Host tracheal and intestinal microbiomes inhibit growth .

Coccidioidomycosis, also known as Valley fever, is a disease caused by the fungal pathogen . Unfortunately, patients are often misdiagnosed with bacterial pneumonia leading to inappropriate antibiotic treatment. Soil bacteria -like species exhibits antagonistic properties against ; however, the antagonistic capabilities of host microbiota against are unexplored. We sought to examine the potential of the tracheal and intestinal microbiomes to inhibit the growth of . We hypothesized that an uninterrupted lawn of microbiota obtained from antibiotic-free mice would inhibit the growth of while partial depletion through antibiotic disk diffusion assays would allow a niche for fungal growth. We observed that the microbiota grown on 2xGYE (GYE) and CNA w/ 5% sheep's blood agar (5%SB-CNA) inhibited the growth of , but that grown on chocolate agar does not. Partial depletion of the microbiota through antibiotic disk diffusion revealed that microbiota depletion leads to diminished inhibition and comparable growth of growth to controls. To characterize the bacteria grown and narrow down potential candidates contributing to the inhibition of , 16s rRNA sequencing of tracheal and intestinal agar cultures and murine lung extracts was performed. The identity of host bacteria that may be responsible for this inhibition was revealed. The results of this study demonstrate the potential of the host microbiota to inhibit the growth of and suggest that an altered microbiome through antibiotic treatment could negatively impact effective fungal clearance and allow a niche for fungal growth .