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PubMed2026

Human skin microbiota and postpartum depression: A bidirectional Mendelian randomization study.

Postpartum depression (PPD) is a common mental health disorder after childbirth. Although microbiome research in PPD has mainly focused on the gut, the role of skin microbiota remains unclear. We used Mendelian randomization (MR) to assess potential causal associations between skin microbiota and PPD. A bidirectional 2-sample MR analysis used genome-wide association study (GWAS) summary statistics. Genetic instruments for skin microbial features were obtained from a published skin microbiota GWAS, and PPD data were derived from 67,205 mothers (7604 cases, 59,601 controls). Instruments were selected at P <1 × 10-5, linkage disequilibrium-clumped, harmonized, and filtered for weak instruments (F statistic <10). Because this microbiome threshold is exploratory, Benjamini-Hochberg false discovery rate correction was applied within taxonomic levels. The inverse-variance weighted method was primary, complemented by weighted median and mode-based methods. Heterogeneity, pleiotropy, and outliers were assessed using Cochran Q, MR-Egger intercept, and MR-PRESSO. Three skin microbial taxa showed nominal associations with PPD. Higher genetically predicted Acinetobacter on the dorsal forearm (dry skin; 9 single nucleotide polymorphisms [SNPs]; mean F = 22.12) and Proteobacteria in the antecubital fossa (moist skin; 6 SNPs; mean F = 23.44) were associated with increased PPD risk, whereas Betaproteobacteria in the antecubital fossa (11 SNPs; mean F = 21.54) was associated with decreased risk. Associations were directionally consistent, with no substantial heterogeneity or horizontal pleiotropy. After multiple-testing assessment, the findings were exploratory rather than definitive. Reverse MR did not support an effect of PPD on the identified skin microbiota. This MR study provides exploratory genetic evidence linking specific skin microbial features to PPD risk. The findings extend microbiota-related hypotheses beyond the gut microbiome but require validation in larger microbiome GWAS datasets, longitudinal cohorts, and mechanistic studies before clinical or causal conclusions are drawn.

Humans↗

PubMed2005

Detection of potentially novel bacterial components of the human skin microbiota using culture-independent molecular profiling.

Although the micro-organisms forming the cutaneous microbiota are considered to play important roles in the modification and prevention of skin diseases, a comprehensive analysis of their composition has not yet been carried out because of difficulties in determining yet-to-be-cultured micro-organisms in the samples. Swab-scrubbed forehead skin samples of five healthy volunteers were analysed by profiling 16S rRNA genes, as well as by conventional culture methods, to provide a profile of the cutaneous microbiota that included yet-to-be-cultured bacteria from normal human skin. Cluster analyses of the 16S rRNA gene sequences indicated a marked increase in diversity compared with that derived from the culture methods. Nineteen previously recognized species and 13 novel phylotypes were obtained from the analysis of 416 clones. In addition to well-known bacteria such as Staphylococcus epidermidis and Propionibacterium acnes, phylotype A, the 16S rRNA gene of which is 97 % similar to that of Methylophilus methylotrophus, was detected in three of the five samples, in one of which it was the predominant clone. Culture-independent genetic profiling of 16S rRNA genes for detecting human cutaneous microbiota has allowed us to detect potentially novel components of the cutaneous microbiota in humans.

Bacteria↗

PubMed2026

Immunological, Inflammatory, and Microbiota Determinants of Carpal Tunnel Syndrome: Evidence from Mendelian Randomization.

INTRODUCTION: Carpal Tunnel Syndrome (CTS) is a common peripheral neuropathy, and immune dysregulation and microbial dysbiosis are believed to play a role in its development. However, the cause-and-effect relationships have yet to be clarified. METHODS: Using publicly available Genome-Wide Association Study (GWAS), there are 731 immune cell phenotypes, 91 inflammatory proteins, 150 skin microbiota taxon, and 473 gut microbiota taxon based on two-sample Mendelian Randomization (MR) analysis to test whether there is a causal relationship between them and CTS. The results from the study were shown to have some degree of stability as demonstrated by various sensitivity analyses, which included running heterogeneity tests, performing MR -PRESSO, and running MR-Egger regressions. On the other hand, reverse MR was performed to verify the direction of the association. In addition, a two-step MR mediation analysis was conducted to explore whether there was a mediation effect of gut microbiota and skin microbiota, respectively, of immune and inflammatory traits on CTS. RESULTS: 22 Immune cell traits, 4 Inflammatory proteins, 18 gut microbiota taxa, and 3 skin microbiota taxa are causally associated with CTS. Reverse MR suggested feedback effects of CTS on select immune traits and gut microbiota. Mediation analysis revealed 4 gut microbiota taxa that substantially mediated immune/inflammatory effects upon CTS, with mediation rates as high as 44%; however, skin microbiota did not demonstrate any mediation. DISCUSSION: The immune dysregulation, inflammation, and the gut microbiota that cause CTS are all revealed through this research. Mendelian randomization analysis suggests that traits and inflammatory proteins of immune cells directly increase the risk of CTS, and certain types of gut microbes partially mediate these effects. Therefore, the results show a central role of the immune-gut axis in CTS pathogenesis, and suggest a systemic, rather than a local, immune-microbial interaction in disease development. CONCLUSION: We provided the first causal evidence that immune cells, inflammatory proteins, and CTS risk are causally associated with some specific taxa of gut microbiota. This contributes to a better understanding of the immune-microbiome interactions in the process of occurrence and development of CTS, and also provides theoretical support for precision prevention and treatment.

Humans↗

PubMed2026

Complementary activity of an ancient combination of natural ingredients on the dysbiosis symptoms linked to acne.

ETHNOPHARMACOLOGICAL RELEVANCE: Acne is one of the most common dermatologic diseases in the world. It is due to the secretion of a high level of sebum that causes follicular hyperkeratinisation, alterations of the cutaneous microbiota, and inflammatory processes. One of the first-line treatments is still an antibiotic prescription, that inhibits bacterial growth and, as a consequence, lowers some of the other symptoms. Nevertheless, this high level of antibiotic prescription contributes to the increase of antibiotic resistance. Alternatives to antibiotics are thus highly required, as acne does not represent per se an infection. AIM OF THE STUDY: In the frame of the IRGAP (Interdisciplinary Research Group on Ancient Pharmacopeias) consortium, different preparations dedicated to cutaneous ailments have been identified based on ancient traditional uses, dating back to Antiquity or Middle Ages. Among them, the combination of Aloe vera and Myrrh was widely conserved over centuries. Even though this combination is no longer in use, we wondered why this combination was so widely conserved. We considered the use of this combination of ingredients to treat acne, a case study for which both plants are still used, but separately. MATERIALS AND METHODS: The effects of both plant extracts were analyzed on the growth of different bacteria from the skin microbiota, cultivated alone or in co-culture conditions. As the skin is a rather heterologous environment, we further tested the robustness of our study by varying the experimental conditions. We further analyzed any complementary effects of these extracts on the inflammation process linked to acne. RESULTS: We showed that both plant extracts have complementary effects on micro-organisms and on macrophages. Indeed, while Myrrh extracts inhibited the growth of specific skin microbiota bacteria, Aloe vera gel extracts on the opposite, favored the growth of others: the two plants could act in a complementary way to restore a healthy microbiota. Another complementarity was also observed on macrophages: while Myrrh extracts showed an anti-inflammatory effect, Aloe vera gel extracts showed an antioxidant effect. CONCLUSION: Our results highlight the potential of the combination of Myrrh and Aloe vera to address both the dysbiosis of the skin microbiota and the inflammation associated with acne. Thus, this exploration of forgotten combinations from historical pharmacopoeias underscores the importance of revisiting past traditional knowledge as a source of innovation.

Aloe vera↗

PubMed2005

Propionibacterium acnes wound contamination at the time of spinal surgery.

UNLABELLED: Bacteria of the normal skin microbiota such as Propionibacterium acnes and coagulase-negative staphylococci often are dismissed as contaminants when detected in clinical samples. Propionibacterium acnes is described as a cause of spinal infection and more recently has been linked to sciatica. To date no researchers formally have examined the incidence of bacterial wound contamination during spinal surgery. Surgical specimens were removed from 79 patients having spinal surgery for analysis using agar culture detection, broth enrichment, and immunofluorescence microscopy. Bacteria were identified in 29.1% of skin samples, 21.5% of tissue samples and 16.5% of washings retrieved from operative wounds. Propionibacterium acnes was identified more frequently than Staphylococcus spp in each of the three sample types. Bacteria were detected using enrichment in 9 (11%) patients and using fluorescence microscopy in 15 (19%). The results of immunofluorescence microscopy suggest that Propionibacterium acnes detected in wounds originates from patient skin. Bacteria from contaminated wounds appeared as single cells using fluorescence microscopy; however previous work shows that bacteria from infected hip prosthesis are observed as large aggregates. Therefore, it is suggested that immunofluorescence microscopy is a useful tool to help discriminate between surgical contamination and infection. LEVEL OF EVIDENCE: Diagnostic study, Level I (prospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Colony Count, Microbial↗

PubMed2005

Demonstration by PCR and DNA sequencing of Corynebacterium pseudodiphtheriticum as a cause of joint infection and isolation of the same organism from a surface swab specimen from the patient.

A case of infectious arthritis following arthroscopy is described. Real-time PCR, using universal bacterial primers targeting the 16S rRNA gene, and subsequent DNA sequencing of the PCR product demonstrated the presence of DNA from Corynebacterium pseudodiphtheriticum in the synovial fluid from the affected knee. Culture from a surface swab from the site of purulent discharge from the knee was initially reported as growing normal skin microbiota. Knowing the result of the DNA analysis, the specimen was re-examined and a diphtheroid bacterium was isolated. The DNA sequence of the isolated bacterium was identical to that of the DNA in the joint. The isolated bacterium was tested for susceptibility to relevant antibiotics. Demonstration and identification of bacterial DNA by PCR and gene sequencing may not by itself give information on important characteristics such as susceptibility to antibiotics of the infecting bacterium. The present case illustrates that the results obtained by the method can be used to isolate the relevant bacterium in culture from other sites and thereby characterize it. It furthermore demonstrates that C. pseudodiphtheriticum can cause severe arthritis when inoculated into joints.

Aged↗

PubMed2026

Antimicrobial resistance in Staphylococcus spp. isolated from sporotrichosis-affected cats in Brazil: Detection of MRSP and MRSA.

Recently, Brazil has experienced a zoonotic emergence of sporotrichosis. The associated cutaneous lesions are often extensive and slow to heal, thereby providing a gateway for opportunistic bacteria belonging to the normal skin microbiota. Among these, Staphylococcus spp. are of particular concern due to their high prevalence and notable levels of antimicrobial resistance. The objective of this study was to identify and characterize Staphylococcus spp. isolated from the cutaneous wounds of domestic cats undergoing treatment for sporotrichosis and exhibiting clinical signs of secondary bacterial infection. A total of 233 samples from 203 cats were analyzed. Staphylococcus spp. was isolated from 156 samples (67%), with S. aureus (42.3%) and S. felis (25.6%) being the most prevalent. Antimicrobial susceptibility testing revealed high levels of resistance to penicillin (51.9%), erythromycin (28.8%), and clindamycin (19.2%). In contrast, most isolates were susceptible to chloramphenicol (98%), ciprofloxacin (96.7%), and nitrofurantoin (93%). Multidrug-resistant strains were identified in 24% (38/156) of the isolates. Overall, 12 isolates (7.7%) were classified as methicillin-resistant staphylococci, including four methicillin-resistant S. pseudintermedius (MRSP) and one methicillin-resistant S. aureus (MRSA). To investigate the genetic profiles and epidemiological relationships of these isolates, all the MRSP and MRSA strains were subjected to whole-genome sequencing. Among the MRSP isolates, four sequence types (STs) were identified, including ST551, the founder of clonal complex (CC)551, which is commonly associated with infection in dogs. The MRSA isolate belonged to ST1176, a member of CC5, which is a globally prevalent lineage and is frequently associated with nosocomial infections in humans. This study demonstrates that Staphylococcus species, including methicillin-resistant isolates, are frequently present in the wounds of sporotrichosis-infected cats exhibiting clinical signs of secondary bacterial infection. The detection of MRSA and MRSP in a cat highlights an additional public health concern associated with feline sporotrichosis and further reinforces the growing concern regarding antimicrobial resistance in companion animals.

Animals↗

PubMed2002

Contaminated operating room boots: the potential for infection.

BACKGROUND: Dirty operating room boots, often contaminated with blood and other infected material, are not only a source of discontent among surgeons and other surgical personnel, but they also pose a potential risk of transmission of viral or bacterial diseases to the wearer and cleaner of the boots. METHOD: Operating room boots were examined for the presence of blood by visual inspection; the presence or absence of blood was confirmed by a specific biochemical test. Bacterial isolation and quantification from boots were performed with conventional methodology. RESULTS: In this study, a spot check revealed that 44% of all operating room boots tested were contaminated with blood and that the majority were contaminated with bacteria. Sixty-three percent of surgeons using the facility had blood-contaminated boots, and a significant number of boots belonging to other surgical personnel were also contaminated with blood and bacteria normally associated with skin microbiota or the environment. Comfort shoes with perforations on their upper surface and plastic boots commonly found in operating rooms were most heavily contaminated, whereas Wellington boots and clogs had less contamination. CONCLUSION: The present practice of manual cleaning of boots is unsatisfactory, and it is recommended that boots be washed in automatic washing machines.

Blood↗

PubMed2026

Causal Relationships Between Oral Microbiota and Inflammatory Skin Diseases.

INTRODUCTION AND AIMS: The oral microbiome has been increasingly linked to systemic inflammation and immune dysregulation, but whether specific oral bacteria causally contribute to inflammatory skin diseases remains unclear due to confounding and reverse causation. This study aimed to assess the causal effects of 43 oral microbiota taxa on the risk of five inflammatory skin diseases using a Mendelian randomization (MR) approach. METHODS: We performed a two-sample MR analysis using genetic instruments for oral microbiota derived from publicly available genome-wide association studies and outcome data from the FinnGen consortium. Causal effects of oral taxa on systemic lupus erythematosus, vitiligo, pemphigus, localized scleroderma, and dermatitis herpetiformis were estimated. The inverse-variance weighted method served as the primary analysis, complemented by sensitivity analyses to evaluate horizontal pleiotropy, heterogeneity, and reverse causality. RESULTS: MR analyses identified several putative causal associations between oral microbiota and inflammatory skin diseases. Genus Granulicatella and an unknown Streptococcus species (ASV0009) showed causal effects on systemic lupus erythematosus. Family Lachnospiraceae_[XIV] and an unknown Rothia species (ASV0016) were associated with vitiligo. Five oral microbiota taxa demonstrated causal associations with pemphigus. Actinomyces species micronuciformis was linked to localized scleroderma. Order Fusobacteriales and an unknown Neisseria species (ASV0004) were associated with dermatitis herpetiformis. No significant heterogeneity or horizontal pleiotropy was detected in sensitivity analyses. CONCLUSION: This MR study provides genetic evidence supporting a causal role of specific oral bacteria in the development of several inflammatory skin diseases, highlighting the oral microbiome as a potential contributor to cutaneous autoimmunity and inflammation. CLINICAL RELEVANCE: Our findings highlight the putative role of the oral microbiome as a plausible candidate for mechanistic and clinical investigations into the prevention or adjunctive management of selected inflammatory skin diseases. However, oral hygiene improvement, targeted antimicrobials, and other microbiota-directed interventions were not directly tested in this MR study and remain hypothetical strategies requiring validation in experimental and clinical studies.

Humans↗

PubMed2006

Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions.

Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broad-range PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin.

Adult↗

PubMed2025

Absolute quantification of the living skin microbiome overcomes relic-DNA bias and reveals specific patterns across volunteers.

BACKGROUND: As the first line of defense against external pathogens, the skin and its resident microbiota are responsible for protection and eubiosis. Innovations in DNA sequencing have significantly increased our knowledge of the skin microbiome. However, current characterizations do not discriminate between DNA from live cells and remnant DNA from dead organisms (relic DNA), resulting in a combined readout of all microorganisms that were and are currently present on the skin rather than the actual living population of the microbiome. Additionally, most methods lack the capability for absolute quantification of the microbial load on the skin, complicating the extrapolation of clinically relevant information. RESULTS: Here, we integrated relic-DNA depletion with shotgun metagenomics and bacterial load determination to quantify live bacterial cell abundances across different skin sites. Though we discovered up to 90% of microbial DNA from the skin to be relic DNA, we saw no significant effect of this on the relative abundances of taxa determined by shotgun sequencing. Relic-DNA depletion prior to sequencing strengthened underlying patterns between microbiomes across volunteers and reduced intraindividual similarity. We determined the absolute abundance and the fraction of population alive for several common skin taxa across body sites and found taxa-specific differential abundance of live bacteria across regions to be different from estimates generated by total DNA (live + dead) sequencing. CONCLUSIONS: Our results reveal the significant bias relic DNA has on the quantification of low biomass samples like the skin. The reduced intraindividual similarity across samples following relic-DNA depletion highlights the bias introduced by traditional (total DNA) sequencing in diversity comparisons across samples. The divergent levels of cell viability measured across different skin sites, along with the inconsistencies in taxa differential abundance determined by total vs live cell DNA sequencing, suggest an important hypothesis for certain sites being susceptible to pathogen infection. Overall, our study demonstrates a characterization of the skin microbiome that overcomes relic-DNA bias to provide a baseline for live microbiota that will further improve mechanistic studies of infection, disease progression, and the design of therapies for the skin. Video Abstract.

Humans↗

PubMed1998

Natural bioburden levels detected on flexible gastrointestinal endoscopes after clinical use and manual cleaning.

BACKGROUND: Colonoscopes present a special bacterial decontamination challenge because the colon has a large and diverse microbial population. METHODS: Bioburden of colonoscope insertion tube surfaces and suction channels were determined after use and after manual cleaning. RESULTS: After use bioburden in suction channels averaged 7.0 x 10(9) colony-forming units (cfu). Cleaning reduced this level to 1.3 x 10(5). Cleaning of tube surfaces reduced the after-use bioburden from a level of 5.1 x 10(5) to 2.2 x 10(4) cfu. Gram-negative rods accounted for approximately 99% of the bioburden within the suction channel after use and after cleaning. After use flora were predominantly Escherichia coli and Bacteroides. The flora shifted to waterborne Pseudomonas organisms, and other members of the family Enterobacteriaceae after cleaning. Gram-positive bacteria were the primary isolates from the device surfaces both after use (56%) and after cleaning (47%). Because gram-positive cocci and diphtheroids are a part of the normal microbiota of the skin, these bacteria may have been introduced by the hospital environment or by handling. CONCLUSIONS: After the cleaning of in-use colonoscopes, fewer than 10(6) vegetative bacteria could be recovered. This value is several logs lower than some previous estimates. This finding may be useful in the formulation of sterilization and disinfection cycles. Microflora from the colonoscopes indicated that the cleaning process introduced waterborne and enteric microorganisms, which highlights the importance of sanitation in the device reprocessing area.

Bacteria, Aerobic↗

PubMedDate not supplied

Malassezia furfur folliculitis in cancer patients. The need for interaction of microbiologist, surgical pathologist, and clinician in facilitating identification by the clinical microbiology laboratory.

Malassezia furfur (MF) is a lipophilic yeast which can be found as a member of the indigenous microbiota of human skin. In immunocompromised transplant patients, MF can cause a distinctive folliculitis which is a clinical look-alike to Candida folliculitis, the latter of more potentially devastating significance. Recovery of MF in culture is dependent upon the addition to culture media of an exogenous source of fatty acids, such as olive oil. The addition of an extra Sabourauds plate with an olive oil overlay to the routine set of media used to inoculate all skin biopsy specimens in order to detect MF is labor-intensive and not cost-effective. Thus, MF may not be isolated in cases of MF folliculitis unless the clinical microbiology laboratory is put on alert by the clinical suspicions of the attending physician, or by histopathologic findings suggestive of folliculitis revealed by review of surgical pathology slides. The clinical, pathological, and microbiological findings of two cases of MF folliculitis are presented where an interactive approach featuring communication between the microbiologist, the surgical pathologist, and the clinician guided the microbiology laboratory to the isolation and identification of isolates of MF that were clinically-relevant. These cases underscore how a combined approach which features communication between the laboratory and the clinical services always provides superior guidance in the diagnosis and therapy of infectious diseases.

Adult↗

PubMed2025

A comprehensive reference catalog of human skin DNA virome reveals novel viral diversity and microenvironmental influences.

UNLABELLED: Human skin serves as a dynamic habitat for a diverse microbiome, including a complex array of viruses whose diversity and roles are not fully understood. A total of 2,760 skin metagenomes from 6 published skin studies were collected. A skin virome catalog was constructed using standard methods in the viromics field. Viral characteristics were identified through cross-cohort meta-analysis and used to characterize viral features across different skin environments. We identified 20,927 viral sequences, which clustered into 2,873 viral operational taxonomic units (vOTUs), uncovering a substantial breadth of viral diversity on human skin. The results also highlight significant differences in viral communities that are associated with varying skin microenvironments. The oily skin is enriched in Papillomaviridae, the dry skin area is enriched in Autographiviridae and Inoviridae, and the moist skin is enriched in Herelleviridae. We also investigated the relationship between bacteriophages and bacteria on the skin surface. We found that skin bacteria such as Pseudomonas, Klebsiella, and Staphylococcus are predicted to be infected by phages from the class Caudoviricetes. This comprehensive skin DNA viral catalog significantly advances our understanding of the virome's role within the skin ecosystem. IMPORTANCE: This study presents a comprehensive reference catalog of the human skin DNA virome, constructed from 2,760 metagenomic datasets collected globally. It identified 20,927 viral sequences, with 90.85% representing previously unknown viruses, greatly expanding our understanding of skin viral diversity. The findings reveal significant differences in viral communities between distinct skin microenvironments (oily, dry, and moist) and highlight close interactions between bacteriophages and their bacterial hosts, suggesting a potential role for the virome in maintaining microbial balance and skin health. This extensive skin viral catalog constitutes a crucial resource for future epidemiological and therapeutic research, potentially facilitating the development of novel phage therapies and diagnostic markers for skin disorders.

Humans↗

PubMed2006

Assembly of the human intestinal microbiota.

Complex microbial ecosystems occupy the skin, mucosa and alimentary tract of all mammals, including humans. Recent advances have highlighted the tremendous diversity of these microbial communities and their importance to host physiology, but questions remain about the ecological processes that establish and maintain the microbiota throughout life. The prevailing view, that the gastrointestinal microbiota of adult humans is a climax community comprised of the superior competitors for a stable set of niches, does not account for all of the experimental data. We argue here that the unique history of each community and intrinsic temporal dynamics also influence the structure of human intestinal communities.

Humans↗

PubMed2025

Impact of the maternal microbiome on neonatal immune development.

Historically, multigenerational health and disease transmission have primarily focused on genetic inheritance. However, the discovery that beneficial microorganisms known as commensal microbiota outnumber human genes tenfold has reshaped this perspective, highlighting their critical role in maintaining homeostasis and protecting against pathogens. Unlike the human genome, commensal microbiota is not genetically inherited but is acquired anew with each generation. with initial gut colonization playing a pivotal role in shaping an infant's immune system, neurodevelopment, and long-term health, all heavily influenced by maternal factors. In this review, we examine emerging research on maternal microbial influences on the fetus beginning in utero. We provide an updated overview of the current insights into the impact of the vaginal microbiome during parturition on offspring immunity and discuss the potential long-term health implications for infants born via cesarean section. We explore the advantages and limitations of techniques designed to mitigate these effects, such as vaginal seeding and emphasize that the development of the neonatal immune system is a dynamic process influenced by maternal factors beyond birth, including the transfer of microbiota through breast milk and skin contact. Finally, we present gaps in current research and propose future research directions to deepen our understanding of the impacts of the maternal microbiome on her child. Together, these insights demonstrate how maternal influence on offspring health and immunity extends beyond genetic factors, encompassing the transmission of microbiota, which, in turn, has profound long-term implications for health and disease resilience, offering a novel perspective on intergenerational health dynamics.

Humans↗

PubMed2026

Exploring the ecological drivers of bacteriophage diversity and functional viral potential in the skin of the axolotl Ambystoma altamirani.

Bacteriophages play important roles in shaping microbial community dynamics across diverse environments. In the amphibian skin, most microbiome studies have focused on bacteria and their interactions with the fungus Batrachochytrium dendrobatidis (Bd), leaving other microbial components, including viruses, largely unexplored. Here, we present the first characterization of the viral community in the amphibian skin microbiome, focusing on ecological drivers of bacteriophage diversity and functional potential in the axolotl Ambystoma altamirani. Using public shotgun metagenomes, we found that the viral fraction was dominated by bacteriophages of the class Caudoviricetes. Bacteriophage diversity was significantly associated with local physicochemical parameters at the time of sampling, and showed a strong positive correlation with bacterial diversity, whereas no significant associations were detected with the presence of Bd. In addition, seasonality influenced the composition and properties of bacteria-bacteriophage co-abundance networks. Functional annotation of assembled bacteriophage sequences revealed a diverse functional potential, including putative auxiliary metabolic genes, superinfection exclusion, toxin-antitoxin, and virulence factors. Overall, these findings highlight the ecological relevance of bacteriophages in amphibian skin microbiomes and underscore the need for further studies on their role in the amphibian host's health.

Animals↗

PubMed2002

A comparative review of cutaneous pH.

This review describes the role of pH in cutaneous structure and function. We first describe the molecules that contribute to the acidity or alkalinity of the skin. Next, differences in cutaneous pH among species, among individuals of the same species and within individuals are described. The potential functions of cutaneous pH in normal and diseased skin are analysed. For example, cutaneous pH has a role in the selection and maintenance of the normal cutaneous microbiota. In addition, cutaneous acidity may protect the skin against infection by microbes. Finally, there is evidence that a cutaneous pH gradient activates pH-dependent enzymes involved in the process of keratinization.

Animals↗