Sequential genotyping ofPseudomonas aeruginosafrom upper and lower airways of cystic fibrosis patients

Abstract

A controversy exists concerning the adequate specimen to characterise colonisation of cystic fibrosis (CF) airways by Pseudomonas aeruginosa. Oropharyngeal, sputum and bronchoalveolar lavage samples were evaluated from 38 stable CF patients for the detection of P. aeruginosa, genetically different isolates within the same host and longitudinal variations in the genotype during repeated examinations.Bacterial isolates were typed by pulsed-field gel electrophoresis of deoxyribonucleic acid macrorestriction fragments.Sensitivity, negative and positive predictive values and specificity to detect P. aeruginosa were 35.7, 73.5, 83.3 and 96.2% for oropharyngeal cultures in nonexpectorating patients and 91.7, 94.1, 100 and 100% for sputum cultures from expectorating patients, respectively. Genotypes of Pseudomonas isolates recovered from oropharyngeal swabs and sputum differed to the strains recovered by bronchoscopy in 55% and 40%, respectively. In 62% longitudinal variations in the genotype occurred. One-half of these alterations were detectable by bronchoscopy only.In conclusion, sputum samples were of equal value as specimens from bronchoalveolar lavage to detect Pseudomonas aeruginosa colonisation. Cultures from the oropharynx are not suitable for characterising bacterial conditions in the cystic fibrosis lung. Different genotypes within the same host and longitudinal genetic alterations are common and may be detectable in the bronchoalveolar lavage fluid exclusively.

Turnover of strains and intraclonal variation amongst Pseudomonas aeruginosa isolates from paediatric CF patients

“…This is consistent with several previous longitudinal studies of CF patients (Burns et al, 2001;Ener et al, 2001;Fegan et al, 1991;Jelsbak et al, 2007;Jung et al, 2002;Mahenthiralingam et al, 1996). A previous study using the AT system to genotype multiple isolates of P. aeruginosa from CF patients also reported evidence of strain replacement, the failure of some strains to establish infection, and genetic variations amongst isolates of the same AT genotype (Jelsbak et al, 2007).…”

Comparison of Three Molecular Techniques for Typing Pseudomonas aeruginosa Isolates in Sputum Samples from Patients with Cystic Fibrosis

“…Several other studies also have reported temporal variation in CF P. aeruginosa isolate PFGE band patterns (22,32,38) and point to evidence of within-host evolution. In contrast, MLST, as shown here and elsewhere (43), reveals evidence of long-term stability.…”

Determining Cystic Fibrosis-Affected Lung Microbiology: Comparison of Spontaneous and Serially Induced Sputum Samples by Use of Terminal Restriction Fragment Length Polymorphism Profiling

“…By far the most widely used sample in productive patients is spontaneously expectorated sputum (SES). SES samples have been shown to have high concordance with bronchoalveolar lavage samples in microbial terms (17), with the impact of contamination during the process of expectoration being minimal (31). Further, the use of SES samples has significant advantages in that they can be collected with a short notice period and with high frequency.…”