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Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014

Between July and November 2014, 15 community-acquired cases of Legionnaires´ disease (LD), including four with Legionella pneumophila serogroup 1 sequence type (ST) 82, were diagnosed in Northern Zealand, Denmark. An outbreak was suspected. No ST82 isolates were found in environmental samples and no...

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Autores principales: Schjørring, Susanne, Stegger, Marc, Kjelsø, Charlotte, Lilje, Berit, Bangsborg, Jette M, Petersen, Randi F, David, Sophia, Uldum, Søren A
Formato: Online Artículo Texto
Lenguaje:English
Publicado: European Centre for Disease Prevention and Control (ECDC) 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490456/
https://www.ncbi.nlm.nih.gov/pubmed/28662761
http://dx.doi.org/10.2807/1560-7917.ES.2017.22.25.30558
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author Schjørring, Susanne
Stegger, Marc
Kjelsø, Charlotte
Lilje, Berit
Bangsborg, Jette M
Petersen, Randi F
David, Sophia
Uldum, Søren A
author_facet Schjørring, Susanne
Stegger, Marc
Kjelsø, Charlotte
Lilje, Berit
Bangsborg, Jette M
Petersen, Randi F
David, Sophia
Uldum, Søren A
author_sort Schjørring, Susanne
collection PubMed
description Between July and November 2014, 15 community-acquired cases of Legionnaires´ disease (LD), including four with Legionella pneumophila serogroup 1 sequence type (ST) 82, were diagnosed in Northern Zealand, Denmark. An outbreak was suspected. No ST82 isolates were found in environmental samples and no external source was established. Four putative-outbreak ST82 isolates were retrospectively subjected to whole genome sequencing (WGS) followed by phylogenetic analyses with epidemiologically unrelated ST82 sequences. The four putative-outbreak ST82 sequences fell into two clades, the two clades were separated by ca 1,700 single nt polymorphisms (SNP)s when recombination regions were included but only by 12 to 21 SNPs when these were removed. A single putative-outbreak ST82 isolate sequence segregated in the first clade. The other three clustered in the second clade, where all included sequences had < 5 SNP differences between them. Intriguingly, this clade also comprised epidemiologically unrelated isolate sequences from the UK and Denmark dating back as early as 2011. The study confirms that recombination plays a major role in L. pneumophila evolution. On the other hand, strains belonging to the same ST can have only few SNP differences despite being sampled over both large timespans and geographic distances. These are two important factors to consider in outbreak investigations.
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spelling pubmed-54904562017-07-11 Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014 Schjørring, Susanne Stegger, Marc Kjelsø, Charlotte Lilje, Berit Bangsborg, Jette M Petersen, Randi F David, Sophia Uldum, Søren A Euro Surveill Surveillance and Outbreak Report Between July and November 2014, 15 community-acquired cases of Legionnaires´ disease (LD), including four with Legionella pneumophila serogroup 1 sequence type (ST) 82, were diagnosed in Northern Zealand, Denmark. An outbreak was suspected. No ST82 isolates were found in environmental samples and no external source was established. Four putative-outbreak ST82 isolates were retrospectively subjected to whole genome sequencing (WGS) followed by phylogenetic analyses with epidemiologically unrelated ST82 sequences. The four putative-outbreak ST82 sequences fell into two clades, the two clades were separated by ca 1,700 single nt polymorphisms (SNP)s when recombination regions were included but only by 12 to 21 SNPs when these were removed. A single putative-outbreak ST82 isolate sequence segregated in the first clade. The other three clustered in the second clade, where all included sequences had < 5 SNP differences between them. Intriguingly, this clade also comprised epidemiologically unrelated isolate sequences from the UK and Denmark dating back as early as 2011. The study confirms that recombination plays a major role in L. pneumophila evolution. On the other hand, strains belonging to the same ST can have only few SNP differences despite being sampled over both large timespans and geographic distances. These are two important factors to consider in outbreak investigations. European Centre for Disease Prevention and Control (ECDC) 2017-06-22 /pmc/articles/PMC5490456/ /pubmed/28662761 http://dx.doi.org/10.2807/1560-7917.ES.2017.22.25.30558 Text en This article is copyright of The Authors, 2017. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0) Licence. You may share and adapt the material, but must give appropriate credit to the source, provide a link to the licence, and indicate if changes were made.
spellingShingle Surveillance and Outbreak Report
Schjørring, Susanne
Stegger, Marc
Kjelsø, Charlotte
Lilje, Berit
Bangsborg, Jette M
Petersen, Randi F
David, Sophia
Uldum, Søren A
Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title_full Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title_fullStr Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title_full_unstemmed Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title_short Genomic investigation of a suspected outbreak of Legionella pneumophila ST82 reveals undetected heterogeneity by the present gold-standard methods, Denmark, July to November 2014
title_sort genomic investigation of a suspected outbreak of legionella pneumophila st82 reveals undetected heterogeneity by the present gold-standard methods, denmark, july to november 2014
topic Surveillance and Outbreak Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490456/
https://www.ncbi.nlm.nih.gov/pubmed/28662761
http://dx.doi.org/10.2807/1560-7917.ES.2017.22.25.30558
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