scholarly journals Listeria monocytogenes Isolates from Foods and Humans Form Distinct but Overlapping Populations

2004 ◽  
Vol 70 (10) ◽  
pp. 5833-5841 ◽  
Author(s):  
Michael J. Gray ◽  
Ruth N. Zadoks ◽  
Esther D. Fortes ◽  
Belgin Dogan ◽  
Steven Cai ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Plaque Assay ◽  
Virulence Gene ◽  
The United States ◽  
Polymorphism Analysis ◽  
Genetic Lineages ◽  
The Public ◽  
Cell Spread ◽  
Specific Food

ABSTRACT A total of 502 Listeria monocytogenes isolates from food and 492 from humans were subtyped by EcoRI ribotyping and PCR-restriction fragment length polymorphism analysis of the virulence gene hly. Isolates were further classified into genetic lineages based on subtyping results. Food isolates were obtained through a survey of selected ready-to-eat food products in Maryland and California in 2000 and 2001. Human isolates comprised 42 isolates from invasive listeriosis cases reported in Maryland and California during 2000 and 2001 as well as an additional 450 isolates from cases that had occurred throughout the United States, predominantly from 1997 to 2001. Assignment of isolates to lineages and to the majority of L. monocytogenes subtypes was significantly associated with the isolate source (food or human), although most subtypes and lineages included both human and food isolates. Some subtypes were also significantly associated with isolation from specific food types. Tissue culture plaque assay characterization of the 42 human isolates from Maryland and California and of 91 representative food isolates revealed significantly higher average infectivity and cell-to-cell spread for the human isolates, further supporting the hypothesis that food and human isolates form distinct populations. Combined analysis of subtype and cytopathogenicity data showed that strains classified into specific ribotypes previously linked to multiple human listeriosis outbreaks, as well as those classified into lineage I, are more common among human cases and generate larger plaques than other subtypes, suggesting that these subtypes may represent particularly virulent clonal groups. These data will provide a framework for prediction of the public health risk associated with specific L. monocytogenes subtypes.

scholarly journals Genetic and phenotypic characterization of Listeria monocytogenes lineage III

Microbiology ◽  
2006 ◽  
Vol 152 (3) ◽  
pp. 685-693 ◽  
Author(s):  
Angela Roberts ◽  
Kendra Nightingale ◽  
Greg Jeffers ◽  
Esther Fortes ◽  
Jose Marcelino Kongo ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Phylogenetic Analyses ◽  
Plaque Assay ◽  
Virulence Gene ◽  
Phenotypic Characterization ◽  
Ecological Niches ◽  
Phenotypic Characteristics ◽  
Putative Virulence Gene ◽  
Clinical Cases

Listeria monocytogenes has been previously grouped into three evolutionary groups, termed lineages I, II and III. While lineages I and II are commonly isolated from various sources, lineage III isolates are rare and have several atypical and unique phenotypic characteristics. Relative to their prevalence in other sources, lineage III strains are overrepresented among isolates from food-production animals, and underrepresented among isolates from human clinical cases and foods. This work describes an extensive genotypic and phenotypic characterization of 46 lineage III isolates. Phylogenetic analyses of partial sigB and actA sequences showed that lineage III represents three distinct subgroups, which were termed IIIA, IIIB and IIIC. Each of these lineage III subgroups is characterized by differentiating genotypic and phenotypic characteristics. Unlike typical L. monocytogenes, all subgroup IIIB and IIIC isolates lack the ability to ferment rhamnose. While all IIIC and most IIIB isolates carry the putative virulence gene lmaA, the majority of subgroup IIIA isolates lack this gene. All three lineage III subgroups contain isolates from human clinical cases as well as isolates that are cytopathogenic in a cell culture plaque assay, indicating that lineage III isolates have the potential to cause human disease. The identification of specific genotypic and phenotypic characteristics among the three lineage III subgroups suggests that these subgroups may occupy different ecological niches and, therefore, may be transmitted by different pathways.

Molecular and Conventional Typing Methods for Listeria monocytogenes: The UK Approach

1996 ◽  
Vol 59 (10) ◽  
pp. 1102-1105 ◽  
Author(s):  
J. McLAUCHLIN
Keyword(s):  
Listeria Monocytogenes ◽  
Fragment Length Polymorphism ◽  
Work Load ◽  
Polymorphism Analysis ◽  
Laboratory Service ◽  
The Public ◽  
Dna Restriction ◽  
Typing Methods ◽  
The Uk ◽  
Index Of Diversity

Subtyping systems for Listeria monocytogenes have proved to be of great use in the elucidation of the epidemiology of listeriosis. Considerations for devising strategies to subtype this organism are discussed, together with the surveillance methods, work load, and resources used by the Public Health Laboratory Service in London (England). A combination of both molecular and conventional typing methods are currently in use, and these comprise the established techniques of serotyping, phage-typing, and DNA restriction-fragment length polymorphism analysis, together with the experimental procedures of resistance to arsenite and cadmium and the detection of plasmid DNA. The efficacy of this approach is assessed using Simpson's index of diversity.

scholarly journals Recurrent and Sporadic Listeria monocytogenes Contamination in Alheiras Represents Considerable Diversity, Including Virulence-Attenuated Isolates

2007 ◽  
Vol 73 (12) ◽  
pp. 3887-3895 ◽  
Author(s):  
M. T. S. Fel�cio ◽  
T. Hogg ◽  
P. Gibbs ◽  
P. Teixeira ◽  
M. Wiedmann
Keyword(s):  
Listeria Monocytogenes ◽  
Control Strategies ◽  
Tetracycline Resistance ◽  
The United States ◽  
Pulsed Field Gel Electrophoresis ◽  
Pathogenic Potential ◽  
Molecular Serotyping ◽  
Production And Distribution ◽  
Invasion Assays

ABSTRACT Microbiological characterization of alheiras, traditional smoked meat sausages produced in northern Portugal, had previously shown that more than 60% of the lots analyzed were contaminated with Listeria monocytogenes at levels higher than 100 CFU/g. In order to better understand L. monocytogenes contamination patterns in alheiras, we characterized 128 L. monocytogenes isolates from alheiras using a variety of subtyping techniques (i.e., molecular serotyping; arsenic, cadmium, and tetracycline resistance typing; and pulsed-field gel electrophoresis [PFGE]). Subtyping of isolates from products collected on two separate dates provided evidence for the persistence of specific L. monocytogenes PFGE types in the production and distribution chains of alheiras from four different processors. A subset of 21 isolates was further characterized using ribotyping and Caco-2 cell invasion assays to evaluate the pathogenic potential of L. monocytogenes present in alheiras. Caco-2 invasion assays revealed seven isolates with invasion efficiencies that were less than 20% of that of the control strain 10403S. All seven isolates had premature stop codons in inlA that represented three distinct mutations, which had previously been observed in isolates from the United States or France. Our findings indicate the need for a comprehensive approach to control L. monocytogenes in alheiras, including strategies to reduce persistence. The presence of considerable diversity in invasion phenotypes among L. monocytogenes strains present in alheiras, including the presence of subtypes likely to be virulence attenuated, may provide an opportunity to initially focus control strategies on the subtypes most likely to cause human disease.

scholarly journals Poor Invasion of Trophoblastic Cells but Normal Plaque Formation in Fibroblastic Cells despite actA Deletion in a Group of Listeria monocytogenes Strains Persisting in Some Food Processing Environments

2010 ◽  
Vol 76 (10) ◽  
pp. 3391-3397 ◽  
Author(s):  
Anne Holch ◽  
Caroline Trebbien Gottlieb ◽  
Marianne Halberg Larsen ◽  
Hanne Ingmer ◽  
Lone Gram
Keyword(s):  
Listeria Monocytogenes ◽  
Molecular Subtype ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Virulence Gene ◽  
Fish Processing ◽  
Trophoblastic Cells ◽  
Processing Plants ◽  
Fibroblastic Cells ◽  
Cell Spread

ABSTRACT We determined mammalian cell invasion and virulence gene (inlA, inlB, and actA) sequences of Listeria monocytogenes strains belonging to a molecular subtype (RAPD 9) that often persists in Danish fish-processing plants. These strains invaded human placental trophoblasts less efficiently than other L. monocytogenes strains, including clinical strains, and they carry a premature stop codon in inlA. Eight of 15 strains, including the RAPD 9 and maternofetal strains, had a 105-nucleotide deletion in actA that did not affect cell-to-cell spread in mouse fibroblasts. The RAPD 9 strains may still be regarded as of low virulence with respect to human listeriosis.

Comment on “Which Earthquake Accounts Matter?” by Susan E. Hough and Stacey S. Martin

2021 ◽  
Author(s):  
David J. Wald
Keyword(s):  
Demographic Data ◽  
The United States ◽  
Macroseismic Data ◽  
Online Data ◽  
The Public ◽  
The World ◽  
Online Data Collection ◽  
Large Earthquakes ◽  
The U.S

Abstract In their analysis of the U.S. Geological Survey’s (USGS) “Did You Feel It?” (DYFI) data Hough and Martin (2021) claim, among other assertions, that the following: Socioeconomic and geopolitical factors can introduce biases in the USGS’ characterization of earthquakes and their effects, especially if online data collection systems are not designed to be broadly accessible;These biases can, in turn, potentially cascade in myriad ways, potentially shaping our understanding of an earthquake’s impact and the characterization of seismic hazard; andCaution should be urged when relying on data from the DYFI system to characterize the distribution of shaking from large earthquakes in India and other parts of the world (outside of the United States). Claims of inequity in access, systematic data biases, or urging caution in the usage of data from critical governmental earthquake information systems should not be made, nor taken, lightly. Several assertions made by Hough and Martin (hereafter, H&M) about the nature of DYFI contributors—and the data they provide—leave a false narrative concerning DYFI system accessibility and quality that H&M have not adequately substantiated. I describe several shortcomings of H&M’s demographic statistics and methodology, focusing on four main concerns. First, DYFI has revolutionized and greatly facilitated access to reporting intensities, in contrast to H&M claims to the contrary. Second, because DYFI does not directly collect demographic data other than the observer’s location, any demographic analyses require extraordinary inferences, well outside the normal bounds of sociodemographic analyses. Third, independent of accessibility and the geographic distribution of contributions from the public, the macroseismic data collected are nonetheless representative of the shaking and impact at each location, of quality, rapid, and thus extremely useful. Lastly, H&M fail to cite critical and pertinent prior, highly relevant scholarly studies, and as such, they misrepresent the novelty of their own work as well as miss key practical matters detailed in those prior studies. Prior to rebutting what H&M claim DYFI does not do, I will remind the reader the ways in which DYFI excels.

scholarly journals Prevalence and Genetic Characterization of Listeria monocytogenes in Retail Broiler Meat in Estonia

2006 ◽  
Vol 69 (2) ◽  
pp. 436-440 ◽  
Author(s):  
KRISTI PRAAKLE-AMIN ◽  
MARJA-LIISA HÄNNINEN ◽  
HANNU KORKEALA
Keyword(s):  
Genetic Diversity ◽  
Listeria Monocytogenes ◽  
Genetic Characterization ◽  
The United States ◽  
Pulsed Field Gel Electrophoresis ◽  
Broiler Meat ◽  
Pfge Typing ◽  
Foreign Origin ◽  
Serotype 1

The prevalence and genetic diversity of Listeria monocytogenes in raw broiler legs at the retail level in Estonia were studied. A total of 240 raw broiler legs (120 from Estonia and 120 of foreign origin, which had been imported to Estonia from Denmark, Finland, Hungary, Sweden, and the United States) from 12 retail stores in the two largest cities in Estonia (Tallinn and Tartu) were investigated from January to December 2002. Of these, 70% were positive for L. monocytogenes. The prevalence of L. monocytogenes in broiler legs of Estonian origin (88%) was significantly higher than in broiler legs of foreign origin (53%) (P < 0.001). Altogether, 169 (106 Estonian and 63 imported) L. monocytogenes isolates were characterized by pulsed-field gel electrophoresis (PFGE) typing after treatment with the restriction enzyme AscI. The isolates showed a wide genetic diversity, with 35 different PFGE types obtained. Of these, 11 PFGE types came only from isolates of broiler legs of Estonian origin, 4 of Danish origin, 2 of Finnish origin, and 4 of Hungarian origin. Fourteen PFGE types came from isolates of broiler legs that originated from various countries. The strains that shared the same PFGE types from isolates of Estonian origin were recovered from broiler legs that came from different stores over the course of several months. Seventy-one L. monocytogenes isolates, including all PFGE types, were serotyped, and three serotypes (1/2a, 1/2b, and 4b) were obtained. Serotype 1/2a accounted for 96% of the isolates.

NATO Status of Forces Agreement—primary right to exercise jurisdiction—offenses committed in performance of official duty—judicial review of characterization of such offenses—double jeopardy

1999 ◽  
Vol 93 (1) ◽  
pp. 219-224 ◽  
Author(s):  
Bernard H. Oxman ◽  
Annalisa Ciampi
Keyword(s):  
Judicial Review ◽  
The United States ◽  
Northern Italy ◽  
Public Prosecutor ◽  
The Public ◽  
Ski Resort ◽  
Car Accident ◽  
Level Training ◽  
Italian Constitution

Public Prosecutor v. Ashby. Judgment No. 161/98.Court of Trento, Italy, July 13, 1998.On February 3, 1998, a U.S. Marine EA-6B aircraft, redeployed at Aviano air base as part of Operation Deliberate Guard in support of the multinational Stabilization Force (SFOR) in Bosnia, was on a low-level training mission over northern Italy when it severed the wires of the cable car at the Cermis ski resort near Cavalese, causing the deaths of twenty people. Because the exercise of criminal action is mandatory under Article 112 of the Italian Constitution, the public prosecutor decided that he had to institute preliminary investigations immediately, with a view to determining whether to prosecute. On July 13, 1998, an Italian judge, in a preliminary hearing, rejected the prosecutor's request that seven U.S. servicemen stand trial for the cable-car accident. The judge found that, under Article VII, paragraph 3(a) (ii) of the NATO Status of Forces Agreement (NATO SOFA), the United States, as the sending state, had the primary right to exercise jurisdiction over the case and that jurisdiction had not been waived. Accordingly, the judge dismissed the case.

scholarly journals ­­­Characterization of integrated prophages within diverse species of clinical nontuberculous mycobacteria

2020 ◽  
Author(s):  
Cody Glickman ◽  
Sara M. Kammlade ◽  
Nabeeh A. Hasan ◽  
L. Elaine Epperson ◽  
Rebecca M. Davidson ◽  
...  
Keyword(s):  
Nontuberculous Mycobacteria ◽  
Gene Annotation ◽  
Virulence Gene ◽  
The United States ◽  
Clinical Samples ◽  
Diverse Species ◽  
Bacterial Fitness ◽  
Environmental Bacteria ◽  
Bacterial Genes

Abstract Background Nontuberculous mycobacterial (NTM) infections are increasing in prevalence, with current estimates suggesting that over 100,000 people in the United States are affected each year. It is unclear how certain species of mycobacteria transition from environmental bacteria to clinical pathogens, or what genetic elements influence the differences in virulence among strains of the same species. A potential mechanism of genetic diversity within mycobacteria is the integration of viruses called prophages. Prophages may act as carriers of bacterial genes, with the potential of altering bacterial fitness through horizontal gene transfer. In this study, we quantify the frequency and composition of prophages within mycobacteria isolated from clinical samples and compare them against the composition of PhageDB, an environmental mycobacteriophage database.Methods Prophages were predicted by agreement between two discovery tools, VirSorter and Phaster, and the frequencies of integrated prophages were compared by growth rate. Prophages were assigned to PhageDB lettered clusters using BLAST-p. Bacterial virulence gene frequency was calculated using a combination of the Virulence Factor Database (VFDB) and the Pathosystems Resource Integration Center virulence database (Patric-VF) within the gene annotation software Prokka. CRISPR elements were discovered using CRT. ARAGORN was used to quantify tRNAs.Results Rapidly growing mycobacteria (RGM) were more likely to contain prophage than slowly growing mycobacteria (SGM). CRISPR elements were not associated with prophage abundance in mycobacteria. The abundance of tRNAs was enriched in SGM compared to RGM.

scholarly journals Characterization and Pathogenic Potential of Listeria monocytogenes Isolates from the Smoked Fish Industry

2001 ◽  
Vol 67 (2) ◽  
pp. 646-653 ◽  
Author(s):  
Dawn M. Norton ◽  
Janet M. Scarlett ◽  
Kelly Horton ◽  
David Sue ◽  
Joanne Thimothe ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Mammalian Cells ◽  
Raw Materials ◽  
Plaque Assay ◽  
Fish Processing ◽  
Pathogenic Potential ◽  
Genetic Lineages ◽  
Smoked Fish ◽  
Fish Industry

ABSTRACT This study was designed to evaluate the hypothesis that some of theListeria monocytogenes subtypes associated with foods, specifically smoked fish, may have an attenuated ability to cause human disease. We tested this hypothesis by using two different approaches: (i) comparison of molecular subtypes found among 117 isolates from smoked fish, raw materials, fish in process, and processing environments with subtypes found among a collection of 275 human clinical isolates and (ii) the evaluation of the cytopathogenicity of industrial isolates. Ribotyping and PCR-restriction fragment length polymorphism typing of the hlyA and actA genes differentiated 23 subtypes among the industrial isolates and allowed classification of the isolates into three genetic lineages. A significantly higher proportion of human isolates (69.1%) than industrial isolates (36.8%) were classified as lineage I, which contains human sporadic isolates and all epidemic isolates. All other industrial isolates (63.2%) were classified as lineage II, which contains only human sporadic isolates. Lineage I ribotypes DUP-1038B and DUP-1042B represented a significantly higher proportion of the human isolates than industrial isolates (5.1%). Lineage II ribotypes DUP-1039C, DUP-1042C, and DUP-1045, shown previously to persist in the smoked fish processing environment, represented nearly 50% of the industrial isolates, compared to 7.6% of the human isolates. Representatives of each subtype were evaluated with a tissue culture plaque assay. Lineage I isolates formed plaques that were significantly larger than those formed by lineage II isolates. Isolates from the smoked fish industry representing three ribotypes formed no plaques or small plaques, indicating that they had an impaired ability to infect mammalian cells. While L. monocytogenes clonal groups linked to human listeriosis cases and outbreaks were isolated, our data also suggest that at least some L. monocytogenes subtypes present in ready-to-eat foods may have limited human-pathogenic potential.

scholarly journals The Posttranslocation Chaperone PrsA2 Contributes to Multiple Facets of Listeria monocytogenes Pathogenesis

2009 ◽  
Vol 77 (7) ◽  
pp. 2612-2623 ◽  
Author(s):  
Francis Alonzo ◽  
Gary C. Port ◽  
Min Cao ◽  
Nancy E. Freitag
Keyword(s):  
Listeria Monocytogenes ◽  
Gene Product ◽  
Bacterial Pathogen ◽  
Virulence Gene ◽  
Host Cells ◽  
Listeriolysin O ◽  
Virulence Gene Expression ◽  
High Concentrations ◽  
Host Infection ◽  
Cell Spread

ABSTRACT 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.

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