Validating a model of mixed biofilm Stenotrophomonas maltophilia / Aspergillus fumigatus

L. Anais, E. Meloul, J. Bonhomme, V. Fihman, J. Guillot, JW Decousser, F. Botterel


Introduction: The bacteria and / or fungi often live in the human body as a biofilm. In these biofilms, the microorganisms synthesize an extracellular matrix (ECM), which protects them from external aggressions.Stenotrophomonas maltophilia (Sm) is a Gram-negative bacterium emerging saprophyte of the environment.Aspergillus fumigatus (Af) is a also saprophytic filamentous fungus of the environment. These two microorganisms coexist such as biofilm, in the respiratory tract or immunocompromised patients with cystic fibrosis.

The purpose of the study was to validate a mixed biofilm Sm / Af by comparing it with a mixed biofilm P.aeruginosa (Pa) / Af.

Methods  : The strain of Af 1373 ATCC used is a modified strain expressing GFP. The bacterial strains are ATCC 13637 strains for Sm and ATCC 27853 to Pa . Fungal cultures and / or bacterial were performed under planktonic form and / or biofilm on polystyrene Labteck® blades. To search for mixed biofilm, the deposit of bacteria on plates was performed before, simultaneously and the deposit mushrooms. The visualization of bacterial biofilms, fungal and mixed and MEC was done by fluorescence microscopy (FM) and scanning electron (SEM). MF different markers were used to visualize GFP strain Af (FITC / filter A488) and bacterial strains (Ac-conjugated anti-LPS fluorochrome alexa 433 (filter Topro3 Cy5)). The MEC étémarquée spoke concanavalin A coupled to rhodamine (TRITC / A546 filter).

Results: Bacterial, fungal and mixed biofilms were visualized MF and ME with highlighted ECM encompassing bacteria and fungal hyphae tangled. The bacteria adhere to hyphae Af before synthesis of MEK and it is a fungicidal action of both bacterial species with more marked Pa that Sm .

Conclusion  : For the first time, a mixed biofilm N - Sm has been evidenced by various analytical methods. The short-term outlook is to determine, before studying more deeply the biofilm structure, if MEC is bacterial and / or fungal.


Full conference title: 

Réunion Interdisciplinaire de Chimiothérapie Anti Infectieuse