Homa Mónika, Sándor Alexandra, Tóth Eszter, Szebenyi Csilla, Nagy Gábor, Vágvölgyi Csaba, Papp Tamás
MTA-SZTE "Lendület" Fungal Pathogenicity Mechanisms Research Group, Szeged, Hungary.
Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
Front Microbiol. 2019 Mar 6;10:441. doi: 10.3389/fmicb.2019.00441. eCollection 2019.
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.
该菌种复合体的成员是囊性纤维化（CF）合并肺部真菌感染患者中分离出的第二常见病原体。即便如此，该感染的主要风险因素仍未明确。根据以往研究，细菌感染可能会降低真菌感染的风险，但抗菌治疗可能会促使几种真菌病原体在气道定植。此外，常用于减轻CF儿童和成人肺部炎症的皮质类固醇，也被证明会促进该菌种的生长。考虑到上述所有要点，我们旨在测试该菌如何影响拟青霉的生长，并研究常用抗菌剂和皮质类固醇对该菌种的潜在影响。使用纸片扩散法测试真菌和细菌菌株之间的直接相互作用。通过平板套平板法研究挥发性化合物介导的间接相互作用，同时使用改良的玻璃纸试验以及在该菌条件培养的液体培养基中测试细菌培养基可溶性分子的作用。为了测试细菌信号分子、抗菌剂和皮质类固醇对真菌生长的影响，采用了肉汤微量稀释法。我们还通过显微镜观察了绿脓菌素和可扩散信号因子存在下该菌分生孢子的萌发能力。根据我们的结果，该菌根据培养条件和相互作用方式，要么抑制要么促进拟青霉的生长。在平板套平板试验中，当两种病原体在物理上彼此分开培养时，细菌的存在能够刺激几种真菌分离株的生长。而在直接物理接触时，细菌菌株抑制真菌生长。这种效应可能归因于细菌信号分子，其也被证明会抑制拟青霉的萌发和生长。此外，抗菌剂对几种该菌分离株表现出促生长作用，而皮质类固醇则表现出生长抑制作用。这些数据增加了这样一种可能性，即该菌感染或先前进行过的抗菌治疗可能会增加CF肺部该菌定植的几率。
