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Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro

BACKGROUND: We aimed to determine the evolutionary pathways of rifampicin resistance in Staphylococcus aureus, and the impact of resistance mutations in the rpoB gene on fitness. METHODS: Three clinical strains and one reference strain were used to select for rifampicin-resistant S. aureus variants....

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Autores principales: Wang, Chong, Fang, Renchi, Zhou, Beibei, Tian, Xuebin, Zhang, Xiucai, Zheng, Xiangkuo, Zhang, Siqin, Dong, Guofeng, Cao, Jianming, Zhou, Tieli
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751903/
https://www.ncbi.nlm.nih.gov/pubmed/31533633
http://dx.doi.org/10.1186/s12866-019-1573-9
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author Wang, Chong
Fang, Renchi
Zhou, Beibei
Tian, Xuebin
Zhang, Xiucai
Zheng, Xiangkuo
Zhang, Siqin
Dong, Guofeng
Cao, Jianming
Zhou, Tieli
author_facet Wang, Chong
Fang, Renchi
Zhou, Beibei
Tian, Xuebin
Zhang, Xiucai
Zheng, Xiangkuo
Zhang, Siqin
Dong, Guofeng
Cao, Jianming
Zhou, Tieli
author_sort Wang, Chong
collection PubMed
description BACKGROUND: We aimed to determine the evolutionary pathways of rifampicin resistance in Staphylococcus aureus, and the impact of resistance mutations in the rpoB gene on fitness. METHODS: Three clinical strains and one reference strain were used to select for rifampicin-resistant S. aureus variants. The mutations responsible for rifampicin resistance in all of the selected isolates in vitro were investigated by polymerase chain reaction (PCR) and DNA sequencing. To compare the fitness cost of rpoB mutations against their corresponding original isolates, we performed bacterial growth curve assays, static biofilm assays, in vitro competition experiments and an infection model of Galleria mellonella larvae. RESULTS: We obtained four rifampicin-resistant S. aureus isolates that showed high levels of resistance to rifampicin with a minimal inhibitory concentration (MIC) of 128 mg/L, and all isolates had a mutation at position 481 (H481F/Y) in RpoB. A broth microdilution assay indicated that mutation of H481F/Y did not affect susceptibility to common antibacterial drugs but slightly increased the vancomycin MIC. To identify the pathways involved in the development of rifampicin resistance, 32 variants (eight mutants for each strain) and four original isolates were selected for gene sequencing. Different generations of isolates were found to harbor various mutations sites. Compared with the corresponding original isolates, an in vitro fitness assay of the variant isolates showed that growth and virulence were reduced, with a statistically significantly decreased fitness, whereas the capacity for biofilm formation was elevated. CONCLUSIONS: Our findings suggested that the acquisition of rifampicin resistance in S. aureus was dynamic and was associated with a significant fitness cost. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12866-019-1573-9) contains supplementary material, which is available to authorized users.
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spelling pubmed-67519032019-09-23 Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro Wang, Chong Fang, Renchi Zhou, Beibei Tian, Xuebin Zhang, Xiucai Zheng, Xiangkuo Zhang, Siqin Dong, Guofeng Cao, Jianming Zhou, Tieli BMC Microbiol Research Article BACKGROUND: We aimed to determine the evolutionary pathways of rifampicin resistance in Staphylococcus aureus, and the impact of resistance mutations in the rpoB gene on fitness. METHODS: Three clinical strains and one reference strain were used to select for rifampicin-resistant S. aureus variants. The mutations responsible for rifampicin resistance in all of the selected isolates in vitro were investigated by polymerase chain reaction (PCR) and DNA sequencing. To compare the fitness cost of rpoB mutations against their corresponding original isolates, we performed bacterial growth curve assays, static biofilm assays, in vitro competition experiments and an infection model of Galleria mellonella larvae. RESULTS: We obtained four rifampicin-resistant S. aureus isolates that showed high levels of resistance to rifampicin with a minimal inhibitory concentration (MIC) of 128 mg/L, and all isolates had a mutation at position 481 (H481F/Y) in RpoB. A broth microdilution assay indicated that mutation of H481F/Y did not affect susceptibility to common antibacterial drugs but slightly increased the vancomycin MIC. To identify the pathways involved in the development of rifampicin resistance, 32 variants (eight mutants for each strain) and four original isolates were selected for gene sequencing. Different generations of isolates were found to harbor various mutations sites. Compared with the corresponding original isolates, an in vitro fitness assay of the variant isolates showed that growth and virulence were reduced, with a statistically significantly decreased fitness, whereas the capacity for biofilm formation was elevated. CONCLUSIONS: Our findings suggested that the acquisition of rifampicin resistance in S. aureus was dynamic and was associated with a significant fitness cost. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12866-019-1573-9) contains supplementary material, which is available to authorized users. BioMed Central 2019-09-18 /pmc/articles/PMC6751903/ /pubmed/31533633 http://dx.doi.org/10.1186/s12866-019-1573-9 Text en © The Author(s). 2019 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Wang, Chong
Fang, Renchi
Zhou, Beibei
Tian, Xuebin
Zhang, Xiucai
Zheng, Xiangkuo
Zhang, Siqin
Dong, Guofeng
Cao, Jianming
Zhou, Tieli
Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title_full Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title_fullStr Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title_full_unstemmed Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title_short Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro
title_sort evolution of resistance mechanisms and biological characteristics of rifampicin-resistant staphylococcus aureus strains selected in vitro
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751903/
https://www.ncbi.nlm.nih.gov/pubmed/31533633
http://dx.doi.org/10.1186/s12866-019-1573-9
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