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    Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources

    Yim, Lucía, Betancor, Laura, Martínez, Arací, Bryant, Clare, Maskell, Duncan, Chabalgoity, José A
    Applied and environmental microbiology, November 2011, Vol.77(21), pp.7740-8 [Peer Reviewed Journal]
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    Title: Naturally occurring motility-defective mutants of Salmonella enterica serovar Enteritidis isolated preferentially from nonhuman rather than human sources
    Author: Yim, Lucía; Betancor, Laura; Martínez, Arací; Bryant, Clare; Maskell, Duncan; Chabalgoity, José A
    Subject: Locomotion ; Salmonella Infections -- Microbiology ; Salmonella Infections, Animal -- Microbiology ; Salmonella Enteritidis -- Isolation & Purification
    Description: Salmonellosis represents a worldwide health problem because it is one of the major causes of food-borne disease. Although motility is postulated as an important Salmonella virulence attribute, there is little information about variation in motility in natural isolates. Here we report the identification of a point mutation (T551 → G) in motA, a gene essential for flagellar rotation, in several Salmonella enterica serovar Enteritidis field isolates. This mutation results in bacteria that can biosynthesize structurally normal but paralyzed flagella and are impaired in their capacity to invade human intestinal epithelial cells. Introduction of a wild-type copy of motA into one of these isolates restored both motility and cell invasiveness. The motA mutant triggered higher proinflammatory transcriptional responses than an aflagellate isolate in differentiated Caco-2 cells, suggesting that the paralyzed flagella are able to signal through pattern recognition receptors. A specific PCR was designed...
    Is part of: Applied and environmental microbiology, November 2011, Vol.77(21), pp.7740-8
    Identifier: 1098-5336 (E-ISSN); 21926214 Version (PMID); 10.1128/AEM.05318-11 (DOI)

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    Repression of flagella is a common trait in field isolates of Salmonella enterica serovar Dublin and is associated with invasive human infections

    Yim, Lucía, Sasías, Sebastián, Martínez, Arací, Betancor, Laura, Estevez, Verónica, Scavone, Paola, Bielli, Alejandro, Sirok, Alfredo, Chabalgoity, José Alejandro
    Infection and immunity, April 2014, Vol.82(4), pp.1465-76 [Peer Reviewed Journal]
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    Title: Repression of flagella is a common trait in field isolates of Salmonella enterica serovar Dublin and is associated with invasive human infections
    Author: Yim, Lucía; Sasías, Sebastián; Martínez, Arací; Betancor, Laura; Estevez, Verónica; Scavone, Paola; Bielli, Alejandro; Sirok, Alfredo; Chabalgoity, José Alejandro
    Subject: Flagella -- Physiology ; Salmonella Infections -- Microbiology ; Salmonella Enterica -- Pathogenicity
    Description: The nontyphoidal Salmonella enterica serovar Dublin is adapted to cattle but infrequently infects humans, very often resulting in invasive infections with high levels of morbidity and mortality. A Salmonella-induced intestinal acute inflammatory response is postulated as a mechanism to prevent bacterial dissemination to systemic sites. In S. enterica serovar Typhimurium, flagella contribute to this response by providing motility and FliC-mediated activation of pattern recognition receptors. In this study, we found 4 Salmonella enterica isolates, with the antigenic formula 9,12:-:-, that, based on fliC sequence and multilocus sequence type (MLST) analyses, are aflagellate S. Dublin isolates. Interestingly, all were obtained from human bloodstream infections. Thus, we investigated the potential role of flagella in the unusual invasiveness exhibited by S. Dublin in humans by analyzing flagellation and proinflammatory properties of a collection of 10 S. Dublin human clinical isolates. We found...
    Is part of: Infection and immunity, April 2014, Vol.82(4), pp.1465-76
    Identifier: 1098-5522 (E-ISSN); 24421045 Version (PMID); 10.1128/IAI.01336-13 (DOI)

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    First Release of the Bacterial Biobank of the Urban Environment (BBUE)

    Antelo, Verónica, Salazar, Cecilia, Martínez, Arací, D’alessandro, Bruno, Castro, Marta, Betancor, Laura, Barcala, María Victoria, Míguez, Diana, Gonnet, Gastón H, Iraola, Gregorio
    Microbiology Resource Announcements, 2018, Vol.7(16) [Peer Reviewed Journal]

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    Generation and selection of anti-flagellin monoclonal antibodies useful for serotyping Salmonella enterica

    Hiriart, Yanina, Serradell, Maria, Martínez, Araci, Sampaolesi, Sofia, Maciel, Dolores Gonzalez, Chabalgoity, Jose Alejandro, Yim, Lucía, Algorta, Gabriela, Rumbo, Martin
    SpringerPlus, 2013, Vol.2, pp.640 [Peer Reviewed Journal]
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    Title: Generation and selection of anti-flagellin monoclonal antibodies useful for serotyping Salmonella enterica
    Author: Hiriart, Yanina; Serradell, Maria; Martínez, Araci; Sampaolesi, Sofia; Maciel, Dolores Gonzalez; Chabalgoity, Jose Alejandro; Yim, Lucía; Algorta, Gabriela; Rumbo, Martin
    Subject: Flagellin ; Monoclonal Antibodies ; Salmonella ; Serotyping
    Description: In developing countries, bacterial acute gastroenteritis continues to be an important cause of morbidity and mortality among young children. Salmonellosis constitutes a major cause of infectious enteritis worldwide, most of them associated to the consumption of contaminated food products. Traditionally, Salmonella has been classified in serovars based on varieties of O and H surface antigens. In the present work we generated and characterized a panel of anti-flagellin monoclonal antibodies (MAbs) in order to select antibodies useful for detecting the H surface antigen. Four different MAbs were obtained by somatic hybridization of splenocytes. We found two MAbs that recognised regions of flagellin conserved among different Salmonella serovars. Other two MAbs recognised structures restricted to Salmonella enterica sv. Typhimurium, being one of them suitable for agglutination tests. Using a diverse panel of S. enterica serovars with different H antigen varieties we confirmed that this MAb...
    Is part of: SpringerPlus, 2013, Vol.2, pp.640
    Identifier: 2193-1801 (ISSN); 24349948 Version (PMID); 10.1186/2193-1801-2-640 (DOI)

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    Genomic Comparison of the Closely Related Salmonella enterica Serovars Enteritidis and Dublin

    Betancor, Laura, Yim, Lucía, Martínez, Arací, Fookes, Maria, Sasias, Sebastian, Schelotto, Felipe, Thomson, Nicholas, Maskell, Duncan, Chabalgoity, José A
    The open microbiology journal, 2012, Vol.6, pp.5-13 [Peer Reviewed Journal]
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    Title: Genomic Comparison of the Closely Related Salmonella enterica Serovars Enteritidis and Dublin
    Author: Betancor, Laura; Yim, Lucía; Martínez, Arací; Fookes, Maria; Sasias, Sebastian; Schelotto, Felipe; Thomson, Nicholas; Maskell, Duncan; Chabalgoity, José A
    Subject: Comparative Genomics ; Host Specificity ; Pseudogenes ; S. Dublin ; S. Enteritidis. ; Salmonella
    Description: The Enteritidis and Dublin serovars of Salmonella enterica are closely related, yet they differ significantly in pathogenicity and epidemiology. S. Enteritidis is a broad host range serovar that commonly causes gastroenteritis and infrequently causes invasive disease in humans. S. Dublin mainly colonizes cattle but upon infecting humans often results in invasive disease.To gain a broader view of the extent of these differences we conducted microarray-based comparative genomics between several field isolates from each serovar. Genome degradation has been correlated with host adaptation in Salmonella, thus we also compared at whole genome scale the available genomic sequences of them to evaluate pseudogene composition within each serovar.Microarray analysis revealed 3771 CDS shared by both serovars while 33 were only present in Enteritidis and 87 were exclusive to Dublin. Pseudogene evaluation showed 177 inactive CDS in S. Dublin which correspond to active genes in S. Enteritidis, nine of...
    Is part of: The open microbiology journal, 2012, Vol.6, pp.5-13
    Identifier: 1874-2858 (E-ISSN); 22371816 Version (PMID); 10.2174/1874285801206010005 (DOI)

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    A Naturally Occurring Deletion in FliE from Salmonella enterica Serovar Dublin Results in an Aflagellate Phenotype and Defective Proinflammatory Properties

    Sasías, Sebastián, Martínez-Sanguiné, Adriana, Betancor, Laura, Martínez, Arací, D'Alessandro, Bruno, Iriarte, Andrés, Chabalgoity, José A, Yim, Lucía
    Infection and immunity, January 2018, Vol.86(1) [Peer Reviewed Journal]
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    Title: A Naturally Occurring Deletion in FliE from Salmonella enterica Serovar Dublin Results in an Aflagellate Phenotype and Defective Proinflammatory Properties
    Author: Sasías, Sebastián; Martínez-Sanguiné, Adriana; Betancor, Laura; Martínez, Arací; D'Alessandro, Bruno; Iriarte, Andrés; Chabalgoity, José A; Yim, Lucía
    Subject: Flie ; Salmonella ; Flagella ; Proinflammatory Capacity ; Serovar Dublin ; Bacterial Proteins -- Genetics ; Flagella -- Genetics ; Salmonella Enterica -- Genetics ; Sequence Deletion -- Genetics
    Description: serovar Dublin is adapted to cattle but is able to infect humans with high invasiveness. An acute inflammatory response at the intestine helps to prevent dissemination to systemic sites. Flagella contribute to this response by providing motility and FliC-mediated signaling through pattern recognition receptors. In a previous work, we reported a high frequency (11 out of 25) of Dublin isolates lacking flagella in a collection obtained from humans and cattle. The aflagellate strains were impaired in their proinflammatory properties and The aim of this work was to elucidate the underlying cause of the absence of flagella in Dublin isolates. We report here that class 3 flagellar genes are repressed in the human aflagellate isolates, due to impaired secretion of FliA anti-sigma factor FlgM. This phenotype is due to an in-frame 42-nucleotide deletion in the gene, which codes for a protein located in the flagellar basal body. The deletion is predicted to produce a protein lacking amino...
    Is part of: Infection and immunity, January 2018, Vol.86(1)
    Identifier: 1098-5522 (E-ISSN); 29061704 Version (PMID); 10.1128/IAI.00517-17 (DOI)

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    A five-year experience with zoonotic Salmonella at a pediatric reference centre

    Barrios, Patricia, Badía, Federica, Misa, Valentina, Mota, M Inés, Martínez, Arací, Mariño, Hebert, Algorta, Gabriela, Prego, Javier, Pírez, M Catalina
    Revista chilena de infectologia : organo oficial de la Sociedad Chilena de Infectologia, August 2017, Vol.34(4), pp.359-364
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    Title: A five-year experience with zoonotic Salmonella at a pediatric reference centre
    Author: Barrios, Patricia; Badía, Federica; Misa, Valentina; Mota, M Inés; Martínez, Arací; Mariño, Hebert; Algorta, Gabriela; Prego, Javier; Pírez, M Catalina
    Subject: Salmonella Infections -- Microbiology
    Description: Salmonella can cause asymptomatic infections, diarrhea, bacteremia and focal infections such as meningitis and osteomyelitis. To describe clinical and microbiological aspects of infections by Salmonella spp. in children in a pediatric referral hospital: Centro Hospitalario Pereira Rossell, in Montevideo, Uruguay. Descriptive and retrospective study of 46 patients, from which Salmonella spp was isolated between January 1, 2005 and December 31, 2010. Salmonella spp was isolated in 46 children younger than 15 years old. 18 were below 2 years old and 5 children below three months. 24% of the children had risk factors, such as HIV infection, oncological diseases and malnutrition; low birth weight and pneumonia were associated conditions. No deaths were reported. The serotypes more frequently found were: Typhimurium and Enteritidis. Most of the strains were susceptible to ampicillin and third generation of cephalosporins. Diarrhea with blood was the predominant clinical presentation, and there were no outbreaks. Typhimurium and Enteritidis were the most common serotypes. Based on the profiles of susceptibility antimicrobial, we could maintain the same recommendations until the moment suggested. we must consider the Salmonella infection in febrile children under risk of an invasive bacterial disease, with or without focal infection.
    Is part of: Revista chilena de infectologia : organo oficial de la Sociedad Chilena de Infectologia, August 2017, Vol.34(4), pp.359-364
    Identifier: 0717-6341 (E-ISSN); 29165513 Version (PMID); 10.4067/s0716-10182017000400359 (DOI)

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    Differential phenotypic diversity among epidemic-spanning Salmonella enterica serovar enteritidis isolates from humans or animals

    Yim, Lucía, Betancor, Laura, Martinez, Arací, Giossa, Gerardo, Bryant, Clare, Maskell, Duncan, Chabalgoity, Jose A
    Applied and environmental microbiology, October 2010, Vol.76(20), pp.6812-20 [Peer Reviewed Journal]
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    Title: Differential phenotypic diversity among epidemic-spanning Salmonella enterica serovar enteritidis isolates from humans or animals
    Author: Yim, Lucía; Betancor, Laura; Martinez, Arací; Giossa, Gerardo; Bryant, Clare; Maskell, Duncan; Chabalgoity, Jose A
    Subject: Salmonella Infections -- Epidemiology ; Salmonella Infections, Animal -- Epidemiology ; Salmonella Enteritidis -- Classification
    Description: Nontyphoidal salmonellae are major causes of food-borne disease worldwide. In Uruguay, Salmonella enterica serovar Enteritidis was the most commonly isolated serovar throughout the last decade, with a marked epidemic period between 1995 and 2004. In a previous study, we conducted comparative genomics of 29 epidemic-spanning S. Enteritidis field isolates, and here we evaluated the pathogenic potential of the same set of isolates using several phenotypic assays. The sample included 15 isolates from human gastroenteritis, 5 from invasive disease, and 9 from nonhuman sources. Contrary to the genetic homogeneity previously observed, we found great phenotypic variability among these isolates. One-third of them were defective in at least one assay, namely, 10 isolates were defective in motility, 8 in invasion of Caco-2 cells, and 10 in survival in egg albumen. Twelve isolates were tested for invasiveness in 3-day-old chickens, and five of these were significantly less invasive than the reference strain. The two oldest preepidemic isolates were reduced in fitness in all assays, providing a plausible explanation for the previous negligible incidence of S. Enteritidis in Uruguay and supporting the view that the introduction or emergence of a more virulent strain was responsible for the marked rise of this serovar. Further, we found differences in fitness among the isolates which depended on the source of isolation. A total of 1 out of 14 isolates from human gastroenteritis, but 6 out of 13 isolates from other sources, was impaired in at least two assays, suggesting enhanced fitness among strains able to cause intestinal disease in humans.
    Is part of: Applied and environmental microbiology, October 2010, Vol.76(20), pp.6812-20
    Identifier: 1098-5336 (E-ISSN); 20802078 Version (PMID); 10.1128/AEM.00497-10 (DOI)

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    First release of the bacterial biobank of the urban environment (BBUE)

    Antelo, Verónica, Salazar, Cecilia, Martínez, Arací, D’alessandro, Bruno, Castro, Marta, Betancor, Laura, Barcala, María V, Míguez, Diana, Gonnet, Gastón H, Iraola, Gregorio
    Microbiology Resource Announcements, 2018
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    Title: First release of the bacterial biobank of the urban environment (BBUE)
    Author: Antelo, Verónica; Salazar, Cecilia; Martínez, Arací; D’alessandro, Bruno; Castro, Marta; Betancor, Laura; Barcala, María V; Míguez, Diana; Gonnet, Gastón H; Iraola, Gregorio
    Description: Metagenomics is providing a broad overview of bacterial functional diversity; however, culturing and biobanking are still essential for microbiology. Here, we present the Bacterial Biobank of the Urban Environment (BBUE), a sizable culture collection for long-term storage and characterization of the microbiota associated with urban environments relevant for public health.
    Is part of: Microbiology Resource Announcements, 2018
    Identifier: 10.3929/ethz-b-000304430 (DOI)

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    Genomic and phenotypic variation in epidemic-spanning Salmonella enterica serovar Enteritidis isolates

    Betancor, Laura, Yim, Lucia, Fookes, Maria, Martinez, Araci, Thomson, Nicholas R, Ivens, Alasdair, Maskell, Sarah, Bryant, Clare, Algorta, Gabriela, Kariuki, Samuel, Schelotto, Felipe, Maskell, Duncan, Dougan, Gordon, Chabalgoity, Jose A
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    Title: Genomic and phenotypic variation in epidemic-spanning Salmonella enterica serovar Enteritidis isolates
    Author: Betancor, Laura; Yim, Lucia; Fookes, Maria; Martinez, Araci; Thomson, Nicholas R; Ivens, Alasdair; Maskell, Sarah; Bryant, Clare; Algorta, Gabriela; Kariuki, Samuel; Schelotto, Felipe; Maskell, Duncan; Dougan, Gordon; Chabalgoity, Jose A
    Date: 2011
    Description: Background Salmonella enterica serovar Enteritidis (S. Enteritidis) has caused major epidemics of gastrointestinal infection in many different countries. In this study we investigate genome divergence and pathogenic potential in S. Enteritidis isolated before, during and after an epidemic in Uruguay. Results 266 S. Enteritidis isolates were genotyped using RAPD-PCR and a selection were subjected to PFGE analysis. From these, 29 isolates spanning different periods, genetic profiles and sources of isolation were assayed for their ability to infect human epithelial cells and subjected to comparative genomic hybridization using a Salmonella pan-array and the sequenced strain S. Enteritidis PT4 P125109 as reference. Six other isolates from distant countries were included as external comparators. Two hundred and thirty three chromosomal genes as well as the virulence plasmid were found as variable among S. Enteritidis isolates. Ten out of the 16 chromosomal regions that varied between...
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