Bacterial colonization and sepsis are strongly associated with compositional and functional shifts in the gut microbiota, with early microbial signatures such as Finegoldia sp. enrichment in colonized non-septic patients potentially representing early markers of microbial destabilization and sepsis risk.
Key Findings
Results
At baseline, colonized patients exhibited significantly reduced alpha diversity compared to non-colonized individuals, particularly those harboring Gram-positive taxa.
132 hospitalized patients were enrolled in the SURVEIL study with longitudinal gut microbiota profiling
Rectal swabs were collected at three time points: baseline, sepsis onset, and discharge
Bacterial colonization status was determined through culture-based methods
Microbiota composition was assessed via 16S rDNA sequencing
The reduction in alpha diversity was most pronounced in patients colonized by Gram-positive taxa
Results
Sepsis was associated with profound dysbiosis characterized by enrichment in opportunistic genera including Finegoldia sp., Anaerococcus sp., and Parabacteroides sp., along with reduced microbial diversity.
Differential abundance analyses were performed using LEfSe (Linear discriminant analysis Effect Size)
Enrichment of opportunistic anaerobic genera was a consistent feature of the septic microbiota profile
Both compositional and functional shifts were documented in association with sepsis onset
Results
Aging independently modulated both alpha diversity and beta diversity patterns in hospitalized patients.
Age was integrated as a clinical metadata variable alongside sepsis status in analyses
Age effects on microbiota diversity were documented independently of colonization and sepsis status
Both diversity indices and beta diversity patterns were affected by aging
The study integrated clinical metadata including age and sepsis status with microbiota data
Results
Functional predictions revealed enhanced representation of anaerobic metabolism, nitrogen/sulfur cycling, and host-adaptive traits in colonized states.
Functional profiles were derived from taxonomic composition data via predictive functional profiling
Functional differences were observed between colonized and non-colonized patient microbiota
Anaerobic metabolic pathways were among the enhanced functional categories in colonized patients
Nitrogen and sulfur cycling pathways were also enriched in colonized states
Host-adaptive traits showed enhanced representation in colonized versus non-colonized microbiota
Results
MDR strains partially overlapped with bloodstream pathogens in septic patients, suggesting a possible link between intestinal colonization and bloodstream infection.
MDR (multidrug-resistant organism) strains were identified through culture-based methods from rectal swabs
Overlap between intestinal MDR colonizers and bloodstream pathogens was observed in septic patients
The authors note this finding 'warrants mechanistic validation' and is described as a partial overlap
MDR carriage was identified as a factor that further shapes microbiota dynamics
The possible translocation pathway from gut colonization to bloodstream infection was not mechanistically confirmed in this study
Results
Finegoldia sp. enrichment in colonized non-septic patients may represent an early marker of microbial destabilization and sepsis risk.
Finegoldia sp. was identified as enriched in colonized patients who had not yet developed sepsis
This finding was identified through LEfSe differential abundance analysis
The authors characterize this as a potential 'early microbial signature' preceding sepsis onset
This suggests pre-septic microbial changes may be detectable before clinical sepsis manifests
Finegoldia sp. also appeared among the opportunistic genera enriched at sepsis onset
Methods
The study employed a longitudinal design with three serial rectal swab collection time points to track microbiota dynamics across the clinical course of sepsis.
Samples were collected at baseline (admission), sepsis onset, and discharge
132 hospitalized patients were enrolled in the SURVEIL project
Both culture-based methods and 16S rDNA sequencing were used in parallel for comprehensive characterization
Diversity indices, taxonomic profiles, functional profiles, and differential abundance analyses were all integrated with clinical metadata
What This Means
This research examined how the community of bacteria living in the gut (the gut microbiota) changes in hospitalized patients who develop sepsis, a life-threatening response to infection. The researchers followed 132 patients over the course of their hospital stay, collecting samples from the gut at admission, at the time of sepsis diagnosis, and at discharge. They used both traditional bacterial culture techniques and modern DNA sequencing to identify which bacteria were present and how diverse the bacterial communities were.
The study found that patients whose guts were already colonized by bacteria—especially certain types called Gram-positive bacteria—had less diverse gut microbiota even before sepsis developed. When patients did develop sepsis, the gut microbiota became even more disrupted, with a takeover by opportunistic bacteria like Finegoldia, Anaerococcus, and Parabacteroides that are not normally dominant. Importantly, some of these opportunistic bacteria were detected in the gut even before sepsis occurred, suggesting these early microbial changes might serve as warning signs of who is at higher risk of developing sepsis. The researchers also observed that drug-resistant bacteria found in the gut sometimes matched bacteria found in the bloodstream of septic patients, hinting that the gut may be a source of bloodstream infections, though this connection needs further study.
This research suggests that monitoring the gut microbiota of hospitalized patients could potentially help identify those at greatest risk of developing sepsis before it fully sets in. The findings also indicate that age and carriage of drug-resistant organisms further alter gut microbiota composition, adding complexity to sepsis risk. While the study is observational and does not prove cause and effect, it points to the gut microbiome as an important factor in sepsis development and potentially a target for early intervention strategies.
Bazzano C, Caramaschi A, Massa N, Collani S, Mellai M, Barizzone N, et al.. (2026). Gut Microbiota as a Key Modulator in the Pathophysiology of Sepsis: SURVEIL Project.. MicrobiologyOpen. https://doi.org/10.1002/mbo3.70301