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Genomic and phenotypic evolution of achromobacter xylosoxidans during chronic airway infections of patients with cystic fibrosis

Hossein Khademi, S. M. LU ; Gabrielaite, Migle ; Paulsson, Magnus LU orcid ; Knulst, Mattis ; Touriki, Eleni ; Marvig, Rasmus L. and Pahlman, Lisa I. LU (2021) In mSystems 6(3).
Abstract

Bacterial pathogens evolve during chronic colonization of the human host by selection for pathoadaptive mutations. One of the emerging and understudied bacterial species causing chronic airway infections in patients with cystic fibrosis (CF) is Achromobacter xylosoxidans. It can establish chronic infections in patients with CF, but the genetic and phenotypic changes associated with adaptation during these infections are not completely understood. In this study, we analyzed the wholegenome sequences of 55 clinical A. xylosoxidans isolates longitudinally collected from the sputum of 6 patients with CF. Four genes encoding regulatory proteins and two intergenic regions showed convergent evolution, likely driven by positive selection for... (More)

Bacterial pathogens evolve during chronic colonization of the human host by selection for pathoadaptive mutations. One of the emerging and understudied bacterial species causing chronic airway infections in patients with cystic fibrosis (CF) is Achromobacter xylosoxidans. It can establish chronic infections in patients with CF, but the genetic and phenotypic changes associated with adaptation during these infections are not completely understood. In this study, we analyzed the wholegenome sequences of 55 clinical A. xylosoxidans isolates longitudinally collected from the sputum of 6 patients with CF. Four genes encoding regulatory proteins and two intergenic regions showed convergent evolution, likely driven by positive selection for pathoadaptive mutations, across the different clones of A. xylosoxidans. Most of the evolved isolates had lower swimming motility and were resistant to multiple classes of antibiotics, while fewer of the evolved isolates had slower growth or higher biofilm production than the first isolates. Using a genome-wide association study method, we identified several putative genetic determinants of biofilm formation, motility and b-lactam resistance in this pathogen. With respect to antibiotic resistance, we discovered that a combination of mutations in pathoadaptive genes (phoQ and bigR) and two other genes encoding regulatory proteins (spoT and cpxA) were associated with increased resistance to meropenem and ceftazidime. Altogether, our results suggest that genetic changes within regulatory loci facilitate within-host adaptation of A. xylosoxidans and the emergence of adaptive phenotypes, such as antibiotic resistance or biofilm formation. IMPORTANCE A thorough understanding of bacterial pathogen adaptation is essential for the treatment of chronic bacterial infections. One unique challenge in the analysis and interpretation of genomics data is identifying the functional impact of mutations accumulated in the bacterial genome during colonization in the human host. Here, we investigated the genomic and phenotypic evolution of A. xylosoxidans in chronic airway infections of patients with CF and identified several mutations associated with the phenotypic evolution of this pathogen using genome-wide associations. Identification of phenotypes under positive selection and the associated mutations can enlighten the adaptive processes of this emerging pathogen in human infections and pave the way for novel therapeutic interventions.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Achromobacter xylosoxidans, Bacterial adaptation, Convergent evolution, Cystic fibrosis, Genome-wide association study, Multidrug antibiotic resistance
in
mSystems
volume
6
issue
3
article number
e00523-21
publisher
American Society for Microbiology
external identifiers
  • scopus:85109288652
  • pmid:34184916
ISSN
2379-5077
DOI
10.1128/mSystems.00523-21
language
English
LU publication?
yes
id
8a3b381b-069c-4816-851f-0e9a32ea1840
date added to LUP
2021-08-16 14:59:45
date last changed
2024-06-16 17:09:20
@article{8a3b381b-069c-4816-851f-0e9a32ea1840,
  abstract     = {{<p>Bacterial pathogens evolve during chronic colonization of the human host by selection for pathoadaptive mutations. One of the emerging and understudied bacterial species causing chronic airway infections in patients with cystic fibrosis (CF) is Achromobacter xylosoxidans. It can establish chronic infections in patients with CF, but the genetic and phenotypic changes associated with adaptation during these infections are not completely understood. In this study, we analyzed the wholegenome sequences of 55 clinical A. xylosoxidans isolates longitudinally collected from the sputum of 6 patients with CF. Four genes encoding regulatory proteins and two intergenic regions showed convergent evolution, likely driven by positive selection for pathoadaptive mutations, across the different clones of A. xylosoxidans. Most of the evolved isolates had lower swimming motility and were resistant to multiple classes of antibiotics, while fewer of the evolved isolates had slower growth or higher biofilm production than the first isolates. Using a genome-wide association study method, we identified several putative genetic determinants of biofilm formation, motility and b-lactam resistance in this pathogen. With respect to antibiotic resistance, we discovered that a combination of mutations in pathoadaptive genes (phoQ and bigR) and two other genes encoding regulatory proteins (spoT and cpxA) were associated with increased resistance to meropenem and ceftazidime. Altogether, our results suggest that genetic changes within regulatory loci facilitate within-host adaptation of A. xylosoxidans and the emergence of adaptive phenotypes, such as antibiotic resistance or biofilm formation. IMPORTANCE A thorough understanding of bacterial pathogen adaptation is essential for the treatment of chronic bacterial infections. One unique challenge in the analysis and interpretation of genomics data is identifying the functional impact of mutations accumulated in the bacterial genome during colonization in the human host. Here, we investigated the genomic and phenotypic evolution of A. xylosoxidans in chronic airway infections of patients with CF and identified several mutations associated with the phenotypic evolution of this pathogen using genome-wide associations. Identification of phenotypes under positive selection and the associated mutations can enlighten the adaptive processes of this emerging pathogen in human infections and pave the way for novel therapeutic interventions.</p>}},
  author       = {{Hossein Khademi, S. M. and Gabrielaite, Migle and Paulsson, Magnus and Knulst, Mattis and Touriki, Eleni and Marvig, Rasmus L. and Pahlman, Lisa I.}},
  issn         = {{2379-5077}},
  keywords     = {{Achromobacter xylosoxidans; Bacterial adaptation; Convergent evolution; Cystic fibrosis; Genome-wide association study; Multidrug antibiotic resistance}},
  language     = {{eng}},
  number       = {{3}},
  publisher    = {{American Society for Microbiology}},
  series       = {{mSystems}},
  title        = {{Genomic and phenotypic evolution of achromobacter xylosoxidans during chronic airway infections of patients with cystic fibrosis}},
  url          = {{http://dx.doi.org/10.1128/mSystems.00523-21}},
  doi          = {{10.1128/mSystems.00523-21}},
  volume       = {{6}},
  year         = {{2021}},
}