title: Understanding the Pathogenicity of Burkholderia contaminans, an Emerging Pathogen in Cystic Fibrosis.
abstract: Several bacterial species from the Burkholderia cepacia complex (Bcc) are feared opportunistic pathogens that lead to debilitating lung infections with a high risk of developing fatal septicemia in cystic fibrosis (CF) patients. However, the pathogenic potential of other Bcc species is yet unknown. To elucidate clinical relevance of Burkholderia contaminans, a species frequently isolated from CF respiratory samples in Ibero-American countries, we aimed to identify its key virulence factors possibly linked with an unfavorable clinical outcome. We performed a genome-wide comparative analysis of two isolates of B. contaminans ST872 from sputum and blood culture of a female CF patient in Argentina. RNA-seq data showed significant changes in expression for quorum sensing-regulated virulence factors and motility and chemotaxis. Furthermore, we detected expression changes in a recently described low-oxygen-activated (lxa) locus which encodes stress-related proteins, and for two clusters responsible for the biosynthesis of antifungal and hemolytic compounds pyrrolnitrin and occidiofungin. Based on phenotypic assays that confirmed changes in motility and in proteolytic, hemolytic and antifungal activities, we were able to distinguish two phenotypes of B. contaminans that coexisted in the host and entered her bloodstream. Whole genome sequencing revealed that the sputum and bloodstream isolates (each representing a distinct phenotype) differed by over 1,400 mutations as a result of a mismatch repair-deficient hypermutable state of the sputum isolate. The inferred lack of purifying selection against nonsynonymous mutations and the high rate of pseudogenization in the derived isolate indicated limited evolutionary pressure during evolution in the nutrient-rich, stable CF sputum environment. The present study is the first to examine the genomic and transcriptomic differences between longitudinal isolates of B. contaminans. Detected activity of a number of putative virulence factors implies a genuine pathogenic nature of this novel Bcc species.
authors: Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic.
authors: Jaroslav
authors: J
authors: Nunvar
authors: Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic.
authors: Lucie
authors: L
authors: Kalferstova
authors: Department of Medical Microbiology & Infectious Disease, University of Manitoba, Winnipeg, Canada.
authors: Ruhi A M
authors: RA
authors: Bloodworth
authors: Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors: Michal
authors: M
authors: Kolar
authors: School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.
authors: Jose
authors: J
authors: Degrossi
authors: Centro Respiratorio Dr. A. Alvarez, Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina.
authors: Silvina
authors: S
authors: Lubovich
authors: Department of Medical Microbiology & Infectious Disease, University of Manitoba, Winnipeg, Canada.
authors: Silvia T
authors: ST
authors: Cardona
authors: Department of Medical Microbiology, 2nd Faculty of Medicine, Charles University and Motol University Hospital, Prague, Czech Republic.
authors: Pavel
authors: P
authors: Drevinek
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D019117:Burkholderia / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D019121:Burkholderia Infections / Q000150:complications*; D002648:Child; D021821:Communicable Diseases, Emerging; D003550:Cystic Fibrosis / Q000150:complications* / Q000382:microbiology; D005260:Female; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006801:Humans; D009894:Opportunistic Infections / Q000150:complications* / Q000382:microbiology; D053038:Quorum Sensing; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors