Examinando por Autor "Toro, Magaly"

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    Antimicrobial resistance in E. coli isolated from dairy calves and bedding material
    (Elsevier Ltd, 2019-11) Astorga, Francisco; Navarrete-Talloni, María J.; Miró, María P.; Bravo, Verónica; Toro, Magaly; Blondel, Carlos J.; Hervé-Claude, Luis P.
    Agriculture; Microbiology; Animal science; Cattle; Livestock management; Veterinary medicine; Animal breeding; Ruminant; Antimicrobial resistance; Dairy; E. coli; Calf. © 2019 The Author(s) Introduction: E. coli is a ubiquitous bacterium commonly used as a sentinel in antimicrobial resistance studies. Here, E. coli was isolated from three groups (sick calves, healthy calves and bedding material), to assess the presence of antimicrobial resistance, describe resistance profiles, and compare these resistances among groups. Material and methods: Samples were collected from calves and calving pens from 20 dairy farms. Using the disc diffusion method, E. coli isolates were screened for antimicrobial resistance against seven antimicrobials: Amoxicillin, Ceftiofur, Gentamicin, Enrofloxacin, Trimethoprim–sulfamethoxazole, Florfenicol and Oxytetracycline. Isolates resistant to all these seven antimicrobials were tested again against an extended 19 antimicrobial drug panel and for the presence of the most common E. coli pathogenicity genes through PCR. Results & discussion: Three hundred forty-nine E. coli isolates were obtained; most isolates were resistant to a single antimicrobial, but 2.3% (8) were resistant to 16 to 19 of the antimicrobials tested. The group with the highest percentage of multiresistant isolates was the calves with diarrhea group. Younger calves provided samples with higher antimicrobial resistance levels. Conclusions: There is a high rate of antimicrobial resistance in dairy farms calving pens. These bacteria could not only be a resistance gene reservoir, but also could have the potential to spread these determinants through horizontal gene transfer to other susceptible bacteria. Measures should be taken to protect colonization of younger calves, based on hygienic measures and proper management. © 2019 The Author(s)
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    Caracterización genómica de una colección de cepas de escherichia coli enterotoxigénicas obtenidas desde granjas de producción industrial de cerdos en Chile
    (Universidad Andrés Bello, 2018) Tichy Navarro, Daniel Alfredo; Castro Nalla, Eduardo; Pieringer, Hans; Moreno, Andrea; Toro, Magaly; Facultad de Ciencias de la Vida; Escuela de Ingeniería en Biotecnología
    La producción industrial de cerdos en Chile está sujeta a la aplicación de medidas y normativas sanitarias exigentes. Sin embargo, es frecuente la aparición de brotes de enfermedades infecciosas de origen bacteriano, entre la que destaca la colibacilosis porcina. Esta enfermedad es causada por Escherichia coli (E. coli), una bacteria que infecta el tracto intestinal de lechones neonatos y de cerdos post-destetados, con una morbilidad de 50% y una mortalidad de 5%, cuyo impacto se traduce en pérdidas de USD$55 millones al año de acuerdo con estimaciones de los productores locales. Las subespecies de E. coli que provocan colibacilosis porcina son aquellas cepas clasificadas como E. coli enterotoxigénicas (ETEC), que se caracterizan por sintetizar enterotoxinas que alteran el equilibrio osmótico de las células epiteliales del intestino e inducen diarreas acuosas. En Chile, los productores aplican programas de profilaxis y metafilaxis basados en el uso de antibióticos y de vacunas diseñadas contra antígenos específicos a partir de la información epidemiológica internacional. Sin embargo, éstos no han cumplido los objetivos para los cuales fueron implementados, ya que se observa que los índices de morbilidad y mortalidad asociados a colibacilosis porcina siguen superando ampliamente la media mundial. Por lo tanto, se identificó la necesidad de caracterizar exhaustivamente las cepas de ETEC presentes en la industria local. Este trabajo tuvo por objetivo caracterizar los elementos determinantes del serotipo, los factores de virulencia, los genes de resistencia a antibióticos y la relación evolutiva de una colección de ETEC aisladas desde fecas de lechones neonatos y post-destetados de granjas industriales en Chile. Se obtuvieron 76 aislados positivos para enterotoxinas a partir de muestras fecales de 133 animales de 6 granjas distintas. Se secuenciaron los genomas y se determinaron in silico los factores determinantes del serotipo, factores de virulencia y genes de resistencia a antibióticos. Los resultados obtenidos indican la presencia de 12 cepas distintas, distribuidas entre las granjas analizadas; cinco toxinas intraintestinales diferentes en distintas combinaciones; nueve perfiles de resistencia a 8 grupos de antibióticos distintos, entre los que destacan múltiples perfiles de multi-resistencia. Además, se evidenció la existencia de múltiples eventos de introducción de ETEC exógenas. Dadas las características genéticas de las cepas ETEC aisladas desde granjas industriales de cerdos en Chile, se puede concluir que estas son distintas a las principales cepas asociadas a la enfermedad a nivel mundial.
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    Probiotic Yeasts and Vibrio anguillarum Infection Modify the Microbiome of Zebrafish Larvae
    (Frontiers Media S.A., 2021-06) Vargas, Orlando; Gutiérrez, María Soledad; Caruffo, Mario; Valderrama, Benjamín; Medina, Daniel A.; García, Katherine; Reyes Jara, Angélica; Toro, Magaly; Feijóo, Carmen G.; Navarrete, Paola
    The host microbiome plays an essential role in health and disease. Microbiome modification by pathogens or probiotics has been poorly explored especially in the case of probiotic yeasts. Next-generation sequencing currently provides the best tools for their characterization. Debaryomyces hansenii 97 (D. hansenii 97) and Yarrowia lipolytica 242 (Y. lipolytica 242) are yeasts that protect wildtype zebrafish (Danio rerio) larvae against a Vibrio anguillarum (V. anguillarum) infection, increasing their survival rate. We investigate the effect of these microorganisms on the microbiome and neutrophil response (inflammation) in zebrafish larvae line Tg(Bacmpx:GFP)i114. We postulated that preinoculation of larvae with yeasts would attenuate the intestinal neutrophil response and prevent modification of the larval microbiome induced by the pathogen. Microbiome study was performed by sequencing the V3-V4 region of the 16S rRNA gene and prediction of metabolic pathways by Piphillin in conventionally raised larvae. Survival and the neutrophil response were both evaluated in conventional and germ-free conditions. V. anguillarum infection resulted in higher neutrophil number in the intestinal area compared to non-infected larvae in both conditions. In germ-free conditions, infected larvae pre-inoculated with yeasts showed fewer neutrophil numbers than infected larvae. In both conditions, only D. hansenii 97 increased the survival of infected larvae. Beta diversity of the microbiota was modified by V. anguillarum and both yeasts, compared to non-inoculated larvae. At 3 days post-infection, V. anguillarum modified the relative abundance of 10 genera, and pre-inoculation with D. hansenii 97 and Y. lipolytica 242 prevented the modification of 5 and 6 of these genera, respectively. Both yeasts prevent the increase of Ensifer and Vogesella identified as negative predictors for larval survival (accounting for 40 and 27 of the variance, respectively). In addition, yeast pre-inoculation prevents changes in some metabolic pathways altered by V. anguillarum’s infection. These results suggest that both yeasts and V. anguillarum can shape the larval microbiota configuration in the early developmental stage of D. rerio. Moreover, modulation of key taxa or metabolic pathways of the larval microbiome by yeasts can be associated with the survival of infected larvae. This study contributes to the understanding of yeast–pathogen–microbiome interactions, although further studies are needed to elucidate the mechanisms involved. © Copyright © 2021 Vargas, Gutiérrez, Caruffo, Valderrama, Medina, García, Reyes-Jara, Toro, Feijóo and Navarrete.
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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.