Summary Dysbiosis and bacterial pathobionts contribute to inflammation in IBD and CRC, yet the molecular drivers of this process remain unclear. We identify the Klebsiella pneumoniae type VI secretion system (T6SS) as a key promoter of intestinal inflammation and tumor progression. Metagenomic analyses revealed enrichment of T6SS encoding genes in the gut microbiota of IBD patients during inflammatory flares. In zebrafish and mouse models, K. pneumoniae T6SS activity exacerbated inflammation and promoted colorectal tumor growth. Mechanistically, T6SS firing enhanced the secretion of LPS via outer membrane vesicles (OMVs), driving NF-κB activation and interferon signalling in host cells. In vivo , T6SS-dependent inflammation was associated with the expansion of regulatory T-cell subsets and an immunosuppressive tumor microenvironment. These findings redefine the T6SS as a microbial determinant of host inflammation and cancer progression, highlighting T6SS inhibition as a potential therapeutic approach for IBD and CRC. Highlights T6SS-encoding Enterobacteria are enriched in the gut microbiota of IBD patients Klebsiella pneumoniae T6SS exacerbates colitis in mice T6SS activity enhances outer membrane vesicle secretion and LPS release T6SS promotes colorectal tumorigenesis and immune dysregulation Graphical abstract

BACKGROUND:Clostridioides difficile infections (CDIs) are associated with antibiotic use, although the link with other drugs remains underexplored. OBJECTIVES:To investigate the association between antibiotic and non-antibiotic drugs with microbiome-modulating activity on new occurrences of CDI. DESIGN:We conducted a Swedish population-based case-control study from 2006 to 2019 including 42 921 cases matched with 355 159 population controls on age and sex, obtained from multiple linked Swedish registries. The effect of antibiotic and non-antibiotic use within 30 days from the index date on CDI occurrence was estimated using multivariable conditional logistic regression additionally with a lasso penalty. Models were adjusted for age and sex by design and for Charlson Comorbidity Index and concomitant drug use, providing adjusted ORs (aORs) with 95% CIs. RESULTS:Antibiotics with the greatest CDI risk were lincosamides (aOR=31.4, 95% CI 27.9 to 35.3), combinations of penicillins (aOR=19.8, 95% CI 15.9 to 24.5), sulfonamides and trimethoprim, and cephalosporins, though no association for tetracyclines. Among non-antibiotic drugs, we found decreased risks of CDI for lipid-modifiers (aOR=0.8, 95% CI 0.8 to 0.8) and aspirin (aOR=0.8, 95% CI 0.7 to 0.8) and increased risks for antidiarrhoeals (aOR=7.3, 95% CI 6.8 to 7.8), corticosteroids (aOR=2.4, 95% CI 2.3 to 2.5), proton-pump inhibitors (PPIs) (aOR=1.8, 95% CI 1.7 to 1.8), nervous system drugs, constipation drugs, histamine H2-receptor antagonists, antidepressants, and beta blockers, but no significant risk for non-steroidal anti-inflammatory drugs. CONCLUSIONS:We found varying effects of antibiotics on CDI, providing evidence for ongoing efforts in prudent prescribing decisions and antimicrobial stewardship. We confirmed PPI as a main risk factor for CDI and provided new evidence for other non-antibiotic drugs as potentially important risk factors considering their high prescription prevalence.

Abstract Miscarriage occurs in approximately 15% of all pregnancies, and recent studies have suggested a potential role of the microbiome. A nested case-control study from the Swedish Maternal Microbiome cohort was conducted, including 34 participants who sent at least one vaginal or fecal microbiome sample and questionnaire data before miscarrying (n = 34), and matched controls (n = 105 for regression models, n = 27 for machine learning models). Non-vaccine type HPV (aOR 3.95, 95%CI 1.04–15.06) and vaginal microbiome with community state type (CST) II (aOR 6.52, 95%CI 1.58–26.98) or CST-IVB (aOR 4.18, 95%CI 1.08–16.18) in early pregnancy were associated with an increased risk of miscarriage. Furthermore, we explored six machine learning algorithms using 70% of the cohort for training and 30% for testing, for the prediction of miscarriage using vaginal (AUROC 85%), fecal (AUROC 81%) and questionnaire (AUROC 82%) data separately and combined (AUROC 82%). Our results highlight the urgency of HPV screening and vaccine development for women’s reproductive health. Despite limitations, including a small number of miscarriage cases, our results indicate the potential for both vaginal and fecal microbiomes in the prediction of miscarriage.

Background: The vaginal microbiome is important for women's health, – yet it remains insufficiently known which factors may affect microbiome composition, abundance and functionality. Methods: This cross-sectional study included 1445 healthy women attending cervical cancer screening. Leveraging extensive registry data and questionnaires (>200 potential determinants), we applied multivariate Supervised Component Generalized Linear Regression. Findings: Age, reproductive, sexual and mental health, and non-antibiotic drugs were drivers of microbial variation across reproductive life stages. Younger women exhibited higher Lactobacillus spp. abundance, whereas postmenopausal women demonstrated increased microbial diversity. Antimicrobial resistance genes were found in 74%. Interpretation: This exploratory study underscores the necessity of integrating multivariate statistical approaches in microbiome research to disentangle the complex interplay of covariates and functional metabolic effects. The extensive registry-linked dataset and population-based design provide a unique resource for future explorations of the intricate relationships between host factors, microbiome composition, and antimicrobial resistance in women’s health.

Background Obesity is associated with gut dysbiosis, which has been implicated in the pathogenesis of gestational diabetes, preeclampsia, and gestational hypertension. Its role in obese pregnant women, the population at highest risk, remains largely unexplored. Methods Within the Swedish Maternal Microbiome (SweMaMi) cohort, we conducted a nested case–control study comparing the second-trimester faecal microbiome between obese pregnant women who developed metabolic complications (n = 98) and complication-free controls (n = 113), using shotgun metagenomics. We developed a multi-modal machine learning framework integrating microbial species abundances, functional profiles, community-level features, and registry and questionnaire data to evaluate predictive performance and identify microbial signatures. Results Cases had higher pre-pregnancy BMI and gestational BMI gain. Socioeconomic score, not microbial diversity, was associated with outcomes after adjustment. Models showed limited discriminatory capacity overall, with the highest performance for preeclampsia, where gut metabolic modules emerged as the strongest predictors. Conclusion BMI and socioeconomic status, rather than gut microbiome composition, appear to be the primary drivers of metabolic risk in this population.

Abstract Bacterial vaginosis (BV) affects 23–29% of reproductive-age women globally and recurs in over half of cases within 6 months, yet the coordinated metabolic and genomic mechanisms underlying it remain incompletely understood. In this cross-sectional study of 111 Swedish women (29 with BV, 82 controls), we combined shotgun metagenomics, targeted liquid chromatography–mass spectrometry metabolomics, and Gardnerella metagenome-assembled genome (MAG) analysis, integrating these layers with supervised (DIABLO) and unsupervised (MOFA2) methods. BV status explained 23.5% of community variance and was characterized by Lactobacillus depletion, enrichment of canonical anaerobes including Gardnerella vaginalis and Fannyhessea vaginae, and a pronounced metabolic shift marked by elevated polyamines (cadaverine, putrescine, N-acetylputrescine, trimethylamine) and depleted nucleosides. Supervised and unsupervised integration converged on the same discriminatory features and prioritized Lactobacillus loss and the polyamine producer Dialister micraerophilus over the most abundant BV taxa. Across 35 Gardnerella MAGs spanning nine species, no accessory genes were associated with BV after correction, yet accessory gene content explained 8.5% of metabolome variance independently of BV status (p = 0.002). These cross-sectional findings are associative and hypothesis-generating, supporting a community-level, metabolically defined model of BV rather than strain-specific pathogenesis.

Cross-sectional studies link gut microbiome alterations to type 2 diabetes (T2D), but prospective evidence remains limited. We aim to identify taxonomic and functional features associated with future T2D risk. We analyze shotgun metagenomic data from 4,685 participants (mean age, 73.9 years; 49.0% women) in the Swedish SIMPLER cohort, followed for a median 5.3 years, during which 383 developed T2D. Six species are associated with increased T2D risk: Desulfovibrio piger, Alistipes communis, Alistipes finegoldii, Akkermansia muciniphila, Ruminococcus gnavus, and GGB3614_SGB4886 (Lachnospiraceae), while three are protective: Erysipelotrichaceae bacterium, Coprococcus catus, and Clostridia unclassified SGB6317. We observe context-specific associations, including a dietary fiber-modified effect for A. muciniphila indicative of diet-dependent patterns. Three gut metabolic modules are associated with incident T2D: asparagine degradation (higher risk), mannose degradation, and the non-oxidative pentose phosphate pathway (lower risk). These prospective findings offer insights into T2D etiology and may support microbiome-informed strategies for risk prediction and prevention.

There is a need to quantify the benefits and harms of colorectal cancer (CRC) screening using primary colonoscopy or fecal immunochemical testing (FIT) compared with usual care with no screening. Guidelines recommend screening in individuals aged 50-75 years using colonoscopy or FIT, and many screening programs use one-sample biennial FIT. Here we compare incidence of diagnosed CRCs and gastrointestinal and cardiovascular events between screening and usual care during the diagnostic phase of the SCREESCO trial. A randomized block method (no masking) assigned 278,280 individuals aged 60 years to once-only colonoscopy, 2 rounds of two-stool FIT with a low cutoff (10 μg g-1 feces) or usual care (control group) in a ratio of 1:6 for colonoscopy versus control and 1:2 for FIT versus control. In the analysis, 31,113 individuals were in the primary colonoscopy arm and 60,267 were in the FIT arm, and there were 186,671 primary colonoscopy controls, of whom 120,521 were also controls for comparison with the FIT arm. After a median follow-up of 4.8 years, the incidence rate of CRC was 107.9 in the colonoscopy arm and 99.9 in controls per 100,000 person-years (incidence rate ratio (IRR): 1.08, 95% confidence interval (CI): 0.91-1.28) and 96.0 in the FIT arm and 103.9 in controls (IRR: 0.92, 95% CI: 0.81-1.05). Rates of stage I-II CRC were higher in the colonoscopy arm (IRR: 1.38, 95% CI: 1.09-1.74) and in the FIT arm (IRR: 1.19, 95% CI: 0.99-1.43) versus controls. Rates of cardiovascular and gastrointestinal events were slightly higher in the intervention arms during the first year and were subsequently more similar to controls. Our findings of an increase in CRC detection implies a benefit of screening while the increase in adverse events suggests some initial harm. ClinicalTrials.gov: NCT02078804 .

Abstract The vaginal microbiome is a critical determinant of women’s health. We investigated the genetic basis of common vaginal microbiome species and their biofilm formation. Genomic analysis of Gardnerella vaginalis ( Gv ) revealed a fundamental phylogenetic split correlating with high- versus low-biofilm phenotypes, driven by clade-specific genomic islands and allelic variants. In a dual-species coculture model of five key vaginal bacteria, Gv achieved numerical dominance, triggering extensive, asymmetric proteomic reprogramming in partner species while showing limited shifts itself. Proteins from biofilm-associated modules showed functional divergence, supported by AI-predicted structural variations in a type II secretion/Tad pilus system, which is first discovered from Gv strains. Integrated metabolomics identified a methyl- β -carboline compound that is elevated in cocultures containing Prevotella bivia ( Pb ). This compound acts as a potent and selective inhibitor of Gv and Pb biofilms, sparing Lactobacillus crispatus . This work establishes a direct genomic basis for Gv virulence and demonstrates how interspecies interactions govern community dynamics and antimicrobial metabolite production. Highlights: Comprehensive genomic resource comparing with high-quality long-read whole genomes and reference Gardnerella vaginalis and Lactobacillus iners strains. Integrated multi-omics and functional analysis on the most common vaginal microbiome species using 16S rRNA gene sequencing, proteomics, metabolomics, and in vitro assays. Key phenotypes quantified, including biofilm formation and polymicrobial interactions. Conserved Type II Secretion/Tad Pilus System identified across all Gardnerella vaginalis strains, with AI-predicted structural modeling. Evaluation of growth inhibition using metabolites against a panel of relevant microbes, including vaginal microbes and opportunistic pathogens.

Abstract The oral microbiome is a complex and dynamic microecosystem that fluctuates continually throughout the lifespan of a woman. Nevertheless, the function of the oral microbiome in reproductive health is not yet fully understood. Monitoring oral health and providing necessary dental care before and during pregnancy could help maintain a balanced oral microecology and support healthier microbial transfer to newborns. Here, we aimed to compare the salivary microbiome of pregnant and non-pregnant women using shotgun metagenomics to describe their taxonomic and functional composition and assess whether the resulting data is better explained by the reproductive stage. We conducted a comparative cross-sectional study involving pregnant women (n = 71; gestational age 37–42 weeks) and non-pregnant women (n = 143 with regular menstrual cycles; 3 saliva samples per participant across different menstrual phases). Shallow shotgun metagenomic sequencing was used to characterize both taxonomic and functional profiles of the oral microbiome. Socransky’s color complex analysis was performed to assess group differences in key microbial complexes. Quantitative PCR was used to validate the abundance of selected oral bacteria. Participant data, including demographic, behavioral, clinical, and oral health variables (such as dentist visits), were collected and incorporated as covariates to adjust for potential confounding effects. Additionally, a sensitivity analysis was performed by excluding participants with identified behavioral or clinical risk factors. Ten phyla including Actinomycetota, Bacteroidota, Chloroflexota Bacillota, Fusobacteriota, Pseudomonadota, Spirochaetota, Synergistota Candidatus Saccharimonadota and Mycoplasmatota, 102 genera, and 410 species were identified. Pregnant women had lower saliva microbiome diversity, driven by reduced richness but unchanged evenness. The microbial composition varied between the groups, even after adjusting for confounding factors. Differential abundance analysis, adjusted for potential confounders, identified 25 species that significantly differed between groups (q < 0.05), with 13 taxa more than three-fold higher in pregnant women. Notably, red complex species were more abundant in pregnant women (p < 0.05). Functional pathway analysis identified 40 modules that differed by pregnancy status. These results further suggest a connection between pregnancy and changes to the oral microbiome in women. As many of these changes are in a pro-inflammatory direction, further research is warranted to assess its potential impact on pregnant women and their newborns.

ABSTRACTThe coronavirus disease 2019 (COVID‐19) is a fatal disease caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2). To date, several vaccines have been developed to combat the spread of this virus. Mucosal vaccines using food‐grade bacteria, such as Lactobacillus spp., are promising strategies for developing safe and effective vaccines against SARS‐CoV‐2. In this study, we designed a non‐GMO surface‐displayed SARS‐CoV‐2 spike S1 epitope on Limosilactobacillus fermentum‐derived bacteria‐like particles (BLPs). After that, we evaluated its efficacy to induce immune responses in immunocompetent mice. Moreover, we examined the influence of oral immunisation on the gut microbiome and microbiota metabolites. Twenty‐eight 6‐week‐old male C57BL/6 mice were orally immunised with the following: PBS (control), Lm. fermentum‐derived BLPs only, BLPs displaying SARS‐CoV‐2 spike S1‐2, or BLPs displaying SARS‐CoV‐2 spike S1‐3 epitopes. Our results showed that mucosal immunisation of mice with surface‐displayed SARS‐CoV‐2 spike epitopes provoked high‐level secretory IgA and systemic IgG production. Moreover, the immunisation exhibited a Th1‐like immune response, characterised by an elevated IgG2a‐to‐IgG1 ratio and high antiviral IFN‐γ production. In addition, we observed gut microbiome modulation and increased butyrate production in immunised mice. Overall, the use of Lm. fermentum‐derived BLPs and the anchor CshA to display SARS‐CoV‐2 spike S1epitopes is a promising novel strategy in developing a cost‐effective, non‐GMO mucosal vaccine alternative against SARS‐CoV‐2.

Approximately 70% of all pregnancies are affected by nausea and vomiting (NVP), yet the mechanisms controlling this phenomenon are not well known. Pregnancy hormones explain a large part of this effect, mostly through human chorionic gonadotropin and fetal production of GDF15, a hormone active in the brain stem. Still, there is a wide variation in the severity of symptoms, ranging from no nausea to severe vomiting requiring hospitalization (hyperemesis gravidarum). Here, we present a nested case‒control study within the large SweMaMi cohort, wherein 337 participants with severe NVP in early pregnancy were matched 1-to-1 with moderate and mild NVP, respectively. Subjects with more severe nausea had lower richness and diversity in their fecal microbiomes. Several taxa were significantly associated with NVP score, where the most extreme are a negative correlation with Lactobacillaceae and positive correlations with Bifidobacterium dentium and Puniceicoccaceae. Finally, higher NVP score was associated with a higher abundance of bacteria encoding for the neuroactive pathways of glutamine degradation, inositol synthesis, and lactate production. In conclusion, the gut microbiota was strongly associated with NVP. Further studies with direct interventions capable of restoring the early-pregnancy gut microbiome could open up new approaches for dealing with the most common symptom of early pregnancy.

BACKGROUND:Clostridioides difficile is a leading cause of healthcare-associated infections globally with proton pump inhibitor (PPI) use as important modifiable risk factor. This study aimed to systematically synthesise global evidence on the dose-response relationship of PPI usage and the Clostridioides difficile infection (CDI) risk and to identify potential safe thresholds of PPI usage regarding CDI. METHODS:PubMed, Embase, Web of Science, and Cochrane Library were searched for longitudinal studies regarding PPIs and CDI. Aggregated data were included in two separate two-stage random-effects dose-response meta-analyses regarding Defined Daily Dose (DDD) and PPI therapy duration. Pooled adjusted relative risks (RRs) with 95% confidence intervals compared to non-users of PPIs were estimated. FINDINGS:Overall, 15 observational cohort and case-control studies were included with 7 studies (n=483,821) in the meta-analysis per DDD and 7 studies (n=516,441) per PPI therapy duration. The risk of bias was modest. Pooled dose-response estimates suggest linear trends with a RR of 1.05 (95% CI 0.89,1.23) per 10 mg DDD and of 1.02 (95% CI 1.00,1.05) per day of PPI therapy. Substantial residual heterogeneity was detected in both analyses (I2=91.4% per DDD and I2=99.4% per therapy duration), but inferring potential sources was limited. INTERPRETATION:Our results indicate a possible increase in the risk of CDI with increasing dose and duration of PPI therapy. Underlying mechanisms and dosage thresholds for a clinically relevant risk increase remain unclear.

The mycobiome is now recognized as a critical part of the human microbial ecosystem, playing a significant role in both health and disease. Mycobiome research is currently in its infancy and relies on fungal-specific primers with challenges in bioinformatics to accurately determine the structure of the mycobiota community. In addition, the majority of computational and experimental methods currently in use have been optimized for bacteria rather than for fungi. Here, we provide a comparative analysis of extraction methodologies for metagenome sequencing and subsequent bioinformatic analysis that will enhance fungal species identification. We utilized cultured mock fungal communities, including both yeast and mold species, to evaluate the efficiency of extraction protocols. We further enhanced computational analysis of the mycobiome, using mock and human metagenome data together with our curated catalogue consisting of 984 fungal genomes specific to the human mycobiome. Application of this optimised workflow for oral and gut samples of healthy individuals detected of novel species from Puccinia and Lentinus genera among the established presence of Malassezia, Rhizophagus, Candida and Saccharomyces genera. In addition, Enterocytozoon, was identified specifically in the gut mycobiome. Our pipeline enabled the comprehensive sampling of all fungal genes in a microbial community within a human sample minimising bias, reducing errors and artefacts from amplification, and providing accurate diversity and abundance data for the human mycobiome. ### Competing Interest Statement VCP has delivered paid lectures for Norgine Pharmaceuticals Ltd and Menarini Diagnostics Ltd.

Supplementary Figure from Use of Antibiotics and Risk of Psychiatric Disorders in Newly Diagnosed Cancer Patients: A Population-Based Cohort Study in Sweden

Background. National epidemiological investigations of microbial infections greatly benefit from the increased information gained by whole-genome sequencing (WGS) in combination with standardized approaches for data sharing and analysis. Aim. To evaluate the quality and accuracy of WGS data generated by different laboratories but analysed by joint pipelines to reach a national surveillance approach. Methods. A national methicillin-resistant Staphylococcus aureus (MRSA) collection of 20 strains was distributed to nine participating laboratories that performed in-house procedures for WGS. Raw data were shared and analysed by three pipelines: 1928 Diagnostics, JASEN (GMS pipeline) and CLC-Genomics Workbench. The outcomes were compared according to quality, correct strain identification and genetic distances. Results. One isolate contained intraspecies contamination and was excluded from further analysis. The mean sequencing depth varied between sites and technologies. However, all analysis methods identified 12 strains that belonged to one of five outbreak clusters. The cut-off definition was set to <10 allele differences for core genome multilocus sequence typing (cgMLST) and <20 genetic differences for SNP analysis in a pairwise comparison. Conclusions. MRSA isolates, which are whole genome sequenced by different laboratories and analysed using the same bioinformatic pipelines, yielded comparable results for outbreak clustering for both cgMLST and SNP, using the 1928 analysis pipeline. In this study, JASEN was best suited to analyse Illumina data and CLC to analyse within respective technology. In the future, real-time sharing of data and harmonized analysis within the Genomic Medicine Sweden consortium will further facilitate investigations of outbreaks and transmission routes.

BACKGROUND:Helicobacter pylori eradication therapy typically consists of a combination of antibiotics and an antisecretory drug. Probiotics may be added to reduce side effects and possibly improve outcomes. MATERIALS AND METHODS:We conducted a double-blind, randomized trial of pantoprazole plus either Lactobacillus reuteri (Gastrus) (high dose) or a matching placebo to assess the impact on the gut microbiota of H. pylori-positive adults. Fecal samples were collected at baseline and after one and 2 months for shotgun metagenomic sequencing. RESULTS:A total of 26 patients were recruited and completed therapy. L. reuteri was only detected in the group that received supplemental L. reuteri and only at the 1-month post-treatment interval. L. reuteri failed to colonize for long-term the gut, and challenge with L. reuteri failed to alter alpha-diversity (Shannon index) or beta-diversity (community ordination) metrics at any time point. Machine learning (PLS-DA) analysis identified the presence of L. reuteri as the most distinguishing feature at 1 month. No other taxa showed a significant difference between groups. CONCLUSION:Short-term administration of pantoprazole and L. reuteri had no lasting effects on gut microbial composition. While L. reuteri transiently bloomed during supplementation, the overall gut microbiota showed resilience, returning to baseline shortly after therapy. TRIAL REGISTRATION:Identifier: NCT03404440.

Preterm birth remains the leading cause of neonatal morbidity and mortality globally, with rates staying unchanged despite advances in obstetric and neonatal care. Inflammation and infection are key mechanisms implicated in preterm birth, with the maternal microbiome emerging as a potential predictor and therapeutic target. This study aimed to predict spontaneous preterm birth by analysing vaginal and faecal microbiomes (collected at <20 weeks and 28–30 weeks of gestation) together with extensive questionnaire data. Leveraging the largest microbiome cohort for preterm birth to date (collected in Sweden, 2017–2021, with 132 cases of spontaneous preterm birth), we developed a machine learning-based prediction model, achieving an AUROC of 0.89. This work underscores the significant potential of early prediction for preterm birth, highlighting that accurate prediction relies on the integration of lifestyle, health status, and microbiome composition. Our results provide a pathway for developing targeted prevention strategies.

OBJECTIVES:Since proton pump inhibitors (PPI) have been introduced, many concerns were raised regarding potential gastric carcinogenicity. We aim to summarise and weigh the epidemiological evidence and address possible causality. DESIGN:Systematic literature review, evidence synthesis and life-course assessment. DATA SOURCES:PubMed, Web of Science and Cochrane database (from inception up to October 2024), and back- and forward citation tracking (Web of Science). ELIGIBILITY CRITERIA:Original studies and quantitative evidence syntheses assessing the association between PPIs and gastric cancer in humans, without language restrictions. DATA EXTRACTION AND SYNTHESIS:Study design, definitions (and participant numbers) of PPI use and gastric cancer, study characteristics (setting, period, follow-up, lag-time), age and sex distribution presented in tables and evidence mapping. RESULTS:We identified 33 original studies, 21 meta-analyses, three umbrella meta-analyses, one individual patient data meta-analysis and a Markov model (2006-2023). PPIs were consistently associated with an increased gastric cancer risk with 20/21 meta-analyses reporting pooled relative risks between 1.3 and 2.9. Available trials were underpowered. Reverse causation/protopathic bias, residual confounding (by indication) and lag time seem the largest methodological challenges, as well as disentangling the effects of Helicobacter pylori and its' eradication. Insufficient data are available on age and sex-specific risks, with no studies specifically addressing PPIs in young populations. We hypothesise a sensitive-period exposure model, in which PPI use during pregnancy and early life may be particularly damaging regarding long-term cancer risk. An exploration of Swedish cancer incidence data suggests potential cohort effects as overall gastric cancer risk decreased over time (1970-2022). The risk has increased in young (<40 years) men since the early 2000s, ~10 years after the introduction of Helicobacter pylori eradication and PPIs. CONCLUSION:Although for older individuals with valid indications, the gastric cancer risk related to PPI use may be limited, we do argue for a more rational and evidence-supported use of PPIs in young populations.

Background: Bacterial vaginosis (BV) is the most common vaginal infection among women of reproductive age worldwide, caused by dysbiosis of the vaginal microbiome. Despite its prevalence, the underlying molecular mechanisms remain poorly understood, making diagnosis and treatment challenging. Although antibiotics are the standard therapy, recurrence rates are high, up to 50% within 1 year, and repeated treatments contribute to the rise of antimicrobial resistance. There is an urgent need for alternative, sustainable, and microbiome-friendly treatment options. Objective: To evaluate whether pHyph, a novel antibiotic-free treatment, promotes a shift in the vaginal microbiome toward a health-associated composition in women with clinically diagnosed BV. Study design: In a randomized, double-blind, placebo-controlled trial, vaginal swabs were collected from 152 women diagnosed with BV. Microbiome composition was assessed before and after a 6-day treatment with pHyph or a placebo-like comparator, using qPCR targeting 25 bacterial, 2 viral, and 8 eukaryotic species. Results: pHyph significantly increased the abundance of Lactobacillus iners, Lactobacillus gasseri and Lactobacillus jensenii after treatment, while decreasing the abundance of BV-associated species, such as Gardnerella vaginalis, BVAB2, and Fannyhessea vaginae (Wilcoxon signed rank test, P<.05). The growth-promoting effect on Lactobacillus was more pronounced in women who had detectable levels at baseline. Notably, a substantial number of participants in the pHyph group (n=33) transitioned to a Lactobacillus-dominated community state type (CST), compared to none in the comparator group. Conclusions: pHyph supports BV resolution by promoting a Lactobacillus-dominated vaginal microbiome and reducing BV-associated species, offering a promising antibiotic-free alternative.