title: Site of isolation determines biofilm formation and virulence phenotypes of Streptococcus pneumoniae serotype 3 clinical isolates.
abstract: Streptococcus pneumoniae is a diverse species causing invasive as well as localized infections that result in massive global morbidity and mortality. Strains vary markedly in pathogenic potential, but the molecular basis is obscured by the diversity and plasticity of the pneumococcal genome. In the present study, S. pneumoniae serotype 3 blood (n = 12) or ear (n = 13) isolates were multilocus sequence typed (MLST) and assessed for biofilm formation and virulence phenotype. Blood and ear isolates exhibited similar MLST distributions but differed markedly in phenotype. Blood isolates formed robust biofilms only at pH 7.4, which were enhanced in Fe(III)-supplemented medium. Conversely, ear isolates formed biofilms only at pH 6.8, and Fe(III) was inhibitory. Biofilm formation paralleled luxS expression and genetic competence. In a mouse intranasal challenge model, blood isolates did not stably colonize the nasopharynx but spread to the blood; none spread to the ear. Ear isolates colonized the nasopharynx at higher levels and also spread to the ear compartment in a significant proportion of animals; none caused bacteremia. Thus, pneumococci of the same serotype and MLST exhibit distinct phenotypes in accordance with clinical site of isolation, indicative of stable niche adaptation within a clonal lineage.
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia.
authors.forename: Claudia
authors.initials: C
authors.lastname: Trappetti
authors.forename: Erika
authors.initials: E
authors.lastname: van der Maten
authors.forename: Zarina
authors.initials: Z
authors.lastname: Amin
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Potter
authors.forename: Austen Y
authors.initials: AY
authors.lastname: Chen
authors.forename: Paula M
authors.initials: PM
authors.lastname: van Mourik
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lawrence
authors.forename: Adrienne W
authors.initials: AW
authors.lastname: Paton
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015373:Bacterial Typing Techniques / Q000379:methods; D018441:Biofilms / Q000254:growth & development*; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism; D005260:Female; D005290:Ferric Compounds / Q000378:metabolism; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D051379:Mice; D009305:Nasopharynx / Q000378:metabolism / Q000382:microbiology; D010641:Phenotype; D011008:Pneumococcal Infections / Q000378:metabolism / Q000382:microbiology*; D012703:Serotyping / Q000379:methods; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005290:Ferric Compounds; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria