Exposure to endocrine disruptors promotes biofilm formation and contributes to increased virulence of Pseudomonas aeruginosa.

Anthropogenic activities contribute to the spread of chemicals considered as endocrine disruptors (ED) in freshwater ecosystems. While several studies have reported interactions of EDs with organisms in those ecosystems, very few have assessed the effect of these compounds on pathogenic bacteria. Here we have evaluated the impact of five EDs found in aquatic resources on the virulence of human pathogen P. aeruginosa. ED concentrations in French aquatic resources of bisphenol A (BPA), dibutyl phthalate (DBP), ethylparaben (EP), methylparaben (MP) and triclosan (TCS) at mean molar concentration were 1.13, 3.58, 0.53, 0.69, and 0.81 nM respectively. No impact on bacterial growth was observed at EDs highest tested concentration. Swimming motility of P. aeruginosa decreased to 28.4% when exposed to EP at 100 μM. Swarming motility increased, with MP at 1 nM, 10 and 100 μM (1.5-fold); conversely, a decrease of 78.5%, with DBP at 100 μM was observed. Furthermore, exposure to 1 nM BPA, DBP and EP increased biofilm formation. P. aeruginosa adhesion to lung cells was two-fold higher upon exposure to 1 nM EP. We demonstrate that ED exposure may simultaneously decrease mobility and increase cell adhesion and biofilm formation, which may promote colonisation and establishment of the pathogen.