Chronic infection phenotypes of Pseudomonas aeruginosa are associated with failure of eradication in children with cystic fibrosis
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Early eradication treatment with inhaled tobramycin is successful in the majority of children with cystic fibrosis (CF) with incident Pseudomonas aeruginosa infection. However, in 10–40 % of cases, eradication fails and the reasons for this are poorly understood. The purpose of this study was to determine whether specific microbial characteristics could explain eradication treatment failure. This was a cross-sectional study of CF patients (aged 0–18 years) with incident P. aeruginosa infection from 2011 to 2014 at the Hospital for Sick Children, Toronto, Canada. Phenotypic assays were done on all incident P. aeruginosa isolates, and eradicated and persistent isolates were compared using the Mann–Whitney test or the two-sided Chi-square test. A total of 46 children with CF had 51 incident P. aeruginosa infections. In 72 % (33/46) of the patients, eradication treatment was successful, while 28 % failed eradication therapy. Persistent isolates were less likely to be motile, with significantly less twitch motility (p = 0.001), were more likely to be mucoid (p = 0.002), and more likely to have a tobramycin minimum inhibitory concentration (MIC) ≥ 128 μg/mL (p = 0.02) compared to eradicated isolates. Although biofilm production was similar, there was a trend towards more persistent isolates with deletions in quorum-sensing genes compared with eradicated isolates (p = 0.06). Initial acquisition of P. aeruginosa with characteristics of chronic infection is associated with failure of eradication treatment.
KeywordsCystic Fibrosis Tobramycin Cystic Fibrosis Patient Eradication Rate Protease Production
This work was supported by the US Cystic Fibrosis Foundation, Canadian Foundation for Infectious Diseases, and The Lung Association of Ontario. Part of this work was presented at the North American Cystic Fibrosis Conference in Atlanta, Georgia, October 2014.
Conflict of interest
None of the authors declare a conflict of interest.
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