Fungal growth inhibition by host microbiome and manipulation of fungal immunity

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Presentation Time: 03:15 PM - 04:30 PM
Poster Board Number: B700
Abstract ID: 5895

Presenting Author:
Katrina K Hoyer , Associate Professor at Univ. of California, Merced, Lawrence Livermore Natl. Lab.

Abstract:

Coccidioidomycosis, or Valley fever, is caused by the fungal pathogen Coccidioides. Patients are often misdiagnosed with bacterial pneumonia leading to inappropriate antibiotic treatment. However, the antagonistic capabilities of host microbiota against Coccidioides are unexplored and antibiotic use alters host immune responses. We examined the potential for tracheal and intestinal microbiomes to inhibit Coccidioides growth in vitro, and to define and manipulate immune responses during infection. We observed that microbiota grown on 2xGYE and CNA with 5% sheep’s blood agar inhibits Coccidioides growth, while commensals grown on chocolate agar do not block Coccidioides. Partial depletion of microbiota through antibiotic disk diffusion reveals diminished inhibition of Coccidioides growth. To identify potential candidates contributing to Coccidioides inhibition we performed 16s rRNA sequencing of tracheal and intestinal agar cultures and murine lung extracts. Host bacterial candidates responsible for Coccidioides inhibition were identified and evaluated for their individual inhibition mechanisms. Innate and adaptive immune changes were evaluated during antibiotic treatment with fungal infection. This study demonstrates the potential of host respiratory tract microbiota to inhibit Coccidioides growth in vitro and suggests that an altered microbiome through antibiotic treatment could negatively impact effective fungal clearance and allow a niche for fungal growth in vivo.