A High-Risk Profile for Invasive Fungal Infections Is Associated with Altered Nasal Microbiota and Niche Determinants

Area of Science:

• Microbiology
• Immunology
• Hematology

Background:

• Microbiota play a crucial role in regulating pathogen-host interactions and infectious disease outcomes.
• Invasive fungal infections (IFIs) are a significant concern for patients with hematological malignancies.

Purpose of the Study:

• To investigate the predictive value of nasal and oropharyngeal microbiota for invasive fungal infection (IFI) risk in patients with hematological malignancies.
• To compare the characteristics of high-risk versus low-risk microbiota at nasal and oropharyngeal sites.

Main Methods:

• A multicenter, prospective, observational study.
• Collection of nasal and oropharyngeal swabs from patients with hematological malignancies.
• Analysis of microbiota composition, tryptophan (Trp) levels, kynurenine production, and interleukin-8 (IL-8) chemokine levels.

Main Results:

• Nasal and oropharyngeal microbiota differ but share characteristics that distinguish high-risk from low-risk samples.
• High-risk nasal samples showed low diversity, loss of beneficial bacteria, and expansion of pathogenic taxa, with reduced Trp.
• Low Trp in nasal samples correlated with defective kynurenine production and reduced IL-8, suggesting impaired host tolerance and fungal clearance.

Conclusions:

• Nasal and oropharyngeal microbiomes provide complementary information for predicting IFI risk in hematological patients.
• Microbiota alterations, particularly in the nose, are associated with increased susceptibility to IFIs.
• Understanding these microbial and host interactions can improve risk stratification and management strategies for IFIs.