METHODOLOGY: Motility, gentamicin susceptibility and growth rates were assessed in four strains coming from three CF patients. The strains were subjected to whole genome sequencing with the Illumina MiSeq platform.Conjugation assays using the mini Tn7 transposon were performed in order to tag bacteria with the fluorescent proteins YFP (yellow) and CFP (cyan). Biofilm experiments were carried out in a flow cell system and images were acquired using a confocal laser microscope (CLSM) on days 3 and 5. Four experiments were performed: Experiment 1 with two clonal isolates from sinus and lungs from patient P01 (CF430-142, CF430-11621)
experiments 2 (CF430-11621 + 75885-B) and 3 (CF430-11621 + 80271-B) with two lung isolates belonging to two different clones from different patients (P02, P03) and experiment 4 with one lung strain (CF430-11621) and CONCLUSION: Mixed biofilms were only observed when identical clones from the same patient were cultured together. Our experiments indicate that twitching motility does not significantly affect biofilm formation or architecture in our isolates.