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Role of small colony variants in persistence of Pseudomonas aeruginosa infections in cystic fibrosis lungs

Authors Malone J

Received 3 May 2015

Accepted for publication 5 June 2015

Published 29 July 2015 Volume 2015:8 Pages 237—247


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 3

Editor who approved publication: Professor Suresh Antony

Jacob G Malone1,2

John Innes Centre, Norwich, UK; 2School of Biological Sciences, University of East Anglia, Norwich, UK

Abstract: Pseudomonas aeruginosa is an opportunistic pathogen that predominates during the later stages of cystic fibrosis (CF) lung infections. Over many years of chronic lung colonization, P. aeruginosa undergoes extensive adaptation to the lung environment, evolving both toward a persistent, low virulence state and simultaneously diversifying to produce a number of phenotypically distinct morphs. These lung-adapted P. aeruginosa strains include the small colony variants (SCVs), small, autoaggregative isolates that show enhanced biofilm formation, strong attachment to surfaces, and increased production of exopolysaccharides. Their appearance in the sputum of CF patients correlates with increased resistance to antibiotics, poor lung function, and prolonged persistence of infection, increasing their relevance as a subject for clinical investigation. The evolution of SCVs in the CF lung is associated with overproduction of the ubiquitous bacterial signaling molecule cyclic-di-GMP, with increased cyclic-di-GMP levels shown to be responsible for the SCV phenotype in a number of different CF lung isolates. Here, we review the current state of research in clinical P. aeruginosa SCVs. We will discuss the phenotypic characteristics underpinning the SCV morphotype, the clinical implications of lung colonization with SCVs, and the molecular basis and clinical evolution of the SCV phenotype in the CF lung environment.

Keywords: small colony variants, cystic fibrosis, cyclic-di-GMP, Pseudomonas aeruginosa, RsmA, antibiotics

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