title: Dynamic in vivo mutations within the ica operon during persistence of Staphylococcus aureus in the airways of cystic fibrosis patients.
abstract: Cystic fibrosis (CF) is associated with chronic bacterial airway infections leading to lung insufficiency and decreased life expectancy. Staphylococcus aureus is one of the most prevalent pathogens isolated from the airways of CF patients. Mucoid colony morphology has been described for Pseudomonas aeruginosa, the most common pathogen in CF, but not for S. aureus. From the airways of 8 of 313 CF patients (2.5%) mucoid S. aureus isolates (n = 115) were cultured with a mean persistence of 29 months (range 1 month, 126 months). In contrast to non-mucoid S. aureus, mucoid isolates were strong biofilm formers. The upstream region of the ica operon, which encodes the proteins responsible for the synthesis of the polysaccharide intercellular adhesin (PIA), of mucoid isolates was sequenced. Spa-types of mucoid and non-mucoid strains were identical, but differed between patients. Mucoid isolates carried a 5 bp deletion in the intergenic region between icaR and icaA. During long-term persistence, from two patients subsequent non-mucoid isolates (n = 12) with 5 bp deletions were cultured, which did not produce biofilm. Sequencing of the entire ica operon identified compensatory mutations in various ica-genes including icaA (n = 7), icaD (n = 3) and icaC (n = 2). Six sequential isolates of each of these two patients with non-mucoid and mucoid phenotypes were subjected to whole genome sequencing revealing a very close relationship of the individual patient's isolates. Transformation of strains with vectors expressing the respective wild-type genes restored mucoidy. In contrast to the non-mucoid phenotype, mucoid strains were protected against neutrophilic killing and survived better under starvation conditions. In conclusion, the special conditions present in CF airways seem to facilitate ongoing mutations in the ica operon during S. aureus persistence.
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Bianca
authors.initials: B
authors.lastname: Schwartbeck
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.|Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School Boston, United States of America.
authors.forename: Johannes
authors.identifier: http://orcid.org/0000-0001-7699-2112
authors.initials: J
authors.lastname: Birtel
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Janina
authors.identifier: http://orcid.org/0000-0002-1072-418X
authors.initials: J
authors.lastname: Treffon
authors.affiliation: Institute for Hygiene, University Clinics Münster, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Langhanki
authors.affiliation: Institute for Hygiene, University Clinics Münster, Germany.
authors.forename: Alexander
authors.identifier: http://orcid.org/0000-0002-0649-5185
authors.initials: A
authors.lastname: Mellmann
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Devika
authors.initials: D
authors.lastname: Kale
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Kahl
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Hirschhausen
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Neumann
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School Boston, United States of America.
authors.forename: Jean C
authors.initials: JC
authors.lastname: Lee
authors.affiliation: Department of Microbial Genetics, University of Tübingen, Tübingen, Germany.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Götz
authors.affiliation: Institut für Medizinische Mikrobiologie, Virologie und Hygiene, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Rohde
authors.affiliation: Institut für Medizinische Mikrobiologie, Virologie und Hygiene, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Hanae
authors.identifier: http://orcid.org/0000-0001-6898-5828
authors.initials: H
authors.lastname: Henke
authors.affiliation: Pediatric Department Clemenshospital Münster, Münster, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Küster
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Peters
authors.affiliation: Institute of Medical Microbiology, University Clinics Münster, Germany.
authors.forename: Barbara C
authors.identifier: http://orcid.org/0000-0001-5155-3383
authors.initials: BC
authors.lastname: Kahl
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D018441:Biofilms; D003550:Cystic Fibrosis / Q000382:microbiology*; D006801:Humans; D018613:Microscopy, Confocal; D060885:Multiplex Polymerase Chain Reaction; D009154:Mutation; D009876:Operon / Q000235:genetics; D013203:Staphylococcal Infections / Q000235:genetics* / Q000473:pathology*; D013211:Staphylococcus aureus
chemical_list: D001426:Bacterial Proteins