Gut microbiota features associated with clinical consciousness trajectories in neurosurgical ICU patients

Background Recovery of consciousness after neurosurgery varies substantially among critically ill patients. Whether gut microbiota features are associated with these clinical trajectories remains unclear. Methods We performed a longitudinal observational analysis of postoperative neurosurgical intensive care unit (ICU) patients. Rectal swabs collected on ICU Days 1, 3, 7, and 14 underwent 16S ribosomal RNA gene sequencing. Patients were classified as having preserved consciousness (P1), GCS score improvement (P2), or persistent impaired consciousness (P3) based on changes between the lowest eligible and ICU endpoint GCS component scores. Microbial diversity, community composition, and differentially abundant genera were evaluated. MaAsLin3 mixed-effects models adjusted for age, sex, body mass index, and antibiotic duration, with patient identifier included as a random effect to account for repeated measurements. Results The analysis included 39 patients and 118 rectal swabs. P3 showed lower Shannon diversity and Pielou’s evenness and higher Simpson index values. Community composition differed modestly among groups despite substantial overlap (permutational multivariate analysis of variance [PERMANOVA], R 2 = 0.03575; p = 0.002). Enterococcus was more abundant in P3, whereas Ruminococcus and Romboutsia were more abundant in P2. These group-associated genera remained consistent in multivariable MaAsLin3 mixed-effects models after adjustment for covariates and repeated measurements. Conclusion Clinical consciousness trajectories were associated with differences in gut microbial evenness and selected genera. These exploratory findings require validation in larger cohorts.