scholarly journals Listeria monocytogenes Isolated from Illegally Imported Food Products into the European Union Harbor Different Virulence Factor Variants

Genes ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 428 ◽  
Author(s):  
Kathrin Rychli ◽  
Beatrix Stessl ◽  
Kati Szakmary-Brändle ◽  
Anja Strauß ◽  
Martin Wagner ◽  
...  
Keyword(s):  
European Union ◽  
Listeria Monocytogenes ◽  
Virulence Factors ◽  
Food Samples ◽  
Pathogen Transmission ◽  
Listeriolysin O ◽  
The European Union ◽  
Genetic Fingerprint ◽  
Genotype Diversity ◽  
Imported Food

Unregulated international flow of foods poses a danger to human health, as it may be contaminated with pathogens. Recent studies have investigated neglected routes of pathogen transmission and reported the occurrence of Listeria monocytogenes in food illegally imported into the European Union (EU), either confiscated at four international airports or sold illegally on the Romanian black market. In this study we investigated the genotype diversity and the amino acid sequence variability of three main virulence factors of 57 L. monocytogenes isolates. These isolates were derived from 1474 food samples illegally imported into the EU and originated from 17 different countries. Multilocus sequence typing revealed 16 different sequence types (STs) indicating moderate genotype diversity. The most prevalent STs were ST2, ST9, and ST121. The pulsed-field gel electrophoresis (PFGE) analysis resulted in 34 unique pulsotypes. PFGE types assigned to the most prevalent STs (ST2, ST9, and ST121) were highly related in their genetic fingerprint. Internalin A (InlA) was present in 20 variants, including six truncated InlA variants, all harbored by isolates of ST9 and ST121. We detected eight ST-specific listeriolysin O (LLO) variants, and among them, one truncated form. The actin-assembly-inducing protein ActA was present in 15 different ST-specific variants, including four ActA variants with an internal truncation. In conclusion, this study shows that L. monocytogenes, isolated from illegally imported food, have moderate genotype diversity, but diverse virulence factors variants, mainly of InlA.

Listeriolysin O-Based Latex Agglutination Test for the Rapid Detection of Listeria monocytogenes in Foods

1997 ◽  
Vol 60 (9) ◽  
pp. 1038-1040 ◽  
Author(s):  
GHASSAN M. MATAR ◽  
PEGGY S. HAYES ◽  
WILLIAM F. BIBB ◽  
BALA SWAMINATHAN
Keyword(s):  
Monoclonal Antibody ◽  
Listeria Monocytogenes ◽  
Rapid Detection ◽  
Rapid Test ◽  
Food Samples ◽  
Cross Reactivity ◽  
Latex Agglutination ◽  
Listeriolysin O ◽  
Agglutination Assay ◽  
Latex Beads

A latex agglutination-based test for the rapid detection of Listeria monocytogenes in foods was developed. An antilisteriolysin O (LLO) monoclonal antibody (HID5E12D7; IgG2b) covalently bound to polystyrene amidine-modified latex beads was used in a slide agglutination assay. The latex reagent detected 0.1 ng/ml of LLO in phosphate-buffered saline plus bovine serum albumin. It reacted with culture supernatants of L. monocytogenes but not with other Listeria species or Streptococcus groups A through G. The listeriolysin O latex agglutination assay (LLOLAT) was applied to 24-h and 48-h USDA primary enrichment cultures of 208 food samples obtained from refrigerators of listeriosis patients enrolled in a study to determine the role of foods in sporadic listeriosis. Of 19 samples positive by cultural techniques, 17 were positive by the LLOLAT. Cultures with low (<0.3 CFU/g) levels of L. monocytogenes were positive in the LLOLAT. No cross-reactivity occurred when using a heterogeneous monoclonal antibody. The LLOLAT is a sensitive, specific and rapid test and may be useful for screening foods for L. monocytogenes.

Incidence and Characterization of Listeria monocytogenes from Domestic and Imported Foods in Korea

2000 ◽  
Vol 63 (2) ◽  
pp. 186-189 ◽  
Author(s):  
SUN-YOUNG BAEK ◽  
SOON-YOUNG LIM ◽  
DONG-HA LEE ◽  
KYUNG-HEE MIN ◽  
CHANG-MIN KIM
Keyword(s):  
Listeria Monocytogenes ◽  
Raw Milk ◽  
Listeriolysin O ◽  
Department Of Agriculture ◽  
Saltwater Fish ◽  
Serotype 1 ◽  
Imported Food ◽  
Polymerase Chain ◽  
Imported Foods

A total of 1,537 domestic and imported food products were examined for the incidence of Listeria monocytogenes between 1993 and 1997 in Korea. L. monocytogenes was detected using the U.S. Department of Agriculture isolation method. Isolated L. monocytogenes was confirmed by polymerase chain reaction with hly1 and hly2 primers designed from the listeriolysin O. Overall, 122 samples (7.9%) contained L. monocytogenes. The rate of isolation was 4.3% for beef, 19.1% for pork, 30.2% for chicken, 1.2% for shellfish, 4.4% for raw milk, 4.4% for frozen smoked mussels, and 6.1% for ice cream. No L. monocytogenes was found in pasteurized milk, pasteurized processed cheese, saltwater fish, dried seafoods, or ham. The overall incidence was lower than that reported in previous studies from other countries. Most isolates were serotype 1/2b except for chicken, in which serotype 1/2a was predominant. The serotyping results might imply the presence of food or geography-specific L. monocytogenes strains.

scholarly journals Listeria monocytogenes Phospholipase C-Dependent Calcium Signaling Modulates Bacterial Entry into J774 Macrophage-Like Cells

1999 ◽  
Vol 67 (4) ◽  
pp. 1770-1778 ◽  
Author(s):  
Sandra J. Wadsworth ◽  
Howard Goldfine
Keyword(s):  
Listeria Monocytogenes ◽  
Calcium Signaling ◽  
Phospholipase C ◽  
Virulence Factors ◽  
Intracellular Signaling ◽  
Lethal Dose ◽  
Listeriolysin O ◽  
Wild Type ◽  
J774 Macrophage ◽  
Kinetics Of

ABSTRACT Listeria monocytogenes secretes several proteins that have been shown to contribute to virulence. Among these is listeriolysin O (LLO), a pore-forming hemolysin that is absolutely required for virulence. Two other virulence factors are phospholipases: a phosphatidylinositol-specific phospholipase C (PI-PLC [plcA]) and a broad-range PLC (plcB). Although mutations in plcA or plcB resulted in small increases in mouse 50% lethal dose (LD50), deletions in both genes resulted in a 500-fold increase in LD50. We have examined the role of these secreted proteins in host intracellular signaling in the J774 macrophage-like cell line. Measurements of cytosolic free calcium ([Ca2+]i) have revealed a rapid spike upon exposure of these cells to wild-typeL. monocytogenes. This is followed by a second peak at 5 min and a third prolonged peak with a maximal [Ca2+]i of 800 to 1,000 nM. The pattern of calcium changes was greatly altered by deletion of any of the three virulence factors. An LLO mutant produced none of these elevations in [Ca2+]i; however, a transient elevation was observed whenever these bacteria entered the cell. A PI-PLC mutant produced a diminished single elevation in [Ca2+]i at 15 to 30 min. A broad-range PLC mutant produced only the first calcium spike. Studies with inhibitors suggested that the first elevation arises from influx of calcium from the extracellular medium through plasma membrane channels and that the second and third elevations come from release of Ca2+ from intracellular stores. We observed that internalization of wild-type bacteria and the broad-range PLC mutant was delayed for 5 to 10 min, but the LLO and PI-PLC mutants were internalized rapidly upon infection. Inhibitors that affected calcium signaling changed the kinetics of association of wild-type bacteria with J774 cells, the kinetics of entry, and the efficiency of escape from the primary phagosome.

scholarly journals Challenge Test as Special Tool to Estimate the Dynamic of Listeria monocytogenes and Other Foodborne Pathogens

Foods ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 32
Author(s):  
Luigi Lanni ◽  
Valeria Morena ◽  
Adriana Scattareggia Marchese ◽  
Gessica Destro ◽  
Marcello Ferioli ◽  
...  
Keyword(s):  
European Union ◽  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Challenge Test ◽  
Growth Potential ◽  
Economic Losses ◽  
Hospital Treatment ◽  
The European Union ◽  
Advantages And Disadvantages ◽  
Challenge Tests

Over 23 million cases of foodborne disease (FBD) occur in Europe each year, with over 4700 deaths. Outbreaks of FBD have a significant impact on our society due to the high economic losses they cause (hospital treatment of affected patients and destruction of contaminated food). Among its health objectives, the European Union has set itself the goal of reducing the incidence of the main FBDs, approving various regulations that codify requirements in order to produce food that is “safe” for human consumption. Among these rules, Regulation 2005/2073 establishes precise food safety criteria for foods that are judged to be most at risk of causing episodes of FBD. The food business operator (FBO) must know their food better and know how to estimate whether a food can support the growth of food pathogens or if they are able to hinder it during the food’s shelf life. It is becoming crucial for each FBO to schedule specific laboratory tests (challenge tests) to establish the growth potential of individual pathogens and their maximum growth rate. In 2008 the European Union published the guidelines for programming the challenge tests for Listeria monocytogenes in RTE foods. These guidelines were further implemented in 2014 and again in 2019. In June 2019 the UNI EN ISO 20976-1 was published, which contains indications for setting up and carrying out challenge tests for all foodborne pathogens in all foods. In this article, we compare the three official documents to highlight their common aspects and differences, highlighting the advantages and disadvantages that each of them offers for those who have to set up a challenge test for the various foodborne pathogens. Our conclusion is that the challenge test is today the most effective tool to estimate the dynamics and growth potential of pathogenic microorganisms in food, if it is designed and implemented in a scrupulous way. It is important to develop a rational experimental design for each challenge test, and for each food, and this requires professionals who are experts in this specific field of study and who must be properly trained.

scholarly journals Validation of HPLC and Enzyme-Linked Immunosorbent Assay (ELISA) Techniques for Detection and Quantification of Aflatoxins in Different Food Samples

Foods ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 661 ◽  
Author(s):  
Sharaf S. Omar ◽  
Moawiya A. Haddad ◽  
Salvatore Parisi
Keyword(s):  
European Union ◽  
Limit Of Detection ◽  
Food Samples ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Consumption ◽  
The European Union ◽  
Total Aflatoxin ◽  
Limit Of Quantification ◽  
Coffee Beans ◽  
Almost All

Background: In Jordan as in other worldwide countries, mycotoxins are considered a serious national problem in food supplies. As a result, almost all nations are setting and adopting different regulations targeting the control of mycotoxins levels in the domestic food supply, including the problem of reliable sampling and analysis methods. Objective: It is necessary to improve and give evidence of analytical abilities of laboratories within Jordan and developing countries enabling them to monitor mycotoxins effectively in food to overcome non-tariff obstacles. Methods: We analyzed 40 samples from wheat, corn, dried fig and dried coffee beans for total aflatoxin content using High Pressure Liquid Chromatography (HPLC) and Enzyme Linked Immunesorbent Assay (ELISA) methods. Results: 40% of samples from wheat, 60% from corn, 30% from dried fig, and 50% from dried coffee beans were found positive when speaking of total aflatoxins, with average values between 1.14 and 4.12 μg/kg. Obtained results allow considering all tested food samples as fit for human consumption if compared with the labeled regulatory limit of allowed aflatoxins in the European Union. In detail, the limit of detection and the limit of quantification for methods used in this study were significantly lower than the maximum limits established by the European Union. Highlights: The procedure used in this study is suitable for detection of mycotoxins at very low concentration.

Virulence potential of Listeria monocytogenes strains recovered from pigs in Spain

2020 ◽  
Vol 187 (11) ◽  
pp. e101-e101
Author(s):  
Jaime Gómez-Laguna ◽  
Fernando Cardoso-Toset ◽  
Jazmín Meza-Torres ◽  
Javier Pizarro-Cerdá ◽  
Juan J Quereda
Keyword(s):  
Listeria Monocytogenes ◽  
Virulence Factors ◽  
Bacterial Pathogen ◽  
Listeriolysin O ◽  
Actin Assembly ◽  
Virulence Potential ◽  
Serotype 1 ◽  
Internalin B ◽  
Meat Samples ◽  
Internalin A

BackgroundListeria monocytogenes is a foodborne bacterial pathogen that causes listeriosis, an infectious disease in animals and people, with pigs acting as asymptomatic reservoirs. In August 2019 an outbreak associated with the consumption of pork meat caused 222 human cases of listeriosis in Spain. Determining the diversity as well as the virulence potential of strains from pigs is important to public health.MethodsThe behaviour of 23 L monocytogenes strains recovered from pig tonsils, meat and skin was compared by studying (1) internalin A, internalin B, listeriolysin O, actin assembly-inducing protein and PrfA expression levels, and (2) their invasion and intracellular growth in eukaryotic cells.ResultsMarked differences were found in the expression of the selected virulence factors and the invasion and intracellular replication phenotypes of L monocytogenes strains. Strains obtained from meat samples and belonging to serotype 1/2a did not have internalin A anchored to the peptidoglycan. Some strains expressed higher levels of the studied virulence factors and invaded and replicated intracellularly more efficiently than an epidemic L monocytogenes reference strain (F2365).ConclusionThis study demonstrates the presence of virulent L monocytogenes strains with virulent potential in pigs, with valuable implications in veterinary medicine and food safety.

Sign in / Sign up

Export Citation Format

Share Document