Structural and functional alteration of the gut microbiomes in ICU staff: a cross-sectional analysis

16S rRNA sequencing has revealed structural alterations in the gut microbiomes of medical workers, particularly those working in intensive care unit (ICU). This study aims to further compare the taxonomic and functional characteristics of gut microbiomes between ICU staff and non-medical individuals using metagenomic sequencing. A prospective cross-sectional cohort study was conducted, fecal samples from 39 individuals in each group—ICU staff and non-medical subjects were analyzed using metagenomic sequencing. PERMANOVA (using the adonis function) was employed to analyze the genus-level profiles and assess the impact of individual parameters on the gut microbiome. Multiple databases were utilized to annotate and compare the functional differences in gut microbiomes between the two groups. We observed that ICU staff exhibited a significant decrease in gut microbiome diversity, characterized by a marked decline in Actinobacteria and a substantial increase in Bacteroides and Bacteroidaceae. CAZy annotation revealed a notable increase in carbohydrate-active enzymes within the ICU staff cohort. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis further indicated an elevated risk of endocrine and metabolic disorders, along with enhanced glycan biosynthesis and metabolism. Additionally, KEGG pathway enrichment analysis highlighted significant enrichment in cancer-related pathways. Analysis using the Virulence Factor Database (VFDB) showed a higher abundance of virulence factors associated with immune modulation, invasion, and antimicrobial activity/competitive advantage among ICU staff. Notably, no discernible difference in the presence of antibiotic resistance genes within the gut microbiomes was observed between the two groups. Importantly, all aforementioned differences demonstrated clear gender disparities. Our findings indicated that ICU staff exhibited a reduction in gut microbiome diversity which was associated with an increase in virulence factors and carbohydrate-active enzymes, as well as with a heightened susceptibility to endocrine and metabolic diseases and cancers.