title: [Polymorphism of mucA and fpvA genes in Pseudomonas aeruginosa isolates from cystic fibrosis patients: co-existence of genetically different variants].
abstract: BACKGROUND
  Pseudomonas aeruginosa is able to colonize the lungs of cystic fibrosis patients (CF) in an adaptive process that results in the selection of a dominant strain through a process of genetic variation.
  
  
  METHODS
  One hundred and twenty tree isolates of P. aeruginosa were sequentially recovered from 6 CF patients during the routine follow-up or exacerbations over periods of 2 to 12 years in the Ramon y Cajal University Hospital (Madrid, Spain). Another 13 isolates were obtained from a single CF patient in a short-term study. They were analysed by restriction fragment length polymorphism (RFLP) and sequencing of mucA and fpvA genes, which code for the alginate biosynthesis regulator and a pyoverdin receptor, respectively, and their antibiotic susceptibility was studied by microdilution.
  
  
  RESULTS
  A dominant colonising strain was found in each patient based on the RFLP profile. The polymorphisms of mucA and fpvA genes correlated well with these profiles, but suggested a relationship between strains isolated from two brothers, not inferred by RFLP. Stop codon mutations in mucA were unique to each dominant strain, indicating the adaptive process suffered. The alternate detection of the same mucA and/or fpvA genotypic variants suggested the coexistence of several subpopulations. This hypothesis was confirmed in a prospective study in which 6 variants were isolated in 7 days from the same patient.
  
  
  CONCLUSIONS
  Genotypic variants of the P. aeruginosa dominant strains can coexist in the chronic colonization in CF patients. These variants can be undetected by RFLP and they might present variable antibiotic susceptibility.
authors.affiliation: Departamento de Biología Celular, Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad San Pablo-CEU, Madrid, España.
authors.forename: María José
authors.initials: MJ
authors.lastname: Pozuelo
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Jiménez
authors.forename: Andrea D
authors.initials: AD
authors.lastname: Valderrey
authors.forename: Ana
authors.initials: A
authors.lastname: Fernández-Olmos
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantón
authors.forename: Rafael
authors.initials: R
authors.lastname: Rotger
mesh_terms: D000293:Adolescent; D000328:Adult; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D002648:Child; D003550:Cystic Fibrosis / Q000382:microbiology*; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D055815:Young Adult
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C082326:FpvA protein, Pseudomonas aeruginosa; C063757:MucA protein, Bacteria