After clinical resolution of diarrhea, the gut microbiota and its metabolites remain significantly different from those observed in healthy children, possibly representing an intermediate stage between diarrhea and a healthy condition.
Key Findings
Results
Significant differences in intestinal microbiota community structure were found among the three conditions (acute diarrhea, post-clinical recovery, and healthy children).
Study population consisted of children under five years old with acute diarrhea, with stool samples collected during diarrheal episodes and after clinical recovery
A comparison group of healthy children was included
Community structure (not just individual taxa) differed significantly across all three conditions
The three conditions represented distinct microbial states rather than a simple binary sick/healthy distinction
Results
Recovery-phase stool samples exhibited greater abundance of genera associated with diarrhea, including Escherichia-Shigella, Streptococcus, Veillonella, and Akkermansia.
These genera were more abundant in recovery samples compared to healthy children
Escherichia-Shigella, Streptococcus, Veillonella, and Akkermansia are described as genera associated with diarrhea
Their persistence in the recovery phase suggests microbial dysbiosis continues after clinical symptom resolution
Recovery samples also showed greater abundance of Bifidobacterium, a genus associated with healthy microbiota
Results
Recovery-phase samples showed a mixed microbial profile containing both diarrhea-associated and health-associated genera simultaneously.
Bifidobacterium, a genus associated with healthy microbiota, was also more abundant in recovery samples
The co-occurrence of diarrhea-associated and health-associated genera in recovery samples supports the characterization of recovery as an intermediate microbial state
This mixed profile was not observed in either the acute diarrhea or healthy conditions in the same pattern
Results
Butyrate levels decreased following clinical recovery, reaching values comparable to those found in healthy children.
Butyrate is a short-chain fatty acid (SCFA) measured in stool samples
Butyrate levels were elevated during acute diarrhea and declined after clinical recovery
Post-recovery butyrate levels were comparable to those in healthy children, suggesting this metabolite normalizes faster than the microbiota composition
The study evaluated both histamine and SCFAs as key metabolites of interest
Results
Histamine levels did not differ significantly among the three conditions (acute diarrhea, clinical recovery, and healthy children).
Histamine was measured in stool samples across all three groups
No statistically significant differences in histamine levels were found between diarrhea, recovery, and healthy states
This contrasts with prior literature suggesting increased histamine during diarrheal episodes
The abstract notes that prior studies have documented increased histamine during diarrheal episodes, but this study did not find significant group differences
Discussion
Gut microbiota recovery to a healthy condition may take longer than clinical recovery from diarrhea and does not necessarily coincide with it.
Clinical recovery was used as the marker for the second sampling time point, but microbiota composition remained distinct from healthy children at that time
The persistence of diarrhea-associated genera after symptom resolution indicates a lag between clinical and microbiological recovery
Authors describe the post-recovery state as 'possibly representing an intermediate stage between diarrhea and a healthy condition'
The findings underscore that clinical resolution of symptoms is not equivalent to restoration of a healthy gut microbiome
What This Means
This research studied the gut bacteria and metabolites (chemical byproducts of bacterial activity) in the stool of children under five years old who had acute diarrhea, tracking them during the illness and again after they clinically recovered. The researchers also compared findings to a group of healthy children. The study found that even after children felt better and their diarrhea had resolved, the community of bacteria in their guts looked quite different from that of healthy children — it contained a mix of bacteria typically associated with diarrhea (such as Escherichia-Shigella, Streptococcus, Veillonella, and Akkermansia) alongside bacteria more typical of healthy guts (like Bifidobacterium). This suggests the gut is in a transitional, intermediate state after illness rather than having returned to normal.
For metabolites, the picture was more nuanced. Butyrate — a beneficial short-chain fatty acid produced by gut bacteria — was elevated during diarrhea but returned to levels similar to healthy children after clinical recovery, suggesting this particular marker normalizes relatively quickly. Histamine levels, however, did not differ significantly between any of the three groups. These findings indicate that different aspects of gut health recover at different rates after diarrhea.
This research suggests that the time it takes for the gut microbiome to fully recover from a diarrheal illness in young children may be longer than the time it takes for symptoms to disappear. This has potential implications for understanding repeated or prolonged gut health issues in young children, particularly in settings where diarrheal disease is common, and may raise questions about whether additional support during the recovery period could help restore a healthy gut microbial community more quickly.
Melipil-Millán D, Izquierdo M, Ovalle R, Espinoza-Cavieres F, Gallardo P, Valenzuela R, et al.. (2026). Dynamics of the gut microbiome and metabolome in children during and after an infectious diarrheal episode.. Frontiers in cellular and infection microbiology. https://doi.org/10.3389/fcimb.2026.1905670