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Open Access Highly Accessed Research article

Phenotypic and genotypic characterization of Stenotrophomonas maltophilia isolates from patients with cystic fibrosis: Genome diversity, biofilm formation, and virulence

Arianna Pompilio12, Stefano Pomponio12, Valentina Crocetta12, Giovanni Gherardi3, Fabio Verginelli4, Ersilia Fiscarelli5, Giordano Dicuonzo3, Vincenzo Savini6, Domenico D'Antonio6 and Giovanni Di Bonaventura12*

Author Affiliations

1 Center of Excellence on Aging, "G. d'Annunzio" University Foundation, Via Colle dell'Ara, Chieti, 66100, Italy

2 Department of Biomedical Sciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti, 66100, Italy

3 Center for Integrated Research, "Campus Biomedico" University, Via Alvaro del Portillo 21, Rome, 00128, Italy

4 Department of Oncology and Neurosciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, Chieti, 66100, Italy

5 "Bambino Gesù" Children's Hospital and Research In stitute, P.zza Sant'Onofrio 4, Rome, 00165, Italy

6 Department of Transfusional Medicine, "Spirito Santo" Hospital, Via Fonte Romana, Pescara, 65100, Italy

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BMC Microbiology 2011, 11:159  doi:10.1186/1471-2180-11-159

Published: 5 July 2011

Abstract

Background

Stenotrophomonas maltophilia is emerging as one of the most frequently found bacteria in cystic fibrosis (CF) patients. In the present study, phenotypic and genotypic traits of a set of 98 isolates of S. maltophilia obtained from clinical (CF and non-CF patients) and environmental sources were comparatively evaluated.

Results

S. maltophilia exhibited a high level of genomic diversity in both CF and non-CF group, thus possibly allowing this bacterium to expand its pathogenic potentials. Strains sharing the same pulsotype infected different patients, thus likely indicating the occurrence of clonal spread or acquisition by a common source. CF isolates differed greatly in some phenotypic traits among each other and also when compared with non-CF isolates, demonstrating increased mean generation time and susceptibility to oxidative stress, but reduced ability in forming biofilm. Furthermore, in CF isolates flagella- and type IV pili-based motilities were critical for biofilm development, although not required for its initiation. Sequential isogenic strains isolated from the same CF patient displayed heterogeneity in biofilm and other phenotypic traits during the course of chronic infection. CF and non-CF isolates showed comparable virulence in a mouse model of lung infection.

Conclusions

Overall, the phenotypic differences observed between CF and non-CF isolates may imply different selective conditions and persistence (adaptation) mechanisms in a hostile and heterogeneous environment such as CF lung. Molecular elucidation of these mechanisms will be essential to better understand the selective adaptation in CF airways in order to design improved strategies useful to counteract and eradicate S. maltophilia infection.