Cytotoxicity and inflammatory potential of two Pseudomonas mosselii strains isolated from clinical samples of hospitalized patients

Background: The genus Pseudomonas includes a heterogeneous set of microorganisms that can be isolated from many different niches and nearly 100 different strains have been described. The best characterized bacterium is Pseudomonas aeruginosa which is the primary agent of opportunistic infection in humans, causing both acute and chronic infections. Other species like fluorescens, putida or mosselii have been sporadically isolated from hospitalized patients but their association with the pathology often remains unclear. Results: This study focuses on the cytotoxicity and inflammatory potential of two strains of Pseudomonas mosselii (ATCC BAA-99 and MFY161) that were recently isolated from clinical samples of hospitalized patients. The behavior of these bacteria was compared to that of the well-known opportunistic pathogen P. aeruginosa PAO1. We found that P. mosselii ATCC BAA-99 and MFY161 are cytotoxic towards Caco-2/TC7 cells, have low invasive capacity, induce secretion of human beta-defensin 2 (HBD-2), alter the epithelial permeability of differentiated cells and damage the F-actin cytoskeleton. Conclusions: These data bring new insights into P. mosselii virulence, since this bacterium has often been neglected due to its rare occurrence in hospital.