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Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens

In recent years, pathogenic strains of Enterococcus cecorum (EC) have emerged as a causing agent of septicemia and skeletal infection in broiler chickens with a high economic impact worldwide. Although research has been conducted, many aspects of the pathogenesis of the EC-associated disease are sti...

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Autores principales: Schreier, Jana, Rautenschlein, Silke, Jung, Arne
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8589174/
https://www.ncbi.nlm.nih.gov/pubmed/34767595
http://dx.doi.org/10.1371/journal.pone.0259904
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author Schreier, Jana
Rautenschlein, Silke
Jung, Arne
author_facet Schreier, Jana
Rautenschlein, Silke
Jung, Arne
author_sort Schreier, Jana
collection PubMed
description In recent years, pathogenic strains of Enterococcus cecorum (EC) have emerged as a causing agent of septicemia and skeletal infection in broiler chickens with a high economic impact worldwide. Although research has been conducted, many aspects of the pathogenesis of the EC-associated disease are still unknown. In the present study, an experimental infection model was established in broiler chickens. Two different EC strains (EC14 and EC15) were compared in two different concentrations of each strain (2 × 10(6) and 2 × 10(8) colony-forming units per milliliter (CFU/mL)) after oral infection of one-day-old chicks. Clinical signs and gross lesions of the EC-associated disease were monitored in the following seven weeks. Although both EC strains were originally isolated from clinical disease outbreaks and had a high embryonic lethality, only EC14 successfully induced the typical course of the EC-associated disease with characteristic clinical signs and gross lesions. In total, 23% of the birds in the two EC14-groups were EC-positive in extraintestinal organs on culture, and no differences were found between the two infectious doses. EC14 was frequently detected via real-time PCR in the free thoracic vertebra (FTV) and femoral heads without any detectable gross lesions. The number of EC positive spleens from infected broilers was comparable using bacterial isolation and a specific real-time PCR. Interestingly, EC15 was not detected in extraintestinal organs, although birds in the EC15 groups were colonized by EC in the ceca after experimental infection. The present study represents first proof that virulence differs among EC strains in experimentally infected chickens, and emphasizes the need to further characterize virulence factors and pathogenic mechanisms of EC. The strain EC14 at a dose of 10(6) CFU is suitable for reproduction of the EC-associated disease. The experimental infection model reported here provides the basis for further research on the EC pathogenesis and possible prevention and intervention strategies.
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spelling pubmed-85891742021-11-13 Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens Schreier, Jana Rautenschlein, Silke Jung, Arne PLoS One Research Article In recent years, pathogenic strains of Enterococcus cecorum (EC) have emerged as a causing agent of septicemia and skeletal infection in broiler chickens with a high economic impact worldwide. Although research has been conducted, many aspects of the pathogenesis of the EC-associated disease are still unknown. In the present study, an experimental infection model was established in broiler chickens. Two different EC strains (EC14 and EC15) were compared in two different concentrations of each strain (2 × 10(6) and 2 × 10(8) colony-forming units per milliliter (CFU/mL)) after oral infection of one-day-old chicks. Clinical signs and gross lesions of the EC-associated disease were monitored in the following seven weeks. Although both EC strains were originally isolated from clinical disease outbreaks and had a high embryonic lethality, only EC14 successfully induced the typical course of the EC-associated disease with characteristic clinical signs and gross lesions. In total, 23% of the birds in the two EC14-groups were EC-positive in extraintestinal organs on culture, and no differences were found between the two infectious doses. EC14 was frequently detected via real-time PCR in the free thoracic vertebra (FTV) and femoral heads without any detectable gross lesions. The number of EC positive spleens from infected broilers was comparable using bacterial isolation and a specific real-time PCR. Interestingly, EC15 was not detected in extraintestinal organs, although birds in the EC15 groups were colonized by EC in the ceca after experimental infection. The present study represents first proof that virulence differs among EC strains in experimentally infected chickens, and emphasizes the need to further characterize virulence factors and pathogenic mechanisms of EC. The strain EC14 at a dose of 10(6) CFU is suitable for reproduction of the EC-associated disease. The experimental infection model reported here provides the basis for further research on the EC pathogenesis and possible prevention and intervention strategies. Public Library of Science 2021-11-12 /pmc/articles/PMC8589174/ /pubmed/34767595 http://dx.doi.org/10.1371/journal.pone.0259904 Text en © 2021 Schreier et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Schreier, Jana
Rautenschlein, Silke
Jung, Arne
Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title_full Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title_fullStr Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title_full_unstemmed Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title_short Different virulence levels of Enterococcus cecorum strains in experimentally infected meat-type chickens
title_sort different virulence levels of enterococcus cecorum strains in experimentally infected meat-type chickens
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8589174/
https://www.ncbi.nlm.nih.gov/pubmed/34767595
http://dx.doi.org/10.1371/journal.pone.0259904
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