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Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils

BACKGROUND: Isolation of the soil bacterium Burkholderia pseudomallei from tropical environments is important to generate a global risk map for man and animals to acquire the infectious disease melioidosis. There is increasing evidence, that the currently recommended soil culture protocol using thre...

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Autores principales: Trinh, Trung T., Assig, Karoline, Tran, Quyen T. L., Goehler, André, Bui, Linh N. H., Wiede, Claudia, Folli, Bettina, Lichtenegger, Sabine, Nguyen, Tinh T., Wagner, Gabriel E., Kohler, Christian, Steinmetz, Ivo
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822774/
https://www.ncbi.nlm.nih.gov/pubmed/31634353
http://dx.doi.org/10.1371/journal.pntd.0007821
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author Trinh, Trung T.
Assig, Karoline
Tran, Quyen T. L.
Goehler, André
Bui, Linh N. H.
Wiede, Claudia
Folli, Bettina
Lichtenegger, Sabine
Nguyen, Tinh T.
Wagner, Gabriel E.
Kohler, Christian
Steinmetz, Ivo
author_facet Trinh, Trung T.
Assig, Karoline
Tran, Quyen T. L.
Goehler, André
Bui, Linh N. H.
Wiede, Claudia
Folli, Bettina
Lichtenegger, Sabine
Nguyen, Tinh T.
Wagner, Gabriel E.
Kohler, Christian
Steinmetz, Ivo
author_sort Trinh, Trung T.
collection PubMed
description BACKGROUND: Isolation of the soil bacterium Burkholderia pseudomallei from tropical environments is important to generate a global risk map for man and animals to acquire the infectious disease melioidosis. There is increasing evidence, that the currently recommended soil culture protocol using threonine-basal salt solution with colistin (TBSS-C50) for enrichment of B. pseudomallei and Ashdown agar for subsequent subculture lacks sensitivity. We therefore investigated, if the otherwise rarely encountered erythritol catabolism of B. pseudomallei might be exploited to improve isolation of this bacterium from soil. METHODOLOGY/PRINCIPAL FINDINGS: Based on TBSS-C50, we designed a new colistin-containing medium with erythritol as the single carbon source (EM). This medium was validated in various culture protocols by analyzing 80 soil samples from 16 different rice fields in Vietnam. B. pseudomallei enrichment was determined in all culture supernatants by a specific quantitative PCR (qPCR) targeting the type three secretion system 1. 51 out of 80 (63.8%) soil samples gave a positive qPCR signal in at least one of the culture conditions. We observed a significantly higher enrichment shown by lower median cycle threshold values for B. pseudomallei in a two-step culture with TBSS-C50 for 48 h followed by EM for 96h compared to single cultures in TBSS-C50 for either 48h or 144h (p<0.0001, respectively). Accordingly, B. pseudomallei could be isolated on Ashdown agar in 58.8% (30/51) of samples after subcultures from our novel two-step enrichment culture compared to only 9.8% (5/51) after standard enrichment with TBSS-C50 for 48h (p<0.0001) or 25.5% (13/51; p<0.01) after TBSS-C50 for 144h. CONCLUSIONS/SIGNIFICANCE: In the present study, we show that specific exploitation of B. pseudomallei metabolic capabilities in enrichment protocols leads to a significantly improved isolation rate of this pathogen from soil compared to established standard procedures. Our new culture method might help to facilitate the creation of environmental risk maps for melioidosis in the future.
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spelling pubmed-68227742019-11-12 Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils Trinh, Trung T. Assig, Karoline Tran, Quyen T. L. Goehler, André Bui, Linh N. H. Wiede, Claudia Folli, Bettina Lichtenegger, Sabine Nguyen, Tinh T. Wagner, Gabriel E. Kohler, Christian Steinmetz, Ivo PLoS Negl Trop Dis Research Article BACKGROUND: Isolation of the soil bacterium Burkholderia pseudomallei from tropical environments is important to generate a global risk map for man and animals to acquire the infectious disease melioidosis. There is increasing evidence, that the currently recommended soil culture protocol using threonine-basal salt solution with colistin (TBSS-C50) for enrichment of B. pseudomallei and Ashdown agar for subsequent subculture lacks sensitivity. We therefore investigated, if the otherwise rarely encountered erythritol catabolism of B. pseudomallei might be exploited to improve isolation of this bacterium from soil. METHODOLOGY/PRINCIPAL FINDINGS: Based on TBSS-C50, we designed a new colistin-containing medium with erythritol as the single carbon source (EM). This medium was validated in various culture protocols by analyzing 80 soil samples from 16 different rice fields in Vietnam. B. pseudomallei enrichment was determined in all culture supernatants by a specific quantitative PCR (qPCR) targeting the type three secretion system 1. 51 out of 80 (63.8%) soil samples gave a positive qPCR signal in at least one of the culture conditions. We observed a significantly higher enrichment shown by lower median cycle threshold values for B. pseudomallei in a two-step culture with TBSS-C50 for 48 h followed by EM for 96h compared to single cultures in TBSS-C50 for either 48h or 144h (p<0.0001, respectively). Accordingly, B. pseudomallei could be isolated on Ashdown agar in 58.8% (30/51) of samples after subcultures from our novel two-step enrichment culture compared to only 9.8% (5/51) after standard enrichment with TBSS-C50 for 48h (p<0.0001) or 25.5% (13/51; p<0.01) after TBSS-C50 for 144h. CONCLUSIONS/SIGNIFICANCE: In the present study, we show that specific exploitation of B. pseudomallei metabolic capabilities in enrichment protocols leads to a significantly improved isolation rate of this pathogen from soil compared to established standard procedures. Our new culture method might help to facilitate the creation of environmental risk maps for melioidosis in the future. Public Library of Science 2019-10-21 /pmc/articles/PMC6822774/ /pubmed/31634353 http://dx.doi.org/10.1371/journal.pntd.0007821 Text en © 2019 Trinh et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://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
Trinh, Trung T.
Assig, Karoline
Tran, Quyen T. L.
Goehler, André
Bui, Linh N. H.
Wiede, Claudia
Folli, Bettina
Lichtenegger, Sabine
Nguyen, Tinh T.
Wagner, Gabriel E.
Kohler, Christian
Steinmetz, Ivo
Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title_full Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title_fullStr Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title_full_unstemmed Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title_short Erythritol as a single carbon source improves cultural isolation of Burkholderia pseudomallei from rice paddy soils
title_sort erythritol as a single carbon source improves cultural isolation of burkholderia pseudomallei from rice paddy soils
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822774/
https://www.ncbi.nlm.nih.gov/pubmed/31634353
http://dx.doi.org/10.1371/journal.pntd.0007821
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