Integrative profiling of oral fungal communities across Mycobacterium Tuberculosis burden groups in Xpert-positive patients.

Abstract

Background: Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a major global health burden. A growing body of evidence suggests that mucosal microbial communities may reflect or modulate host responses during infection. However, the oral microbiome in TB patients with different bacterial loads remains poorly characterized. This study aimed to investigate alterations in oral fungal communities among Xpert-positive patients, stratified by Mtb burden based on Xpert MTB/RIF testing.

Methods: In this prospective multicenter cohort study (May-August 2024), 278 Xpert-positive TB patients were enrolled across five hospitals in China. Participants were stratified into high, medium, low, and very low Mtb burden groups according to Xpert MTB/RIF cycle threshold values. Paired sputum and tongue swab samples were collected. Oral fungal profiles were characterized via ITS sequencing, followed by taxonomic assignment, diversity analysis, and multivariable association testing (MaAsLin 2) to identify robust biomarkers.

Results: Oral fungal community structure varied significantly across Mtb burden strata. Beta-diversity analysis revealed distinct clustering between the very low burden group and higher burden groups (high, medium, low). High-burden patients were enriched with environmental taxa such as Blumeria and Toxicocladosporium, whereas low-burden groups exhibited higher abundances of Candida, Aspergillus, and Penicillium. Notably, MaAsLin 2 analysis confirmed that Penicillium and Podosphaera were independently associated with lower Mtb burden after adjusting for confounders. Neutral model analysis indicated that stochastic processes predominantly drive the assembly of these oral fungal communities. Functional prediction suggested enhanced aerobic respiration and metabolic enzyme activity in high-burden groups.

Conclusions: This study analyzed the oral fungal microbiome stratified by Mtb burden strata in Xpert-positive patients, revealing distinct shifts in fungal composition and functional potential. Fungal dysbiosis and altered microbial metabolic capacity may offer insight into host-microbe interactions in pulmonary TB (PTB). These findings underscore the potential value of fungal microbiome profiling for assessing Mtb burden, beyond its application in TB diagnosis alone.