Nasal microbiota dysbiosis and functional alterations in children with adenoid hypertrophy: potential biomarkers and post-surgical microbial recovery.

Nasal cavity and nasopharynx are habitats for both pathogenic and non-pathogenic bacteria. Adenoid hypertrophy (AH) is the main cause in children, with a high incidence, for the airflow reduction in the upper airways. However, limited research described the differences of nasal microbial compositions in AH patients and healthy children. To determine the association between nasal microbiota and AH, total DNAs were collected and extracted from the nasal cavity and the hypertrophic adenoid of the donors, and the 16S rRNA gene V3-V4 region was sequenced. Microbial diversity was compared between the healthy and AH groups, and the enriched functional pathways were predicted. Although the alpha-diversity of microbial communities did not show statistically significant differences between the groups, principal coordinate analysis (PCoA) revealed that the microbiota component in the nasal cavity as well as in the hypertrophic adenoid tissues of children with AH was significantly different from that of healthy children. Genera Alloiococcus, Moraxella, Streptococcus, and Bacteroides were specifically enriched in the AH group's samples, among which Moraxella spp. was significantly enriched in both nasal cavity and adenoid tissues, indicating a potential association of it with AH. In addition, Tax4fun prediction revealed disordered microbial functions in AH children. Nutrient metabolism, signaling system, chemotactic reaction, genetic replication, and reproduction-related pathways significantly decreased in the AH group but increased after adenoidectomy treatment. This study revealed a high association between specific microorganisms and AH disease. Future work is needed to investigate the role of Moraxella spp. in AH development. KEY POINTS: • Microbiota in the nasal cavity has high specificity in distinguishing patients with adenoidal hypertrophy from healthy individuals, indicating that the homeostasis of microbiota in the nasal cavity is highly associated with the healthy status of adenoid. • Several bacterial taxa, including Alloiococcus, Moraxella, Streptococcus, and Bacteroides, are bio-markers for adenoidal hypertrophy, which enriches specifically in both nasal cavities and hypertrophied adenoid tissues of patients. • In the nasal cavity of patients with adenoidal hypertrophy, microbial functions related to pathogenicity were enriched, indicating an association between adenoidal hypertrophy and disorder of microbiota in the nasal cavity.