Acute gastroenteritis remains one of the most frequent reasons for pediatric consultation and hospitalization worldwide, particularly among children under five and in low- and middle-income countries where limited access to clean water, inadequate sanitation, and lower rotavirus vaccination coverage amplify both incidence and severity. Despite advances in oral rehydration therapy, zinc supplementation, and supportive care, diarrheal diseases continue to impose a heavy clinical and economic burden through increased healthcare utilization, caregiver strain, and impaired child growth and development. The COVID-19 pandemic further disrupted the epidemiology of pediatric gastroenteritis: circulation of major enteric pathogens declined during periods of non-pharmaceutical interventions, then resurged after restrictions eased, before gradually returning toward pre-pandemic patterns in a manner that varied by region and vaccination coverage.

The intestinal microbiota plays a central role in gut homeostasis, immune modulation, and resistance to enteric pathogens. Acute diarrheal episodes are associated with transient but sometimes profound disruptions of microbial composition, which may prolong symptoms, impair intestinal barrier function, and predispose children to recurrence. Probiotics, defined as live microorganisms that confer a health benefit when administered in adequate amounts, have been extensively studied as adjuncts to rehydration in acute infectious diarrhea. However, their effects are strain- and indication-specific, so evidence for one product cannot be extrapolated to another; each strain must be evaluated individually. This principle is precisely why the new review focused on a single, well-characterized strain rather than pooling different probiotic products.

Limosilactobacillus reuteri DSM 17938, formerly classified as Lactobacillus reuteri, is a human-derived strain developed from the parent strain ATCC 55730 by removal of two antibiotic-resistance plasmids. It has demonstrated immunomodulatory activity, antimicrobial effects through the production of reuterin, a broad-spectrum antimicrobial compound that inhibits enteropathogen growth, and supportive actions on epithelial barrier function in both experimental and clinical settings. The strain is among the most extensively studied probiotics in pediatric gastrointestinal disorders and appears, with varying strength, in international and regional guidelines. The World Gastroenterology Organization lists it among probiotics that may reduce the duration of diarrhea in acute gastroenteritis, while the ESPGHAN Special Interest Group on Gut Microbiota and Modifications suggests it may be considered alongside rehydration therapy, though this remains a conditional recommendation based on very-low-certainty evidence.

The most recent quantitative synthesis specific to this strain and indication, published in 2019, pooled four randomized controlled trials and reported a reduction in diarrhea duration of 0.87 days, with high heterogeneity and very-low certainty of evidence. Since then, additional double-blind trials have been published, including two conducted during and after the COVID-19 pandemic in emergency-department and outpatient settings outside the previously dominant European, mostly inpatient trial base. The updated review therefore aimed to incorporate these newly published trials, re-examine the magnitude and robustness of the effect in the context of changing gastroenteritis epidemiology, and strengthen the previous analysis with a full time-course of diarrhea persistence.

Methodologically, the review followed the PRISMA 2020 statement and the Cochrane Handbook, with the protocol registered in PROSPERO. Two independent reviewers performed study selection, data extraction, and risk of bias assessment using the Cochrane Risk of Bias 2 tool, which evaluates five domains including the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. The search covered MEDLINE via PubMed, Embase, Scopus, and the Science Citation Index Expanded from inception to April 1, 2026, with no language or date restrictions. Random-effects models pooled mean differences and risk ratios, and the certainty of evidence was appraised via the GRADE approach. Because the DerSimonian-Laird estimator may underestimate between-study variance when the number of trials is small, the authors prespecified a sensitivity analysis using the restricted maximum likelihood estimator with the Hartung-Knapp adjustment, which yields more conservative confidence intervals under these conditions.

The six included trials were conducted in Italy, Türkiye, Poland, Paraguay, and Thailand, randomizing children aged between 3 months and 5 years. Three trials were conducted in hospitalized children and three in outpatient or emergency-department settings. Four trials were double-blind and placebo-controlled, and two were single-blind. The daily dose of the strain ranged from 1 x 10^8 to 4 x 10^8 colony-forming units, administered for 5 days in all trials except one lasting 7 days. In all trials, the probiotic was given in addition to rehydration therapy, with placebo as the comparator in four trials and no treatment in two. No trial was judged to be at high risk of bias, though five trials were rated as having some concerns, largely related to blinding of outcome ascertainment or absence of prospective registration.

Beyond the primary outcome, the review examined the proportion of children with persisting diarrhea at successive time points. The treatment effect was modest at 24 hours, with a risk ratio of 0.87, then became substantially greater at 48 hours, with a risk ratio of 0.45, and reached its maximum at 72 hours, with a risk ratio of 0.41, roughly a halving of the risk of persisting diarrhea. The benefit remained statistically significant at 96 and 120 hours, though attenuated as most children in both groups recovered. This temporal pattern suggests that any clinical benefit of the strain is concentrated in the first two to three days of illness. Two trials also showed fewer watery stools per day on days 2 and 3, while the pooled estimate for duration of hospitalization, based on only two trials, was not statistically significant. No serious or treatment-related adverse events were reported across the trials, and where adverse events were recorded, their frequency was comparable between the probiotic and control groups.

A central observation of the review is the concordance between blinding, risk of bias, and effect size. The two single-blind trials produced the largest effects, with a pooled mean difference of 0.99 days, whereas the four double-blind trials yielded approximately half the magnitude, 0.42 days, with markedly lower heterogeneity. The formal test for subgroup differences was not statistically significant, an expected limitation given only six trials, but the pattern is consistent with the well-documented tendency of unblinded trials to inflate subjective outcomes. Because diarrhea duration is a caregiver-ascertained endpoint, trials without participant blinding may be particularly vulnerable to performance and detection bias. The double-blind estimate may therefore provide a more conservative, and possibly less biased, reflection of the true effect. The authors also note that the two post-pandemic trials showed a smaller and more homogeneous effect than the pre-pandemic trials, a finding compatible with the hypothesis that a changing etiological landscape may modify probiotic efficacy, though it cannot be disentangled from differences in design, setting, and dose, and rests on only two trials.

The authors conclude that Limosilactobacillus reuteri DSM 17938 produces a small, probably genuine reduction in the duration of childhood acute gastroenteritis and a moderate reduction in diarrhea persistence at 48 to 72 hours, with a favorable safety profile, but that the effect on the primary outcome is of uncertain clinical importance and rests on very-low-certainty evidence. Future research should prioritize adequately powered, double-blind trials with systematic pathogen characterization, standardized definitions of diarrhea resolution, and intention-to-treat analysis, ideally conducted in the current post-pandemic epidemiological context. The recently proposed Probiotic Human Study Design and Reporting recommendations offer a practical framework for this purpose, emphasizing precise strain identification, transparent reporting of dose and viable count, prospective registration, prespecified standardized outcomes, and intention-to-treat analysis. Only trials of this quality will be able to establish whether the small, sub-one-day benefit suggested by the current evidence represents a reproducible and clinically meaningful effect, and to identify the subgroups in which it is most likely to matter.

Subject of Research: Probiotic strain shortens childhood diarrhea by about 16 hours, but evidence remains shaky

Article Title: Efficacy and safety of Limosilactobacillus reuteri DSM 17938 for the treatment of acute gastroenteritis in children: a systematic review and meta-analysis of randomized controlled trials

Article References: Dinleyici, E. C., Indrio, F., Gutierrez-Castrellon, P., & Rosa, D. (2026). Efficacy and safety of Limosilactobacillus reuteri DSM 17938 for the treatment of acute gastroenteritis in children: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Pediatrics, 14, Article 1941872. https://doi.org/10.3389/fped.2026.1941872

Image Credits: AI Generated

DOI: 10.3389/fped.2026.1941872

Keywords: Limosilactobacillus reuteri DSM 17938, probiotics, acute gastroenteritis, children, diarrhea, meta-analysis, systematic review, pediatrics, GRADE, microbiota, Efficacy, safety

The study took the form of a single-centre retrospective analysis of 226 children aged zero to eighteen years who presented with acute gastroenteritis between April 2024 and March 2026. Rather than imposing an arbitrary severity score, the researchers classified each child’s disposition exactly as it happened in practice, using a hierarchical scheme with three levels: outpatient discharge, observation only, and hospitalization. Laboratory tests were not drawn uniformly; instead, they were obtained at the discretion of the treating clinician, either at presentation, at the moment of intravenous cannulation, or before fluids were administered. This design choice is crucial, because it means the study captures the messy, decision-driven reality of pediatric emergency care rather than an idealized research protocol.

That reality came with a statistical complication the author was careful to confront head-on. Laboratory testing was obtained in only 43 percent of children who were discharged as outpatients, compared with a near-universal 98 percent of those placed under observation or hospitalized. In other words, the data were not missing at random: clinicians ordered blood work precisely for the children they were already worried about, a phenomenon statisticians call informative missingness. Any comparison between tested and untested children is therefore biased by design, and the analysis was deliberately restricted to the tested subgroup, with the explicit framing that the findings describe associations with real-world management rather than a universal prediction rule for all children with gastroenteritis.

Within that tested subgroup, the differences between children who were escalated and those who were sent home were clear and statistically robust. Compared with outpatients, children escalated to observation or hospitalization had lower lymphocyte counts, higher neutrophil counts, and higher urea values, and all three differences survived correction for multiple comparisons using the Benjamini–Hochberg false discovery rate across eleven laboratory parameters. Group comparisons employed the Mann–Whitney U test for two-group contrasts and the Kruskal–Wallis test with Dunn post-hoc procedures for the three-level disposition comparison, non-parametric methods well suited to the skewed distributions typical of clinical laboratory data. The analyses were conducted in Python 3 using the SciPy and statsmodels libraries, and the full analysis code was made available as supplementary material, an unusual and welcome degree of transparency for a single-centre study.

The three-group comparison added an important nuance. Lower lymphocyte count separated outpatients from children who were escalated, with a Kruskal–Wallis statistic of 20.1 and a p-value below 0.001, but it did not distinguish children who were merely observed from those who were admitted to the ward. This suggests that lymphopenia may function in practice as a signal that a child is sick enough to warrant escalation of some kind, rather than as a fine-grained discriminator between intermediate and intensive levels of care. For a condition in which the pivotal decision is often simply whether to keep a child in the hospital at all, that distinction matters, and it hints that different markers or combinations of markers may be needed to separate observation from admission.

To quantify how strongly each laboratory parameter was associated with escalation, the study turned to multivariable logistic regression, reporting adjusted odds ratios alongside variance inflation factors to check for problematic collinearity between correlated blood counts. In the composite model, lower lymphocyte count emerged as the strongest correlate of escalation, with an adjusted odds ratio of 0.575 per unit increase, a 95 percent confidence interval of 0.419 to 0.789, and a p-value of 0.001. Adding lymphocyte count to the available clinical variables, which included fever, vomiting, and measured temperature, was associated with a statistically significant improvement in model fit within the tested subgroup, with a likelihood-ratio p-value below 0.001, and the apparent area under the receiver operating characteristic curve rose from 0.75 to 0.81. Discrimination for the full escalation model, after bootstrap optimism correction, was a c-statistic of 0.77, down from an apparent 0.82, a correction that guards against the inflated performance that plagues many small clinical prediction studies.

Among the composite inflammatory indices, the neutrophil-to-lymphocyte ratio, a marker widely studied in adult critical care and oncology but far less in pediatric gastroenteritis, showed the numerically highest single-marker discrimination for escalation, with an area under the curve of 0.78 and a 95 percent confidence interval of 0.68 to 0.86. The author was careful to note, however, that this confidence interval overlapped substantially with those of the lymphocyte and neutrophil counts themselves, meaning the ratio cannot claim superiority over its component measurements on this evidence. The platelet-to-lymphocyte ratio was assessed as a second exploratory composite but did not emerge as a standout. In a sobering secondary finding, no laboratory parameter survived false discovery rate correction when the outcome was narrowed specifically to hospitalization, as opposed to the combined escalation outcome, underscoring how much harder it is to predict the most serious dispositions than the broader decision to escalate.

One virological detail caught the eye: rotavirus positivity was associated with admission, with an odds ratio of 2.74 and a p-value of 0.015. This association is biologically plausible, since rotavirus is classically responsible for some of the most dehydrating episodes of childhood gastroenteritis, and clinicians may reasonably have a lower threshold for admitting a child with a confirmed rotavirus infection. It also serves as a reminder that disposition decisions are shaped by the full clinical picture, including etiological diagnosis, and not by blood counts alone. The study’s ethical footing was solid: the Scientific Research Ethics Committee of Eskişehir City Hospital approved the work in April 2026, waiving informed consent for the retrospective analysis of anonymized data, and the study was conducted in accordance with the Declaration of Helsinki, with no funding received and no competing interests declared.

The author is refreshingly candid about the study’s central limitation, which is incorporation bias: the very laboratory values under investigation informed the disposition decisions being studied, so the analysis inevitably finds that the tests correlate with decisions they helped to shape. Combined with the selective, clinician-directed testing, this means the results are hypothesis-generating rather than predictive, and they cannot be generalized to all children with acute gastroenteritis, most of whom never have a blood count drawn at all. Still, the study earns its place in the literature by documenting, with unusual statistical rigor and full methodological transparency, what actually happens in the real world of pediatric emergency care. Lower lymphocyte counts, elevated neutrophil counts, rising urea, and a high neutrophil-to-lymphocyte ratio cluster around the children clinicians choose to keep, and a prospective study that tests these markers before decisions are made, ideally across multiple centres and in the untested majority of children, would be the natural next step toward turning this observational signal into genuinely useful decision support.

Subject of Research: Laboratory correlates of observation and hospitalization decisions in children with acute gastroenteritis

Article Title: Laboratory correlates of observation and hospitalization decisions in children with acute gastroenteritis: an exploratory association study

Article References: Cengiz, M. (2026). Laboratory correlates of observation and hospitalization decisions in children with acute gastroenteritis: an exploratory association study. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07783-6

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07783-6

Keywords: acute gastroenteritis, children, lymphocyte count, neutrophil-to-lymphocyte ratio, hospitalization, rotavirus, pediatrics, laboratory markers, clinical decision-making, retrospective study, diagnostic markers, emergency care

Acute gastroenteritis remains one of the most common reasons young children end up in emergency departments worldwide. The illness, usually viral, produces vomiting and diarrhea that can rapidly dehydrate a small body. The cornerstone of treatment is oral rehydration therapy, a carefully balanced solution of salts and sugars. The problem is that persistent vomiting often defeats oral rehydration before it can work, forcing clinicians toward intravenous lines, hospital admission, and prolonged distress. Ondansetron, a selective serotonin 5-HT3 receptor antagonist originally developed for chemotherapy-induced nausea, blocks the signaling pathway that triggers the vomiting reflex at the level of the gut and the brain’s vomiting center. Its adoption in pediatric emergency care has grown steadily, but the evidence base has needed updating.

The previous comprehensive meta-analysis on the question was published in 2020, and the research team identified three specific gaps it left open. It could not incorporate a subsequently published trial of multidose ondansetron given after hospital discharge, it did not evaluate the volume of oral rehydration solution children actually tolerated, and it did not formally explore sources of statistical heterogeneity through meta-regression. The new analysis, conducted and reported according to the PRISMA 2020 statement and guided by the AMSTAR 2 appraisal tool, set out to close those gaps. The researchers searched PubMed, CENTRAL, ScienceDirect, Google Scholar, and ClinicalTrials.gov through June 2026, and assessed risk of bias with the Cochrane RoB 2 tool and certainty of evidence with GRADE.

The headline results are striking in their consistency across measures of vomiting morbidity. Compared with placebo, ondansetron reduced the risk of ongoing vomiting by more than half, with a pooled risk ratio of 0.48. Children given the drug experienced on average 0.73 fewer vomiting episodes. Failure of oral rehydration therapy fell dramatically, with a risk ratio of 0.39, and the use of intravenous fluids dropped to 0.57 times the rate seen with placebo. Perhaps most tellingly for frontline practice, children who received ondansetron tolerated significantly more oral rehydration solution, a mean difference of nearly 48 milliliters more than placebo recipients. For a therapy whose entire purpose is to keep fluids going in by mouth rather than through a needle, that volume difference is clinically meaningful.

The picture darkens somewhat around the outcomes that matter most for health systems and families over longer horizons. The analysis found no significant difference between ondansetron and placebo in hospitalization rates, repeat healthcare visits, ongoing diarrhea, diarrheal episodes, or adverse events. Moreover, the hospitalization result proved fragile: it reached statistical significance only when a single large trial was omitted from the pooling, a sensitivity finding that undermines confidence in any true effect on admissions. Reassuringly for safety, the drug did not appear to worsen diarrhea, a concern sometimes raised because intestinal motility is partly serotonin-mediated. But the authors emphasize that the safety comparison rests on very few estimable comparisons and very few adverse events, meaning the analysis simply cannot rule out uncommon or delayed harms.

The durability of the antiemetic effect emerged as another key nuance. On subgroup analysis by follow-up duration, the benefit for ongoing vomiting was statistically significant through the first twenty-four hours but attenuated at forty-eight hours and beyond. This time-limited effect provides what the authors call a plausible rationale, though not direct evidence from the synthesis itself, for the extended multidose post-discharge regimen evaluated in the largest included trial. That trial, which the 2020 meta-analysis could not include, tested whether continued ondansetron after children left the emergency department could sustain the protection that a single dose evidently cannot. The updated evidence base now incorporates those findings, strengthening the argument that duration of action is a central design question rather than an afterthought.

Beneath the pooled estimates lies a more uncomfortable statistical story. The trials showed substantial heterogeneity, meaning their results varied far more than chance alone would predict. Exploratory meta-regression, introduced during revision and notably not specified in the registered protocol, suggested that the baseline proportion of male participants, baseline vomiting-episode frequency, and baseline diarrheal-episode frequency acted as study-level moderators of the effect on ongoing vomiting, while mean age did not. More concerning, Egger’s test indicated statistically significant funnel-plot asymmetry for both outcomes where publication bias could be assessed: ongoing vomiting, with a p-value of 0.03070, and number of vomiting episodes, with a p-value of 0.04627. Begg and Mazumdar’s rank correlation test was significant for neither, leaving the signal equivocal but sufficient for the authors to rate certainty of evidence as low for ongoing vomiting and very low for the number of vomiting episodes.

What does funnel-plot asymmetry mean in practical terms? Small trials with favorable results tend to be published more readily than small trials with null findings, so when the smaller studies in a meta-analysis cluster at one extreme of the funnel plot, it suggests the literature may be missing negative results. If so, the pooled effect sizes that look so impressive in the forest plots may overstate what a typical child would experience. The authors state this directly: the pooled magnitude of benefit on vomiting may be overstated. This kind of self-critical transparency is increasingly expected of high-quality systematic reviews, and it distinguishes this update from simpler aggregations that report point estimates without interrogating the shape of the evidence behind them.

The research team, which also included authors from Hawassa University in Ethiopia and Ad Diriyah Hospital in Riyadh, concludes that ondansetron significantly reduces vomiting morbidity in children with acute gastroenteritis, with no statistically significant difference versus placebo in adverse events or diarrhea. Their prescription for future research is precise: further randomized trials directly comparing single-dose and multidose regimens, particularly in high-burden, low-resource settings where gastroenteritis still kills, along with individual patient-data analyses that can resolve the heterogeneity that study-level meta-regression only glimpses. The review was registered prospectively on PROSPERO under identifier CRD420261447906, received no extramural funding, and is published open access. For emergency clinicians deciding whether a dose of ondansetron is worth offering a vomiting, dehydrated child, the accumulated evidence now points, with acknowledged caveats, toward yes.

Subject of Research: Efficacy and safety of ondansetron versus placebo for acute gastroenteritis-associated vomiting in children

Article Title: Updated evidence on efficacy and safety of ondansetron compared with placebo for acute gastroenteritis-associated vomiting in children: a systematic review and meta-analysis of randomized controlled trials

Article References: Althunayyan, B. S., Alhoushani, R. A., Alhesayani, L. M., Alsallal, S. A., Aldakhil, L. N., Alharbi, S. J., Alharbi, M. M., Aldaher, Y. J., Aljumah, Y. S., Alharbi, W. A., Yusuf, S. A., & Alrashidi, S. H. (2026). Updated evidence on efficacy and safety of ondansetron compared with placebo for acute gastroenteritis-associated vomiting in children: a systematic review and meta-analysis of randomized controlled trials. BMC Pediatrics. https://doi.org/10.1186/s12887-026-07694-6

Image Credits: AI Generated

DOI: 10.1186/s12887-026-07694-6

Keywords: ondansetron, acute gastroenteritis, vomiting, children, oral rehydration therapy, meta-analysis, randomized controlled trials, pediatrics, emergency care, intravenous fluids, publication bias, GRADE