title: Genetic analysis of Pseudomonas aeruginosa isolates from the sputa of Australian adult cystic fibrosis patients.
abstract: Genetic investigations were carried out with 50 phenotypically selected strains of Pseudomonas aeruginosa from 18 patients attending an Australian cystic fibrosis (CF) center. The isolates were analyzed by restriction fragment length polymorphism (RFLP) analysis by pulsed-field gel electrophoresis (PFGE). Phylogenetic analysis of the macrorestriction patterns showed rates of genetic similarity ranging from 76 to 100%; 24 (48%) of the strains from 11 patients had greater than 90% similarity. A dominant strain emerged: 15 isolates from seven patients had identical PFGE patterns, and 4 other isolates were very closely related. The 50 isolates were grouped into 21 pulsotypes on the basis of visual delineation of a three-band difference. Ten of the 18 (56%) patients were infected with clonal or subclonal strains. Sequence analysis of PCR products derived from the mucA gene showed 20 mutations, with the number of mutations in individual isolates ranging from 1 to 4; 19 of these changes are reported here for the first time. Potentially functional changes were found in 22 (44%) isolates. Eight changes (five transversions and three single base deletions) led to premature stop codons, providing support for the presence of mucA mutations as one pathway to mucoidy. There was a trend toward an association between the dominant strain and lack of potentially functional mucA mutations (P = 0.09 by the chi(2) test) but no relationship between genotype and phenotype. This is the first study of genetic variation in P. aeruginosa isolates from adult Australian CF patients. The findings highlight the need for further investigations on the transmissibility of P. aeruginosa in CF patients.
authors.affiliation: Department of Infectious Diseases, Faculty of Medicine, University of Sydney, Australia.
authors.forename: Mario
authors.initials: M
authors.lastname: Anthony
authors.forename: Barbara
authors.initials: B
authors.lastname: Rose
authors.forename: Mary Beard
authors.initials: MB
authors.lastname: Pegler
authors.forename: Mark
authors.initials: M
authors.lastname: Elkins
authors.forename: Helen
authors.initials: H
authors.lastname: Service
authors.forename: Keerthi
authors.initials: K
authors.lastname: Thamotharampillai
authors.forename: Jason
authors.initials: J
authors.lastname: Watson
authors.forename: Michael
authors.initials: M
authors.lastname: Robinson
authors.forename: Peter
authors.initials: P
authors.lastname: Bye
authors.forename: John
authors.initials: J
authors.lastname: Merlino
authors.forename: Colin
authors.initials: C
authors.lastname: Harbour
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001315:Australia; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D003550:Cystic Fibrosis / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000145:classification* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013183:Sputum / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; C063757:MucA protein, Bacteria