Abstract
Chronic airway infections caused by Pseudomonas aeruginosa contribute to the progression of pulmonary disease in individuals with cystic fibrosis (CF). In the setting of CF, within-patient adaptation of a P. aeruginosa strain generates phenotypic diversity that can complicate microbiological analysis of patient samples. We investigated within- and between- sample diversity of 34 phenotypes among 235 P. aeruginosa isolates cultured from sputum samples collected from a single CF patient over the span of one year, and assessed colony morphology as a screening tool for predicting phenotypes, including antimicrobial susceptibilities. We identified 15 distinct colony morphotypes that varied significantly in abundance both within and between sputum samples. Substantial within sample phenotypic heterogeneity was also noted in other phenotypes, with morphotypes being unreliable predictors of antimicrobial susceptibility and other phenotypes. Emergence of isolates with reduced susceptibility to β-lactams was observed during periods of clinical therapy with aztreonam. Our findings confirm that the P. aeruginosa population in chronic CF lung infections is highly dynamic, and that intra-sample phenotypic diversity is underestimated if only one or few colonies are analyzed per sample.
Highlights
Ancestral strains[5,8,9,10,11,12,13]
Twelve sputum samples were collected over a 350-day period from patient CF67, a 34 year old female (Δ F508/ CFTRdele[2,3] genotype) with advanced lung disease (average forced expiratory volume in 1 second (FEV1) of 21% predicted; range: 15 to 25%)
Phenotypic analyses were performed on 235 isolates which passed quality control, all of which were of the same multilocus sequence type (ST), ST-274 (DSG, unpublished data)
Summary
Ancestral strains[5,8,9,10,11,12,13]. These adaptations correlate with increasingly diverse colony morphologies, or morphotypes, that are visible during routine culture of expectorated sputum[12,14,15]. The few studies to date with increased sampling depth have found discordant relationships between morphotype and other phenotypic characteristics when multiple isolates from the same sample are tested, with colonies of the same morphotype often displaying different antimicrobial susceptibility profiles[6,14,24,25,26]. This variability provides evidence to fuel concerns over the reliability of using morphotype-based approaches to predict additional phenotypes of clinical significance in P. aeruginosa isolates from the CF airways. The objectives of the present study were (i) to characterize within-host diversity of morphotypes and adaptive phenotypes in a non-LES or PES strain of P. aeruginosa; (ii) to examine temporal changes in patterns of susceptibility following exposure to antimicrobials, and (iii) to identify relationships between morphotypes and other phenotypic characteristics, antimicrobial susceptibility
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
