Examinando por Autor "Retamal, Patricio"

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    Characterization of MgtC, a virulence factor of Salmonella enterica serovar typhi
    (Public Library of Science, 2009-04-14) Retamal, Patricio; Castillo-Ruiz, Mario; Mora, Guido C.
    The MgtC is a virulence factor in Salmonella Typhimurium that is required for growth at low-Mg2+ concentrations and intramacrophage survival. This gene is codified in a conserved region of the Salmonella pathogenicity island 3 (SPI-3), and is also present in the chromosome of other Salmonella serovars. In this study we characterized the MgtC factor in S. Typhi, a human specific pathogen, by using mgtC and SPI-3 mutant strains. We found that MgtC is the most important factor codified in the SPI-3 of S. Typhi for growth in low-Mg2+ media and survival within human cells. In addition, by using reporter genes we determined that the low-Mg2+ concentration, acidic media and PhoP regulator induce mgtC expression in S. Typhi. We suggest that MgtC is the most important virulence factor codified in the SPI-3 of S. Typhi. © 2009 Retamal et al.
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    Modified intracellular-associated phenotypes in a recombinant Salmonella typhi expressing S. typhimurium SPI-3 sequences
    (Public Library of Science, 2010-02-24) Retamal, Patricio; Castillo-Ruiz, Mario; Villagra, Nicolás A.; Morgado, Juan; Mora, Guido C.
    A bioinformatics comparison of Salmonella Pathogenicity Island 3 sequences from S. Typhi and S. Typhimurium serovars showed that ten genes are highly conserved. However three of them are pseudogenes in S. Typhi. Our aim was to understand what functions are lost in S. Typhi due to pseudogenes by constructing a S. Typhi genetic hybrid carrying the SPI-3 region of S. Typhimurium instead of its own SPI-3. We observed that under stressful conditions the hybrid strain showed a clear impairment in resistance to hydrogen peroxide and decreased survival within U937 culture monocytes. We hypothesized that the marT-fidL operon, encoded in SPI-3, was responsible for the new phenotypes because marT is a pseudogen in S. Typhi and has a demonstrated role as a transcriptional regulator in S. Typhimurium. Therefore we cloned and transferred the S. Typhimurium marT-fidL operon into S. Typhi and confirmed that invasion of monocytes was dramatically decreased. Finally, our findings suggest that the genomic and functional differences between SPI-3 sequences have implications in the host specificity of Typhi and Typhimurium serovars. Copyright: © 2010 Retamal et al.
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    Transduction as a Potential Dissemination Mechanism of a Clonal qnrB19-Carrying Plasmid Isolated From Salmonella of Multiple Serotypes and Isolation Sources (Frontiers in Microbiology, (2019), 10, 10.3389/fmicb.2019.02503)
    (Frontiers Media S.AFrontiers in MicrobiologyOpen AccessVolume 117 April 2020 Article number 547, 2020-04) Moreno-Switt, Andrea I.; Pezoa, David; Sepúlveda, Vanessa; González, Iván; Rivera, Dácil; Retamal, Patricio; Navarrete, Paola; Reyes-Jara, Angélica; Toro, Magaly
    In the original article, “Andres et al. (2013)” was not cited and referenced in the article. The citation has now been inserted in the Introduction, paragraph three and in the Discussion section, paragraph four and should read. © Copyright © 2020 Moreno-Switt, Pezoa, Sepúlveda, González, Rivera, Retamal, Navarrete, Reyes-Jara and Toro.
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    Virulence and antimicrobial resistance factors in Salmonella enterica serotypes isolated from pigs and chickens in central Chile
    (Frontiers Media S.A., 2022-09) Retamal, Patricio; Gaspar, Joaquim; Benavides, María Belén; Saenz, Leonardo; Galarce, Nicolás; Aravena, Trinidad; Cornejo, Javiera; Lapierre, Lisette
    Salmonella enterica is a food-borne pathogen with a wide host-range that during decades has been of public health concern in developed and developing countries. In Chile, the poultry and pig industries represent the biggest contribution of meat consumption in the population, and sanitary regulations have been imposed for Salmonella control. The aim of this work was to determine and characterize Salmonella strains isolated from pigs and chicken raised on commercials farms in Chile. For this, isolates belonging to pigs (n = 46) and poultry (n = 57) were genotyped by two multiplex PCR reactions and virulotyped by the PCR detection of virulence-associated genes. In addition, isolates were serotyped and analyzed by the Kirby Bauer assay to determine their antimicrobial resistance phenotypes. From these analyses 52 genotypes, six serotypes and several multidrug resistance phenotypes and different combinations of virulence-associated genes were detected. These results suggest that S. enterica in pigs and poultry in central Chile should be monitored due to potential consequences in public and animal health. Copyright © 2022 Retamal, Gaspar, Benavides, Saenz, Galarce, Aravena, Cornejo and Lapierre.