Adhesion to and biofilm formation on IB3-1 bronchial cells by Stenotrophomonas maltophilia isolates from cystic fibrosis patients

Abstract

BackgroundStenotrophomonas maltophilia has recently gained considerable attention as an important emerging pathogen in cystic fibrosis (CF) patients. However, the role of this microorganism in the pathophysiology of CF lung disease remains largely unexplored. In the present study for the first time we assessed the ability of S. maltophilia CF isolates to adhere to and form biofilm in experimental infection experiments using the CF-derived bronchial epithelial IB3-1cell line. The role of flagella on the adhesiveness of S. maltophilia to IB3-1 cell monolayers was also assessed by using fliI mutant derivative strains.ResultsAll S. maltophilia CF isolates tested in the present study were able, although at different levels, to adhere to and form biofilm on IB3-1 cell monolayers. Scanning electron and confocal microscopy revealed S. maltophilia structures typical of biofilm formation on bronchial IB3-1 cells. The loss of flagella significantly (P < 0.001) decreased bacterial adhesiveness, if compared to that of their parental flagellated strains. S. maltophilia CF isolates were also able to invade IB3-1 cells, albeit at a very low level (internalization rate ranged from 0.01 to 4.94%). Pre-exposure of IB3-1 cells to P. aeruginosa PAO1 significantly increased S. maltophilia adhesiveness. Further, the presence of S. maltophilia negatively influenced P. aeruginosa PAO1 adhesiveness.ConclusionsThe main contribution of the present study is the finding that S. maltophilia is able to form biofilm on and invade CF-derived IB3-1 bronchial epithelial cells, thus posing a rationale for the persistence and the systemic spread of this opportunistic pathogen in CF patients. Experiments using in vivo models which more closely mimic CF pulmonary tissues will certainly be needed to validate the relevance of our results.

A Polysaccharide Lyase from Stenotrophomonas maltophilia with a Unique, pH-regulated Substrate Specificity

“…S. maltophilia is an emerging, multidrug-resistant organism often associated with chronic lung infections, especially in cystic fibrosis patients. Of particular note, the prevalence of biofilm-producing S. maltophilia strains isolated from the lungs of cystic fibrosis patients and from contaminated medical equipment has implicated biofilm formation as a mechanism contributing to S. maltophilia infection and multidrug resistance (18). We find that Smlt1473 is secreted when overexpressed in Escherichia coli, and secretion depends on a predicted lipoprotein secretion signal sequence.…”

Type II Secretion-Dependent Degradative and Cytotoxic Activities Mediated by Stenotrophomonas maltophilia Serine Proteases StmPr1 and StmPr2

“…Mutants of strain K279a were constructed using the gene replacement vector pEX18Tc as described previously (21,24,25). A mutant (NUS5) with a deletion of the entire stmPr1 coding region (SMLT_RS03270) was obtained using PCR overlap extension protocol as previously described (26).…”

Stenotrophomonas maltophilia: an Emerging Global Opportunistic Pathogen

“…maltophilia can form biofilms on lung cells (73,83,268). Confocal microscopy of biofilms formed by CF isolate S. maltophilia OBGTC9 on CF sputum-derived bronchial epithelial IB3-1 cell monolayers revealed that S. maltophilia formed microcolonies embedded in a matrix (268).…”

“…A significant feature of S. maltophilia is its ability to form biofilms on surfaces including Teflon, glass, and plastics and on host tissues (83,84,166,268). Biofilms have been estimated to be associated with 65% of hospital-acquired infections (270).…”