Interactions of With Species Frequently Associated With Cystic Fibrosis.

Members of the species complex are the second most frequently isolated pathogens after from cystic fibrosis (CF) patients with fungal pulmonary infections. Even so, the main risk factors for the infection are unrevealed. According to previous studies, bacterial infections might reduce the risk of a fungal infection, but an antibacterial therapy may contribute to the airway colonization by several fungal pathogens. Furthermore, corticosteroids, which are often used to reduce lung inflammation in children and adults with CF, are also proved to enhance the growth of . Considering all the above discussed points, we aimed to test how influences the growth of scedosporia and to investigate the potential effect of commonly applied antibacterial agents and corticosteroids on species. Direct interactions between fungal and bacterial strains were tested using the disk inhibition method. Indirect interactions via volatile compounds were investigated by the plate-in-plate method, while the effect of bacterial media-soluble molecules was tested using a modified cellophane assay and also in liquid culture media conditioned by . To test the effect of bacterial signal molecules, antibacterial agents and corticosteroids on the fungal growth, the broth microdilution method was used. We also investigated the germination ability of conidia in the presence of pyocyanin and diffusible signal factor by microscopy. According to our results, either inhibited or enhanced the growth of scedosporia depending on the culture conditions and the mode of interactions. When the two pathogens were cultured physically separately from each other in the plate-in-plate tests, the presence of the bacteria was able to stimulate the growth of several fungal isolates. While in direct physical contact, bacterial strains inhibited the fungal growth. This effect might be attributed to bacterial signal molecules, which also proved to inhibit the germination and growth of scedosporia. In addition, antibacterial agents showed growth-promoting, while corticosteroids exhibited growth inhibitory effect on several isolates. These data raise the possibility that a infection or a previously administered antibacterial therapy might be able to increase the chance of a colonization in a CF lung.