Search Results (117)

Allergic rhinitis (AR) is a common heterogeneous chronic disease characterized by high prevalence, complex pathogenesis, and susceptibility to multiple contributing factors. Currently, its prevalence ranges from 20% to 30% in adults and reaches up to 40% in children. Extensive research has confirmed significant differences in nasal microbiota composition between AR patients and healthy individuals, most notably alterations in the abundance of four dominant phyla: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Among these, the most striking abundance alterations occur in Staphylococcus aureus and Streptococcus salivarius within the nasal mucosa of AR patients, suggesting a critical role of nasal microbiota in AR initiation and progression. In response, researchers have proposed microbiome-targeted therapeutic strategies. For example, nasal local administration of probiotics (e.g., Lactobacillus and Bifidobacterium) aims to reshape the nasal microbiota. Additionally, protective bacteria such as Corynebacterium accolens and Dolosigranulum pigrum can inhibit pathogenic bacteria, thereby correcting microbial dysbiosis and alleviating AR symptoms. This review summarizes the composition of the nasal microbiota, the latest research progress on its association with AR, and the underlying potential mechanisms. It provides novel insights and potential therapeutic strategies for the prevention and treatment of AR. Full article

Background: The human microbiome holds promise for identifying biomarkers and therapeutic targets. In obesity, interactions between oral and gut communities are increasingly implicated and end in organ injury. Methods: From the IMAGINE study, we analyzed 418 shotgun metagenomes from three specimen types (dental plaque (n = 143; 65 non-obese, 78 obese), saliva (n = 166; 75 non-obese, 91 obese), and stool (n = 109; 57 non-obese, 52 obese)) to compare site-specific microbial shifts between obese (BMI > 30 kg/m²) and non-obese individuals. Differential abundance was assessed with ANCOM-BC; effect sizes were summarized as Cohen’s d. Results: Across all samples, we detected 240 bacterial species in plaque, 229 in saliva, and 231 in stool, with 46 species present across all three sites. Absolute effect sizes were significantly larger in plaque (mean |d| = 0.26) and saliva (0.25) than in stool (0.21; p = 9 × 10⁻³). Several taxa showed an opposite directionality between oral and gut sites, including Streptococcus salivarius and Bifidobacterium longum, indicating site-specific associations. Notably, Actinomyces sp. and Streptococcus sp. exhibited promising effect sizes as diagnostic markers. Conclusions: The oral and gut microbiomes capture complementary obesity-related signals, with stronger shifts observed in oral sites. We suggest that integrating oral and gut profiling could enhance diagnostic and therapeutic strategies in obesity. Full article

Streptococcus salivarius (S. salivarius) is a prominent oral commensal bacterium with probiotic potential and relevance to both oral and systemic health. Accurate and accessible methods for quantitative measurement of this species are needed to support microbiota studies and clinical interventions. We describe a simple, low-cost, culture-based method for quantifying S. salivarius in human saliva using Mitis-Salivarius Agar. Saliva samples from 18 healthy adult volunteers were analyzed through serial dilutions and selective plating. CFU (colony forming unit)/mL were calculated after 24 and 48 h incubation. The method proved reliable for quantifying S. salivarius in concentrations ranging from 5.8 × 10⁵ to 6.1 × 10⁸ CFU/mL. Although Mitis-Salivarius Agar is a standard medium, we demonstrate its systematic validation and optimization for human saliva in a low-resource clinical setting, where molecular tools are often unavailable. Full article

This study evaluated the safety, antimicrobial activity, and upper gastrointestinal gastroprotection of a postbiotic powder derived from Lactobacillus salivarius AP-32, Lactobacillus paracasei ET-66, and Lactobacillus plantarum LPL28. Safety assessments were performed in rodent models through acute and subchronic oral toxicity tests, genotoxicity assays, and biogenic amine analysis. No signs of toxicity were observed in either the acute (20 g/kg body weight, BW) or subchronic (3 g/kg BW) toxicity tests. Genotoxicity evaluations indicated no mutagenic activity in the Ames test (≤5000 µg/plate) and no chromosomal or micronuclear abnormalities in the spermatocyte or the peripheral blood assays (≤10 g/kg BW). Biogenic amines were undetectable in the postbiotic powder, further reinforcing its safety. The postbiotic powder showed significant direct antimicrobial activity. Additionally, it enhanced the inhibitory effects of probiotics against key upper gastrointestinal pathobionts including Streptococcus mutans, Porphyromonas gingivalis, Fusobacterium nucleatum subsp. polymorphum, and Actinobacillus actinomycetemcomitans, Helicobacter pylori. Moreover, the postbiotic powder demonstrated gastroprotective effects by promoting recovery in a hydrogen peroxide-induced gastric injury model. Based on these findings, the postbiotic powder is safe, non-toxic, and suitable for oral consumption at the tested doses, with promising antimicrobial and gastroprotective potential. Future research should explore its potential applications in health promotion and food safety. Full article

Background: With the increasing popularity and diversification of cosmetic products, an expanding number of retail stores are providing in-store testers to allow consumers to try products before purchasing. However, growing concerns have been raised about microbial contamination and the associated risk of infection due to the shared use of these testers. This study aimed to investigate consumer awareness and perceived susceptibility to microbial infection associated with the use of lip cosmetic testers, and to identify major pathogenic bacteria, thereby offering evidence to support the need for improved hygiene management practices. Methods: The survey examined the use of lip cosmetic testers and related side effects, as well as perceptions of product hygiene and microbial contamination. Awareness of microbial infection and consumer sensitivity to product safety were measured using a five-point Likert scale. Microorganisms were detected through PCR analysis of genomic DNA. Results: Among 134 respondents, 95% had previously used lip cosmetic testers, and 90% recognized the potential for microbial contamination. Sensitivity to product safety was not significantly associated with sociodemographic factors. However, susceptibility to microbial infection from tester use was significantly higher among participants of older age and with higher education levels. PCR analysis of lip cosmetic testers revealed frequent detection of Staphylococcus epidermidis and Pseudomonas aeruginosa. Other detected bacteria included Streptococcus oralis, Streptococcus salivarius, Streptococcus pneumoniae, and Escherichia coli, all of which are known to cause oral and respiratory infections. Conclusions: The analysis revealed that the majority of individuals who have used lip cosmetic testers expressed a high level of concern regarding product contamination and the potential for infection. Multiple pathogenic bacteria linked to oral and respiratory diseases were identified in the opened tester products. These findings underscore the necessity of establishing regulatory guidelines for the management of lip cosmetic testers and highlight the importance of enhancing consumer awareness regarding hygiene practices. Full article

Background/Objectives: There are many commercial mouthrinses, used for a variety of purposes, including antiseptic activity. The objective of this study was to determine the antibacterial activity of various TheraBreath™ oral rinses against the cariogenic bacterium, Streptococcus mutans, and saliva-derived microbial communities, and their antibiofilm activity against S. mutans in vitro biofilms. Methods: Bactericidal activity against planktonic S. mutans was assessed by colony counting after 30 and 2 min exposures to mouthrinses. Ten saliva samples were exposed to mouthrinses for 30 s and plated aerobically on blood agar and Mitis Salivarius agar. Mature biofilms of S. mutans were treated with mouthrinses for 15 min followed by fluorescent vitality staining and polysaccharide measurement, followed by crystal violet staining for measurement of total biofilm remaining. Statistical analysis was performed using Kruskal–Wallis with Dunn’s multiple comparisons test comparing all mean ranks (α = 0.05). Results: TheraBreath™ Fresh Breath, Healthy Smile, and Dry Mouth exhibited no significant antibacterial activity. TheraBreath™ Healthy Gums showed antibacterial activity against S. mutans and microbes from saliva samples similar to Listerine^® Naturals at all exposure times. Whitening Fresh Breath showed intermediate killing of S. mutans after 30 min in liquid but not after 2 min or against salivary microbes. Live/Dead fluorescence vitality staining showed that Healthy Gums and Whitening Fresh Breath had antibacterial activity against mature biofilms of S. mutans statistically similar to Listerine^® Naturals and Colgate^® Total; however, Whitening Fresh Breath did not have significant killing compared to PBS. Conclusions: TheraBreath™ Healthy Gums demonstrated similar antiseptic activity levels to other antiseptic-claiming commercial rinses. Whitening Fresh Breath was comparable but unable to kill in short exposure times. Full article

Human milk bacteria contribute to gut microbiome establishment in breastfed infants. Although breastfeeding is recommended throughout infancy, temporal variation in the milk microbiome—particularly beyond solid food introduction—remains understudied. We analyzed 539 milk samples from 83 mother–infant dyads between 1 week and 12 months postpartum using full-length 16S rRNA gene sequencing. The microbiota was dominated by Streptococcus (34%), Cutibacterium (12%), and Staphylococcus (9%), with marked inter-individual variation. Microbiome profiles remained largely stable across lactation, with only six taxa showing temporal fluctuations, including increases in typical oral bacteria such as Streptococcus salivarius, Streptococcus lactarius, Rothia mucilaginosa, and Granulicatella adiacens. Richness and evenness were higher at 1 week compared to 1 month postpartum (p = 0.00003 and p = 0.007, respectively), then stabilized. Beta diversity also remained stable over time. Maternal pre-pregnancy BMI was positively associated with Gemella haemolysans (p = 0.016), while Haemophilus parainfluenzae was more abundant in milk from mothers with allergies (p = 0.003) and those who gave birth in autumn or winter (p = 0.006). The introduction of solid food was linked to minor taxonomic shifts. Overall, the milk microbiome remained robustly stable over the first year of lactation, with limited but notable fluctuations in specific taxa. This study supports the role of human milk as a consistent microbial source for infants and identifies maternal BMI, allergy status, and birth season as key variables warranting further investigation. Full article

Three-dimensional (3D) scaffold systems have proven instrumental in advancing our understanding of polymicrobial biofilm dynamics and probiotic interactions within the oral environment. Among oral probiotics, Streptococcus salivarius K12 (Ssk12) has shown considerable promise in modulating microbial homeostasis; however, its long-term therapeutic benefits are contingent upon successful and sustained colonization of the oral mucosa. Despite its clinical relevance, the molecular mechanisms underlying the adhesion, persistence, and integration of Ssk12 into the native oral microbiome/biofilm remain inadequately characterized. In this pilot study, we explored the temporal colonization dynamics of Ssk12 and its impact on the structure and functional profiles of salivary-derived biofilms cultivated on melt-electrowritten poly(ε-caprolactone) (MEW-mPCL) scaffolds, which emulate the native oral niche. Colonization was monitored via fluorescence in situ hybridization (smFISH), confocal microscopy, and RT-qPCR, while shifts in community composition and function were assessed using 16S rRNA sequencing and meta-transcriptomics. A single administration of Ssk12 exhibited transient colonization lasting up to 7 days, with detectable presence diminishing by day 10. This was accompanied by short-term increases in Lactobacillus and Bifidobacterium populations. Functional analyses revealed increased transcriptional signatures linked to oxidative stress resistance and metabolic adaptation. These findings suggest that even short-term probiotic colonization induces significant functional changes, underscoring the need for strategies to enhance probiotic persistence. Full article

Background: Halitosis is frequently observed in patients undergoing orthodontic treatment with multibracket appliances, primarily due to volatile sulfur compounds (VSCs) produced by oral anaerobic bacteria. Cetylpyridinium chloride (CPC) is a widely used antimicrobial agent in oral care products and may help alleviate halitosis.This study aimed to evaluate the effects of 0.05% CPC mouthwash on halitosis, oral hygiene indices, and the tongue microbiota in orthodontic patients with elevated VSC levels. Methods: In this randomized, double-blind, placebo-controlled clinical trial, 30 orthodontic patients with elevated VSCs (≥150 ppb) were assigned to a CPC mouthwash group or a placebo group. Participants used the assigned mouthwash three times daily for 1 month. Halitosis was quantitatively assessed by gas chromatography (Oral Chroma™), and oral hygiene parameters including Plaque Index (PI), Gingival Index (GI), Tongue Coating Index (TCI), and unstimulated salivary flow rate were evaluated at baseline and after the intervention. The tongue microbiota was analyzed by 16S rRNA sequencing. Results: The CPC mouthwash group showed significant reductions in total VSCs, hydrogen sulfide, methyl mercaptan, PI, GI, and TCI (p < 0.05), while salivary flow rate and dimethyl sulfide remained unchanged. Microbiome analysis revealed decreases in halitosis-associated genera (Actinomyces, Corynebacterium, Tannerella) and increases in beneficial species such as Streptococcus salivarius. Conclusions: CPC mouthwash (0.05%) effectively reduced halitosis and improved oral hygiene parameters in orthodontic patients, likely through modulation of the tongue microbiota. This mouthwash may serve as a safe and practical adjunct to conventional oral hygiene practices during orthodontic treatment. Full article

A diverse bacterial community colonizes the respiratory system, including commensals such as Staphylococcus epidermidis (S. epidermidis) and Streptococcus salivarius (S. salivarius), as well as facultative pathogens like Staphylococcus aureus (S. aureus). This study aimed to establish a colonized cell culture model to investigate the impact of these bacteria on influenza A virus (IAV) infection. Respiratory epithelial cells were exposed to S. epidermidis, S. salivarius, or S. aureus, using either live or heat-inactivated bacteria, followed by IAV infection. Cell integrity was assessed microscopically, cytotoxicity was measured via LDH assay, and inflammatory responses were analyzed through cytokine expression. Additionally, macrophage function was examined in response to bacterial colonization and IAV infection. While commensals maintained epithelial integrity for 48 h, S. aureus induced severe cell damage and death. The most pronounced epithelial destruction was caused by coinfection with S. aureus and IAV. Notably, commensals did not confer protection against IAV but instead enhanced epithelial inflammation. These effects were dependent on live bacteria, as inactivated bacteria had no impact. However, prior exposure to S. epidermidis and S. salivarius improved macrophage-mediated immune responses against IAV. These findings suggest that while individual commensals do not directly protect epithelial cells, they may contribute to immune training and enhance lung defense mechanisms. Full article

In poultry production, antibiotics have been excessively used as growth promoters to support well-being and decrease mortality caused by pathogenic microorganisms. The overuse of antibiotics has led to the emergence of antibiotic-resistant bacteria and the presence of antibiotic residues in poultry products. To counteract this problem, probiotics could be used as adjuncts or as substitutes for preserving a diverse and balanced microflora to prevent the colonization and multiplication of pathogenic bacteria in the GI tract. This study aimed to isolate and characterize the potential probiotic properties of lactic acid bacteria from the small intestine of 23-week-old broiler breeders, with the goal of identifying potential probiotic candidates. Four phenotypically healthy broiler breeders were selected, and intestinal contents were aseptically collected and cultured on MRS agar. From the initial pool of 39 colonies, six isolates were identified based on Gram-positive and catalase-negative characteristics and further classified using 16S rRNA sequencing as Levilactobacillus brevis (n = 3), Pediococcus pentosaceus (n = 2), and Streptococcus salivarius (n = 1). These strains were further evaluated for probiotic properties such as transit resistance to simulated upper gastrointestinal conditions, antagonist activity, haemolytic activity, and cell surface properties such as autoaggregation, co-aggregation and hydrophobicity, in vitro. L. brevis NKFS8 showed good tolerance to pH 3, while P. pentosaceus NKSF10 exhibited good tolerance to pH 4 acidic conditions. All isolates demonstrated good survivability in bile salt concentration of 3% (w/v), with P. pentosaceus NKSF10 exhibiting the highest tolerance. The isolates showed a wide range of antagonistic activity against the test pathogens Pseudomonas aeruginosa (ATCC 27853), Salmonella typhimurium, Salmonella enterica (ATCC 13314), Staphylococcus aureus (ATCC 29213), and Listeria monocytogenes (ATCC 7644). Furthermore, these strains exhibited good auto-aggregation, co-aggregation, and hydrophobicity properties. In conclusion, lactic acid bacteria from the small intestine of broiler breeders present a valuable prospect for the development of effective probiotics. These probiotics can be utilized as a supplementary inclusion in poultry feed, obviating the need for antibiotics as growth promoters. Nevertheless, additional in vivo studies are required to closely monitor and assess the effects of probiotics on the gastrointestinal system of chickens. Full article

Yogurt and postbiotics are both beneficial for intestinal health of pets. This study was conducted to investigate the effects of yogurt with postbiotics in cats. A total of 18 adult cats were randomly divided into three groups, CK group (Control n = 6, free feeding and drinking without any probiotic products), Y group (Yogurt, n = 6, 50 g/day), and YP group (Yogurt + 2% postbiotics, 50 g/day), with the same environment and diet. On the 21st day, blood and fecal samples were collected and tested for biochemical indices, immunological parameters, inflammatory factors, and fecal flora, respectively. The results showed that feeding postbiotic yogurt to cats significantly reduced the levels of total bilirubin (TBIL), total bile acids (TBA), triglycerides (TG), glucose (GLU), urea nitrogen (BUN), creatinine (CREA), tumor necrosis factor-alpha (TNF-α), and Interleukin-6 (IL-6) (p < 0.05), and significantly increased Immunoglobulin A (sIgA) (p < 0.05) compared to the CK group. The abundance of Bifidobacterium in YP group was elevated, the Shannon violin plots showed that the intestinal flora of the YP group was less dispersed. Notably Enterococcaceae and Enterococcus were significantly elevated in the Y group (p < 0.05) and Streptococcus salivarius subsp. thermophilus in the YP group (p < 0.05). Therefore, this study suggests that yogurt with postbiotic is a good choice for improving intestinal health and immune function in cats and possesses good research and application prospects. Full article

The study of bacteriocins has significantly enhanced our understanding of microbial interactions, notably within the genus Streptococcus. Among the most functionally diverse and clinically relevant bacteriocins are those belonging to the lantibiotic class, which exhibit potent antimicrobial properties and are central to the competitive dynamics of streptococcal species. This review focuses on the discovery and characterization of bacteriocins produced by Streptococcus pyogenes and Streptococcus salivarius, emphasizing their biological significance within their exclusive human host. A cornerstone of these studies has been the development and application of the pioneer agar culture-based bacteriocin detection methodology, known as streptococcal bacteriocin fingerprinting. This approach has proven invaluable for the initial detection and differentiation of a wide array of bacteriocin-like inhibitory substances (BLIS) in streptococcal populations. A central theme of this review is the diverse biological roles of lantibiotics in S. pyogenes and S. salivarius, particularly in relation to microbial competition, colonization dynamics, and host interactions. The expression of lantibiotic determinants provides distinct advantages to the producing strain, including enhanced niche establishment and the ability to suppress competing microbes. Furthermore, the presence of specific lantibiotic immunity mechanisms safeguards the producer from self-inhibition and potential antagonism from closely related competitors. In S. pyogenes, lantibiotic production has been implicated in virulence modulation, raising important questions about its role in pathogenicity and host immune evasion. Conversely, S. salivarius, a prominent commensal and probiotic candidate species, utilizes its lantibiotic arsenal to confer colonization benefits and mediate beneficial interactions, especially within the oral and upper respiratory tract microbiomes. The implications of in situ lantibiotic expression extend beyond microbial ecology, presenting opportunities for innovative probiotic and therapeutic applications. The potential for harnessing bacteriocin-producing streptococci in antimicrobial interventions, particularly in combating antibiotic-resistant pathogens, underscores the translational relevance of these findings. This review integrates historical and contemporary perspectives on streptococcal bacteriocin research, providing insights into future avenues for leveraging these bioactive peptides in clinical and biotechnological contexts. Full article

Background/Objectives: The overuse and misuse of antibiotics has contributed significatively to the growing problem of the emergence and spread of antibiotic resistance genes among bacteria, posing a serious global challenge to the treatment of bacterial infectious diseases. For these reasons, there is a current and growing interest in the development of effective alternative or complementary strategies to antibiotic therapy for the prevention of fish diseases, which are mainly based on the use of probiotics—in particular, those belonging to the Lactic Acid Bacteria (LAB) group. In this context, the aim of the present study was to characterise, evaluate the genetic diversity and assess the safety of candidate probiotic LAB strains for aquaculture isolated from faeces and intestines of European hakes (Merluccius merluccius, L.) caught in the Northeast Atlantic Ocean (Ireland). Methods: The direct antimicrobial activity of the LAB isolates was tested by the Stab-On-Agar method against key ichthyopathogens. Subsequently, their taxonomic classification and genetic diversity were determined by 16SrDNA sequencing and Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR), respectively. To ensure the in vitro safety of the LAB isolates, their biofilm-forming ability was assessed by a microtiter plate assay; their sensitivity to major antibiotics used in aquaculture, human and veterinary medicine by a broth microdilution method and their haemolytic and gelatinase activity by microbiological assays. Results: All LAB isolates were biofilm producers and susceptible to chloramphenicol, oxytetracycline, flumequine and amoxicillin. A total of 30 isolates (85.7%) were resistant to at least one of the tested antibiotics. None of the 35 LAB isolates showed haemolytic or proteolytic activity. Conclusions: Among the isolated strains, five LAB strains exhibiting the highest antimicrobial activity against aquaculture-relevant ichthyopathogens, taxonomically identified as Streptococcus salivarius, Enterococcus avium and Latilactobacillus sakei, were selected for further characterisation as potential probiotic candidates to promote sustainable aquaculture. To our knowledge, this is the first study to report that hake intestines and faeces represent viable ecological niches for the isolation of LAB strains with antimicrobial activity. Full article

Starter culture significantly influences the texture and flavor of yogurt, making the selection of appropriate fermentation strains a key focus in yogurt starter research. In this study, protease-producing Lactiplantibacillus plantarum NH-24, identified in prior experiments, was combined with Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophiles for yogurt fermentation. Indicators such as coagulation state, acidity, and water-holding capacity were measured to determine the optimal fermentation temperature and starter ratio. Additionally, the effects of this strain on the yogurt’s texture, sensory properties, and volatile flavor compounds were evaluated. The results indicate that a fermentation temperature of 37 °C and a starter ratio of 4:4:3 were most suitable for yogurt production. Further analysis demonstrated that incorporating Lp. plantarum NH-24 improved the yogurt’s texture and flavor while reducing post-acidification during storage. Thus, protease-producing Lp. plantarum NH-24 holds significant promise as a yogurt starter culture. Full article