, S; Tang, J Y H; Nakaguchi, Y; Nishibuchi, M; Mahyudin, N A; Radu, S

    2013-06-01

    A total of 216 chicken offal samples (chicken liver = 72; chicken heart = 72; chicken gizzard = 72) from wet markets and hypermarkets in Selangor, Malaysia, were examined for the presence and density of Listeria monocytogenes by using a combination of the most probable number and PCR method. The prevalence of L. monocytogenes in 216 chicken offal samples examined was 26.39%, and among the positive samples, the chicken gizzard showed the highest percentage at 33.33% compared with chicken liver (25.00%) and chicken heart (20.83%). The microbial load of L. monocytogenes in chicken offal samples ranged from <3 to 93.0 most probable number per gram. The presence of L. monocytogenes in chicken offal samples may indicate that chicken offal can act as a possible vehicle for the occurrence of foodborne listeriosis. Hence, there is a need to investigate the biosafety level of chicken offal in Malaysia. PMID:23687164

  10. 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

  11. Heat resistance of Listeria monocytogenes in vegetables: evaluation of blanching processes.

    PubMed

    Mazzotta, A S

    2001-03-01

    The heat resistance of a Listeria monocytogenes composite (serotypes 1/2a, 1/2b, and 4b) was determined in fresh broccoli florets, sweet green peppers, onions, mushrooms, and peas using an end-point procedure in polyester pouches. The heat resistance of L. monocytogenes was higher in peas (D(60 degrees C) = 1.0 min) and mushrooms (D(60 degrees C) = 0.7 min) than in other vegetables tested (D(60 degrees C) in onions = 0.2 min) and was highest when cells were subjected to starvation before the thermal death time experiments (D(60 degrees C) of starved L. monocytogenes in mushrooms = 1.6 min). The results showed that blanching can be used as an antilisterial treatment (inactivation of 5 logs of L. monocytogenes) when the cold spot of vegetables is treated for at least 10 s at 75 degrees C or instantaneously (<1 s) at temperatures above 82 degrees C.

  12. 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

  13. Evaluation of Listeria monocytogenes survival in ice cream mixes flavored with herbal tea using Taguchi method.

    PubMed

    Ozturk, Ismet; Golec, Adem; Karaman, Safa; Sagdic, Osman; Kayacier, Ahmed

    2010-10-01

    In this study, the effects of the incorporation of some herbal teas at different concentrations into the ice cream mix on the population of Listeria monocytogenes were studied using Taguchi method. The ice cream mix samples flavored with herbal teas were prepared using green tea and sage at different concentrations. Afterward, fresh culture of L. monocytogenes was inoculated into the samples and the L. monocytogenes was counted at different storage periods. Taguchi method was used for experimental design and analysis. In addition, some physicochemical properties of samples were examined. Results suggested that there was some effect, although little, on the population of L. monocytogenes when herbal tea was incorporated into the ice cream mix. Additionally, the use of herbal tea caused a decrease in the pH values of the samples and significant changes in the color values.

  14. The handling of Listeria monocytogenes by macrophages: the search for an immunogenic molecule in antigen presentation.

    PubMed

    Allen, P M; Beller, D I; Braun, J; Unanue, E R

    1984-01-01

    The activation of T lymphocytes for immunity to the intracellular pathogen Listeria monocytogenes requires that Ia-positive macrophages ingest the bacteria. The subsequent handling of Listeria by macrophages was examined in this report and related to antigen presentation to T cells. Macrophages pulsed with radiolabeled Listeria, besides releasing acid-soluble radioactivity--an indication of extensive catabolism of the Listeria-derived proteins--were also found to release acid-insoluble peptides. The rate of release of the peptides was not markedly affected by treatment with chloroquine, ammonia, or monensin and was independent of the state of activation and the level of Ia expression of the macrophage. The peptides were not associated with fragments of membranes and were represented by several molecular species. Listeria-derived peptides were also found associated with the macrophage plasma membrane. The membrane-associated peptides behaved like integral membrane proteins and could be released by proteases or detergents. Their expression was independent of the dose of Listeria and the level of Ia expression of the macrophage, and their presence could not be inhibited by protease inhibitors or chloroquine. The Listeria peptides released by the macrophages were very weakly immunogenic in a T cell proliferation assay. Purified plasma membranes from Listeria-pulsed macrophages, which contained membrane-associated Listeria peptides, were not immunogenic by themselves but could be reprocessed by additional macrophages to subsequently stimulate T cells. Trypsin treatment of Listeria-pulsed macrophages did not cause a significant reduction in their ability to stimulate T cells. No association was found between Ia molecules and either the membrane-associated or the released peptides with the use of several technical approaches. Hence, after internalization of Listeria, potentially immunogenic material can be found at the cell surface as well as in the culture fluid. The

  15. Metastatic Listeria monocytogenes infection of the peritoneum in mice with cyclosporine a-induced peritonitis.

    PubMed

    Prats, N; López, S; Domingo, M; Briones, V; Domínguez, L; Marco, A J

    2002-01-01

    Inoculation of mice with Listeria monocytogenes intragastrically or by parenteral routes has not been reported to cause peritonitis. In this study, however, severe listerial peritonitis was induced in mice infected subcutaneously and treated intraperitoneally with cyclosporin A (Cs A) in an oil carrier. In both uninfected and listeria-infected mice, intraperitoneal administration of Cs A consistently produced overexpression of P-selectin in the peritoneal microvasculature and pyogranulomatous inflammation of the peritoneum, suggesting that Cs A causes endothelial damage. We suggest that in listeria-infected mice the non-specific irritant peritonitis induced by the intraperitoneal administration of Cs A results in transfer of listeria-infected phagocytes from the liver and spleen to the peritoneal microvasculature, producing metastatic infection.

  16. Pulsed-field gel electrophoresis typing of Listeria monocytogenes isolated in two Finnish fish farms.

    PubMed

    Katzav, Marianne; Hyvönen, Paula; Muje, Petri; Rantala, Leila; Von Wright, Atte

    2006-06-01

    The aim of this study was to find sources of Listeria monocytogenes contamination in fish products from a fish farm. The occurrence of L. monocytogenes also was compared in two freshwater fish farms with different types of fishponds. Samples collected from chilled rainbow trout (Oncorhynchus mykiss) and the slaughterhouse environment did not contain L. monocytogenes, but Listeria innocua was found in two samples from the slaughterhouses. Ten isolates of L. monocytogenes were discovered in sediment and water samples from farming tanks and earth ponds. Further characterization by serovar revealed the same serovar (1/2a) for all the isolates. Pulsed-field gel electrophoresis was used to divide the isolates into five different pulsotypes, three of which have been identified previously in fish products on the retail market. This finding supports the assumption that the primary production, and probably the raw fish, is a source of Listeria contamination in fish products. Some of the isolates were associated with a certain type of fishpond, indicating the need for hygienic analysis of the suitability of different types of farming ponds. PMID:16786871

  17. Inhibition of Listeria monocytogenes by enterocin 4 during the manufacture and ripening of Manchego cheese.

    PubMed

    Nuñez, M; Rodríguez, J L; García, E; Gaya, P; Medina, M

    1997-12-01

    The inhibitory effect of enterocin 4, a bacteriocin produced by Enterococcus faecalis INIA 4, on Listeria monocytogenes strains Ohio and Scott A during the manufacture and ripening of Manchego cheese was investigated. Raw ewe's milk was inoculated with ca 10(5) cfu ml-1 of L. monocytogenes and with 1% of a commercial lactic starter, 1% of an Ent. faecalis INIA 4 culture, or 1% of each culture. Manchego cheeses were manufactured according to usual procedures. Listeria monocytogenes Ohio counts decreased by 3 log units after 8 h and by 6 log units after 7 d in cheese made from milk inoculated with Ent. faecalis INIA 4 or with both cultures, whereas no inhibition was recorded after 60 d in cheese made from milk inoculated with commercial lactic starter. Listeria monocytogenes Scott A was not inhibited by enterocin 4 during cheese manufacture, but decreases of 1 log unit after 7 d and of 2 log units after 60 d were achieved in cheese made from milk inoculated with both commercial lactic starter and Ent. faecalis INIA 4. PMID:9449804

  18. Detection of Listeria monocytogenes in pork and beef using the VIDAS® LMO2 automated enzyme linked immunoassay method.

    PubMed

    Meyer, Cornelia; Fredriksson-Ahomaa, Maria; Sperner, Brigitte; Märtlbauer, Erwin

    2011-07-01

    Listeria (L.) monocytogenes, a foodborne pathogen, is known to be a possible contaminant of foods during production and processing. Samples (n=985) of raw meat and by-products obtained from beef and pork were first screened by the VIDAS system for the presence of Listeria spp., followed by testing for the presence of L. monocytogenes. Positive L. monocytogenes results were confirmed by plating on selective agars: 14% of the samples were positive for Listeria and 4% tested positive for L. monocytogenes, of which 3% were confirmed on selective agars. In by-products (17%) the contamination with listeriae was higher than in meat cuts (10%). Only samples strongly positive for Listeria spp. by VIDAS were positive for L. monocytogenes. Overall, the prevalence of L. monocytogenes in beef and pork samples was rather low in comparison to most previous studies. The VIDAS system was shown to be a suitable method for screening out Listeria-negative samples; the main advantage being a markedly reduced assay time.

  19. 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

  20. 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.

  1. 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

  2. Effects of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing surfaces.

    PubMed

    Liu, Chengchu; Duan, Jingyun; Su, Yi-Cheng

    2006-02-15

    The effects of electrolyzed oxidizing (EO) water on reducing Listeria monocytogenes contamination on seafood processing surfaces were studied. Chips (5 x 5 cm(2)) of stainless steel sheet (SS), ceramic tile (CT), and floor tile (FT) with and without crabmeat residue on the surface were inoculated with L. monocytogenes and soaked in tap or EO water for 5 min. Viable cells of L. monocytogenes were detected on all chip surfaces with or without crabmeat residue after being held at room temperature for 1 h. Soaking contaminated chips in tap water resulted in small-degree reductions of the organism (0.40-0.66 log cfu/chip on clean surfaces and 0.78-1.33 log cfu/chip on dirty surfaces). Treatments of EO water significantly (p<0.05) reduced L. monocytogenes on clean surfaces (3.73 log on SS, 4.24 log on CT, and 5.12 log on FT). Presence of crabmeat residue on chip surfaces reduced the effectiveness of EO water on inactivating Listeria cells. However, treatments of EO water also resulted in significant reductions of L. monocytogenes on dirty surfaces (2.33 log on SS and CT and 1.52 log on FT) when compared with tap water treatments. The antimicrobial activity of EO water was positively correlated with its chlorine content. High oxidation-reduction potential (ORP) of EO water also contributed significantly to its antimicrobial activity against L. monocytogenes. EO water was more effective than chlorine water on inactivating L. monocytogenes on surfaces and could be used as a chlorine alternative for sanitation purpose. Application of EO water following a thorough cleaning process could greatly reduce L. monocytogenes contamination in seafood processing environments. PMID:16219378

  3. Detection and characterization of Listeria monocytogenes in Sao Jorge (Portugal) cheese production.

    PubMed

    Kongo, J M; Malcata, F X; Ho, A J; Wiedmann, M

    2006-11-01

    Listeria monocytogenes is a foodborne pathogen that can cause serious invasive disease in humans. Because human listeriosis cases have previously been linked to consumption of contaminated cheese, control of this pathogen throughout the cheese production chain is of particular concern. To understand the potential for L. monocytogenes transmission via São Jorge cheese, a Portuguese artisanal cheese variety that bears a Protected Denomination of Origin classification, 357 raw milk, curd, natural whey starter, and cheese samples representative of the production chain of this cheese were collected over one year and tested for the presence of L. monocytogenes and selected physicochemical parameters. Although neither L. monocytogenes nor other Listeria spp. were detected in whey, curd, or cheese samples, 2 of the 105 raw milk samples analyzed were positive for L. monocytogenes. These 2 raw milk isolates represented a ribotype that has previously been linked to multiple human listeriosis outbreaks and cases elsewhere, indicating the potential of these isolates to cause human listeriosis. On average, physicochemical parameters of São Jorge cheese ripened for 4 mo presented values that likely minimize the risk of L. monocytogenes outgrowth during ripening and storage (mean pH = 5.48; mean moisture = 37.79%; mean NaCl concentration = 4.73%). However, some cheese samples evaluated in this study were characterized by physicochemical parameters that may allow growth and survival of L. monocytogenes. Even though our results indicate that raw milk used for São Jorge cheese manufacture as well as finished products is rarely contaminated with L. monocytogenes, continued efforts to control the presence of this pathogen in the São Jorge cheese production chain are urged and are critical to ensure the safety of this product.

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

    PubMed

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

    2016-08-29

    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

  5. 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

  6. Detection of Low Levels of Listeria monocytogenes Cells by Using a Fiber-Optic Immunosensor

    PubMed Central

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

    2004-01-01

    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 × 103 CFU/ml for a pure culture of L. monocytogenes grown at 37°C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10°C with 3.5% NaCl, the detection threshold was 4.1 × 104 or 2.8 × 107 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

  7. Molecular ecology of Listeria monocytogenes and other Listeria species in small and very small ready-to-eat meat processing plants.

    PubMed

    Williams, Shanna K; Roof, Sherry; Boyle, Elizabeth A; Burson, Dennis; Thippareddi, Harshavardhan; Geornaras, Ifigenia; Sofos, John N; Wiedmann, Martin; Nightingale, Kendra

    2011-01-01

    A longitudinal study was conducted to track Listeria contamination patterns in ready-to-eat meats from six small or very small meat processing plants located in three states over 1 year. A total of 688 environmental sponge samples were collected from nonfood contact surfaces during bimonthly visits to each plant. Overall, L. monocytogenes was isolated from 42 (6.1%) environmental samples, and its prevalence ranged from 1.7 to 10.8% across different plants. Listeria spp., other than L. monocytogenes, were isolated from 9.5% of samples overall, with the prevalence ranging from 1.5 to 18.3% across different plants. The prevalence of L. monocytogenes correlated well with that of other Listeria spp. for some but not all plants. One L. monocytogenes isolate representing each positive sample was characterized by molecular serotyping, EcoRI ribotyping, and pulsed-field gel electrophoresis typing. Seven sample sites tested positive for L. monocytogenes on more than one occasion, and the same ribotype was detected more than once at five of these sites. Partial sigB sequencing was used to speciate other Listeria spp. isolates and assign an allelic type to each isolate. Other Listeria spp. were isolated more than once from 14 sample sites, and the same sigB allelic type was recovered at least twice from seven of these sites. One plant was colonized by an atypical hemolytic L. innocua strain. Our findings indicate that small and very small meat processing plants that produce ready-to-eat meat products are characterized by a varied prevalence of Listeria, inconsistent correlation between contamination by L. monocytogenes and other Listeria spp., and a unique Listeria molecular ecology.

  8. 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

  9. Listeria monocytogenes induced Rac1-dependent signal transduction in endothelial cells.

    PubMed

    Schmeck, Bernd; Beermann, Wiebke; van Laak, Vincent; Opitz, Bastian; Hocke, Andreas C; Meixenberger, Karolin; Eitel, Julia; Chakraborty, Trinad; Schmidt, Gudula; Barth, Holger; Suttorp, Norbert; Hippenstiel, Stefan

    2006-11-30

    Infection of endothelial cells by Listeria monocytogenes is an essential step in the pathogenesis of listeriosis. Small GTPases of the Rho family act as molecular switches in signal transduction. We tested the hypothesis that Rho GTPases contribute to the regulation of cytokine expression following L. monocytogenes infection. L. monocytogenes induced release of distinct CC and CXC, as well as Th1 and Th2 cytokines and growth factors by endothelial cells and activated RhoA and Rac1. Inhibition of Rac1 by inhibitor Nsc23766 reduced cytokine expression, and slightly yet significantly the uptake of bacteria. Blocking of Rho proteins by Clostridium difficile toxin B-10463 (TcdB) reduced Listeria-dependent cytokine expression, whereas activating Rho proteins by Escherichia coli CNF1 increased it. We analyzed regulation of IL-8 expression in more detail: Listeria-induced IL-8 release was reduced by inhibition of RhoA, Rac1 and Cdc42 (TcdB) or Rac1 while blocking of RhoA/B/C by Clostridium limosum C3 fusion toxin (C3FT) or Rho kinase by Y27632 reduced cytokine expression only slightly. Activation of RhoA, Rac1 and Cdc42 (CNF1), but not of RhoA alone (CNF(Y)), enhanced Listeria-dependent IL-8 release significantly. Furthermore, inhibition of RhoA, Rac1 and Cdc42 (TcdB) and Rac1 (Nsc23766), but not of RhoA (C3FT) reduced Listeria-related recruitment of NF-kappaB/p65 and RNA polymerase II to the il8 promoter, as well as acetylation of histone H4 and Ser10/Lys14-phosphorylation/acetylation of histone H3 at the il8 gene promoter in HUVEC. In conclusion, Rac1 contributed to L. monocytogenes-induced cytokine expression by human endothelial cells.

  10. Effect of acidified sorbate solutions on the lag phase durations and growth rates of Listeria monocytogenes on meat surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surfaces of ready-to-eat meats are susceptible to post-processing contamination by Listeria monocytogenes. This study quantified the lag phase durations (LPD) and growth rates (GR) of L. monocytogenes on the surfaces of cooked ham as affected by sorbate solutions of different concentrations and...

  11. 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

  12. 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...

  13. 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....

  14. 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

  15. Molecular Studies on the Ecology of Listeria monocytogenes in the Smoked Fish Processing Industry

    PubMed Central

    Norton, Dawn M.; McCamey, Meghan A.; Gall, Kenneth L.; Scarlett, Janet M.; Boor, Kathryn J.; Wiedmann, Martin

    2001-01-01

    We have applied molecular approaches, including PCR-based detection strategies and DNA fingerprinting methods, to study the ecology of Listeria monocytogenes in food processing environments. A total of 531 samples, including raw fish, fish during the cold-smoking process, finished product, and environmental samples, were collected from three smoked fish processing facilities during five visits to each facility. A total of 95 (17.9%) of the samples tested positive for L. monocytogenes using a commercial PCR system (BAX for Screening/Listeria monocytogenes), including 57 (27.7%) environmental samples (n = 206), 8 (7.8%) raw material samples (n = 102), 23 (18.1%) samples from fish in various stages of processing(n = 127), and 7 (7.3%) finished product samples (n = 96). L. monocytogenes was isolated from 85 samples (16.0%) using culture methods. Used in conjunction with a 48-h enrichment in Listeria Enrichment Broth, the PCR system had a sensitivity of 91.8% and a specificity of 96.2%. To track the origin and spread of L. monocytogenes, isolates were fingerprinted by automated ribotyping. Fifteen different ribotypes were identified among 85 isolates tested. Ribotyping data established possible contamination patterns, implicating raw materials and the processing environment as potential sources of finished product contamination. Analysis of the distribution of ribotypes revealed that each processing facility had a unique contamination pattern and that specific ribotypes persisted in the environments of two facilities over time (P ≤ 0.0006). We conclude that application of molecular approaches can provide critical information on the ecology of different L. monocytogenes strains in food processing environments. This information can be used to develop practical recommendations for improved control of this important food-borne pathogen in the food industry. PMID:11133446

  16. 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

  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.

  18. Prevalence and characteristics of Listeria monocytogenes in bovine colostrum in Japan.

    PubMed

    Hasegawa, Megumi; Iwabuchi, Eriko; Yamamoto, Shiori; Esaki, Hidetake; Kobayashi, Kazuhiko; Ito, Masahiko; Hirai, Katsuya

    2013-02-01

    This study was conducted to determine the prevalence and characteristics of Listeria monocytogenes in bovine colostrum in Japan. We collected bovine colostrum samples from 210 dams from 21 dairy farms in Hokkaido prefecture (Japan) between March and June 2009. L. monocytogenes was detected in samples from 6 (28.6%) of the 21 farms. Of the 210 samples, 16 (7.6%) were positive for L. monocytogenes. We recovered 80 L. monocytogenes isolates; 44 (55%) isolates were classified as serotype 1/2b and 36 (45%) were classified as serotype 4b. The isolates were susceptible to penicillin, ampicillin, amoxicillin, gentamicin, kanamycin, streptomycin, erythromycin, vancomycin, tetracycline, chloramphenicol, ciprofloxacin, and trimethoprim-sulfamethoxazole. Pulsed-field gel electrophoresis (PFGE) characterization of the 80 isolates revealed six PFGE types. Two PFGE types corresponded to human listeriosis cases. Most L. monocytogenes isolates possessed virulence-associated genes (actA, hly, iap, inlA, inlC, mpl, plcA, plcB, opuCA, prfA, and clpC). One PFGE type isolate possessed an epidemic clone II marker. Our findings suggest that isolates from bovine colostrum have the potential to cause human and animal listeriosis. This is the first study on the prevalence and characteristics of L. monocytogenes isolated from bovine colostrum obtained from dairy farms. Our results have important implications for improving public health and elucidating the epidemiology of L. monocytogenes in bovine colostrum. PMID:23433372

  19. 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

  20. 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

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

    PubMed

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

    2015-09-07

    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.

  2. 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.

  3. Detection of Listeria monocytogenes in raw and pasteurized liquid whole eggs and characterization by PFGE.

    PubMed

    Rivoal, Katell; Quéguiner, Stéphane; Boscher, Evelyne; Bougeard, Stéphanie; Ermel, Gwennola; Salvat, Gilles; Federighi, Michel; Jugiau, Florence; Protais, Jocelyne

    2010-03-31

    Listeria monocytogenes has been recognized as a human pathogen for decades and is known to be an important foodborne pathogen. There have been no documented foodborne L. monocytogenes illnesses due to the consumption of eggs or egg products, even though the bacterium has been isolated from faeces, body fluid, and oviducts of asymptomatic laying hens. In order to describe L. monocytogenes contamination of egg products, 144 liquid whole egg samples were collected from 3 different egg-breaking plants during 3 sampling periods. L. monocytogenes detection was performed on raw samples stored at 2 degrees C for two days (D+2) and on pasteurized samples stored at 2 degrees C at D+2 and at shelf-life date (SLD). L. monocytogenes was detected in 25 of the 144 raw egg samples collected, in 4 of the 144 pasteurized egg samples at D+2 and in 2 of the 144 ones analysed at SLD. Contamination of raw egg products appeared to be season dependant and was higher during summer and winter than during autumn. One hundred and ninety-six L. monocytogenes isolates were collected and serotyped; 3 serovars were demonstrated. The dominant serovar was L. monocytogenes 1/2a which was presented by 94.4% of the isolates. Typing of 196 L. monocytogenes isolates was carried out by macrorestriction of the genomic DNA with ApaI and AscI enzymes followed by pulsed field gel electrophoresis (PFGE). A large diversity was observed with 21 genotypes of L. monocytogenes, even for a given manufacturer. Nevertheless, most of the egg product samples were contaminated by one genotype, except for five samples which were contaminated by two or three distinct genotypes. The genotypes seem to be specific to each manufacturer. No cluster of L. monocytogenes was found to recur in the different plants over successive seasons.

  4. 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

  5. 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

  6. 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

  7. 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

  8. Evaluation of a chemiluminescent DNA probe assay for the rapid confirmation of Listeria monocytogenes.

    PubMed

    Okwumabua, O; Swaminathan, B; Edmonds, P; Wenger, J; Hogan, J; Alden, M

    1992-02-01

    A Listeria monocytogenes-specific, acridinium-ester-labelled DNA probe was evaluated in a chemiluminescent homogeneous protection assay (HPA) for the rapid confirmation of suspect L. monocytogenes colonies from blood agar plates. The HPA uses an acridinium-ester-labelled chemiluminescent DNA probe in a free-solution hybridization format. After the DNA probe hybridized with the target ribosomal RNA, the acridinium label on the unhybridized probe was inactivated by a chemical differential hydrolysis step. Formation of a hybrid between probe and target was detected in a luminometer after the addition of a detection reagent. The assay can be completed in 30 to 45 min and allows for simultaneous processing of several (50-100) samples. The probe showed 100% sensitivity and 100% specificity for L. monocytogenes when evaluated in the HPA against L. monocytogenes, other Listeria species and other Gram-positive bacteria. The lower detection limit of the HPA was between 10(4) and 10(5) cells. In an evaluation with 296 bacterial colonies isolated from food, the HPA colony confirmation showed 100% agreement with conventional biochemical characterization. HPA will be useful for the rapid confirmation of L. monocytogenes isolated from food and clinical specimens.

  9. Behaviour of Listeria monocytogenes during the manufacture and ripening of Manchego and Chihuahua Mexican cheeses.

    PubMed

    Solano-López, C; Hernández-Sánchez, H

    2000-12-01

    The ability of Listeria monocytogenes to survive the Mexican Manchego and Chihuahua cheese-making processes and its persistence during the ripening stages of both cheeses was examined. Commercial pasteurized and homogenized whole milk was inoculated with Listeria monocytogenes (strain ATCC 19114) to a level between 2 x 10(6) and 9 x 10(6) CFU/ml. The milk was used to make Mexican Manchego and Chihuahua cheeses in a 25-l vat. Mexican Manchego cheese was ripened for 5 days and Chihuahua cheese for 6 weeks at 12 degrees C and 85% RH. Listeria present in the cheese was enumerated by diluting samples in sterile 0.1% peptone water and plating on Oxford agar. Duplicate samples were taken at each step of the manufacturing process. During the first week of ripening samples were taken daily from both cheeses. For Chihuahua cheese, samples were taken weekly after the first week of the ripening stage. During the manufacture of Mexican Manchego cheese, Listeria counts remained relatively constant at 10(6) CFU/ml, while with Chihuahua cheese there was a one log decrease in numbers (10(6) to 10(5) CFU/ml). After pressing both curds overnight, numbers of bacteria decreased in Mexican Manchego cheese to 8.2 x 10(5) but increased in Chihuahua cheese from 1.7 x 10(5) to 1.2 x 10(6) CFU/ml. During the ripening stage, counts of Listeria remained constant in both cheeses. However, since the Chihuahua cheese ripening stage is about 6 weeks, the number of bacteria decreased from 2 x 10(6) to 4 x 10(4) CFU/g. The results show that Listeria monocytogenes is able to survive the manufacture and ripening processes of both Mexican cheeses. PMID:11139015

  10. Meningoencephalitis due to Listeria monocytogenes in a pregnant rhesus macaque (Macaca mulatta).

    PubMed

    Lemoy, Marie-Josee M F; Lopes, Danielle A; Reader, J Rachel; Westworth, Diccon R; Tarara, Ross P

    2012-10-01

    We here report a spontaneous case of meningoencephalitis due to Listeria monocytogenes in an adult primiparous rhesus macaque (Macaca mulatta) during an outbreak of listeriosis in an outdoor enclosure. Clinical signs included tremors, abnormal posture, and altered mental status. Hematology and analyses of cerebrospinal fluid were consistent with bacterial infection. Pure cultures of L. monocytogenes were recovered from the placenta-abortus, cerebrospinal fluid, and brain tissue. The macaque did not respond to treatment and was euthanized. Histopathologic examination of the brain revealed acute meningoencephalitis. This case represents an unusual clinical and pathologic presentation of listeriosis in a nonhuman primate in which the dam and fetus both were affected.

  11. [Study by multiplex PCR of Listeria monocytogenes serotypes isolated in Argentine].

    PubMed

    Callejo, R; Prieto, M; Martínez, C; Aguerre, L; Rocca, F; Martínez, G; Palmieri, O

    2008-01-01

    A multiplex PCR assay, recently validated to characterize the serotypes of Listeria monocytogenes was evaluated in comparison to conventional serotyping. Three hundred forty two L. monocytogenes strains isolated from human, food, animal and environmental sources during the 1992-2005 period were assayed. The concordance between the two methods for serotypes 1/2a, 1/2b and 1/2c was 100%, whereas for serotype 4b it was 98%. Serotyping is a useful tool for first line strain differentiation during epidemiological surveillance and outbreaks. The multiplex PCR assay offers a fast and low-cost alternative, which is easily adaptable to clinical bacteriology and bromatology laboratories.

  12. Rapid colorimetric sensing platform for the detection of Listeria monocytogenes foodborne pathogen.

    PubMed

    Alhogail, Sahar; Suaifan, Ghadeer A R Y; Zourob, Mohammed

    2016-12-15

    Listeria monocytogenes is a serious cause of human foodborne infections worldwide, which needs spending billions of dollars for inspection of bacterial contamination in food every year. Therefore, there is an urgent need for rapid, in-field and cost effective detection techniques. In this study, rapid, low-cost and simple colorimetric assay was developed using magnetic nanoparticles for the detection of listeria bacteria. The protease from the listeria bacteria was detected using D-amino acid substrate. D-amino acid substrate was linked to the carboxylic acid on the magnetic nanoparticles using EDC/NHS chemistry. The cysteine residue at the C-terminal of the substrate was used for the self-assembled monolayer formation on the gold sensor surface, which in turn the black magnetic nanobeads will mask the golden color. The color will change from black to golden color upon the cleavage of the specific peptide sequence by the Listeria protease. The sensor was tested with serial dilutions of Listeria bacteria. It was found that the appearance of the gold surface area is proportional to the bacterial concentrations in CFU/ml. The lowest detection limit of the developed sensor for Listeria was found to be 2.17×10(2) colony forming unit/ml (CFU/ml). The specificity of the biosensor was tested against four different foodborne associated bacteria (Escherichia coli, Salmonella, Shigella flexnerii and Staphylococcus aureus). Finally, the sensor was tested with artificially spiked whole milk and ground meat spiked with listeria. PMID:27543841

  13. Rapid colorimetric sensing platform for the detection of Listeria monocytogenes foodborne pathogen.

    PubMed

    Alhogail, Sahar; Suaifan, Ghadeer A R Y; Zourob, Mohammed

    2016-12-15

    Listeria monocytogenes is a serious cause of human foodborne infections worldwide, which needs spending billions of dollars for inspection of bacterial contamination in food every year. Therefore, there is an urgent need for rapid, in-field and cost effective detection techniques. In this study, rapid, low-cost and simple colorimetric assay was developed using magnetic nanoparticles for the detection of listeria bacteria. The protease from the listeria bacteria was detected using D-amino acid substrate. D-amino acid substrate was linked to the carboxylic acid on the magnetic nanoparticles using EDC/NHS chemistry. The cysteine residue at the C-terminal of the substrate was used for the self-assembled monolayer formation on the gold sensor surface, which in turn the black magnetic nanobeads will mask the golden color. The color will change from black to golden color upon the cleavage of the specific peptide sequence by the Listeria protease. The sensor was tested with serial dilutions of Listeria bacteria. It was found that the appearance of the gold surface area is proportional to the bacterial concentrations in CFU/ml. The lowest detection limit of the developed sensor for Listeria was found to be 2.17×10(2) colony forming unit/ml (CFU/ml). The specificity of the biosensor was tested against four different foodborne associated bacteria (Escherichia coli, Salmonella, Shigella flexnerii and Staphylococcus aureus). Finally, the sensor was tested with artificially spiked whole milk and ground meat spiked with listeria.

  14. 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

  15. 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.

  16. 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

  17. 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

  18. Absence of growth of Listeria monocytogenes in naturally contaminated Cheddar cheese.

    PubMed

    Dalmasso, Marion; Jordan, Kieran

    2014-02-01

    Each cheese producer is responsible by the legislation for the number of Listeria monocytogenes in cheese and is required to prove that numbers will not exceed 100 cfu/g throughout the shelf-life of the cheese. Even in the case of hard-cheese such as Cheddar cheese, the absence of growth of List. monocytogenes during ripening has to be demonstrated to comply with EU legislation. Studies dedicated to assessing List. monocytogenes growth throughout cheese shelf-life are generally based on artificially contaminated cheeses. Contrary to the majority of works, the current study focused on the growth of List. monocytogenes in naturally contaminated raw milk farmhouse Cheddar cheeses during a five-month ripening period. List. monocytogenes growth was assessed by direct count and its presence was detected by enrichment in two naturally contaminated cheese batches. In order to track routes of contamination, 199 processing environment samples from inside and outside the processing facility were taken, and their analysis for the presence of List. monocytogenes was performed on four occasions over a 9-month period. List. monocytogenes isolates were differentiated using PFGE and serotyping. List. monocytogenes never exceeded 20 cfu/g in the cheeses and could not be detected after five months of ripening. Eleven pulsotypes were identified. One pulsotype was found in the yard outside the processing facility, in a vat, on the processing area floor and in a cheese. This indicated that the outside environment constitutes a potential source of contamination of the processing environment and of the cheese. These results demonstrate that this farmhouse Cheddar cheese does not support List. monocytogenes growth and suggests that the efforts to reduce processing environment contamination are worthwhile. PMID:24345459

  19. 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

  20. 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

  1. Bactericidal activity of lauric arginate in milk and Queso Fresco cheese against Listeria monocytogenes cold growth.

    PubMed

    Soni, K A; Nannapaneni, R; Schilling, M W; Jackson, V

    2010-10-01

    Lauric arginate (LAE) at concentrations of 200 ppm and 800 ppm was evaluated for its effectiveness in reducing cold growth of Listeria monocytogenes in whole milk, skim milk, and Queso Fresco cheese (QFC) at 4°C for 15 to 28 d. Use of 200 ppm of LAE reduced 4 log cfu/mL of L. monocytogenes to a nondetectable level within 30 min at 4°C in tryptic soy broth. In contrast, when 4 log cfu/mL of L. monocytogenes was inoculated in whole milk or skim milk, the reduction of L. monocytogenes was approximately 1 log cfu/mL after 24 h with 200 ppm of LAE. When 800 ppm of LAE was added to whole or skim milk, the initial 4 log cfu/mL of L. monocytogenes was nondetectable following 24 h, and no growth of L. monocytogenes was observed for 15 d at 4°C. With surface treatment of 200 or 800 ppm of LAE on vacuum-packaged QFC, the reductions of L. monocytogenes within 24 h at 4°C were 1.2 and 3.0 log cfu/g, respectively. In addition, the overall growth of L. monocytogenes in QFC was decreased by 0.3 to 2.6 and by 2.3 to 5.0 log cfu/g with 200 and 800 ppm of LAE, respectively, compared with untreated controls over 28 d at 4°C. Sensory tests revealed that consumers could not determine a difference between QFC samples that were treated with 0 and 200 ppm of LAE, the FDA-approved level of LAE use in foods. In addition, no differences existed between treatments with respect to flavor, texture, and overall acceptability of the QFC. Lauric arginate shows promise for potential use in QFC because it exerts initial bactericidal activity against L. monocytogenes at 4°C without affecting sensory quality.

  2. Listeria monocytogenes Invades the Epithelial Junctions at Sites of Cell Extrusion

    PubMed Central

    Pentecost, Mickey; Otto, Glen

    2006-01-01

    Listeria monocytogenes causes invasive disease by crossing the intestinal epithelial barrier. This process depends on the interaction between the bacterial surface protein Internalin A and the host protein E-cadherin, located below the epithelial tight junctions at the lateral cell-to-cell contacts. We used polarized MDCK cells as a model epithelium to determine how L. monocytogenes breaches the tight junctions to gain access to this basolateral receptor protein. We determined that L. monocytogenes does not actively disrupt the tight junctions, but finds E-cadherin at a morphologically distinct subset of intercellular junctions. We identified these sites as naturally occurring regions where single senescent cells are expelled and detached from the epithelium by extrusion. The surrounding cells reorganize to form a multicellular junction that maintains epithelial continuity. We found that E-cadherin is transiently exposed to the lumenal surface at multicellular junctions during and after cell extrusion, and that L. monocytogenes takes advantage of junctional remodeling to adhere to and subsequently invade the epithelium. In intact epithelial monolayers, an anti-E-cadherin antibody specifically decorates multicellular junctions and blocks L. monocytogenes adhesion. Furthermore, an L. monocytogenes mutant in the Internalin A gene is completely deficient in attachment to the epithelial apical surface and is unable to invade. We hypothesized that L. monocytogenes utilizes analogous extrusion sites for epithelial invasion in vivo. By infecting rabbit ileal loops, we found that the junctions at the cell extrusion zone of villus tips are the specific target for L. monocytogenes adhesion and invasion. Thus, L. monocytogenes exploits the dynamic nature of epithelial renewal and junctional remodeling to breach the intestinal barrier. PMID:16446782

  3. Biotic and abiotic soil properties influence survival of Listeria monocytogenes in soil.

    PubMed

    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.

  4. 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.

  5. 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.

  6. Detection and isolation of Listeria monocytogenes from food samples: implications of sublethal injury.

    PubMed

    Donnelly, Catherine W

    2002-01-01

    Detection of L. monocytogenes is often limited by the performance of the enrichment media used to support bacterial growth to detectable levels. Because Listeria may exist at extremely low levels in foods, sample enrichment protocols must amplify these low initial populations to detectable limits. Listeria may also exist in an injured state in food products as a result of processing treatments such as heating, freezing, exposure to acids, or exposure to sanitizing compounds. Selective agents in enrichment media normally used for recovery of Listeria may inhibit repair and detection of sublethally injured Listeria, which may go on to repair, grow, and regain pathogenicity. Simple modifications to existing regulatory protocols, such as those that use more than one enrichment broth, raise sensitivity of detection to 90%. This review shows the efficacy of repair/enrichment strategies, which increase sensitivity of detection to 97.5-98.8% compared with 65-70% by standard regulatory protocols. Ribotype analysis of isolates obtained from meat samples reveals a complex microbial ecology, with striking differences in both number and distribution of distinct genetic types of Listeria, depending upon whether samples are enriched in selective or repair/enrichment media. In studies on enrichment of dairy environmental samples in University of Vermont medium and Listeria repair broth (UVM and LRB), combining these 2 primary enrichment media into a single tube of Fraser broth for dual secondary enrichment yielded a significantly higher percentage (p < 0.05) of Listeria-positive samples than did use of either LRB or UVM alone. Refinement of conventional Listeria recovery methods should consider the importance of the enrichment step, the nutritional needs of specific genetic types, and the physiological condition of Listeria isolates in foods.

  7. 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.

  8. 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

  9. A solid agar overlay method for recovery of heat-injured Listeria monocytogenes.

    PubMed

    Yan, Zhinong; Gurtler, Joshua B; Kornacki, Jeffrey L

    2006-02-01

    A solid agar overlay method was developed for recovery of heat-injured Listeria monocytogenes. Presolidified nonselective tryptic soy agar with 0.6% yeast extract (TSAYE, 2% agar) was overlaid on top of solidified modified Oxford agar (MOX). Heat injury of L. monocytogenes was conducted at 58 degrees C for 6 min in a jacketed flask filled with tryptic soy broth. Both noninjured and heat-treated L. monocytogenes cells were plated onto TSAYE, MOX, and TSAYE-MOX plates. No significant differences (P > 0.05) in recovery were found among the three media for noninjured bacterial cells. Recovery of heat-injured L. monocytogenes cells on TSAYE-MOX overlay plates was equivalent to that on the nonselective TSAYE medium, whereas recovery on the selective MOX medium was significantly lower (P < 0.05) compared with both TSAYE and the overlay plates. There were no significant differences (P > 0.05) among the overlay plates prepared 0, 2, 4, 6, 8, 16, and 24 h prior to plating heat-injured bacterial cells. The TSAYE-MOX overlay also allowed differentiation of L. monocytogenes from a mixture of four other types of foodborne pathogens. This solid agar overlay method for recovery of heat-injured L. monocytogenes cells is less time-consuming and less complicated than the conventional overlay-underlay technique and the double overlay modification of the thin agar layer method and may allow for greater laboratory plating efficiencies.

  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. Transcriptome analysis of Listeria monocytogenes grown on a ready-to-eat meat matrix.

    PubMed

    Bae, Dongryeoul; Crowley, Michael R; Wang, Chinling

    2011-07-01

    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 determined with a microarray. Microarray data were validated with a quantitative real-time reverse transcription PCR assay. Based on the microarray data, 39 and 45 genes from L. monocytogenes were transcriptionally upregulated and down-regulated, respectively. The genes regulated at the transcriptional level were mainly involved in energy metabolism, fatty acid and phospholipid metabolism, biosynthesis of proteins, transport and binding proteins, DNA metabolism, cellular processes, and regulatory functions. No significant change was noted for the expression of genes encoding known virulence factors such as sigB, prfA, inlA, inlB, plcA, plcB, and hly. These results suggest that L. monocytogenes grown on RTE deli meat changes its transcription of proteins involved in its metabolic pathways to obtain an energy source or to adapt to environmental change without increasing the expression of virulence factors. The global transcriptome profiles provide a better understanding of the growth or adaptation of L. monocytogenes in RTE meat products.

  12. 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.

  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.

  14. 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

  15. Listeria monocytogenes lineage group classification by MAMA-PCR of the listeriolysin gene.

    PubMed

    Jinneman, K C; Hill, W E

    2001-08-01

    Nucleotide sequence differences within several virulence genes, including the listeriolysin O (hly) gene, are associated with three evolutionary lineage groups of Listeria monocytogenes. Because the ability of L. monocytogenes to cause disease may vary by evolutionary lineage group, rapid discrimination among the three lineage types may be important for estimating pathogenic potential. A Mismatch Amplification Mutation Assay (MAMA) was developed and used to rapidly screen and characterize L. monocytogenes isolates with regard to lineage type. A standard PCR amplified a 446-bp region within the hly gene with all three L. monocytogenes lineage genotypes. MAMA primers to four different sites within this region of the hly gene were designed to amplify under the same PCR conditions and generated amplicons, the size of which depended on the isolate genotype. Ninety-seven L. monocytogenes isolates were screened. All isolates, except ATCC 19116, could be classified by MAMA PCR as one of the three hly genotypes. Overall, 56, 36, and 4 of the 97 isolates tested were type 1, 2, or 3 respectively. Among the 26 patient isolates, 85%, 15%, and 0% were type 1, 2, or 3 respectively; for the 60 food isolates, 54% were type 1, 43% were type 2, and 3% were type 3. The combination of these MAMA PCR analyses provides a rapid method to screen and categorize L. monocytogenes isolates because of conserved nucleotide differences within the hly gene.

  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. 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

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

    PubMed

    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.

  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. 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

  1. Listeria monocytogenes cross-contamination of cheese: risk throughout the food supply chain.

    PubMed

    Sauders, B D; D'Amico, D J

    2016-10-01

    Listeria monocytogenes has been the most common microbial cause of cheese-related recalls in both the United States and Canada in recent years. Since L. monocytogenes is inactivated by pasteurization, the majority of these cases have been linked to environmental and cross-contamination of fresh-soft, soft-ripened, and semi-soft cheeses. Cross-contamination of foods with L. monocytogenes is a continuous risk throughout the food supply chain and presents unique challenges for subsequent illness and outbreak investigations. Reports on outbreaks of listeriosis attributed to cross-contamination downstream from primary processing help highlight the critical role of epidemiological investigation coupled with coordinated molecular subtyping and surveillance in the recognition and investigation of complex foodborne outbreaks. Despite their complexity, environmental sampling throughout the supply chain coupled with improved genotyping approaches and concomitant analysis of foodborne illness epidemiological exposure data are needed to help resolve these and similar cases more rapidly and with greater confidence. PMID:27435307

  2. Changes in Gene Expression during Adaptation of Listeria monocytogenes to the Soil Environment

    PubMed Central

    Piveteau, Pascal; Depret, Géraldine; Pivato, Barbara; Garmyn, Dominique; Hartmann, Alain

    2011-01-01

    Listeria monocytogenes is a ubiquitous opportunistic pathogen responsible for listeriosis. In order to study the processes underlying its ability to adapt to the soil environment, whole-genome arrays were used to analyse transcriptome modifications 15 minutes, 30 minutes and 18 h after inoculation of L. monocytogenes EGD-e in soil extracts. Growth was observed within the first day of incubation and large numbers were still detected in soil extract and soil microcosms one year after the start of the experiment. Major transcriptional reprofiling was observed. Nutrient acquisition mechanisms (phosphoenolpyruvate-dependent phosphotransferase systems and ABC transporters) and enzymes involved in catabolism of specific carbohydrates (β-glucosidases; chitinases) were prevalent. This is consistent with the overrepresentation of the CodY regulon that suggests that in a nutrient depleted environment, L. monocytogenes recruits its extensive repertoire of transporters to acquire a range of substrates for energy production. PMID:21966375

  3. Listeria monocytogenes cross-contamination of cheese: risk throughout the food supply chain.

    PubMed

    Sauders, B D; D'Amico, D J

    2016-10-01

    Listeria monocytogenes has been the most common microbial cause of cheese-related recalls in both the United States and Canada in recent years. Since L. monocytogenes is inactivated by pasteurization, the majority of these cases have been linked to environmental and cross-contamination of fresh-soft, soft-ripened, and semi-soft cheeses. Cross-contamination of foods with L. monocytogenes is a continuous risk throughout the food supply chain and presents unique challenges for subsequent illness and outbreak investigations. Reports on outbreaks of listeriosis attributed to cross-contamination downstream from primary processing help highlight the critical role of epidemiological investigation coupled with coordinated molecular subtyping and surveillance in the recognition and investigation of complex foodborne outbreaks. Despite their complexity, environmental sampling throughout the supply chain coupled with improved genotyping approaches and concomitant analysis of foodborne illness epidemiological exposure data are needed to help resolve these and similar cases more rapidly and with greater confidence.

  4. 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.

  5. 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

  6. 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.

  7. Protective role of heme oxygenase-1 in Listeria monocytogenes-induced abortion.

    PubMed

    Tachibana, Masato; Hashino, Masanori; Nishida, Takashi; Shimizu, Takashi; Watarai, Masahisa

    2011-01-01

    It is well-known fact that various pathogens, including bacteria, virus, and protozoa, induce abortion in humans and animals. However the mechanisms of infectious abortion are little known. In this study, we demonstrated that Listeria monocytogenes infection in trophoblast giant cells decreased heme oxygenase (HO)-1 and B-cell lymphoma-extra large (Bcl-XL) expression, and that their overexpression inhibited cell death induced by the infection. Furthermore, HO-1 and Bcl-XL expression levels were also decreased by L. monocytogenes in pregnant mice. Treatment with cobalt protoporphyrin, which is known to induce HO-1, inhibited infectious abortion. Taken together, our study indicates that L. monocytogenes infection decreases HO-1 and Bcl-XL expression and induces cell death in placenta, leading to infectious abortion.

  8. 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.

  9. Listeria monocytogenes Infection in a Sugar Glider (Petaurus breviceps) - New Mexico, 2011.

    PubMed

    Nichols, M; Takacs, N; Ragsdale, J; Levenson, D; Marquez, C; Roache, K; Tarr, C L

    2015-06-01

    Listeria monocytogenes is a Gram-positive, facultative anaerobic, rod-shaped bacterium that can infect and cause disease in many species. In this case report, we describe a case of L. monocytogenes infection causing sepsis in a sugar glider (Petaurus breviceps). The sugar glider consumed a varied diet consisting of human food items, including cantaloupe. A nationwide outbreak of L. monocytogenes foodborne illness associated with cantaloupes occurred simultaneously with this incident case. In this case, the bacterial strains from the outbreak and glider were genetically distinct. Although rare, veterinarians should be aware of the emergence of foodborne pathogens' ability to infect exotic animals residing in domestic environments. PMID:24815369

  10. 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

  11. Occurrence and antimicrobial resistance patterns of Listeria monocytogenes isolated from vegetables.

    PubMed

    de Vasconcelos Byrne, Vanessa; Hofer, Ernesto; Vallim, Deyse Christina; de Castro Almeida, Rogeria Comastri

    2016-01-01

    Although the consumption of fresh and minimally processed vegetables is considered healthy, outbreaks related to the contamination of these products are frequently reported. Among the food-borne pathogens that contaminate vegetables is Listeria monocytogenes, a ubiquitous organism that exhibits the ability to survive and multiply at refrigerated temperatures. This study aimed to evaluate the occurrence of L. monocytogenes in vegetables as well as the antimicrobial resistance of isolates. The results showed that 3.03% of samples were contaminated with L. monocytogenes, comprising 2.22% of raw vegetables and 5.56% of ready-to-eat vegetables. Multiplex PCR confirmed the virulence potential of the isolates. Antimicrobial resistance profiling showed that 50% of the isolates were susceptible to the antibiotics used. The resistance of one isolate to penicillin G, a commonly employed therapeutic agent, and the presence of serotype 4b, a serotype commonly associated with food-borne outbreaks, could be potential health hazards for consumers. PMID:26991279

  12. 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

  13. [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.

  14. An improved cloning vector for construction of gene replacements in Listeria monocytogenes.

    PubMed

    Li, Guojie; Kathariou, S

    2003-05-01

    Listeria monocytogenes is a gram-positive, facultative intracellular bacterium implicated in severe food-borne illness (listeriosis) in humans. The construction of well-defined gene replacements in the genome of L. monocytogenes has been instrumental to several genetic studies of the virulence and other attributes of the organism. Construction of such mutations by currently available procedures, however, tends to be labor intensive, and gene replacement mutants are sometimes difficult to recover due to lack of direct selection for the construct. In this study we describe the construction and use of plasmid vector pGF-EM, which can be conjugatively transferred from Escherichia coli S17-1 to L. monocytogenes and which provides the genetic means for direct selection of gene replacements.

  15. 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

  16. 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

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

    PubMed

    Quereda, Juan J; Pizarro-Cerdá, Javier; Balestrino, Damien; Bobard, Alexandre; Danckaert, Anne; Aulner, Nathalie; Shorte, Spencer; Enninga, Jost; Cossart, Pascale

    2015-10-23

    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.

  18. 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

  19. The evolution and epidemiology of Listeria monocytogenes in Europe and the United States.

    PubMed

    Lomonaco, Sara; Nucera, Daniele; Filipello, Virginia

    2015-10-01

    Listeria monocytogenes is an opportunistic food-borne pathogen responsible for listeriosis, a disease associated with high mortality rates. L. monocytogenes causes invasive syndromes and case-fatality can be as high as 30%, in specific high-risk population groups such as the elderly, immuno-compromised individuals, fetuses and newborns. Acquisition of the disease is mainly due to consumption of contaminated (predominantly ready-to-eat) food. We aimed to provide a state-of-the-art collection of different likely evolutionary models, based on recombination and positive selection, and the phylogenetic relationship between lineages of L. monocytogenes and between them and other Listeria species. We described the most recent findings in comparative pan-genomics, considering the core and accessory genome in relation to virulence and adaptation to different environments. Finally, this review illustrates L. monocytogenes epidemiology and transmission in humans, foods and animals, the surveillance systems of the European Union and United States and the application of molecular techniques as a core tool in epidemiological investigation.

  20. Listeria monocytogenes in retailed raw chicken meat in Turkey.

    PubMed

    Siriken, Belgin; Ayaz, Naim Deniz; Erol, Irfan

    2014-01-01

    The objectives of this study were, to find the prevalence and antimicrobial resistance of L. monocytogenes from a total of 116 chicken meat samples including 50 carcasses and 66 meat parts marketed in Turkey between 2008 and 2009 using immunomagnetic separation (IMS) based cultivation technique, to detect the hlyA gene for the verification of the isolates by PCR, and to identify the genoserotypes of the L. monocytogenes isolates by multiplex PCR assay. In the study, 51 L. monocytogenes colonies were isolated from 34 (29.3%) chicken meat samples (eleven [22.0%] carcasses and 23 [34.8%] pieces of meat) by IMS based cultivation technique and confirmed by PCR. According to the multiplex PCR results, all the 51 isolates were identified as genoserotype IIa (1/2a or 3a). L. monocytogenes isolates were also tested for their susceptibility to eight antibiotic (gentamicin, vancomycin, chloramphenicol, streptomycin, tetracycline, ampicillin, penicillin G, erythromycin) agents using the disk diffusion method. 14 isolates (27.45%) were susceptible to all eight antimicrobials drugs tested and the remaining 37 isolates (72.54%) were resistant to gentamicin (one isolate, 1.96%), vancomycin (four isolates, 7.84%), penicillin G (six isolates, 11.76%), streptomycin (nine isolates, 17.64%; resistant or intermediate), tetracycline (seven isolates, 13.72%) and ampicillin (six isolates, 11.76%). This study showed that antimicrobial resistance is not highly prevalent in L. monocytogenes isolated from chicken carcasses and pieces of meat. The presence of L. monocytogenes in chicken samples suggests an importance of this pathogen in chicken.

  1. 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

  2. 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.

  3. Bactericidal Activity of Human Macrophages: Analysis of Factors Influencing the Killing of Listeria monocytogenes

    PubMed Central

    Cline, Martin J.

    1970-01-01

    A technique is described for the measurement of listericidal activity of human macrophages grown from blood monocytes. Phagocytosis of Listeria monocytogenes was inhibited by a glycolytic poison (NaF) but was unaffected by anaerobic conditions, cyanide, or 2,4-dinitrophenol (DNP). Killing by macrophages was slower than that by neutrophils, and Listeria phagocytized by macrophages began to synthesize deoxyribonucleic acid within 3 hr of the time of ingestion. Differentiated macrophages ingested and killed more organisms per cell than newly isolated monocytes. Maximal killing of Listeria required oxygen but was unaffected by cyanide or DNP. Macrophages isolated from patients with chronic intracellular infection (leprosy, tuberculosis, fungal diseases) and from patients with active Hodgkin's disease were more bactericidal than macrophages from normal subjects. Images PMID:16557814

  4. 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

  5. Antimicrobial Activity of Chitosan Films With Essential Oils Against Listeria monocytogenes on Cabbage

    PubMed Central

    Jovanovic, Gordana D.; Klaus, Anita S.; P. Niksic, Miomir

    2016-01-01

    Background The highest incidence of listeriosis, due to consumption of ready-to-eat foods and fresh, shredded, minimally processed vegetables, occurs among pregnant women and the elderly. In order to reduce the prevalence of listeriosis among consumers, better protective measures are recommended. Chitosan films, with or without added essential oils, represent a modern, safe method of preserving the quality of such vegetables and significantly reducing the incidence of Listeria monocytogenes in these foods. Objectives The present study was conducted to evaluate the antimicrobial properties of composite chitosan-gelatin films with and without essential oils against two strains of L. monocytogenes, ATCC 19115 and ATCC 19112, in fresh shredded cabbage. Methods Shredded cabbage was inoculated with L. monocytogenes and packed between two layers of the chitosan composite film, then placed in Petri dishes. The prepared samples were stored at 4°C then analyzed for total viable count on PALCAM agar while incubated at 37°C, every 24 hours for 7 days. Results Average L. monocytogenes content ranged from 4.2 - 5.4 log CFU/g, reaching values of 7.2 - 8.6 log CFU/g in samples of untreated cabbage. A complete reduction of L. monocytogenes ATCC 19115 on cabbage was achieved after 120 hours in the presence of 0.5% chitosan film, whereas reduction of L. monocytogenes ATCC 19112 was achieved after 144 hours. In the presence of 1% chitosan film, the bacteria withered more quickly and complete reduction of both species of L. monocytogenes was achieved after 96 hours. Conclusions All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of both strains of L. monocytogenes on cabbage. The best effect was achieved with a 1% chitosan concentration. The addition of essential oils increased the antimicrobial activity of all tested films. PMID:27800143

  6. Aerobic plate counts and ATP levels correlate with Listeria monocytogenes detection in retail delis.

    PubMed

    Hammons, Susan R; Stasiewicz, Matthew J; Roof, Sherry; Oliver, Haley F

    2015-04-01

    Listeria monocytogenes is a foodborne pathogen that causes an estimated 1,591 cases of illness and 255 deaths annually in the United States, the majority of which are attributed to ready-to-eat deli meats processed in retail delis. Because retail delis distribute product directly to consumers, rapid methods to validate cleaning and sanitation are needed to improve retail food safety. This study investigated the relationships among ATP levels, standard aerobic plate count (APC), and L. monocytogenes presence in fully operational delis. Fifteen full-service delis were concurrently sampled for ATP, APC, and L. monocytogenes during preoperational hours once monthly for 3 months. Fifteen additional delis were recruited for 6 months of operational sampling (n = 30). A 1-log increase in APC was equivalent to a 3.3-fold increase in the odds of detecting L. monocytogenes (P < 0.001) and a 1.9-log increase in L monocytogenes population (P = 0.03). An ATP level increase of 1 log relative light unit correlated to a 0.22-log increase in APC (P < 0.001). A preoperational ATP level mean increase by 1 log relative light unit increased the odds of detecting L. monocytogenes concurrently fourfold. A 0.5-log increase in mean ATP level during preoperational sampling corresponded to a 2% increase in the predicted L. monocytogenes prevalence during operation (P < 0.01). Additionally, 10 statistically representative sites were identified and recommended for use in sanitation monitoring programs. Our data support the use of ATP as a rapid method to validate effective cleaning and sanitation to reduce L. monocytogenes in retail delis.

  7. 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

  8. Influence of soft rot bacteria on growth of Listeria monocytogenes on potato tuber slices.

    PubMed

    Liao, C H; Sapers, G M

    1999-04-01

    Growth of Listeria monocytogenes on potato tuber slices and its interaction with four representative species of soft rot bacteria (Pseudomonas fluorescens, P. viridiflava, Erwinia carotovora subsp. carotovora, and Xanthomonas campestris) were investigated. When potato tuber slices were inoculated with one of two L. monocytogenes strains (Scott A and ATCC 15313), an increase in numbers of 3 to 4 logs per gram of tissue was observed with samples that were stored at 20 degrees C for 6 days. However, an increase of about 2 logs was observed with samples that were stored at 8 degrees C for 12 days. When potato slices were simultaneously inoculated with L. monocytogenes and one of the four soft rot bacteria, the growth of L. monocytogenes was inhibited in the presence of P. fluorescens or P. viridiflava but was not significantly affected in the presence of E. carotovora or X. campestris. The antagonism of the two pseudomonads to L. monocytogenes was also observed in potato tuber extract and in culture media. Formation of inhibition zones was observed only in iron-deficient media but not in the medium supplemented with FeCl3. In addition, production of fluorescent siderophore (pyoverdin) by these two pseudomonads was demonstrated. L. monocytogenes was unable to colonize macerated plant tissue induced by soft-rotting bacteria 2 days before inoculation of the pathogen. These results indicate that growth of L. monocytogenes on potato tuber slices is differentially affected by soft rot bacteria and that antagonism of fluorescent pseudomonads to L. monocytogenes is possibly caused by the production of iron-chelating siderophore by these pseudomonads. PMID:10419206

  9. 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

  10. 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

  11. 78 FR 27939 - Draft Interagency Risk Assessment-Listeria monocytogenes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ... Food Safety and Inspection Service DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration....usda.gov/PDF/Listeria-Transcript_062309.pdf ). As announced by FSIS in the Federal Register (78 FR... Inspection Service and Department of Health and Human Service, Food and Drug Administration/Center for...

  12. 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.

  13. 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.

  14. An ecological perspective of Listeria monocytogenes biofilms in food processing facilities.

    PubMed

    Valderrama, Wladir B; Cutter, Catherine N

    2013-01-01

    Listeria monocytogenes can enter the food chain at virtually any point. However, food processing environments seem to be of particular importance. From an ecological point of view, food processing facilities are microbial habitats that are constantly disturbed by cleaning and sanitizing procedures. Although L. monocytogenes is considered ubiquitous in nature, it is important to recognize that not all L. monocytogenes strains appear to be equally distributed; the distribution of the organism seems to be related to certain habitats. Currently, no direct evidence exists that L. monocytogenes-associated biofilms have played a role in food contamination or foodborne outbreaks, likely because biofilm isolation and identification are not part of an outbreak investigation, or the definition of biofilm is unclear. Because L. monocytogenes is known to colonize surfaces, we suggest that contamination patterns may be studied in the context of how biofilm formation is influenced by the environment within food processing facilities. In this review, direct and indirect epidemiological and phenotypic evidence of lineage-related biofilm formation capacity to specific ecological niches will be discussed. A critical view on the development of the biofilm concept, focused on the practical implications, strengths, and weaknesses of the current definitions also is discussed. The idea that biofilm formation may be an alternative surrogate for microbial fitness is proposed. Furthermore, current research on the influence of environmental factors on biofilm formation is discussed.

  15. 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.

  16. 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.

  17. Reduction of Listeria monocytogenes in raw catfish fillets by essential oils and phenolic constituent carvacrol.

    PubMed

    Desai, Monil A; Soni, Kamlesh A; Nannapaneni, Ramakrishna; Schilling, M Wes; Silva, Juan L

    2012-09-01

    The antimicrobial activity of various essential oils and carvacrol was determined on fresh raw catfish fillets against a 4-strain Listeria monocytogenes mixture representing serotypes 1/2b, 3b, 4b, and 4c that were predominantly isolated from catfish processing environments. Thyme oil, oregano oil and carvacrol exhibited concentration and time dependent responses in broth against L. monocytogenes; for example 0.5% concentrations resulted in 4 log CFU/mL reduction within 30 min whereas 0.1% concentrations required more than 24 h for the same level of reduction. Lemon, orange, and tangerine oils, at 0.5% showed listeriostatic effect in which 4 log CFU/mL of the initial L. monocytogenes load was unchanged at 4 °C in 10 d whereas 1% concentrations were listericidal in a time dependent manner. Apart from carvacrol, efficacy of tested essential oils in reducing L. monocytogenes and total microbial load from catfish fillet was very limited. Dipping treatment of catfish fillets in 2% carvacrol solution for 30 min at 4 °C reduced L. monocytogenes to an undetectable level from their initial load of 5 log CFU/g and reduced total microbial load from catfish fillets by approximately 5 log CFU/g. In sensory analysis trained panelist preferred control samples over 2% carvacrol treated samples implying potential limitation in applicability of carvacrol for fillet treatments. PMID:22901012

  18. 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

  19. Eradicating Listeria monocytogenes from fully cooked franks by using an integrated pasteurization-packaging system.

    PubMed

    Murphy, R Y; Hanson, R E; Feze, N; Johnson, N R; Scott, L L; Duncan, L K

    2005-03-01

    Surface pasteurization by applying steam or hot water before or after packaging of processed foods may be used to eliminate pathogens such as Listeria monocytogenes from ready-to-eat meat and poultry products. Surface pasteurization treatment with a mixture of pressurized steam and hot water was integrated into a continuous vacuum-packaging system to reduce L. monocytogenes from fully cooked franks. The franks (2.54 cm diameter by 15.24 cm length) were surface inoculated to contain up to 6 log CFU/cm2 L. monocytogenes. The inoculated franks were treated at 121 degrees C for 1.5 s in an arrangement of six franks per packaging chamber followed by immediate vacuum sealing of the top films of food packages in the same unit. A 3-log CFU/cm2 reduction of L. monocytogenes on fully cooked franks was obtained using the integrated pasteurization-packaging system. The pasteurization depth was 1.27 mm below the surfaces of the franks. This process provides a commercially applicable means of ensuring food safety by effectively eradicating L. monocytogenes from ready-to-eat meat and poultry products at the very last possible step of food packaging before reaching retail consumers.

  20. Inhibition of Listeria monocytogenes by Lactobacillus bavaricus MN in beef systems at refrigeration temperatures.

    PubMed Central

    Winkowski, K; Crandall, A D; Montville, T J

    1993-01-01

    The ability of Lactobacillus bavaricus, a meat isolate, to inhibit the growth of three Listeria monocytogenes strains was examined in three beef systems: beef cubes, beef cubes in gravy, and beef cubes in gravy containing glucose. The beef was minimally heat treated, inoculated with L. bavaricus at 10(5) or 10(3) CFU/g and L. monocytogenes at 10(2) CFU/g, vacuum sealed, and stored at 4 or 10 degrees C. The meat samples were monitored for microbial growth, pH, and bacteriocin production. The pathogen was inhibited by L. bavaricus MN. At 4 degrees C, L. monocytogenes was inhibited or killed depending on the initial inoculum level of L. bavaricus. At 10 degrees C, at least a 10-fold reduction of the pathogen occurred, except in the beef without gravy. This system showed a transient inhibition of the pathogen during the first week of storage followed by growth to control levels by the end of the incubation period. Bacteriocin was detected in the samples, and inhibition could not be attributed to acidification. Low refrigeration temperatures significantly (P < or = 0.05) enhanced L. monocytogenes inhibition. Moreover, the addition of glucose-containing gravy and the higher inoculum level of L. bavaricus were significantly (P < or = 0.05) more effective in reducing L. monocytogenes populations in most of the systems studied. PMID:8368843

  1. 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.

  2. 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

  3. 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.

  4. Identification of a Peptide-Pheromone that Enhances Listeria monocytogenes Escape from Host Cell Vacuoles

    PubMed Central

    Xayarath, Bobbi; Alonzo, Francis; Freitag, Nancy E.

    2015-01-01

    Listeria monocytogenes is a Gram-positive facultative intracellular bacterial pathogen that invades mammalian cells and escapes from membrane-bound vacuoles to replicate within the host cell cytosol. Gene products required for intracellular bacterial growth and bacterial spread to adjacent cells are regulated by a transcriptional activator known as PrfA. PrfA becomes activated following L. monocytogenes entry into host cells, however the signal that stimulates PrfA activation has not yet been defined. Here we provide evidence for L. monocytogenes secretion of a small peptide pheromone, pPplA, which enhances the escape of L. monocytogenes from host cell vacuoles and may facilitate PrfA activation. The pPplA pheromone is generated via the proteolytic processing of the PplA lipoprotein secretion signal peptide. While the PplA lipoprotein is dispensable for pathogenesis, bacteria lacking the pPplA pheromone are significantly attenuated for virulence in mice and have a reduced efficiency of bacterial escape from the vacuoles of nonprofessional phagocytic cells. Mutational activation of PrfA restores virulence and eliminates the need for pPplA-dependent signaling. Experimental evidence suggests that the pPplA peptide may help signal to L. monocytogenes its presence within the confines of the host cell vacuole, stimulating the expression of gene products that contribute to vacuole escape and facilitating PrfA activation to promote bacterial growth within the cytosol. PMID:25822753

  5. 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

  6. 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

  7. 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

  8. Identification of a peptide-pheromone that enhances Listeria monocytogenes escape from host cell vacuoles.

    PubMed

    Xayarath, Bobbi; Alonzo, Francis; Freitag, Nancy E

    2015-03-01

    Listeria monocytogenes is a Gram-positive facultative intracellular bacterial pathogen that invades mammalian cells and escapes from membrane-bound vacuoles to replicate within the host cell cytosol. Gene products required for intracellular bacterial growth and bacterial spread to adjacent cells are regulated by a transcriptional activator known as PrfA. PrfA becomes activated following L. monocytogenes entry into host cells, however the signal that stimulates PrfA activation has not yet been defined. Here we provide evidence for L. monocytogenes secretion of a small peptide pheromone, pPplA, which enhances the escape of L. monocytogenes from host cell vacuoles and may facilitate PrfA activation. The pPplA pheromone is generated via the proteolytic processing of the PplA lipoprotein secretion signal peptide. While the PplA lipoprotein is dispensable for pathogenesis, bacteria lacking the pPplA pheromone are significantly attenuated for virulence in mice and have a reduced efficiency of bacterial escape from the vacuoles of nonprofessional phagocytic cells. Mutational activation of PrfA restores virulence and eliminates the need for pPplA-dependent signaling. Experimental evidence suggests that the pPplA peptide may help signal to L. monocytogenes its presence within the confines of the host cell vacuole, stimulating the expression of gene products that contribute to vacuole escape and facilitating PrfA activation to promote bacterial growth within the cytosol.

  9. 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.

  10. 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.

  11. 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

  12. The Posttranslocation Chaperone PrsA2 Contributes to Multiple Facets of Listeria monocytogenes Pathogenesis▿ †

    PubMed Central

    Alonzo, Francis; Port, Gary C.; Cao, Min; Freitag, Nancy E.

    2009-01-01

    Listeria monocytogenes is an intracellular bacterial pathogen whose virulence depends on the regulated expression of numerous secreted bacterial factors. As for other gram-positive bacteria, many proteins secreted by L. monocytogenes are translocated across the bacterial membrane in an unfolded state to the compartment existing between the membrane and the cell wall. This compartment presents a challenging environment for protein folding due to its high density of negative charge, high concentrations of cations, and low pH. We recently identified PrsA2 as a gene product required for L. monocytogenes virulence. PrsA2 was identified based on its increased secretion by strains containing a mutationally activated form of prfA, the key regulator of L. monocytogenes virulence gene expression. The prsA2 gene product is one of at least two predicted peptidyl-prolyl cis/trans-isomerases encoded by L. monocytogenes; these proteins function as posttranslocation protein chaperones and/or foldases. In this study, we demonstrate that PrsA2 plays a unique and important role in L. monocytogenes pathogenesis by promoting the activity and stability of at least two critical secreted virulence factors: listeriolysin O (LLO) and a broad-specificity phospholipase. Loss of PrsA2 activity severely attenuated virulence in mice and impaired bacterial cell-to-cell spread in host cells. In contrast, mutants lacking prsA1 resembled wild-type bacteria with respect to intracellular growth and cell-to-cell spread as well as virulence in mice. PrsA2 is thus distinct from PrsA1 in its unique requirement for the stability and full activity of L. monocytogenes-secreted factors that contribute to host infection. PMID:19451247

  13. 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

  14. Metal ion homeostasis in Listeria monocytogenes and importance in host-pathogen interactions.

    PubMed

    Jesse, Helen E; Roberts, Ian S; Cavet, Jennifer S

    2014-01-01

    Listeria monocytogenes is responsible for one of the most life-threatening food-borne infections and the leading cause of food-poisoning associated deaths in the UK. Infection may be of the unborn/newly born infant where disease may manifest as listeric abortion, stillbirth or late-onset neonatal listeriosis, while in adults, infection usually affects the central nervous system causing meningitis. Crucial to the survival of L. monocytogenes, both inside and outside the host, is its ability to acquire metals which act as cofactors for a broad range of its cellular proteins. However, L. monocytogenes must also protect itself against the innate toxicity of metals. The importance of metals in host-pathogen interactions is illustrated by the restriction of metals (including zinc and iron) in vertebrates in response to infection and the use of high levels of metals (copper and zinc) as part of the antimicrobial defences within host phagocytes. As such, L. monocytogenes is equipped with various mechanisms to tightly control its cellular metal pools and avoid metal poisoning. These include multiple DNA-binding metal-responsive transcription factors, metal-acquisition, metal-detoxification and metal-storage systems, some of which represent key L. monocytogenes virulence determinants. This review discusses current knowledge of the role of metals in L. monocytogenes infections, with a focus on the mechanisms that contribute to zinc and copper homeostasis in this organism. The requirement to precisely control cellular metal levels may impose a vulnerability to L. monocytogenes which can be exploited in antimicrobials and therapeutics. PMID:25476765

  15. 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

  16. Hygiene and Safety in the Meat Processing Environment from Butcher Shops: Microbiological Contamination and Listeria monocytogenes.

    PubMed

    Silva, Danilo Augusto Lopes da; Dias, Mariane Rezende; Cossi, Marcus Vinícius Coutinho; Castilho, Natália Parma Augusto de; 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.

  17. 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.

  18. Listeria monocytogenes transfer during mechanical dicing of celery and growth during subsequent storage.

    PubMed

    Kaminski, Chelsea N; Davidson, Gordon R; Ryser, Elliot T

    2014-05-01

    The transfer of Listeria monocytogenes to previously uncontaminated product during mechanical dicing of celery and its growth during storage at various temperatures were evaluated. In each of three trials, 275 g of retail celery stalks was immersed in an aqueous five-strain L. monocytogenes cocktail to obtain an average of 5.6 log CFU/g and then was diced using a hand-operated dicer, followed by sequential dicing of 15 identical 250-g batches of uninoculated celery using the same dicer. Each batch of diced celery was examined for numbers of Listeria initially and after 3 and 7 days of storage at 4, 7, and 10 °C. Additionally, the percentage by weight of inoculated product transferred to each of 15 batches of uninoculated celery was determined using inoculated red stems of Swiss chard as a surrogate. Listeria transfer to diced celery was also assessed after removing the Swiss chard. L. monocytogenes transferred from the initial batch of inoculated celery to all 15 batches of uninoculated celery during dicing, with populations decreasing from 5.2 to 2.0 log CFU/g on the day of processing. At 10 °C, Listeria reached an average population of 3.4 log CFU/g in all batches of uninoculated celery. Fewer batches of celery showed significant growth during storage at 4 and 7 °C (P < 0.05). Swiss chard pieces were recovered from all 15 batches of celery, with similar amounts seen in batches 2 to 15 (P > 0.05). L. monocytogenes was also recovered from each batch of uninoculated celery after the removal of Swiss chard, with populations decreasing from 4.7 to 1.7 log CFU/g. Storing the diced celery at 10 °C yielded a L. monocytogenes generation time of 0.87 days, with no significant growth observed during storage at 4 or 7 °C. Consequently, mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery.

  19. 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.

  20. Survival of Listeria monocytogenes in a food colorant derived from red beets.

    PubMed

    el-Gazzar, F E; Marth, E H

    1991-01-01

    Three commercial lots of the red beet colorant were inoculated to contain circa 10(3) to 10(7) Listeria monocytogenes strains California, V7, or Scott A per milliliter and stored for 56 d at 7 degrees C. McBride listeria agar was used to determine numbers of survivors. Selected colonies thought to be L. monocytogenes were confirmed biochemically. When necessary, samples were tested by cold enrichment (up to 8 weeks). Samples of colorant initially containing 10(3) to 10(4) strain California/ml were always free of the pathogen after 56 d, and sometimes after 42 d. Samples with high initial numbers (10(5) to 10(6)/ml) were not free of the pathogen after 8 wk at 7 degrees C. Strains V7 and Scott A, regardless of size of initial population, always survived beyond 56 d. Before inoculation, all test samples of colorant were free of L. monocytogenes (direct plating or cold enrichment). PMID:1903135

  1. 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

  2. Antibiosis of some lactic acid bacteria including Lactobacillus acidophilus toward Listeria monocytogenes.

    PubMed

    Raccach, M; McGrath, R; Daftarian, H

    1989-08-01

    Eleven strains of lactic acid bacteria were tested by the 'spot' on the 'lawn' method for their antagonistic activity against four strains of Listeria monocytogenes. Four out of the five strains of lactic acid bacteria most antagonistic toward the pathogen were those cultures known to produce bacteriocins. Four other strains of lactic acid bacteria were not antagonistic against Listeria by this method. Seventeen inhibition zones of the pathogen were obtained at 25 degrees C as compared to 10 at 32 degrees C. Lactobacillus acidophilus strains NU-A and 88, growing in the presence of L. monocytogenes in milk prevented the latter from attaining populations it would have in pure culture (P less than 0.01). 10(1.4)-10(3.5) lower numbers were noted. L. acidophilus in most cases exhibited a bacteriostatic effect toward the pathogen except for strain 88 which appeared to have a bactericidal effect (P less than 0.01) against Listeria strain OH. The lactobacilli reduced the pH of the milk to 4.7 over a 24 h period, showing that acid played a role in the observed antibiosis.

  3. Behaviour of Listeria monocytogenes during the traditional manufacture of water-buffalo Mozzarella cheese.

    PubMed

    Villani, F; Pepe, O; Mauriello, G; Moschetti, G; Sannino, L; Coppola, S

    1996-05-01

    The behaviour of a four-strains mixture of Listeria monocytogenes (strains Scott A, V7, OH and Cal) during the traditional manufacture of water-buffalo Mozzarella cheese was investigated at two levels of inoculation: ca 10(5) and 10(3) cfu ml-1 of vat milk. No significant change in Listeria counts was observed during the curd ripening (4.0-4.5 h), at the end of which the pH ranged between 4.83 and 4.91. A decrease of about 2 log was observed after stretching of the curd in hot water (95 degrees C), followed by complete elimination of Listeria after 48 and 24 h of storage of the final cheese in the conditioning liquid (skim water resulting from the stretching, pH ca 4.0) with initial high and low contamination of the cheese milk respectively. Results also indicated that a 1.7 log reduction of L. monocytogenes could be achieved during the preparation of the natural whey culture utilized as starter in cheesemaking.

  4. Role of Macrophage Scavenger Receptors in Response to Listeria monocytogenes Infection in Mice

    PubMed Central

    Ishiguro, Takuro; Naito, Makoto; Yamamoto, Takashi; Hasegawa, Go; Gejyo, Fumitake; Mitsuyama, Masao; Suzuki, Hiroshi; Kodama, Tatsuhiko

    2001-01-01

    Type I and type II macrophage scavenger receptors (SR-A I/II) recognize a variety of polyanions including bacterial cell-wall products such as lipopolysaccharide, suggesting a role for SR-A I/II in immunity against bacterial infection. SR-A I/II-deficient (MSR-A−/−) mice were more susceptible to infection with listeriolysin-O (LLO)-producing Listeria monocytogenes. After infection, Kupffer cells in wild-type (MSR-A+/+) mice phagocytized larger numbers of Listeria than those in MSR-A−/− mice. The number and the diameter of hepatic granulomas were larger in MSR-A−/− mice than MSR-A+/+ mice. L. monocytogenes replicated at higher levels in the liver of MSR-A−/− mice compared with MSR-A+/+ mice, and macrophages from MSR-A−/− mice showed impaired ability to kill Listeria in vitro. However, macrophages from MSR-A+/+ and MSR-A−/− mice showed similar levels of listericidal activity against isogenic mutant L. monocytogenes with an inactivated LLO gene. The listerial phagocytic activities of MSR-A+/+ macrophages treated with an anti-SR-A I/II antibody (2F8) and MSR-A−/− macrophages were significantly impaired compared with untreated MSR-A+/+ macrophages, indicating that SR-A I/II function as a receptor for L. monocytogenes. Electron microscopy revealed that most L. monocytogenes had been eliminated from the lysosomes of MSR-A+/+ macrophages in vivo and in vitro. In contrast, L. monocytogenes rapidly lysed the phagosomal membrane and escaped to the cytosol in MSR-A−/− macrophages and in MSR-A+/+ macrophages treated with 2F8 before phagosome-lysosome fusion. These findings imply that SR-A I/II plays a crucial role in host defense against listerial infection not only by functioning as a receptor but also by mediating listericidal mechanisms through the regulation of LLO-dependent listerial escape from the macrophages. PMID:11141491

  5. Anti-Listerial Activity of Four Seaweed Essential Oils Against Listeria monocytogenes

    PubMed Central

    Patra, Jayanta Kumar; Baek, Kwang-Hyun

    2016-01-01

    Background Listeria monocytogenes is one of the most virulent types of bacteria and causes severe foodborne illness, such as listeriosis. Because this pathogen has become resistant to sanitizers and other disinfectants that are used to clean utensils and surfaces during food processing, it poses a serious threat to the food industry. Objectives The study was conducted to determine the anti-listerial potential of essential oils extracted from four edible seaweeds against L. monocytogenes. Materials and Methods Essential oil was extracted from four edible seaweeds (Enteromorpha linza, Undaria pinnatifida, Laminaria japonica, and Porphyra tenera) against L. monocytogenes using the microwave hydrodistillation method. The anti-listerial activity of the essential oil was determined using the standard disc diffusion method. Results Among the four essential oils, E. linza (ELEO) was most effective against all three strains of L. monocytogenes (11.3 - 16.0 mm). The other three essential oils were only effective against two strains, L. monocytogenes ATCC 19115 (10.0 - 10.5 mm) and L. monocytogenes ATCC 7644 (11.0 - 15.0 mm). The minimum inhibitory concentration and the minimum bactericidal concentration of all four essential oils varied from 12.5 - 25.0 mg/mL. Further, the mode of action of ELEO against L. monocytogenes was investigated by examining its effect on cell viability, the release of 260-nm absorbing materials, the number of K+ ions, the relative electrical conductivity, and the salt tolerance capacity. The results indicated that the essential oils exhibited strong anti-listerial activity against multiple strains of L. monocytogenes. It displayed potential inhibitory effects on the viability of bacterial cells and loss of integrity as indicated by an increase in the relative electrical conductivity, leakage of K+ ions and other 260-nm absorbing materials, and a loss of the salt tolerance capacity. Conclusions The results presented herein provided insight into a

  6. Anti-Listerial Activity of Four Seaweed Essential Oils Against Listeria monocytogenes

    PubMed Central

    Patra, Jayanta Kumar; Baek, Kwang-Hyun

    2016-01-01

    Background Listeria monocytogenes is one of the most virulent types of bacteria and causes severe foodborne illness, such as listeriosis. Because this pathogen has become resistant to sanitizers and other disinfectants that are used to clean utensils and surfaces during food processing, it poses a serious threat to the food industry. Objectives The study was conducted to determine the anti-listerial potential of essential oils extracted from four edible seaweeds against L. monocytogenes. Materials and Methods Essential oil was extracted from four edible seaweeds (Enteromorpha linza, Undaria pinnatifida, Laminaria japonica, and Porphyra tenera) against L. monocytogenes using the microwave hydrodistillation method. The anti-listerial activity of the essential oil was determined using the standard disc diffusion method. Results Among the four essential oils, E. linza (ELEO) was most effective against all three strains of L. monocytogenes (11.3 - 16.0 mm). The other three essential oils were only effective against two strains, L. monocytogenes ATCC 19115 (10.0 - 10.5 mm) and L. monocytogenes ATCC 7644 (11.0 - 15.0 mm). The minimum inhibitory concentration and the minimum bactericidal concentration of all four essential oils varied from 12.5 - 25.0 mg/mL. Further, the mode of action of ELEO against L. monocytogenes was investigated by examining its effect on cell viability, the release of 260-nm absorbing materials, the number of K+ ions, the relative electrical conductivity, and the salt tolerance capacity. The results indicated that the essential oils exhibited strong anti-listerial activity against multiple strains of L. monocytogenes. It displayed potential inhibitory effects on the viability of bacterial cells and loss of integrity as indicated by an increase in the relative electrical conductivity, leakage of K+ ions and other 260-nm absorbing materials, and a loss of the salt tolerance capacity. Conclusions The results presented herein provided insight into a

  7. Differentiation of different mixed Listeria strains and also acid-injured, heat-injured, and repaired cells of Listeria monocytogenes using fourier transform infrared spectroscopy.

    PubMed

    Nyarko, Esmond; Donnelly, Catherine

    2015-03-01

    Fourier transform infrared (FT-IR) spectroscopy was used to differentiate mixed strains of Listeria monocytogenes and mixed strains of L. monocytogenes and Listeria innocua. FT-IR spectroscopy was also applied to investigate the hypothesis that heat-injured and acid-injured cells would return to their original physiological integrity following repair. Thin smears of cells on infrared slides were prepared from cultures for mixed strains of L. monocytogenes, mixed strains of L. monocytogenes and L. innocua, and each individual strain. Heat-injured and acid-injured cells were prepared by exposing harvested cells of L. monocytogenes strain R2-764 to a temperature of 56 ± 0.2°C for 10 min or lactic acid at pH 3 for 60 min, respectively. Cellular repair involved incubating aliquots of acid-injured and heat-injured cells separately in Trypticase soy broth supplemented with 0.6% yeast extract for 22 to 24 h; bacterial thin smears on infrared slides were prepared for each treatment. Spectral collection was done using 250 scans at a resolution of 4 cm(-1) in the mid-infrared wavelength region. Application of multivariate discriminant analysis to the wavelength region from 1,800 to 900 cm(-1) separated the individual L. monocytogenes strains. Mixed strains of L. monocytogenes and L. monocytogenes cocultured with L. innocua were successfully differentiated from the individual strains when the discriminant analysis was applied. Different mixed strains of L. monocytogenes were also successfully separated when the discriminant analysis was applied. A data set for injury and repair analysis resulted in the separation of acid-injured, heat-injured, and intact cells; repaired cells clustered closer to intact cells when the discriminant analysis (1,800 to 600 cm(-1)) was applied. FT-IR spectroscopy can be used for the rapid source tracking of L. monocytogenes strains because it can differentiate between different mixed strains and individual strains of the pathogen.

  8. Petiveria alliacea L. extract protects mice against Listeria monocytogenes infection--effects on bone marrow progenitor cells.

    PubMed

    Quadros, M R; Souza Brito, A R; Queiroz, M L

    1999-02-01

    In this study we have investigated the effects of Petiveria alliacea on the hematopoietic response of mice infected with Listeria monocytogenes. Our results demonstrate a protective effect of the crude extract of P. alliacea since the survival of the treated/infected was higher than that in the infected group. Moreover, the number of granulocyte/macrophage colonies (CFU-GM) and the serum colony stimulating activity levels were increased in the treated/infected mice in relation to the infected group. These results suggest an immunomodulation of Petiveria alliacea extract on hematopoiesis, which may be responsible, at least in part, for the increased resistance of mice to Listeria monocytogenes infection.

  9. 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.

  10. 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

  11. 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.

  12. Ribotype diversity of Listeria monocytogenes isolates from two salmon processing plants in Norway.

    PubMed

    Klaeboe, Halvdan; Rosef, Olav; Fortes, Esther; Wiedmann, Martin

    2006-10-01

    The purpose of this study was to use automated ribotyping procedure to track Listeria monocytogenes transmission in the cold smoked fish production chain and to characterize L. monocytogenes subtypes associated with the salmon processing industry. A total of 104 isolates, which had previously been obtained from a raw fish slaughter and processing plant (plant B) and an adjacent, downstream, salmon smoking operation (plant A), were characterized. These isolates had been obtained through a longitudinal study on Listeria presence, which covered a 31-week period, in both plants. Isolates had been obtained from samples taken from different machinery used throughout the production process. In addition, six isolates obtained from products produced in plant A two years after the initial study were included, so that a total of 110 isolates were characterized. Automated ribotyping was performed using both the restriction enzymes EcoRI and PvuII to increase the discriminatory power. The 110 L. monocytogenes isolates could be divided into 11 EcoRI ribotypes; PvuII ribotype data yielded multiple subtypes within 7 EcoRI ribotypes for a total of 21 subtypes based on both EcoRI and PvuII ribotyping. A total of three EcoRI ribotypes (DUP-1023C, DUP-1045B, and DUP-1053E) were isolated at multiple sampling times from both plants. In addition, one subtype (DUP-1053B) was isolated at multiple sampling times in only plant A, the salmon smoking operation. These data not only support that L. monocytogenes can persist throughout the salmon production system, but also showed that L. monocytogenes may be transmitted between slaughter and smoking operations or may be unique to smoking operations. While the majority of subtypes isolated have been rarely or never linked to human listeriosis cases, some subtypes have previously caused human listeriosis outbreaks and cases. Molecular subtyping thus is critical to identify L. monocytogenes transmission and niches in order to allow design and

  13. Diagnosis of Listeria monocytogenes Meningoencephalitis by Real-Time PCR for the hly Gene ▿ §

    PubMed Central

    Le Monnier, Alban; Abachin, Eric; Beretti, Jean-Luc; Berche, Patrick; Kayal, Samer

    2011-01-01

    Listeria monocytogenes is a bacterial pathogen that can invade the central nervous system (CNS), causing meningoencephalitis and brain abscesses. The diagnosis of CNS listeriosis, based on the isolation of the bacteria in the cerebrospinal fluid (CSF), can be difficult because of previous antibiotic treatment and a low number of bacteria in the CSF. To improve the sensitivity of microbiological diagnosis, we have developed a real-time PCR assay for detecting and quantifying L. monocytogenes DNA in the CSF. The designed primers specifically amplify the L. monocytogenes hly gene, which encodes listeriolysin O, a pore-forming cytolysin. The PCR assay for the hly gene (PCR-hly) provides reproducible quantitative results over a wide dynamic range of concentrations and was highly sensitive while detecting a single gene copy/ml. By assaying a large panel of bacterial species, including species secreting pore-forming cytolysin, we determined the specificity of the PCR-hly, which exclusively detects the L. monocytogenes DNA. We then analyzed 214 CSF samples from patients suspected of having CNS listeriosis. PCR-hly was positive in all cases in which L. monocytogenes was isolated by culture. Positive PCR-hly of the CSF was also obtained for five additional, clinically confirmed cases of CNS listeriosis for which bacterial cultures were negative presumably due to previous treatment with antibiotics. As a complement to classical bacteriological CSF culture, our designed real-time PCR-hly assay proved to be valuable by enhancing the rapidity and the accuracy of the diagnosis of CNS infection by L. monocytogenes. In addition, the quantitative results provided may, in some instances, be useful for the follow-up of patients under treatment. PMID:21918022

  14. 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

  15. Listeriolysin O Is Necessary and Sufficient to Induce Autophagy during Listeria monocytogenes Infection

    PubMed Central

    Meyer-Morse, Nicole; Robbins, Jennifer R.; Rae, Chris S.; Mochegova, Sofia N.; Swanson, Michele S.; Zhao, Zijiang; Virgin, Herbert W.; Portnoy, Daniel

    2010-01-01

    Background Recent studies have suggested that autophagy is utilized by cells as a protective mechanism against Listeria monocytogenes infection. Methodology/Principal Findings However we find autophagy has no measurable role in vacuolar escape and intracellular growth in primary cultured bone marrow derived macrophages (BMDMs) deficient for autophagy (atg5−/−). Nevertheless, we provide evidence that the pore forming activity of the cholesterol-dependent cytolysin listeriolysin O (LLO) can induce autophagy subsequent to infection by L. monocytogenes. Infection of BMDMs with L. monocytogenes induced microtubule-associated protein light chain 3 (LC3) lipidation, consistent with autophagy activation, whereas a mutant lacking LLO did not. Infection of BMDMs that express LC3-GFP demonstrated that wild-type L. monocytogenes was encapsulated by LC3-GFP, consistent with autophagy activation, whereas a mutant lacking LLO was not. Bacillus subtilis expressing either LLO or a related cytolysin, perfringolysin O (PFO), induced LC3 colocalization and LC3 lipidation. Further, LLO-containing liposomes also recruited LC3-GFP, indicating that LLO was sufficient to induce targeted autophagy in the absence of infection. The role of autophagy had variable effects depending on the cell type assayed. In atg5−/− mouse embryonic fibroblasts, L. monocytogenes had a primary vacuole escape defect. However, the bacteria escaped and grew normally in atg5−/− BMDMs. Conclusions/Significance We propose that membrane damage, such as that caused by LLO, triggers bacterial-targeted autophagy, although autophagy does not affect the fate of wild-type intracellular L. monocytogenes in primary BMDMs. PMID:20062534

  16. Pathogenicity and immunogenicity of a mutant strain of Listeria monocytogenes in the chicken infection model.

    PubMed

    Yin, Yuelan; Tian, Debin; Jiao, Hongmei; Zhang, Chenju; Pan, Zhiming; Zhang, Xiaoming; Wang, Xiaobo; Jiao, Xinan

    2011-03-01

    Listeria monocytogenes has been exploited as a vaccine carrier based upon its ability to induce a strong cell-mediated immune response. At present, the safety of live, attenuated L. monocytogenes vaccines in patients is being studied in clinical trials. L. monocytogenes is also an attractive vaccine vector for use in poultry; however, the pathogenicity and immunogenicity of this organism in poultry remain to be fully elucidated. In this study, we investigated the pathogenicity and immunogenicity of an actA- and plcB-deficient L. monocytogenes strain, yzuLM4ΔactA/plcB, and its wild-type parent strain, yzuLM4, in an avian infection model. The results showed that the wild-type strain could infect ISA brown chickens, causing serious tissue disruptions, including various degrees of degeneration, necrotic lesions, and inflammatory cell infiltration in the liver, spleen, heart, and kidney. However, the mutant strain showed reduced virulence in embryonated eggs compared with that of the parent strain (the 50% lethal dose [LD(50)] was 3 logs higher). The mutant strain also showed low virulence in chickens and was rapidly eliminated by the host. There were no obvious pathological changes in tissue sections, but the mutant strain still retained the ability to stimulate high levels of antibody against the protein listeriolysin O (LLO). Booster immunization with the mutant strain led to rapid bacterial clearance from the livers and spleens of chickens challenged by the intramuscular route or the oral route. Collectively, our data suggest that the wild-type serotype 1/2a L. monocytogenes strain can cause serious disease in chickens but the mutant strain with a deletion of the actA and plcB genes is less virulent but induces a strong immune response. This mutant strain of L. monocytogenes is therefore a promising candidate as a safe and effective vector for the delivery of heterologous antigens to prevent zoonosis and infectious disease in poultry.

  17. Listeria monocytogenes inhibition by whey protein films and coatings incorporating lysozyme.

    PubMed

    Min, Seacheol; Harris, Linda J; Han, Jung H; Krochta, John M

    2005-11-01

    The effects of whey protein isolate (WPI) films and coatings incorporating lysozyme (LZ) on the inhibition of Listeria monocytogenes both in and on microbial media, as well as on cold-smoked salmon, were studied. The antimicrobial effects of LZ were examined using various growth media by turbidity and plate counting tests. Disc-covering and disc-surface-spreading tests were also used to evaluate the effects of WPI films incorporating LZ. Smoked salmon was used as a model food to test the antimicrobial effects of WPI coatings incorporating LZ, both initially and during storage at 4 and 10 degrees C for 35 days. Tensile properties (elastic modulus, tensile strength, and percentage of elongation), oxygen permeability, and color (Hunter L, a, and b) of WPI films with and without LZ were also compared. LZ inhibited L. monocytogenes in broth and on agar media. The number of cells surviving after LZ treatments depended on the type of media. WPI films incorporating 204 mg of LZ per g of film (dry basis) inhibited the growth of a preparation of 4.4 log CFU/cm2 L. monocytogenes. WPI coatings prepared with 25 mg of LZ per g of coating solution initially inactivated more than 2.4, 4.5, and 3.0 log CFU/g of L. monocytogenes, total aerobes, and yeasts and molds in smoked salmon samples, respectively. The WPI coatings incorporating LZ efficiently retarded the growth of L. monocytogenes at both 4 and 10 degrees C. The anti-L. monocytogenes effect of LZ-WPI coating was more noticeable when the coating was applied before inoculation than when the coating was applied after inoculation. Significantly higher elastic modulus values and lower percentage of elongation and oxygen permeability values were measured with the WPI films incorporating LZ than with the plain WPI films.

  18. Faecal shedding and strain diversity of Listeria monocytogenes in healthy ruminants and swine in Northern Spain

    PubMed Central

    Esteban, Jon I; Oporto, Beatriz; Aduriz, Gorka; Juste, Ramón A; Hurtado, Ana

    2009-01-01

    Background Listeria monocytogenes is among the most important foodborne bacterial pathogens due to the high mortality rate and severity of the infection. L. monocytogenes is a ubiquitous organism occasionally present in the intestinal tract of various animal species and faecal shedding by asymptomatically infected livestock poses a risk for contamination of farm environments and raw food at the pre-harvest stages. The aim of this study was to determine the prevalence and strain diversity of L. monocytogenes in healthy ruminants and swine herds. Results Faecal samples from 30 animals per herd were collected from 343 herds (120 sheep, 124 beef cattle, 82 dairy cattle and 17 swine) in the Basque Country and screened in pools by an automated enzyme-linked fluorescent immunoassay (VIDAS®) to estimate the prevalence of positive herds. Positive samples were subcultured onto the selective and differential agar ALOA and biochemically confirmed. L. monocytogenes was isolated from 46.3% of dairy cattle, 30.6% beef cattle and 14.2% sheep herds, but not from swine. Within-herd prevalence investigated by individually analysing 197 sheep and 221 cattle detected 1.5% of faecal shedders in sheep and 21.3% in cattle. Serotyping of 114 isolates identified complex 4b as the most prevalent (84.2%), followed by 1/2a (13.2%), and PFGE analysis of 68 isolates showed a highly diverse L. monocytogenes population in ruminant herds. Conclusion These results suggested that cattle represent a potentially important reservoir for L. monocytogenes in the Basque Country, and highlighted the complexity of pathogen control at the farm level. PMID:19133125

  19. Neonatal host defense mechanisms against Listeria monocytogenes infection: the role of lipopolysaccharides and interferons.

    PubMed

    Bortolussi, R; Issekutz, T; Burbridge, S; Schellekens, H

    1989-03-01

    The human newborn infant is susceptible to lethal infection caused by a number of bacterial species including Listeria monocytogenes, a gram-positive rod which is pathogenic by virtue of its ability to survive intracellularly. In adult animals interferon (IFN)-alpha/beta and IFN-gamma or agents that induce or augment IFN production confer protection against lethal L. monocytogenes infection. Regulation and production of IFN is poorly understood during the neonatal period. We therefore evaluated the role of IFN-alpha/beta and IFN-gamma, IFN-inducers (polyinosinic:polycytidylic acid, amino-bromo-phenyl-pyrimidinone, amino-iodophenyl pyrimidinone) and lipopolysaccharide in modifying neonatal L. monocytogenes infection. Pretreatment of juvenile rats with polyinosinic:polycytidylic acid or lipopolysaccharide protected them against a lethal challenge with L. monocytogenes. Among newborn rats, polyinosinic:polycytidylic acid, amino-iodo-phenyl pyrimidinone and amino-bromophenyl-pyrimidinone gave significant protection, however, lipopolysaccharide did not influence survival. The role of IFN was further examined. Pretreatment of 3-d-old rats with purified IFN-alpha/beta, native rat IFN-gamma or rDNA rat IFN-gamma protected them against the lethality of subsequent L. monocytogenes injection. At 3 d after bacterial challenge, bacterial content in the spleens of 3-d-old rats pretreated with rIFN-gamma were significantly decreased compared to controls: IFN-alpha/beta-pretreated animals had less of a decrease, which become significant only 5 d after challenge. Our experiments indicate a role for IFN in neonatal host defense against L. monocytogenes infection.

  20. Adenovirus-based vaccine against Listeria monocytogenes: extending the concept of invariant chain linkage.

    PubMed

    Jensen, Søren; Steffensen, Maria Abildgaard; Jensen, Benjamin Anderschou Holbech; Schlüter, Dirk; Christensen, Jan Pravsgaard; Thomsen, Allan Randrup

    2013-10-15

    The use of replication-deficient adenoviruses as vehicles for transfer of foreign genes offers many advantages in a vaccine setting, eliciting strong cellular immune responses involving both CD8(+) and CD4(+) T cells. Further improving the immunogenicity, tethering of the inserted target Ag to MHC class II-associated invariant chain (Ii) greatly enhances both the presentation of most target Ags, as well as overall protection against viral infection, such as lymphocytic choriomeningitis virus (LCMV). The present study extends this vaccination concept to include protection against intracellular bacteria, using Listeria monocytogenes as a model organism. Protection in C57BL/6 mice against recombinant L. monocytogenes expressing an immunodominant epitope of the LCMV glycoprotein (GP33) was greatly accelerated, augmented, and prolonged following vaccination with an adenoviral vaccine encoding GP linked to Ii compared with vaccination with the unlinked vaccine. Studies using knockout mice demonstrated that CD8(+) T cells were largely responsible for this protection, which is mediated through perforin-dependent lysis of infected cells and IFN-γ production. Taking the concept a step further, vaccination of C57BL/6 (L. monocytogenes-resistant) and BALB/c (L. monocytogenes-susceptible) mice with adenoviral vectors encoding natural L. monocytogenes-derived soluble Ags (listeriolysin O and p60) revealed that tethering of these Ags to Ii markedly improved the vaccine-induced CD8(+) T cell response to two of three epitopes studied. More importantly, Ii linkage accelerated and augmented vaccine-induced protection in both mouse strains and prolonged protection, in particular that induced by the weak Ag, p60, in L. monocytogenes-susceptible BALB/c mice.

  1. 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

  2. Inhibition of Listeria monocytogenes and Salmonella by combinations of oriental mustard, malic acid, and EDTA.

    PubMed

    Olaimat, Amin N; Holley, Richard A

    2014-04-01

    The antimicrobial activities of oriental mustard extract alone or combined with malic acid and EDTA were investigated against Salmonella spp. or Listeria monocytogenes at different temperatures. Five strain Salmonella or L. monocytogenes cocktails were separately inoculated in Brain Heart Infusion broth containing 0.5% (w/v) aqueous oriental mustard extract and incubated at 4 °C to 21 °C for 21 d. For inhibitor combination tests, Salmonella Typhimurium 02:8423 and L. monocytogenes 2-243 were individually inoculated in Mueller Hinton broth containing the mustard extract with either or both 0.2% (w/v) malic acid and 0.2% (w/v) EDTA and incubated at 10 °C or 21 °C for 10 to 14 d. Mustard extract inhibited growth of the L. monocytogenes cocktail at 4 °C up to 21 d (2.3 log10 CFU/mL inhibition) or at 10 °C for 7 d (2.4 log10 CFU/mL inhibition). Salmonella spp. viability was slightly, but significantly reduced by mustard extract at 4 °C by 21 d. Although hydrolysis of sinigrin in mustard extract by both pathogens was 2 to 6 times higher at 21 °C than at 4 °C to 10 °C, mustard was not inhibitory at 21 °C, perhaps because of the instability of its hydrolysis product (allyl isothiocyanate). At 21 °C, additive inhibitory effects of mustard extract with EDTA or malic acid led to undetectable levels of S. Typhimurium and L. monocytogenes by 7 d and 10 d, respectively. At 10 °C, S. Typhimurium was similarly susceptible, but combinations of antimicrobials were not more inhibitory to L. monocytogenes than the individual agents.

  3. 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.

  4. Effect of gamma irradiation on Listeria monocytogenes in frozen, artificially contaminated sandwiches.

    PubMed

    Clardy, S; Foley, D M; Caporaso, F; Calicchia, M L; Prakash, A

    2002-11-01

    Gamma irradiation has been shown to effectively control L monocytogenes in uncooked meats but has not been extensively studied in ready-to-eat foods. The presence of Listeria in ready-to-eat foods is often due to postprocess contamination by organisms in the food-manufacturing environment. Because gamma irradiation is applied after products are packaged, the treated foods are protected from environmental recontamination. Currently, a petition to allow gamma irradiation of ready-to-eat foods is under review by the Food and Drug Administration. This study was conducted to determine if gamma irradiation could be used to control L. monocytogenes in ready-to-eat sandwiches. Ham and cheese sandwiches were contaminated with L. monocytogenes, frozen at -40 degrees C, and exposed to gamma irradiation. Following irradiation, sandwiches were assayed for L. monocytogenes. A triangle test was performed to determine if irradiated and nonirradiated sandwiches differed in sensory quality. We found that the D10-values ranged from 0.71 to 0.81 kGy and that a 5-log reduction would require irradiation with 3.5 to 4.0 kGy. The results of a 39-day storage study of sandwiches inoculated with 10(7) CFU of L monocytogenes per g indicated that counts for nonirradiated sandwiches remained fairly constant. Counts for sandwiches treated with 3.9 kGy decreased by 5 log units initially and then decreased further during storage at 4 degrees C. Sensory panelists could distinguish between irradiated and nonirradiated sandwiches but were divided on whether irradiation adversely affected sandwich quality. Our results suggest that manufacturers of ready-to-eat foods could use gamma irradiation to control L. monocytogenes and improve the safety of their products.

  5. 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.

  6. 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

  7. Epidemiological Survey of Listeria monocytogenes in a gravlax salmon processing line

    PubMed Central

    Cruz, C.D.; Silvestre, F.A.; Kinoshita, E.M.; Landgraf, M.; Franco, B.D.G.M.; Destro, M.T.

    2008-01-01

    Listeria monocytogenes is a cause of concern to food industries, mainly for those producing ready-to-eat (RTE) products. This microorganism can survive processing steps such as curing and cold smoking and is capable of growing under refrigeration temperatures. Its presence in RTE fish products with extended shelf life may be a risk to the susceptible population. One example of such a product is gravlax salmon; a refrigerated fish product not exposed to listericidal processes and was the subject of this study. In order to evaluate the incidence and dissemination of L. monocytogenes 415 samples were collected at different steps of a gravlax salmon processing line in São Paulo state, Brazil. L. monocytogenes was confirmed in salmon samples (41%), food contact surfaces (32%), non-food contact surfaces (43%) and of food handlers’ samples (34%), but could not be detected in any ingredient. 179 L. monocytogenes isolates randomly selected were serogrouped and typed by PFGE. Most of L. monocytogenes strains belonged to serogroup 1 (73%). 61 combined pulsotypes were found and a dendrogram identified six clusters: most of the strains (120) belonged to cluster A. It was suggested that strains arriving into the plant via raw material could establish themselves in the processing environment contaminating the final product. The wide dissemination of L. monocytogenes in this plant indicates that a great effort has to be taken to eliminate the microorganism from these premises, even though it was not observed multiplication of the microorganism in the final product stored at 4°C up to 90 days. PMID:24031233

  8. 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

  9. 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

  10. Listeria monocytogenes that lyse in the macrophage cytosol trigger AIM2-mediated pyroptosis

    PubMed Central

    Sauer, John-Demian; Witte, Chelsea E.; Zemansky, Jason; Hanson, Bill; Lauer, Peter; Portnoy, Daniel A.

    2010-01-01

    Summary To gain insight into the mechanisms by which host cells detect cytosolic invasion by intracellular pathogens, a genetic screen was performed to identify Listeria monocytogenes mutants that induced altered levels of host cell death. A mutation in lmo2473 resulted in hyper-stimulation of host cell death and IL-1β secretion (pyroptosis) following bacteriolysis in the macrophage cytosol. In addition, strains engineered to lyse in the cytosol by expression of both bacteriophage holin and lysin or induced to lyse by treatment with ampicillin stimulated pyroptosis. Pyroptosis was independent of the Nlrp3 and Nlrc4 receptors, but dependent on ASC and AIM2. Importantly, wild type L. monocytogenes were also found to lyse, albeit at low levels, and trigger AIM2-dependent pyroptosis. Since AIM2 is activated by DNA, these data suggested that pyroptosis is triggered by bacterial DNA released during lysis. PMID:20417169

  11. Listeria monocytogenes triggers AIM2-mediated pyroptosis upon infrequent bacteriolysis in the macrophage cytosol.

    PubMed

    Sauer, John-Demian; Witte, Chelsea E; Zemansky, Jason; Hanson, Bill; Lauer, Peter; Portnoy, Daniel A

    2010-05-20

    A host defense strategy against pathogens is the induction of cell death, thereby eliminating the pathogen's intracellular niche. Pyroptosis, one such form of cell death, is dependent on inflammasome activation. In a genetic screen to identify Listeria monocytogenes mutants that induced altered levels of host cell death, we identified a mutation in lmo2473 that caused hyperstimulation of IL-1beta secretion and pyroptosis following bacteriolysis in the macrophage cytosol. In addition, strains engineered to lyse in the cytosol by expression of both bacteriophage holin and lysin or induced to lyse by treatment with ampicillin stimulated pyroptosis. Pyroptosis was independent of the Nlrp3 and Nlrc4 inflammasome receptors but dependent on the inflammasome adaptor ASC and the cytosolic DNA sensor AIM2. Importantly, wild-type L. monocytogenes were also found to lyse, albeit at low levels, and trigger AIM2-dependent pyroptosis. These data suggested that pyroptosis is triggered by bacterial DNA released during cytosolic lysis.

  12. Effect of prior heat shock on heat resistance of Listeria monocytogenes in meat.

    PubMed Central

    Farber, J M; Brown, B E

    1990-01-01

    The effect of prior heat shock on the thermal resistance of Listeria monocytogenes in meat was investigated. A sausage mix inoculated with approximately 10(7) L. monocytogenes per g was initially subjected to a heat shock temperature of 48 degrees C before being heated at a final test temperature of 62 or 64 degrees C. Although cells heat shocked at 48 degrees C for 30 or 60 min did not show a significant increase in thermotolerance as compared with control cells (non-heat shocked), bacteria heat shocked for 120 min did, showing an average 2.4-fold increase in the D64 degrees C value. Heat-shocked cells shifted to 4 degrees C appeared to maintain their thermotolerance for at least 24 h after heat shock. PMID:2116757

  13. Habituation to organic acid anions induces resistance to acid and bile in Listeria monocytogenes.

    PubMed

    Zhang, Yimin; Carpenter, Charles E; Broadbent, Jeff R; Luo, Xin

    2014-03-01

    We evaluated the intrinsic and inducible resistance of four human pathogenic strains of Listeria monocytogenes to acid and bile, factors associated with virulence. Cells were grown in media at pH 7.4, or in media at pH 6.0 containing 0 (HCl control) or 4.75 mM of different organic acids, harvested at stationary or mid log phase, and challenged for 1h in acid or bile. Stationary phase cells were intrinsically more resistant to either challenge than log phase cells, and large differences between strains were evident among the latter. Compared to the HCl control, habituation to log phase with organic acids induced significant (p<0.05) and meaningful (≥1 log) increases in acid resistance of three of four strains tested, and in bile resistance of two strains suggesting that exposure to organic acid anions may enhance virulence in L. monocytogenes.

  14. [Neonatal meningitis due to Listeria monocytogenes after 3 weeks of maternal treatment during pregnancy].

    PubMed

    Fayol, L; Beizig, S; Le Monnier, A; Lacroze, V; Simeoni, U

    2009-04-01

    We report the case of a pregnant woman with listeriosis at 26 gestational weeks followed by premature labor at 30 gestational weeks. Bacterial meningitis was suspected in the neonate with ventriculitis on sonography, a high level of protein in the cerebrospinal fluid (CSF), and an identified specific bacterial genome of Listeria monocytogenes (PCR 16S rDNA and sequencing and specific amplification of L. monocytogenes hly gene) in CSF. Neonatal meningitis was complicated with cerebral venous sinus thrombosis and ventriculomegaly. Listeriosis during pregnancy can lead to severe complications in the neonate. Thus, listeriosis should be a diagnostic concern in febrile pregnant women at any stage of pregnancy. First-line treatment is based on high-dose amoxicillin (> or =6g/day) and must be used for at least 3 weeks for treatment of listeriosis during pregnancy. If the fetus survives, longer therapy until delivery can be discussed. PMID:19195853

  15. 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

  16. Outbreak of Listeria monocytogenes infections associated with pasteurized milk from a local dairy--Massachusetts, 2007.

    PubMed

    2008-10-10

    On November 27, 2007, a local health officer in central Massachusetts contacted the Massachusetts Department of Public Health (MDPH) to report listeriosis in a man aged 87 years. Pulsed-field gel electrophoresis (PFGE) performed on the patient's Listeria monocytogenes isolate produced a pattern indistinguishable from that of isolates from three other cases identified in residents of central Massachusetts in June, October, and early November 2007. MDPH, in collaboration with local public health officials, conducted an investigation, which implicated pasteurized, flavored and nonflavored, fluid milk produced by a local dairy (dairy A) as the source of the outbreak. This report summarizes the results of that investigation. In all, five cases were identified, and three deaths occurred. This outbreak illustrates the potential for contamination of fluid milk products after pasteurization and the difficulty in detecting outbreaks of L. monocytogenes infections.

  17. 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

  18. 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.

  19. Differential diagnosis between Streptococcus agalactiae and Listeria Monocytogenes in the clinical laboratory.

    PubMed

    Kontnick, C; von Graevenitz, A; Piscitelli, V

    1977-01-01

    Streptococci of the group B (S. agalactiae) and Listeria monocytogenes resemble each other in many morphological and biochemical characteristics. Ten beta-hemolytic strains of each species were subjected to 26 tests commonly and easily performed in the clinical laboratory. Macroscopic and microscopic morphology on solid media showed differences only in the size of the colonies and in the length of the individual organisms. Among many other tests, hippurate hydrolysis and the CAMP reaction were positive in both species. In the presence of these two reaction, a negative catalase test and chaining in broth would make a presumptive diagnosis of S. agalactiae, while motility at 25 C, the presence of the Henry effect, and resistance to furadantin would be indicative of L. monocytogenes.

  20. 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

  1. Adhesion to and viability of Listeria monocytogenes on food contact surfaces.

    PubMed

    Silva, Sónia; Teixeira, Pilar; Oliveira, Rosario; Azeredo, Joana

    2008-07-01

    Listeria monocytogenes is an important pathogen responsible for major outbreaks associated with food products. Adhesion to surfaces leads to significant modifications in cell physiology. The aim of this work was to determine the adhesion ability of 10 isolates of L. monocytogenes to eight materials commonly used in kitchens and to evaluate the viability of the adhered cells. The materials assayed were stainless steel 304, marble, granite, glass, polypropylene from a bowl and from a cutting board, and two kinds of silestone. All L. monocytogenes strains attached to all surfaces, although to different extents. L. monocytogenes adhered most tightly to granite and marble, followed by stainless steel 304, glass, silestones, and finally polypropylene surfaces. Surfaces at the threshold between hydrophobicity and hydrophilicity, with high electron acceptor capability and a regular pattern of roughness, were more prone to attachment. Polypropylene surfaces displayed the highest percentage of viable bacteria (nearly 100%), whereas marble and granite had a lower percentage of cultivable cells, 69.5 and 78.7%, respectively. The lowest percentage of culturable bacteria was found on white silestone (18.5%). These results indicate that there are differences in adhered cell viability on different materials. Cell viability assays are important to better understand the cross-contamination process because only adhered bacteria that remain viable are responsible for postprocess contamination.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. Antimicrobial properties of three lactic acid bacterial cultures and their cell free supernatants against Listeria monocytogenes.

    PubMed

    Milillo, Sara R; Story, Robert S; Pak, Dolar; O'Bryan, Corliss A; Crandall, Philip G; Ricke, Steven C

    2013-01-01

    Control of Listeria monocytogenes in ready-to-eat (RTE) food products is a significant challenge and improved means for control are needed. In this study, the anti-listerial effects of three lactic acid bacteria (LAB) were investigated. Spot-on-lawn assays demonstrated the largest zones of inhibition against L. monocytogenes were produced by the Pediococcus acidilactici strain, with zone diameters ranging from 13 to 18 mm. Minimum inhibitory concentration (MIC) experiments using cell free supernatant (CFS) from the LAB revealed that while two of the strains were effective at inhibiting L. monocytogenes growth only up to a 1:4 dilution, P. acidilactici was able to inhibit growth up to a 1:256 dilution. Survival assays performed at 7°C determined that the P. acidilactici strain was capable of producing a 4.5 log reduction in L. monocytogenes counts and maintaining the reduction for 21 days. The effectiveness of P. acidilactici was reduced under log phase growth, autoclaving for longer than 15 min (121°C and 15 psi), and treatment with proteinase K (25 mg/mL).

  7. Growth Potential of Listeria Monocytogenes in Sliced Turkey Bresaola Packed in Modified Atmosphere

    PubMed Central

    Cosciani-Cunico, Elena; D’Amico, Stefano; Sfameni, Chiara; Bertasi, Barbara; Losio, Marina N.; Serraino, Andrea; Daminelli, Paolo

    2014-01-01

    According to EC Regulation No 2073/2005, for food business operators that produce ready-to-eat (RTE) product, it is crucial to be able to demonstrate if the product supports the growth of Listeria monocytogenes. The objective of the study was therefore to evaluate the behaviour of L. monocytogenes in sliced RTE turkey bresaola (made by cured turkey breast 4.5% NaCl, 1% sodium lactate, sodium nitrite 150 ppm and flavouring) during the shelf life of the product, simulating a contamination during the slicing operation. Considering a shelf life of 90 days, as defined by manufacturer, the packages of sliced bresaola were stored at 5°C for 7 days and at 8°C for the remaining storage time (83 days). L. monocytogenes count decreased during storage test from 1.43/1.98 log cfu/g in the three batches tested to 1.03 log cfu/g in one batch and to undetectable levels in the other two batches. The results show that the investigated product is unable to support the growth of L. monocytogenes. PMID:27800323

  8. Cold shock proteins contribute to the regulation of listeriolysin O production in Listeria monocytogenes.

    PubMed

    Schärer, Kerstin; Stephan, Roger; Tasara, Taurai

    2013-12-01

    Cold shock proteins (Csps) are multifunctional nucleic acid binding proteins used to regulate a wide range of gene expression responses in bacteria. We report here that Csps regulate the production of the pore-forming cytolysin listeriolysin (LLO) and hemolysis phenotypes in Listeria monocytogenes. A triple csp gene deletion mutant incapable of producing any Csps, as well as double csp gene deletion mutants only producing either CspA or CspD, caused less hemolysis and produced lower LLO concentration. On the other hand, another double csp gene deletion mutant that produces CspB retained hemolysis and LLO production levels that are similar to the parental wild-type strain. Transcription analysis showed that in absence of all three csp genes or cspB alone, L. monocytogenes cells have decreased levels of hly gene transcripts, which code for the synthesis of LLO proteins. A comparative examination of mRNA stability showed that hly transcripts were more rapidly degraded in L. monocytogenes triple csp gene deletion mutant cells that are not capable of producing Csps. Overall, our results indicate that Csps, in particular CspB, are important components of gene expression regulatory mechanisms that promote efficient LLO production and hence virulence responses of L. monocytogenes.

  9. Role of cold shock proteins in growth of Listeria monocytogenes under cold and osmotic stress conditions.

    PubMed

    Schmid, Barbara; Klumpp, Jochen; Raimann, Eveline; Loessner, Martin J; Stephan, Roger; Tasara, Taurai

    2009-03-01

    The gram-positive bacterium Listeria monocytogenes is a food-borne pathogen of both public health and food safety significance. It possesses three small, highly homologous protein members of the cold shock protein (Csp) family. We used gene expression analysis and a set of mutants with single, double, and triple deletions of the csp genes to evaluate the roles of CspA, CspB, and CspD in the cold and osmotic (NaCl) stress adaptation responses of L. monocytogenes. All three Csps are dispensable for growth at optimal temperature (37 degrees C). These proteins are, however, required for efficient cold and osmotic stress tolerance of this bacterium. The hierarchies of their functional importance differ, depending on the environmental stress conditions: CspA>CspD>CspB in response to cold stress versus CspD>CspA/CspB in response to NaCl salt osmotic stress. The fact that Csps are promoting L. monocytogenes adaptation against both cold and NaCl stress has significant implications in view of practical food microbial control measures. The combined or sequential exposure of L. monocytogenes cells to these two stresses in food environments might inadvertently induce cross-protection responses.

  10. 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

  11. Reduction of Listeria monocytogenes biofilms on stainless steel and polystyrene surfaces by essential oils.

    PubMed

    Desai, Monil A; Soni, Kamlesh A; Nannapaneni, Ramakrishna; Schilling, M Wes; Silva, Juan L

    2012-07-01

    Plant-derived essential oils were tested for their ability to eliminate biofilms of Listeria monocytogenes on polystyrene and stainless steel surfaces. Various concentrations of essential oils were tested with different contact times on biofilms of various ages. Preliminarily screening of nine essential oils and related phenolic compounds in a disk diffusion assay revealed that thyme oil, oregano oil, and carvacrol had the highest antimicrobial activity. Further screening of these three compounds against 21 L. monocytogenes strains representing all 13 serotypes indicated some strain-specific variations in antimicrobial activity. For 1-day-old biofilms of mixed L. monocytogenes strains produced at 22°C on polystyrene microtiter plates, only 0.1% concentrations of thyme oil, oregano oil, and carvacrol were needed to eliminate 7 log CFU per well. On the stainless steel coupons, a 0.5% concentration of these compounds was adequate to completely eliminate 4-day-old biofilms at 7 log CFU per coupon. Our findings indicate that these compounds are potential candidates for elimination of L. monocytogenes biofilms on stainless steel and polystyrene surfaces.

  12. Protective effect of N-acetyl chitohexaose on Listeria monocytogenes infection in mice.

    PubMed

    Tokoro, A; Kobayashi, M; Tatewaki, N; Suzuki, K; Okawa, Y; Mikami, T; Suzuki, S; Suzuki, M

    1989-01-01

    A water-soluble oligosaccharide, N-acetyl chitohexaose (NACOS-6) was able to enhance the protecting effect of BALB/c male mice against Listeria monocytogenes infection, when administered intraperitoneally 24 hr before the challenge with this microbe. Significant decrease in number of microbes within the peritoneal cavity, spleen, and liver from the mice of NACOS-6-administered group was not observed 1 day after the infection but 4 days after the infection. Administration of NACOS-6 enhanced the delayed-type hypersensitivity response against sheep red blood cells (SRBC) or heat-killed L. monocytogenes. Splenic T lymphocytes from mice administered NACOS-6 released macrophage activating factor (MAF). These results suggested that NACOS-6 was also able to elevate the function of cellular immunity. Macrophages treated with a combination of NACOS-6 and the culture supernatant of splenic T lymphocytes from mice administered NACOS-6, "NACOS-6 sup," were found to exert a fairly strong growth-inhibitory effect on L. monocytogenes. Interferon-gamma (IFN-gamma) and interleukin 2 (IL-2) were able to enhance the growth-inhibitory effect on L. monocytogenes by the NACOS-6-treated macrophages.

  13. Efflux pump-mediated benzalkonium chloride resistance in Listeria monocytogenes isolated from retail food.

    PubMed

    Jiang, Xiaobing; Yu, Tao; Liang, Yu; Ji, Shengdong; Guo, Xiaowei; Ma, Jianmin; Zhou, Lijun

    2016-01-18

    In this study, efflux pump-mediated benzalkonium chloride (BC) resistance, including plasmid-encoded (Qac protein family and BcrABC) and chromosome-borne efflux pumps, was investigated in Listeria monocytogenes from retail food in China. Among the 59 L. monocytogenes strains, 13 (22.0%) strains were resistant to BC. The PCR results showed that bcrABC was harbored by 2 of 13 BC resistant strains. However, none of the qac genes were detected among the 59 strains. The bcrABC was absent in both of the plasmid cured strains, indicating that this BC resistance determinant was plasmid-encoded in the two bcrABC-positive strains. In the presence of reserpine, most of the bcrABC-negative strains had decreases in the MICs of BC, suggesting the existence of other efflux pumps and their role in BC resistance. After exposed to reserpine, the reduction in BC MICs was observed in the two cured strains, indicating that efflux pumps located on chromosome was also involved in BC resistance. Our findings suggest that food products may act as reservoirs for BC resistant isolates of L. monocytogenes and plasmid- and chromosome-encoded efflux pumps could mediate the BC resistance of L. monocytogenes, which is especially relevant to the adaption of this organism in food-related environments with frequent BC use. PMID:26513255

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Ultra sensitive detection of Listeria monocytogenes in milk by the polymerase chain reaction (PCR).

    PubMed

    Starbuck, M A; Hill, P J; Stewart, G S

    1992-12-01

    The polymerase chain reaction (PCR) has been used to detect Listeria monocytogenes in whole milk at a level of 0.1 cfu per 30 ml. This high degree of sensitivity has been achieved following enzymatic digestion, polysulphonone membrane filtration and amplification of a nucleotide sequence within the promoter region of hlyA. Key elements of the procedure are the absence of enrichment culture and a complete solubilization of the membrane filter, ensuring total nucleic acid recovery. The simplicity of the protocol coupled with high sample volumes and exquisite sensitivity extends the relevance of PCR within food and environmental microbiology. PMID:1368996

  19. Growth response of Listeria monocytogenes NCTC 7973 in two different media at four incubation temperatures.

    PubMed

    Hany, O E; Siddiqi, R; Khan, M A

    1993-05-01

    Listeria monocytogenes NCTC 7973 was cultivated in tryptose phosphate broth (TPB) and tryptone soya broth (TSB) at four different temperatures: 4 degrees, 20 degrees, 30 degrees and 37 degrees C. Cells grown in TSB at 20 degrees C displayed maximum absorbance over cells grown in TPB at the same temperature. Moreover, this observation was further confirmed by dry mass determination and viable count. We determined that cells grown in TSB at 20 degrees C exhibited significant enhanced growth as compared to cells grown in TPB at the same temperature, hence TSB was found to be the medium of choice for maximum biomass production.

  20. Listeria monocytogenes σH Contributes to Expression of Competence Genes and Intracellular Growth

    PubMed Central

    Medrano Romero, Veronica

    2016-01-01

    ABSTRACT The alternative sigma factor σH has two functions in Gram-positive bacteria: it regulates sporulation and the development of genetic competence. Listeria monocytogenes is a nonsporulating species in which competence has not yet been detected. Nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape. In this study, strains overexpressing σH and strains with a σH deletion were used to elucidate the contribution of σH to the expression of the competence machinery genes in L. monocytogenes. Gene expression analysis showed that σH is, indeed, involved in comG and comE regulation. Unexpectedly, we observed a unique regulation scheme in which σH and the transcription factor ComK were involved. Population-level analysis showed that even with the overexpression of both factors, only a fraction of the cells expressed the competence machinery genes. Although we could not detect competence, σH was crucial for phagosomal escape, which implies that this alternative sigma factor has specifically evolved to regulate the L. monocytogenes intracellular life cycle. IMPORTANCE Listeria monocytogenes can be an intracellular pathogen capable of causing serious infections in humans and animal species. Recently, the competence machinery genes were described as being necessary for optimal phagosomal escape, in which the transcription factor ComK plays an important role. On the other hand, our previous phylogenetic analysis suggested that the alternative sigma factor σH might play a role in the regulation of competence genes. The present study shows that some of the competence genes belong to the σH regulon and, importantly, that σH is essential for intracellular growth, implying a unique physiological role of σH among Firmicutes. PMID:26833412

  1. Effects of erythromycin in combination with penicillin, ampicillin, or gentamicin on the growth of Listeria monocytogenes.

    PubMed Central

    Penn, R L; Ward, T T; Steigbigel, R T

    1982-01-01

    Since the optimal antimicrobial therapy for infections caused by Listeria monocytogenes, particularly in patients allergic to penicillin, is uncertain, we investigated the in vitro effects of erythromycin, alone and in combination with other antibiotics, on listeriae. Seven strains of listeriae were inhibited but not killed by erythromycin, penicillin G, or ampicillin when tested by a microtiter broth dilution method. Susceptibility to gentamicin decreased when tryptose phosphate broth was substituted for Mueller-Hinton broth, but was independent of their calcium and magnesium concentrations. Quantitative killing studies performed with erythromycin combined with either penicillin G or ampicillin yielded antagonism for all strains, in contrast to microtiter checkerboard determinations, which did not indicate antagonism in all instances. Antagonism occurred with strains in both the stationary and log phases of growth and was slightly reversed by a 120-min preincubation of the listeriae with penicillin before the addition of erythromycin. Erythromycin and gentamicin were antagonistic in quantitative killing studies. Based on these in vitro findings, we conclude that the addition of gentamicin to erythromycin offers no advantage in the treatment of listeriosis in the penicillin-allergic patient. PMID:6821458

  2. Evaluation of immunomagnetic separation in combination with ALOA Listeria chromogenic agar for the isolation and identification of Listeria monocytogenes in ready-to-eat foods.

    PubMed

    Wadud, Shaila; Leon-Velarde, Carlos G; Larson, Nathan; Odumeru, Joseph A

    2010-05-01

    A study was conducted to evaluate the performance of the ALOA (chromogenic media) in combination with immunomagnetic separation (IMS) for the detection of Listeria monocytogenes in ready-to-eat food products. IMS-ALOA method was found to be equivalent to Health Canada's reference culture method as well as comparable to BAX-PCR method in terms of the sensitivity of the methods for the detection of L. monocytogenes in ready-to-eat foods such as turkey roast, beef roast, mixed vegetable salads, potato and egg salad, soft cheese and smoked salmon. The IMS-ALOA method gave 100% sensitivity in the inclusivity tests with 42 pure L. monocytogenes strains. Exclusivity testing with five other species of Listeria genus and 29 pure non-L. monocytogenes strains from 21 different genera showed 97% specificity. The method was able to detect L. monocytogenes at levels near or below 1cfu/25g regulatory limit in ready-to-eat food matrices after 24h enrichment, with a turnaround time of 3days compared to 7-8days for culture method. IMS-ALOA method is a valuable alternate test method for the screening of L. monocytogenes in a variety of foods especially ready-to-eat foods.

  3. Ecology of Listeria monocytogenes in the environment of raw poultry meat and raw pork meat processing plants.

    PubMed

    Chasseignaux, Elise; Gérault, Pascale; Toquin, Marie-Thérèse; Salvat, Gilles; Colin, Pierre; Ermel, Gwennola

    2002-05-01

    The zoonotic Listeria monocytogenes is mainly transmitted to humans by the food-borne route. This bacterium was often found in the environment of food processing plants. Therefore the aims of this study were (i) the identification of environmental factors associated with L. monocytogenes contamination on working and non-working surfaces in poultry or pork processing plants and (ii) the understanding of its survival in such environments. The physicochemical risk profiles showed that a surface in resin or plastic, rather than uneven, with organic residues, with a neutral pH, a low temperature and a high hygrometry was associated with L. monocytogenes contamination.

  4. Effects of trimethoprim and co-trimoxazole on the morphology of Listeria monocytogenes in culture medium and after phagocytosis.

    PubMed

    Minkowski, P; Staege, H; Groscurth, P; Schaffner, A

    2001-08-01

    The purpose of this study was to compare the extra- and intracellular activity of antifolates on Listeria monocytogenes. The fortuitous discovery of elongated bacteria in response to trimethoprim revealed a novel effect on the morphology of Listeria in cell culture medium and after phagocytosis. This phenomenon permitted the quantification of trimethoprim activity, revealing comparable activity intra- and extracellularly. Subinhibitory concentrations of trimethoprim resulted in bacterial elongation, which was reversed after removal of trimethoprim. We attribute this effect of trimethoprim to an inhibition of cell wall synthesis and/or cell separation of Listeria. PMID:11481287

  5. 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

  6. 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

  7. Control of Listeria monocytogenes in fresh cheese using protective lactic acid bacteria.

    PubMed

    Coelho, M C; Silva, C C G; Ribeiro, S C; Dapkevicius, M L N E; Rosa, H J D

    2014-11-17

    In the past years, there has been a particular focus on the application of bacteriocins produced by lactic acid bacteria (LAB) in controlling the growth of pathogenic bacteria in foods. The aim of this study was to select LAB strains with antimicrobial activity, previously isolated from a traditional Azorean artisanal cheese (Pico cheese), in order to identify those with the greatest potential in reducing Listeria monocytogenes in fresh cheese. Eight bacteriocin producer strains identified as Lactococcus lactis (1) and Enterococcus faecalis (7) were tested. In general, the bacteriocin-producing strains presented a moderate growth in fresh cheese at refrigeration temperatures (4 °C), increasing one log count in three days. They exhibited slow acidification capacity, despite the increased production of lactic acid displayed by some strains after 24h. Bacteriocin activity was only detected in the whey of fresh cheese inoculated with two Enterococcus strains, but all cheeses made with bacteriocin-producing strains inhibited L. monocytogenes growth in the agar diffusion bioassay. No significant differences were found in overall sensory evaluation made by a non-trained panel of 50-52 tasters using the isolates as adjunct culture in fresh cheese, with the exception of one Enterococcus strain. To test the effect of in situ bacteriocin production against L. monocytogenes, fresh cheese was made from pasteurized cows' milk inoculated with bacteriocin-producing LAB and artificially contaminated with approximately 10(6) CFU/mL of L. monocytogenes. The numbers of L. monocytogenes were monitored during storage of fresh cheese at refrigeration temperature (4 °C) for up to 15 days. All strains controlled the growth of L. monocytogenes, although some Enterococcus were more effective in reducing the pathogen counts. After 7 days, this reduction was of approximately 4 log units compared to the positive control. In comparison, an increase of 4 log CFU/mL in pathogen numbers was

  8. Control of Listeria monocytogenes in fresh cheese using protective lactic acid bacteria.

    PubMed

    Coelho, M C; Silva, C C G; Ribeiro, S C; Dapkevicius, M L N E; Rosa, H J D

    2014-11-17

    In the past years, there has been a particular focus on the application of bacteriocins produced by lactic acid bacteria (LAB) in controlling the growth of pathogenic bacteria in foods. The aim of this study was to select LAB strains with antimicrobial activity, previously isolated from a traditional Azorean artisanal cheese (Pico cheese), in order to identify those with the greatest potential in reducing Listeria monocytogenes in fresh cheese. Eight bacteriocin producer strains identified as Lactococcus lactis (1) and Enterococcus faecalis (7) were tested. In general, the bacteriocin-producing strains presented a moderate growth in fresh cheese at refrigeration temperatures (4 °C), increasing one log count in three days. They exhibited slow acidification capacity, despite the increased production of lactic acid displayed by some strains after 24h. Bacteriocin activity was only detected in the whey of fresh cheese inoculated with two Enterococcus strains, but all cheeses made with bacteriocin-producing strains inhibited L. monocytogenes growth in the agar diffusion bioassay. No significant differences were found in overall sensory evaluation made by a non-trained panel of 50-52 tasters using the isolates as adjunct culture in fresh cheese, with the exception of one Enterococcus strain. To test the effect of in situ bacteriocin production against L. monocytogenes, fresh cheese was made from pasteurized cows' milk inoculated with bacteriocin-producing LAB and artificially contaminated with approximately 10(6) CFU/mL of L. monocytogenes. The numbers of L. monocytogenes were monitored during storage of fresh cheese at refrigeration temperature (4 °C) for up to 15 days. All strains controlled the growth of L. monocytogenes, although some Enterococcus were more effective in reducing the pathogen counts. After 7 days, this reduction was of approximately 4 log units compared to the positive control. In comparison, an increase of 4 log CFU/mL in pathogen numbers was

  9. Prevalence and concentration of Listeria monocytogenes in sliced ready-to-eat meat products in the Hellenic retail market.

    PubMed

    Angelidis, Apostolos S; Koutsoumanis, Konstantinos

    2006-04-01

    The aim of this work was to estimate the prevalence and concentration of Listeria monocytogenes in packaged precut (slices or cubes) ready-to-eat (RTE) meat products available in the Hellenic retail market. Samples of these RTE meat products (n = 209) were taken from local supermarkets during a 3-month period and analyzed for the presence of L. monocytogenes with an automated enzymatic qualitative immunoassay followed by biochemical confirmation of positive results. The concentration of the pathogen in the positive samples was also determined. Seventeen samples (8.1%) were positive for L. monocytogenes. Eight (47.1%) of these 17 samples were from the same manufacturer; 36.4% of the products tested from this manufacturer were positive for L. monocytogenes. When bacon samples were not considered, the estimated prevalence of L. monocytogenes in sliced RTE meat products was much lower (3.1%). The L. monocytogenes populations in all positive samples were low, < or = 10 CFU/g. In 64.7% of the L. monocytogenes-positive samples, other Listeria species, including L. innocua and L. welshimeri, were also present at <10 to 690 CFU/g. These results indicate that L. monocytogenes is present in low numbers but is in a considerable proportion of the packaged precut RTE meat products that are sold in the Hellenic retail market. Cooked ham and bacon cut in cubes were the sample types most often contaminated with L. monocytogenes. The higher level of handling (e.g., cutting) associated with these products may further increase the risk of contamination with L. monocytogenes.

  10. Detection of Listeria spp. in liquid egg products and in the egg breaking plants environment and tracking of Listeria monocytogenes by PFGE.

    PubMed

    Rivoal, Katell; Fablet, Aurore; Courtillon, Céline; Bougeard, Stéphanie; Chemaly, Marianne; Protais, Jocelyne

    2013-08-16

    Human listeriosis, caused by Listeria monocytogenes, is a severe bacterial infection that can lead to meningitis, cerebromeningitis, bacteremia or septicemia, with acute lethality and potentially leading to death. A study has shown that 29.5% of the caged laying hens in France are contaminated by L. monocytogenes (Chemaly et al., 2008). However, very little information regarding egg and egg product contamination is currently available. The objective of this study is to determine the sanitary status of egg products and egg breaking plants in France regarding Listeria spp. and L. monocytogenes contaminations. The sampling scheme performed in five egg breaking plants in Western France during one year have revealed that 8.5% of raw egg products were contaminated by L. monocytogenes. No pasteurized egg products have been shown to be contaminated by L. monocytogenes. However, a high level of contamination by Listeria spp., and particularly by L. innocua, has been shown with 26.2% and 1.8% of raw and pasteurized egg products contaminated, respectively. This work has also revealed the presence of Listeria spp. and L. monocytogenes in the environment of egg breaking plants with 65.1% and 8.0% of contaminated samples, respectively. The typing of 253 isolates of L. monocytogenes by PFGE using ApaI and AscI enzymes has revealed a high diversity with 46 different pulsotypes and has shown that the raw material is a source of contamination of egg breaking plants. One L. monocytogenes cluster was dominant in the 5 egg-breaking plants during the four seasons studied. The issue of which strains are better adapted to egg products must be considered and studied in depth by comparing them to pulsotypes from strains of other chains. However, the traceability of L. monocytogenes in plants during the various seasons has also made it possible to highlight the presence of strains that are specific to egg breaking plants. The study of cleaning and disinfection methods in these plants as well

  11. Extracting additional risk managers information from a risk assessment of Listeria monocytogenes in deli meats.

    PubMed

    Pérez-Rodríguez, F; van Asselt, E D; Garcia-Gimeno, R M; Zurera, G; Zwietering, M H

    2007-05-01

    The risk assessment study of Listeria monocytogenes in ready-to-eat foods conducted by the U.S. Food and Drug Administration is an example of an extensive quantitative microbiological risk assessment that could be used by risk analysts and other scientists to obtain information and by managers and stakeholders to make decisions on food safety management. The present study was conducted to investigate how detailed sensitivity analysis can be used by assessors to extract more information on risk factors and how results can be communicated to managers and stakeholders in an understandable way. The extended sensitivity analysis revealed that the extremes at the right side of the dose distribution (at consumption, 9 to 11.5 log CFU per serving) were responsible for most of the cases of listeriosis simulated. For concentration at retail, values below the detection limit of 0.04 CFU/g and the often used limit for L. monocytogenes of 100 CFU/g (also at retail) were associated with a high number of annual cases of listeriosis (about 29 and 82%, respectively). This association can be explained by growth of L. monocytogenes at both average and extreme values of temperature and time, indicating that a wide distribution can lead to high risk levels. Another finding is the importance of the maximal population density (i.e., the maximum concentration of L. monocytogenes assumed at a certain temperature) for accurately estimating the risk of infection by opportunistic pathogens such as L. monocytogenes. According to the obtained results, mainly concentrations corresponding to the highest maximal population densities caused risk in the simulation. However, sensitivity analysis applied to the uncertainty parameters revealed that prevalence at retail was the most important source of uncertainty in the model.

  12. 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.

  13. The Listeria monocytogenes ChiA Chitinase Enhances Virulence through Suppression of Host Innate Immunity

    PubMed Central

    Chaudhuri, Swarnava; Gantner, Benjamin N.; Ye, Richard D.; Cianciotto, Nicholas P.; Freitag, Nancy E.

    2013-01-01

    ABSTRACT Environmental pathogens survive and replicate within the outside environment while maintaining the capacity to infect mammalian hosts. For some microorganisms, mammalian infection may be a relatively rare event. Understanding how environmental pathogens retain their ability to cause disease may provide insight into environmental reservoirs of disease and emerging infections. Listeria monocytogenes survives as a saprophyte in soil but is capable of causing serious invasive disease in susceptible individuals. The bacterium secretes virulence factors that promote cell invasion, bacterial replication, and cell-to-cell spread. Recently, an L. monocytogenes chitinase (ChiA) was shown to enhance bacterial infection in mice. Given that mammals do not synthesize chitin, the function of ChiA within infected animals was not clear. Here we have demonstrated that ChiA enhances L. monocytogenes survival in vivo through the suppression of host innate immunity. L. monocytogenes ΔchiA mutants were fully capable of establishing bacterial replication within target organs during the first 48 h of infection. By 72 to 96 h postinfection, however, numbers of ΔchiA bacteria diminished, indicative of an effective immune response to contain infection. The ΔchiA-associated virulence defect could be complemented in trans by wild-type L. monocytogenes, suggesting that secreted ChiA altered a target that resulted in a more permissive host environment for bacterial replication. ChiA secretion resulted in a dramatic decrease in inducible nitric oxide synthase (iNOS) expression, and ΔchiA mutant virulence was restored in NOS2−/− mice lacking iNOS. This work is the first to demonstrate modulation of a specific host innate immune response by a bacterial chitinase. PMID:23512964

  14. A Differential Fluorescence-Based Genetic Screen Identifies Listeria monocytogenes Determinants Required for Intracellular Replication

    PubMed Central

    Perry, Kyle J.

    2013-01-01

    Listeria monocytogenes is a Gram-positive, facultative intracellular pathogen capable of causing severe invasive disease with high mortality rates in humans. While previous studies have largely elucidated the bacterial and host cell mechanisms necessary for invasion, vacuolar escape, and subsequent cell-to-cell spread, the L. monocytogenes factors required for rapid replication within the restrictive environment of the host cell cytosol are poorly understood. In this report, we describe a differential fluorescence-based genetic screen utilizing fluorescence-activated cell sorting (FACS) and high-throughput microscopy to identify L. monocytogenes mutants defective in optimal intracellular replication. Bacteria harboring deletions within the identified gene menD or pepP were defective for growth in primary murine macrophages and plaque formation in monolayers of L2 fibroblasts, thus validating the ability of the screening method to identify intracellular replication-defective mutants. Genetic complementation of the menD and pepP deletion strains rescued the in vitro intracellular infection defects. Furthermore, the menD deletion strain displayed a general extracellular replication defect that could be complemented by growth under anaerobic conditions, while the intracellular growth defect of this strain could be complemented by the addition of exogenous menaquinone. As prior studies have indicated the importance of aerobic metabolism for L. monocytogenes infection, these findings provide further evidence for the importance of menaquinone and aerobic metabolism for L. monocytogenes pathogenesis. Lastly, both the menD and pepP deletion strains were attenuated during in vivo infection of mice. These findings demonstrate that the differential fluorescence-based screening approach provides a powerful tool for the identification of intracellular replication determinants in multiple bacterial systems. PMID:23687268

  15. 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

  16. Predominance and Distribution of a Persistent Listeria monocytogenes Clone in a Commercial Fresh Mushroom Processing Environment.

    PubMed

    Murugesan, Latha; Kucerova, Zuzana; Knabel, Stephen J; LaBorde, Luke F

    2015-11-01

    A longitudinal study was conducted to determine the prevalence of Listeria spp. in a commercial fresh mushroom slicing and packaging environment. Samples were collected at three different sampling periods within a 13-month time interval. Of the 255 environmental samples collected, 18.8% tested positive for L. monocytogenes, 4.3% for L. innocua, and 2.0% for L. grayi. L. monocytogenes was most often found on wet floors within the washing and slicing and packaging areas. Each of the 171 L. monocytogenes isolates found in the environment could be placed into one of three different serotypes; 1/2c was predominant (93.6%), followed by 1/2b (3.5%) and 1/2a (2.9%). Of 58 isolates subtyped using multi-virulence-locus sequence typing, all 1/2c isolates were identified as virulence type (VT) 11 (VT11), all 1/2b isolates were VT105, and 1/2a isolates were either VT107 or VT56. VT11 was designated as the predominant and persistent clone in the environment because it was isolated repeatedly at numerous locations throughout the study. The overall predominance and persistence of VT11 indicates that it likely colonized the mushroom processing environment. Areas adjacent to the trench drain in the washing and slicing area and a floor crack in the packaging area may represent primary harborage sites (reservoirs) for VT11. Improvements made to sanitation procedures by company management after period 2 coincided with a significant (P ≤ 0.001) reduction in the prevalence of L. monocytogenes from 17.8% in period 1 and 30.7% in period 2 to 8.5% in period 3. This suggests that targeted cleaning and sanitizing procedures can be effective in minimizing the occurrence of L. monocytogenes contamination in processing facilities. Additional research is needed to understand why VT11 was predominant and persistent in the mushroom processing environment.

  17. 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

  18. 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

  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.

  20. 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

  1. 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

  2. Multifaceted activity of listeriolysin O, the cholesterol-dependent cytolysin of Listeria monocytogenes.

    PubMed

    Seveau, Stephanie

    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.

  3. 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.

  4. Performance of stress resistant variants of Listeria monocytogenes in mixed species biofilms with Lactobacillus plantarum.

    PubMed

    Metselaar, Karin I; Saá Ibusquiza, Paula; Ortiz Camargo, Angela R; Krieg, Myriam; Zwietering, Marcel H; den Besten, Heidy M W; Abee, Tjakko

    2015-11-20

    Population diversity and the ability to adapt to changing environments allow Listeria monocytogenes to grow and survive under a wide range of environmental conditions. In this study, we aimed to evaluate the performance of a set of acid resistant L. monocytogenes variants in mixed-species biofilms with Lactobacillus plantarum as well as their benzalkonium chloride (BAC) resistance in these biofilms. L. monocytogenes LO28 wild type and acid resistant variants were capable of forming mixed biofilms with L. plantarum at 20°C and 30°C in BHI supplemented with manganese and glucose. Homolactic fermentation of glucose by L. plantarum created an acidic environment with pH values below the growth boundary of L. monocytogenes. Some of the variants were able to withstand the low pH in the mixed biofilms for a longer time than the WT and there were clear differences in survival between the variants which could not be correlated to (lactic) acid resistance alone. Adaptation to mild pH of liquid cultures during growth to stationary phase increased the acid resistance of some variants to a greater extent than of others, indicating differences in adaptive behaviour between the variants. Two variants that showed a high level of acid adaptation when grown in liquid cultures, showed also better performance in mixed species biofilms. There were no clear differences in BAC resistance between the wild type and variants in mixed biofilms. It can be concluded that acid resistant variants of L. monocytogenes show diversity in their adaptation to acidic conditions and their capacity to survive in mixed cultures and biofilms with L. plantarum.

  5. 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.

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. Genome Sequence of Listeria monocytogenes Plasmid pLM-C-273 Carrying Genes Related to Stress Resistance

    PubMed Central

    Liang, Lindsay; Gnaneshan, Saravanamuttu; Garduño, Rafael A.

    2016-01-01

    Mobile genetic elements in bacteria, such as plasmids, act as important vectors for the transfer of antibiotic resistance, virulence, and metal resistance genes. Here, we report the genome sequence of a new plasmid pLM-C-273, identified in a Listeria monocytogenes strain isolated from a clinical sample in Ontario, Canada. PMID:27738039

  15. 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 ...

  16. 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. ...

  17. 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

  18. A P60 mutant of Listeria monocytogenes is impaired in its ability to cause infection in intragastrically inoculated mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A spontaneous P60 mutant of Listeria monocytogenes was less able to cause systemic infection in A/J mice, following intragastric inoculation, than the parental wild type strain (SLCC 5764, serotype 1/2a). Significantly fewer CFU were recovered from internal organs (spleen, liver, gall bladder) and f...

  19. 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...

  20. 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...

  1. 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...

  2. BEHAVIOR OF ESCHERICHIA COLI O157:H7, LISTERIA MONOCYTOGENES, AND SALMONELLA TYPHIMURIUM IN TEEWURST, A RAW SPREADABLE SAUSAGE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fate of Listeria monocytogenes, Salmonella Typhimurium, or Escherichia coli O157:H7 were separately monitored both in and on teewurst, a traditional raw and spreadable sausage of Germanic origin. Multi-strain cocktails of each pathogen (ca. 5.0 log CFU/g) were used to separately inoculate teewur...

  3. Draft Genome Sequences of 15 Isolates of Listeria monocytogenes Serotype 1/2a, Subgroup ST204

    PubMed Central

    Allnutt, Theodore R.; Bradbury, Mark I.; Fanning, Séamus; Chandry, P. Scott

    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

  4. 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. ...

  5. 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.

  6. Prevalence of Listeria in Chinese food products from 13 provinces between 2000 and 2007 and virulence characterization of Listeria monocytogenes isolates.

    PubMed

    Chen, Jianshun; Zhang, Xiaofeng; Mei, Lingling; Jiang, Lingli; Fang, Weihuan

    2009-01-01

    Listeriosis is a severe disease with high mortality rate, especially in immunosuppressed individuals. The causative organism Listeria monocytogenes is primarily transmitted to humans through contaminated foods. To gain an understanding of the prevalence of Listeria in Chinese food products, we reviewed relevant papers from journals published in China from 2000 to 2007. The average recovery rate of Listeria spp. was 3.7% (0.1-7.7%) in all food categories in 13 provinces, with raw meat being the leading source. L. innocua (28.9%, 271/937) and L. monocytogenes (25.3%, 237/937) were more commonly isolated, both at higher proportion in all food types. Subtyping schemes in three laboratories in different provinces revealed that the majority of the L. monocytogenes isolates belonged to lineage II (67.1%), followed by lineage I at 31.6%, including the pathogenic serovars 1/2a, 1/2b, and 4b isolates. Lineage III isolates comprising the low-pathogenic serovar 4a were rare. Knowledge of the prevalence of Listeria in various food products in different regions of China may be useful for developing intervention strategies for control of contaminations along the production chains.

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. Effect of Vitamin A on Listeria monocytogenes Infection in a Silkworm Model

    PubMed Central

    Watanabe, Kenta; Shimizu, Takashi; Watarai, Masahisa

    2016-01-01

    Insect infection models have been used increasingly to study various pathogenic agents in evaluations of pathogenicity and drug efficacy. In this study, we demonstrated that larvae of the silkworm Bombyx mori are useful for studying Listeria monocytogenes infections in insects. Infection with the L. monocytogenes wild-type strain induced silkworm death. Infection by a listeriolysin O (LLO) deletion mutant also induced silkworm death, but the bacterial numbers in silkworms were lower than those of the wild-type strain. Intracellular growth was observed when the silkworm ovary-derived cell line BmN4 was infected with the wild-type strain. Explosive replication was not observed in BmN4 cells infected with the LLO mutant and the bacterial numbers of the LLO mutant were lower than those of the wild-type strain. Pretreatment with vitamin A did not affect silkworm mortality after bacterial infection, but the efficiency of infecting the hemocytes and BmN4 cells was decreased with vitamin A treatment. Our results indicate that silkworm larvae are a useful insect infection model for L. monocytogenes and that vitamin A has protective effects against bacterial infection in silkworms. PMID:27669511

  15. 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

  16. 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

  17. 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

  18. Listeria monocytogenes MDR transporters are involved in LTA synthesis and triggering of innate immunity during infection

    PubMed Central

    Tadmor, Keren; Pozniak, Yair; Burg Golani, Tamar; Lobel, Lior; Brenner, Moran; Sigal, Nadejda; Herskovits, Anat A.

    2014-01-01

    Multi-drug resistance (MDR) transporters are known eponymously for their ability to confer resistance to various antimicrobial drugs. However, it is likely that this is not their primary function and that MDR transporters evolved originally to play additional roles in bacterial physiology. In Listeria monocytogenes a set of MDR transporters was identified to mediate activation of innate immune responses during mammalian cell infection. This phenotype was shown to be dependent on c-di-AMP secretion, but the physiological processes underlying this phenomenon were not completely resolved. Here we describe a genetic approach taken to screen for L. monocytogenes genes or physiological pathways involved in MDR transporter-dependent triggering of the type I interferon response. We found that disruption of L. monocytogenes lipoteichoic acid (LTA) synthesis results in enhanced triggering of type I interferon responses in infected macrophage cells yet does not impact bacterial intracellular growth. This innate immune response required the MDR transporters and could be recapitulated by exposing macrophage cells to culture supernatants derived from LTA mutant bacteria. Notably, we found that the MDR transporters themselves are required for full production of LTA, an observation that links MDR transporters to LTA synthesis for the first time. In light of our findings, we propose that the MDR transporters play a role in regulating LTA synthesis, possibly via c-di-AMP efflux, a physiological function in cell wall maintenance that triggers the host innate immune system. PMID:24611134

  19. Microbiological Challenge Testing for Listeria Monocytogenes in Ready-to-Eat Food: A Practical Approach

    PubMed Central

    Scarano, Christian; Ibba, Michela; Pala, Carlo; Spanu, Vincenzo; De Santis, Enrico Pietro Luigi

    2014-01-01

    Food business operators (FBOs) are the primary responsible for the safety of food they place on the market. The definition and validation of the product’s shelf-life is an essential part for ensuring microbiological safety of food and health of consumers. In the frame of the Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs, FBOs shall conduct shelf-life studies in order to assure that their food does not exceed the food safety criteria throughout the defined shelf-life. In particular this is required for ready-to-eat (RTE) food that supports the growth of Listeria monocytogenes. Among other studies, FBOs can rely on the conclusion drawn by microbiological challenge tests. A microbiological challenge test consists in the artificial contamination of a food with a pathogen microorganism and aims at simulating its behaviour during processing and distribution under the foreseen storage and handling conditions. A number of documents published by international health authorities and research institutions describes how to conduct challenge studies. The authors reviewed the existing literature and described the methodology for implementing such laboratory studies. All the main aspects for the conduction of L. monocytogenes microbiological challenge tests were considered, from the selection of the strains, preparation and choice of the inoculum level and method of contamination, to the experimental design and data interpretation. The objective of the present document is to provide an exhaustive and practical guideline for laboratories that want to implement L. monocytogenes challenge testing on RTE food. PMID:27800369

  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

  1. Outbreak of hospital-acquired gastroenteritis and invasive infection caused by Listeria monocytogenes, Finland, 2012.

    PubMed

    Jacks, A; Pihlajasaari, A; Vahe, M; Myntti, A; Kaukoranta, S-S; Elomaa, N; Salmenlinna, S; Rantala, L; Lahti, K; Huusko, S; Kuusi, M; Siitonen, A; Rimhanen-Finne, R

    2016-10-01

    During one week in July 2012, two patients from the same ward at the municipal hospital in Vaasa, Finland, were diagnosed with septicaemia caused by Listeria monocytogenes. An outbreak investigation revealed eight concomitant cases of febrile gastroenteritis caused by L. monocytogenes on the same ward. Median age of the cases was 82 years and median incubation time for listerial gastroenteritis was 21 h (range 9-107). An additional 10 cases of invasive listeriosis caused by the same outbreak strain were identified across the whole country during the summer of 2012. Environmental investigation at the affected municipal hospital ward revealed ready-sliced meat jelly as the suspected source of the infection. During inspection of the meat jelly production plant, one pooled sample taken from a floor drain and a trolley wheel in the food processing environment was positive for the outbreak strain of L. monocytogenes. After the producer stopped the production of meat jelly, no further cases of listeriosis with the outbreak strain were identified via nationwide surveillance.

  2. 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.

  3. Control of Listeria monocytogenes in the processing environment by understanding biofilm formation and resistance to sanitizers.

    PubMed

    Manios, Stavros G; Skandamis, Panagiotis N

    2014-01-01

    Listeria monocytogenes can colonize in the food processing environment and thus pose a greater risk of cross-contamination to food. One of the proposed mechanisms that facilitates such colonization is biofilm formation. As part of a biofilm, it is hypothesized that L. monocytogenes can survive sanitization procedures. In addition, biofilms are difficult to remove and may require additional physical and chemical mechanisms to reduce their presence and occurrence. The initial stage of biofilm formation is attachment to surfaces, and therefore it is important to be able to determine the ability of L. monocytogenes strains to attach to various inert surfaces. In this chapter, methods to study bacterial attachment to surfaces are described. Attachment is commonly induced by bringing planktonic cells into contact with plastic, glass, or stainless steel surfaces with or without food residues ("soil") in batch or continuous (e.g., with constant flow of nutrients) culture. Measurement of biofilm formed is carried out by detaching cells (with various mechanical methods) and measuring the viable counts or by measuring the total attached biomass. Resistance of biofilms to sanitizers is commonly carried out by exposure of the whole model surface bearing the attached cells to a solution of sanitizer, followed by measuring the survivors as described above.

  4. Effects of intermediate filaments on actin-based motility of Listeria monocytogenes.

    PubMed

    Giardini, P A; Theriot, J A

    2001-12-01

    How does subcellular architecture influence the intracellular movements of large organelles and macromolecular assemblies? To investigate the effects of mechanical changes in cytoplasmic structure on intracellular motility, we have characterized the actin-based motility of the intracellular bacterial pathogen Listeria monocytogenes in normal mouse fibroblasts and in fibroblasts lacking intermediate filaments. The apparent diffusion coefficient of L. monocytogenes was two-fold greater in vimentin-null fibroblasts than in wild-type fibroblasts, indicating that intermediate filaments significantly restrict the Brownian motion of bacteria. However, the mean speed of L. monocytogenes actin-based motility was statistically identical in vimentin-null and wild-type cells. Thus, environmental drag is not rate limiting for bacterial motility. Analysis of the temporal variations in speed measurements indicated that bacteria in vimentin-null cells displayed larger fluctuations in speed than did trajectories in wild-type cells. Similarly, the presence of the vimentin meshwork influenced the turning behavior of the bacteria; in the vimentin-null cells, bacteria made sharper turns than they did in wild-type cells. Taken together, these results suggest that a network of intermediate filaments constrains bacterial movement and operates over distances of several microns to reduce fluctuations in motile behavior.

  5. 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.

  6. 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

  7. Changes in the immune functions and susceptibility to Listeria monocytogenes infection in mice fed dietary lipids.

    PubMed

    Puertollano, María A; Puertollano, Elena; Ruiz-Bravo, Alfonso; Jiménez-Valera, María; De Pablo, Manuel A; De Cienfuegos, Gerardo Alvarez

    2004-08-01

    The direct examination of the effects that fish oil diets (composed of long-chain n-3 polyunsaturated fatty acids) exert on immune system function indicates a reduction of host natural resistance to infectious diseases mainly because of a suppression of immune function generated by the fatty acids contained in this diet. Here, we evaluated the concentration of IL-12, IL-4, prostaglandin E2 and leukotriene B4 in the serum from BALB/c mice receiving four different diets. Each group was fed a diet that differed only in the source of fat: a low-fat diet (2.5% by weight), an olive oil diet (20% by weight), a fish oil diet (20% by weight) or a hydrogenated coconut oil diet (20% by weight). Mice were fed for 4 weeks and then infected with the intracellular pathogen Listeria monocytogenes. An initial reduction in the Th1-type response as a result of a decrease in IL-12p70 secretion, an inefficient action of IL-4 (Th2-type response) and no modification of pro-inflammatory lipid-mediator production could be, at least in part, the key events responsible for the inadequate elimination of L. monocytogenes from the spleens of mice fed a fish oil diet. Furthermore, our results suggest that the type of dietary lipids may affect the circulating concentration of IL-12p70 and IL-4, leading to a modulation in the protective cellular immune response to L. monocytogenes infection.

  8. Outbreak of hospital-acquired gastroenteritis and invasive infection caused by Listeria monocytogenes, Finland, 2012.

    PubMed

    Jacks, A; Pihlajasaari, A; Vahe, M; Myntti, A; Kaukoranta, S-S; Elomaa, N; Salmenlinna, S; Rantala, L; Lahti, K; Huusko, S; Kuusi, M; Siitonen, A; Rimhanen-Finne, R

    2016-10-01

    During one week in July 2012, two patients from the same ward at the municipal hospital in Vaasa, Finland, were diagnosed with septicaemia caused by Listeria monocytogenes. An outbreak investigation revealed eight concomitant cases of febrile gastroenteritis caused by L. monocytogenes on the same ward. Median age of the cases was 82 years and median incubation time for listerial gastroenteritis was 21 h (range 9-107). An additional 10 cases of invasive listeriosis caused by the same outbreak strain were identified across the whole country during the summer of 2012. Environmental investigation at the affected municipal hospital ward revealed ready-sliced meat jelly as the suspected source of the infection. During inspection of the meat jelly production plant, one pooled sample taken from a floor drain and a trolley wheel in the food processing environment was positive for the outbreak strain of L. monocytogenes. After the producer stopped the production of meat jelly, no further cases of listeriosis with the outbreak strain were identified via nationwide surveillance. PMID:26493730

  9. Diversity assessment of heat resistance of Listeria monocytogenes strains in a continuous-flow heating system.

    PubMed

    van der Veen, Stijn; Wagendorp, Arjen; Abee, Tjakko; Wells-Bennik, Marjon H J

    2009-05-01

    Listeria monocytogenes is a foodborne pathogen that has the ability to survive relatively high temperatures compared with other nonsporulating foodborne pathogens. This study was performed to determine whether L. monocytogenes strains with relatively high heat resistances are adequately inactivated in a high-temperature, short-time pasteurization process (72 degrees C for 15 s). To obtain heat-resistant strains, 48 strains were exposed to 55 degrees C for up to 3 h. The energy of activation constant and inactivation constant of strains that survived best (strains 1E and NV8) were subsequently determined in a continuous-flow-through system. Strain Scott A was taken along as a reference. The 3 strains were cultured in whole milk and in brain heart infusion broth at 30 and 7 degrees C. Strains 1E and NV8 were significantly more heat resistant than was strain Scott A after growth in brain heart infusion broth at 30 degrees C and after growth in milk at 7 degrees C. From the inactivation parameters, it was calculated that exposure to high-temperature, short-time pasteurization (72 degrees C for 15 s) will result in 12.1-, 14.2-, and 87.5-log reductions for the strains 1E, NV8, and Scott A, respectively. These results demonstrate that industrial pasteurization conditions suffice to inactivate the most heat-resistant L. monocytogenes strains tested in this study.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Sample preparation and DNA extraction procedures for polymerase chain reaction identification of Listeria monocytogenes in seafoods.

    PubMed

    Agersborg, A; Dahl, R; Martinez, I

    1997-04-15

    Five grams of seafood products were inoculated with one to 500 viable or 10(9) heat-killed cells of Listeria monocytogenes. The presence of the pathogen was detected by the polymerase chain reaction (PCR) with primers specific for fragments of the listeriolysin O (hly) gene (two sets) and for the invasion-associated protein (iap) gene (one set). For DNA preparation, boiling, either alone or in combination with lysozyme and proteinase K treatment, was not always sufficient to lyse L. monocytogenes, while treatment with Triton X-100 produced consistently good DNA suitable for amplification. To avoid false-negative and false-positive results, 48 h incubations were necessary and a subculturing step after an initial 24 h incubation greatly improved the results. The primers that amplified regions of the listeriolysin O gene gave clearer and stronger products than primers for the invasion-associated protein gene. Using this method we were able to detect one to five L. monocytogenes cells in 5 g of product in a total of 55 h.

  15. Staphylococcus aureus and Listeria monocytogenes in Norwegian raw milk cheese production.

    PubMed

    Jakobsen, Ragnhild Aakre; Heggebø, Ragna; Sunde, Elin Bekvik; Skjervheim, Magne

    2011-05-01

    The aim of this study was to survey the presence of Staphylococcus aureus and Listeria monocytogenes during the cheese making process in small-scale raw milk cheese production in Norway. The prevalence of S. aureus in bovine and caprine raw milk samples was 47.3% and 98.8%, respectively. An increase in contamination during the first 2-3 h resulted in a 73.6% prevalence of contamination in the bovine curd, and 23 out of 38 S. aureus-negative bovine milk samples gave rise to S. aureus-positive curds. The highest contamination levels of S. aureus were reached in both caprine and bovine cheese after 5-6 h (after the first pressing). There was no contamination of L. monocytogenes in caprine cheeses and only one (1.4%) contaminated bovine cheese. This work has increased our knowledge about S. aureus and L. monocytogenes contamination during the process of raw milk cheese production and gives an account of the hygiene status during the manufacture of Norwegian raw milk cheeses.

  16. Antimicrobial activity of reuterin produced by Lactobacillus reuteri on Listeria monocytogenes in cold-smoked salmon.

    PubMed

    Montiel, R; Martín-Cabrejas, I; Langa, S; El Aouad, N; Arqués, J L; Reyes, F; Medina, M

    2014-12-01

    Lactobacillus reuteri INIA P579 was used for the production and purification of reuterin. The purity of reuterin was assessed by high resolution electrospray ionization mass spectrometry (HRESIMS) and nuclear magnetic resonance (NMR) spectroscopy. After purification, reuterin concentration obtained was 1.3 M. The inhibitory activity using Escherichia coli K12 as indicator strain was estimated to be 510 AU/ml. Survival curves in tryptic soy broth revealed that reuterin required to inhibit the growth of three Listeria monocytogenes strains was in the range of 2-4 AU/ml. Purified reuterin (10 AU/g) significantly reduced the growth of L. monocytogenes in cold-smoked salmon kept under moderate or strong temperature abuse conditions. After 15 d at 8 °C, cold-smoked salmon with added reuterin exhibited L. monocytogenes counts 2.0 log CFU/g lower than control smoked salmon with no reuterin added. At 30 °C, reuterin also controlled the growth of the pathogen, with counts 1.4 and 0.9 log CFU/g lower than those observed in control smoked salmon after 24 and 48 h, respectively. The addition of purified reuterin might be used as a hurdle technology to improve the safety and extend the shelf-life of lightly preserved seafood products such as cold-smoked salmon.

  17. 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

  18. 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

  19. 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

  20. Incidence and growth of Listeria monocytogenes in persimmon (Diospyros kaki) fruit.

    PubMed

    Uchima, C A; de Castro, M F P M; Gallo, C R; Rezende, A C B; Benato, E R; Penteado, A L

    2008-08-15

    The incidence of Listeria monocytogenes on persimmon (Diospyros kaki) surface of 'Fuyu' and 'Rama Forte' was evaluated during a 5-month-period (from March to July) of two seasons periods (years 2005 and 2006). The fruits were collected in wholesale and street markets and retail in Sao Paulo and Campinas City, Brazil. A total of 582 fruits were analyzed using the Bax System which is based on the Polymerase Chain Reaction. The ability of this pathogen to grow on the peel and pulp of the two persimmon varieties was also verified at different incubation periods at the temperatures of 10, 20 and 30 degrees C. The growth parameters were obtained by modeling the experimental data using the Gompertz function. The incidence survey showed the absence of L. monocytogenes. The growth curves showed that L. monocytogenes can grow on the peel as well as in the pulp of the two persimmon varieties studied incubated at 10, 20 and 30 degrees C and that low temperatures can reduce the generation rate but does not inhibit its growth.