Metagenomic analysis for evaluating gut microbiome alterations in cardiac surgery-associated acute kidney injury

Cardiac surgery-associated acute kidney injury (CSA_AKI) is linked to increased morbidity and mortality in intensive care unit (ICU) patients. Emerging evidence indicates a bidirectional interaction between CSA_AKI and gut microbiota dysbiosis. This exploratory study aimed to further investigate the potential relationships between CSA_AKI and alterations in the gut microbiota during disease progression. A cohort of patients undergoing cardiac surgery was enrolled. Based on AKI diagnosis and prognosis, faecal samples were categorised into Non_AKI, CSA_AKI and Recovered_AKI groups. The taxonomic composition and functional pathways of the gut microbiota were profiled through shotgun metagenomic sequencing. The Shannon index and Bray–Curtis dissimilarity were calculated for α- and β-diversity assessment, respectively. Differentially abundant taxa and pathways were identified using linear discriminant analysis effect size and two-tailed Welch’s t -tests. Of the 39 patients, 19 (48.7%) developed AKI. Abundance profiling revealed Bacteroides, Prevotella and Escherichia as the predominant genera across the groups, and a shift from strict anaerobes to facultative anaerobes was observed during CSA_AKI treatment. Pathway diversity was higher in the Recovered_AKI group than in the other groups. At the genus level, Sellimonas was enriched in the Non_AKI group, Campylobacter and Streptococcus in the CSA_AKI group and Flavonifractor in the Recovered_AKI group. Correlation analyses suggested that changes in functional pathways were associated with these differentially abundant genera. CSA_AKI is accompanied by significant alterations in gut microbiota composition, and treatment does not restore the microbial community to a pre-AKI state. This exploratory investigation highlights potential gut microbiota biomarkers linked to CSA_AKI onset and progression, offering novel insights into its pathogenesis.