Safety Assessment of Streptococcus salivarius UBSS-01 in Rats and Double-Blind Placebo-Controlled Study in Healthy Individuals.

Streptococcus salivarius is a common, harmless, and prevalent member of the oral microbiota in humans. In the present study, the safety of S. salivarius UBSS-01 was evaluated using in silico methods and preclinical and clinical studies. In an acute toxicity study, rats were administered with 5 g/kg (500 × 109 CFU) S. salivarius UBSS-01. The changes in phenotypic behaviors and hematological, biochemical, electrolytes, and urine analyses were monitored. No toxicity was observed at 14 days post-treatment. The no observable effects limit (NOEL) of S. salivarius UBSS-01 was >5 g/kg in rats. In a 28-day repeat dose toxicity study, rats were administered S. salivarius UBSS-01 once daily at doses of 0.1, 0.5, and 1 g/kg (10, 50, and 100 billion CFU/kg, respectively) body weight. S. salivarius UBSS-01 did not influence any of the hematology parameters and clinical chemistry parameters in plasma and serum samples after 28-day repeated administration. No structural abnormality was observed in the histological examination of organs. Whole genome analysis revealed the absence of virulence factors or genes that may transmit antibiotic resistance. In the double-blind study with 60 human participants (aged 18-60 years), consumption of S. salivarius UBSS-01 for 30 days was found to be safe and results were comparable with placebo treatment These findings indicate that S. salivarius UBSS-01 may be safe for human consumption.

Mendelian randomization analysis reveals a causal effect of Streptococcus salivarius on diabetic retinopathy through regulating host fasting glucose.

Diabetic retinopathy (DR) is one of leading causes of vision loss in adults with increasing prevalence worldwide. Increasing evidence has emphasized the importance of gut microbiome in the aetiology and development of DR. However, the causal relationship between gut microbes and DR remains largely unknown. To investigate the causal associations of DR with gut microbes and DR risk factors, we employed two-sample Mendelian Randomization (MR) analyses to estimate the causal effects of 207 gut microbes on DR outcomes. Inputs for MR included Genome-wide Association Study (GWAS) summary statistics of 207 taxa of gut microbes (the Dutch Microbiome Project) and 21 risk factors for DR. The GWAS summary statistics data of DR was from the FinnGen Research Project. Data analysis was performed in May 2023. We identified eight bacterial taxa that exhibited significant causal associations with DR (FDR < 0.05). Among them, genus Collinsella and species Collinsella aerofaciens were associated with increased risk of DR, while the species Bacteroides faecis, Burkholderiales bacterium_1_1_47, Ruminococcus torques, Streptococcus salivarius, genus Burkholderiales_noname and family Burkholderiales_noname showed protective effects against DR. Notably, we found that the causal effect of species Streptococcus salivarius on DR was mediated through the level of host fasting glucose, a well-established risk factor for DR. Our results reveal that specific gut microbes may be causally linked to DR via mediating host metabolic risk factors, highlighting potential novel therapeutic or preventive targets for DR.

Streptococcus salivarius K12 Alleviates Oral Mucositis in Patients Undergoing Radiotherapy for Malignant Head and Neck Tumors: A Randomized Controlled Trial.

PURPOSE: Oral mucositis (OM) is a common debilitating toxicity associated with radiotherapy (RT) for malignant head and neck tumors. This prospective, randomized, double-blind, placebo-controlled trial aimed to evaluate the efficacy and safety of Streptococcus salivarius K12 (SsK12) in reducing the incidence, duration, and severity of severe OM (SOM). METHODS: A total of 160 patients with malignant head and neck tumors undergoing definitive or postoperative adjuvant RT were randomly assigned (1:1) to receive SsK12 probiotic (n = 80) or placebo (n = 80) at West China Hospital, Sichuan University, Chengdu, China. Patients were instructed to suck SsK12 or placebo lozenges thrice daily from the initiation to the end of RT. OM was evaluated twice a week during RT and once a week thereafter for up to 8 weeks. The primary end point was the incidence of SOM. Adverse events were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. RESULTS: Baseline patient characteristics were similar in the SsK12 and placebo groups. The incidence of SOM was significantly lower in the SsK12 group as compared with the placebo group (36.6% v 54.2%; P = .0351). The duration (median, 0.0 days v 7.0 days; mean, 8.9 days v 18.3 days; P = .0084) and time to develop SOM (median, not estimable v 42.0 days; hazard ratio, 0.55 [95% CI, 0.34 to 0.89]; log-rank test: P = .0123) were also improved in the case of the SsK12 group. Adverse events were similar between the groups, and mild or moderate gastrointestinal reactions (flatulence or dyspepsia) associated with the lozenges were observed in two patients in the SsK12 group. High-throughput sequencing results indicated that SsK12 inhibited opportunistic pathogens and enriched oral commensals during RT. CONCLUSION: In this prospective, randomized clinical trial, SsK12 probiotic significantly reduced the incidence, onset, and duration of SOM with a good safety profile.

Streptococcus salivarius subsp. thermophilus CCFM1312 enhanced mice resilience to activity-based anorexia.

Probiotic intervention, already showing promise in the treatment of various psychiatric disorders like depression, emerges as a potential therapy for anorexia nervosa (AN) with minimal side effects. In this study, we established an activity-based anorexia (ABA) model to probe the pathogenesis of AN and assess the impact of probiotics on ABA mice. ABA resulted in a compensatory increase in duodenal ghrelin levels, impairing the regulation of feeding and the brain reward system. Intervention with Streptococcus salivarius subsp. thermophilus CCFM1312 ameliorated these ABA-induced effects, and the activation of neurons in the nucleus tractus solitarius (NTS) was observed following probiotic administration, revealing the advantageous role of probiotics in AN through the vagus nerve. Furthermore, our metabolomics analysis of cecal contents unveiled that S. salivarius subsp. thermophilus CCFM1312 modulated gut microbiota metabolism and thereby regulated intestinal ghrelin levels.

Noniatrogenic Meningitis Caused by Streptococcus salivarius Associated with Early Esophageal Cancer and Early Gastric Cancer.

Streptococcus salivarius is part of the normal oral cavity and gastrointestinal tract microflora and an unusual cause of acute bacterial meningitis. We herein report an 81-year-old man with S. salivarius meningitis, which led to a diagnosis of early esophageal cancer and early gastric cancer. S. salivarius infection may occur through the gastrointestinal mucosa when it is disrupted in association with early gastrointestinal cancer. To our knowledge, this is the first report describing S. salivarius meningitis associated with multiple early gastrointestinal cancers in the absence of other sources of infection.

Streptococcus salivarius Probiotics to Prevent Acute Otitis Media in Children: A Randomized Clinical Trial.

Importance: New approaches for the prevention of acute otitis media (AOM), the most common reason for antibiotic use in children, are needed. Objective: To assess the efficacy of the Streptococcus salivarius K12 oral probiotics in the primary prevention of AOM. Design, Setting, and Participants: This double-blind, randomized placebo-controlled clinical trial was conducted from August 1, 2020, to May 31, 2021, at 50 day care centers in the Oulu region of Finland. A total of 827 children aged 1 to 6 years attending day care were included. The exclusion criteria consisted of ongoing antimicrobial prophylaxis or immunodeficiency. The follow-up time was 6 months and was completed on May 31, 2021. Data were analyzed from October 24, 2022, to September 16, 2023, based on intention to treat. Intervention: Eligible participants were randomly allocated to receive 1 daily dose of a S salivarius K12 product or placebo every evening for 6 months. A daily dose was defined as 1 sachet of soluble oral powder for children younger than 3 years or 1 chewable tablet for children 3 years or older containing 1 × 109 colony-forming units of S salivarius K12. Main Outcomes and Measures: The primary outcome was the proportion of children with at least 1 episode of AOM requiring antimicrobial therapy within 6 months of randomization. All physician visits and purchases of antimicrobial drugs were retrieved from the electronic national medical record and prescription register. The primary outcome was met if the legal guardian had purchased an antimicrobial prescription for AOM. Results: A total of 827 children with a mean (SD) age of 4.1 (1.6) years (433 boys [52.4%]) were randomized to S salivarius K12 oral products (n = 413) or placebo (n = 414). Thirty-four children (8.2%) in the S salivarius group and 24 children (5.8%) in the placebo group experienced at least 1 episode of AOM requiring antimicrobial therapy during the 6-month follow-up period (relative risk, 1.42 [95% CI, 0.86-2.34]; proportion difference, -2.44% [95% CI, -5.94% to 1.09%]; P = .17). Time to first AOM episode did not differ between the groups (174 [95% CI, 171-177] days in the S salivarius group vs 176 [95% CI, 173-179] days in the placebo group; P = .18). Conclusions and Relevance: In this randomized placebo-controlled clinical trial, the daily use of the S salivarius K12 products for 6 months did not reduce the occurrence of AOM. New approaches for primary prevention of AOM among children are needed. Trial Registration: ClinicalTrialsRegister.eu Identifier: 2020-001076-14.

α-d-(1 → 3)-graft-(1 → 6)-glucan: Comb-like polysaccharide synthesized in vitro with α-1,3/1,6-glucosyltransferase L from Streptococcus salivarius.

We demonstrated that a unique polysaccharide with extremely high molecular weight can be easily obtained via a low-cost, mild reaction in a water medium from sucrose, a photosynthetic product. α-1,3/1,6-Glucosyltransferase L (GtfL) from Streptococcus salivarius produced water-insoluble α-d-glucan from sucrose at 37 °C. Gel permeation chromatography revealed the molecular weight was extremely high; the weight-average molecular weight values were more than 1,000,000 irrespective of the substrate concentration. The Smith degradation of neat glucan and NMR spectroscopic analyses of the acetyl derivative revealed a structure similar to that of a comb-type graft copolymer, α-d-(1 â†’ 3)-graft-(1 â†’ 6)-glucan. The anhydroglucose units (AGUs) in the main-chain backbone are linked by (1 â†’ 3)-glycosidic bonds, whereas a side chain consisting of four AGUs via (1 â†’ 6)-glycosidic bonds alternately extends from C6 of the main chain.

Oral Probiotics, Streptococcus salivarius K12 and M18, Suppress the Release of Volatile Sulfur Compounds and a Virulent Protease from Oral Bacteria: An In-Vitro Study.

PURPOSE: To evaluate the inhibitory effects of Streptococcus salivarius K12 and M18 strains on the growth of six oral pathogens as well as their release of volatile sulfur compounds (VSCs), and whether these probiotics can inhibit the expression of arginine-specific gingipain A (RgpA), a protease secreted by Porphyromonas gingivalis. MATERIALS AND METHODS: After six halitogenic oral pathogens (P. gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, and Eikenella corrodens) were cultured with or without S. salivarius K12 and M18, the concentration of two VSCs was measured. Moreover, the antimicrobial activity of S. salivarius K12 and M18 against these pathogens and the suppressive effect on RgpA release by P. gingivalis were assessed. RESULTS: In the co-culture of S. salivarius K12 or M18 with oral pathogenic bacteria, the growth of all six oral pathogens was significantly inhibited (p < 0.01). Additionally, S. salivarius K12 and M18 had an inhibitory effect on the production of the halitogenic substances H2S and CH3SH (p < 0.01) as well as the expression of P. gingivalis RgpA. Finally, we demonstrated that the addition of only culture supernatants of the two strains K12/M18 to oral pathogen cultures was sufficient to mimic the effects of K12/M18 co-cultures upon VSCs production and protease expression. CONCLUSIONS: S. salivarius K12 and M18 inhibited VSC release by all six of the major oral pathogens that were assayed and reduced the expression of RgpA.

Anti-Inflammatory Efficacy of Human-Derived Streptococcus salivarius on Periodontopathogen-Induced Inflammation.

Streptococcus salivarius is a beneficial bacterium in oral cavity, and some strains of this bacterium are known to be probiotics. The purpose of this study was to investigate the anti-inflammatory effect and mechanism of S. salivarius G7 lipoteichoic acid (LTA) on lipopolysaccharide (LPS) and LTA of periodontopathogens. The surface molecules of S. salivarius G7 was extracted, and single- or co-treated on human monocytic cells with LPS and LTA of periodontopathogens. The induction of cytokine expression was evaluated by real-time PCR and ELISA. After labeling fluorescence on LPS and LTA of periodontopathogens, it was co-treated with S. salivarius LTA to the cell. The bound LPS and LTA were measured by a flow cytometer. Also, the biding assay of the LPS and LTA to CD14 and LPS binding protein (LBP) was performed. The surface molecules of S. salivarius G7 did not induce the expression of inflammatory cytokines, and S. salivarius G7 LTA inhibited the inflammatory cytokines induced by LPS and LTA of periodontopathogens. S. salivarius G7 LTA inhibited the binding of its LPS and LTA to cells. Also, S. salivarius G7 LTA blocked the binding of its LPS and LTA to CD14 and LBP. S. salivarius G7 has an inhibitory effect on inflammation induced by LPS or LTA of periodontopathogens, and may be a candidate probiotics for prevention of periodontitis.

Antimicrobial activity of probiotic Streptococcus salivarius LAB813 on in vitro cariogenic biofilms.

OBJECTIVE: To investigate the antimicrobial activity of a novel commensal strain of Streptococcus salivarius, LAB813, against Streptococcus mutans biofilms. METHODS: The inhibitory activity of LAB813 towards S. mutans was tested using mono-, dual-, and multi-species cariogenic biofilms formed on three types of orthodontic appliances (metal, ceramic, aligner). The activity of the commercially available probiotic, BLIS M18™ was used as control. RESULTS: LAB813 significantly inhibited S. mutans biofilms with cell killing approximating 99% for all materials. LAB813 showed effectiveness at inhibiting S. mutans in more complex multi-species biofilms with cell killing approximating 90% for all three materials. When comparing the killing kinetics of the probiotics, LAB813 had a faster rate of killing biofilms than M18. Experiments conducted with cell-free culture supernatant confirmed the presence of an inhibitory substance of proteinaceous nature. The addition of xylitol, a common sugar substitute used for human consumption, potentiated the inhibitory effects of LAB813 against S. mutans embedded in a more complex fungal-bacterial biofilm. CONCLUSIONS: LAB813 possesses strong antimicrobial activity, potent anti-biofilm properties, and enhanced antimicrobial activity in the presence of xylitol. The identification and characterization of strain LAB813 exhibiting antimicrobial activity towards S. mutans hold exciting promise for this novel strain to be developed as an oral probiotic for use in the prevention of dental caries.

Streptococcus lactarius MB622 and Streptococcus salivarius MB620 isolated from human milk reduce chemokine IL-8 production in response to TNF-α in Caco-2 cell line, an exploratory study.

Streptococci are a predominant genera of the human milk microbiome. Among different lactic acid bacteria (LAB) a few Streptococcal strains are also considered as probiotics. Probiotic bacteria are reported to modulate immunity when consumed in adequate amount and bacterial hydrophobicity can be considered as a preliminary experiment for the adhesive capability of probiotic bacteria to the epithelial cells. The present study aimed to investigate the probiotic, hydrophobic and immune modulation property of Streptococcus lactarius MB622 and Streptococcus salivarius MB620, isolated from human milk. S. lactarius MB622 and S. salivarius MB620 displayed higher hydrophobicity (78 % and 59 % respectively) in addition to intrinsic probiotic properties such as gram positive classification, catalase negative activity, resistance to artificially stimulated gastric juice and gastrointestinal bile salt concentration. In conclusion Streptococcus lactarius MB622 and Streptococcus salivarius MB620 isolated from human milk when administered in sufficient amount and for certain duration could be used to reduce inflammation inside the colon by reducing the production of inflammatory booster (IL-8) in diseased state.

Streptococcus salivarius as an Important Factor in Dental Biofilm Homeostasis: Influence on Streptococcus mutans and Aggregatibacter actinomycetemcomitans in Mixed Biofilm.

A disturbed balance within the dental biofilm can result in the dominance of cariogenic and periodontopathogenic species and disease development. Due to the failure of pharmacological treatment of biofilm infection, a preventive approach to promoting healthy oral microbiota is necessary. This study analyzed the influence of Streptococcus salivarius K12 on the development of a multispecies biofilm composed of Streptococcus mutans, S. oralis and Aggregatibacter actinomycetemcomitans. Four different materials were used: hydroxyapatite, dentin and two dense polytetrafluoroethylene (d-PTFE) membranes. Total bacteria, individual species and their proportions in the mixed biofilm were quantified. A qualitative analysis of the mixed biofilm was performed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results showed that in the presence of S. salivarius K 12 in the initial stage of biofilm development, the proportion of S. mutans was reduced, which resulted in the inhibition of microcolony development and the complex three-dimensional structure of the biofilm. In the mature biofilm, a significantly lower proportion of the periodontopathogenic species A. actinomycetemcomitans was found in the salivarius biofilm. Our results show that S. salivarius K 12 can inhibit the growth of pathogens in the dental biofilm and help maintain the physiological balance in the oral microbiome.

Airway delivery of Streptococcus salivarius is sufficient to induce experimental pulmonary hypertension in rats.

BACKGROUND AND PURPOSE: The causal relationship between altered host microbiome composition, especially the respiratory tract microbiome, and the occurrence of pulmonary hypertension (PH) has not yet been studied. An increased abundance of airway streptococci is seen in patients with PH compared with healthy individuals. This study aimed to determine the causal link between elevated airway exposure to Streptococcus and PH. EXPERIMENTAL APPROACH: The dose-, time- and bacterium-specific effects of Streptococcus salivarius (S. salivarius), a selective streptococci, on PH pathogenesis were investigated in a rat model established by intratracheal instillation. KEY RESULTS: Exposure to S. salivarius successfully induced typical PH characteristics, such as elevated right ventricular systolic pressure (RVSP), right ventricular hypertrophy (Fulton's index) and pulmonary vascular remodelling, in a dose- and time-dependent manner. Moreover, the S. salivarius-induced characteristics were absent in either the inactivated S. salivarius (inactivated bacteria control) treatment group or the Bacillus subtilis (active bacteria control) treatment group. Notably, S. salivarius-induced PH is characterized by elevated inflammatory infiltration in the lungs, in a pattern different from the classic hypoxia-induced PH model. Moreover, in comparison with the SU5416/hypoxia-induced PH model (SuHx-PH), S. salivarius-induced PH causes similar histological changes (pulmonary vascular remodelling) but less severe haemodynamic changes (RVSP, Fulton's index). S. salivarius-induced PH is also associated with altered gut microbiome composition, suggesting potential communication of the lung-gut axis. CONCLUSION AND IMPLICATIONS: This study provides the first evidence that the delivery of S. salivarius in the respiratory tract could cause experimental PH in rats.

Use of Streptococcus salivarius K12 in supporting the mucosal immune function of active young subjects: A randomised double-blind study.

Introduction: Upper respiratory tract infections (URTI) are the most common illnesses affecting athletes, causing absences from training and competition. Salivary immunoglobulin A (sIgA) is the main immune factor in saliva, and a consistent association between low concentrations of sIgA and an increased incidence of URTIs has been reported. The oral probiotic Streptococcus salivarius K12 has been suggested to have the potential to improve oral diseases and mucosal barrier function. However, the effects of this probiotic on active young subjects performing a high-intensity training (HIT) program have not been investigated. Methods: Active young students were randomised into a treated group (S. salivarius K12) and a control (placebo) group and asked to take the product daily for 30 days. After this period, participants performed a graded exercise test and five HIT sessions, all within 3 days. They were also asked to complete the Wisconsin Upper Respiratory Symptom Survey daily to monitor URTI's presence. Before and after the 30 days, and at 0h, 24h and 72h after the last training session, saliva samples were collected to quantify sIgA level, secretion rate, and flow. The effect of S. salivarius K12 intake on these parameters was tested using an ANOVA for repeated measures. Results: Twenty (M = 14, F = 6) young subjects (23.5 ± 2.3 years old) participated in the study. The total accumulated training load (sRPE) in the supplementation period was similar in the two groups (treated: 4345 ± 3441 AU; control: 4969 ± 4165 AU; p > 0.05). Considering both sIgA level and secretion rate, significant time (F(4,15) = 3.38; p = 0.037; F(4,15) = 6.00; p = 0.004) and time×group interactions (F(4,15) = 2.49; p = 0.049; F(4,15) = 5.01; p = 0.009) were reported, with the treated group showing higher sIgA levels at 72h post-exercise and increased secretion rate both at 0h and 72h. The number of URTI episodes was similar in the treated and control groups (χ² = 1.83; p > 0.05). Conclusion: This study demonstrates that relatively short-term S. salivarius K12 supplementation increased sIgA level and secretion in healthy subjects performing a demanding exercise-training programme composed of HIT sessions.

Exacerbation of allergic rhinitis by the commensal bacterium Streptococcus salivarius.

Allergic rhinitis (AR)-commonly called hay fever-is a widespread condition that affects the quality of life of millions of people. The pathophysiology of AR remains incompletely understood. In particular, it is unclear whether members of the colonizing nasal microbiota contribute to AR. Here, using 16S ribosomal RNA sequencing, we show that the nasal microbiome of patients with AR (n = 55) shows distinct differences compared with that from healthy individuals (n = 105), including decreased heterogeneity and the increased abundance of one species, Streptococcus salivarius. Using ex vivo and in vivo models of AR, we demonstrate that this commensal bacterium contributes to AR development, promoting inflammatory cytokine release and morphological changes in the nasal epithelium that are characteristic of AR. Our data indicate that this is due to the ability of S. salivarius to adhere to the nasal epithelium under AR conditions. Our study indicates the potential of targeted antibacterial approaches for AR therapy.

Lyophilized cell-free supernatants of the oral probiotics Streptococcus salivarius M18 and Streptococcus salivarius K12 show promises for milk safety.

The functional food ingredients market has been growing due to the preferences for healthier, nutritional, environment-friendly, and convenience foods. Here, we evaluated the antimicrobial potential of the lyophilized cell-free supernatants of the two most promising oral probiotic strains Streptococcus salivarius M18 and S. salivarius K12 on Pseudomonas aeruginosa to be applied for safety purposes in the milk. We showed that the lyophilized culture supernatant of the strain M18 inhibited the pathogen growth in milk by about 75%, 70%, and 60% when incubated at 37°C, room temperature, and +4°C, respectively. The inhibition levels were about 50%, 30%, and 45% for the lyophilized K12 cell-free supernatant. Besides, the lyophilized culture supernatants of the oral probiotics, especially of S. salivarius M18, exhibited anti-cancer activities on colon cancer cells in vitro. Thus, the results of this manuscript suggest that the cell-free supernatants of the M18 and K12 strains are potential candidates, which merit more investigation for their applications, as biopreservatives in foods and beverages and as anti-cancer biotics for human health.

A Genome-Wide CRISPR Interference Screen Reveals an StkP-Mediated Connection between Cell Wall Integrity and Competence in Streptococcus salivarius.

Competence is one of the most efficient bacterial evolutionary and adaptative strategies by synchronizing production of antibacterial compounds and integration of DNA released by dead cells. In most streptococci, this tactic is orchestrated by the ComRS system, a pheromone communication device providing a short time window of activation in which only part of the population is responsive. Understanding how this developmental process integrates multiple inputs to fine-tune the adequate response is a long-standing question. However, essential genes involved in the regulation of ComRS have been challenging to study. In this work, we built a conditional mutant library using CRISPR interference and performed three complementary screens to investigate competence genetic regulation in the human commensal Streptococcus salivarius. We show that initiation of competence increases upon cell wall impairment, suggesting a connection between cell envelope stress and competence activation. Notably, we report a key role for StkP, a serine-threonine kinase known to regulate cell wall homeostasis. We show that StkP controls competence by a mechanism that reacts to peptidoglycan fragments. Together, our data suggest a key cell wall sensing mechanism coupling competence to cell envelope integrity. IMPORTANCE Survival of human commensal streptococci in the digestive tract requires efficient strategies which must be tightly and collectively controlled for responding to competitive pressure and drastic environmental changes. In this context, the autocrine signaling system ComRS controlling competence for natural transformation and predation in salivarius streptococci could be seen as a multi-input device integrating a variety of environmental stimuli. In this work, we revealed novel positive and negative competence modulators by using a genome-wide CRISPR interference strategy. Notably, we highlighted an unexpected connection between bacterial envelope integrity and competence activation that involves several cell wall sensors. Together, these results showcase how commensal streptococci can fine-tune the pheromone-based competence system by responding to multiple inputs affecting their physiological status in order to calibrate an appropriate collective behavior.

Synbiotic Musa acuminata skin extract and Streptococcus salivarius K12 inhibit candida species biofilm formation.

This study aimed to determine the effect of synbiotic Musa acuminata skin extract (MASE) and Streptococcus salivarius K12 (K12) on Candida species biofilm formation. Liquid chromatography quadrupole time-of-flight (LC-Q-TOF-MS) was conducted to characterize MASE. To determine the effect of synbiotic on Candida biofilm, 200 µL of RPMI-1640 containing Candida, K12, and MASE were pipetted into the same well and incubated at 37 °C for 72 h. A similar protocol was repeated with K12 or MASE to determine the probiotic and prebiotic effects, respectively. Dimorphism, biofilm biomass, and Candida total cell count (TCC) were determined. A total of 60 compounds were detected in MASE. C. albicans (ALT5) and Candida lusitaniae exhibited the highest reduction in biofilm biomass when co-cultured with prebiotic (77.70 ± 7.67%) and synbiotic (97.73 ± 0.28%), respectively. All Candida spp. had decreased TCC and hyphae when co-cultured with synbiotic. In conclusion, MASE and K12 inhibit Candida biofilm formation.

Effect of a bacteriocin-producing Streptococcus salivarius on the pathogen Fusobacterium nucleatum in a model of the human distal colon.

The gut microbiome is a vast reservoir of microbes, some of which produce antimicrobial peptides called bacteriocins that may inhibit specific bacteria associated with disease. Fusobacterium nucleatum is an emerging human bacterial pathogen associated with gastrointestinal diseases including colorectal cancer (CRC). In this study, fecal samples of healthy donors were screened for potential bacteriocin-producing probiotics with antimicrobial activity against F. nucleatum. A novel isolate, designated as Streptococcus salivarius DPC6993 demonstrated a narrow-spectrum of antimicrobial activity against F. nucleatum in vitro. In silico analysis of the S. salivarius DPC6993 genome revealed the presence of genes involved in the production of the bacteriocins salivaricin A5 and salivaricin B. After 6 h in a colon fermentation model, there was a significant drop in the number of F. nucleatum in samples that had been simultaneously inoculated with S. salivarius DPC6993 + F. nucleatum DSM15643 compared to those inoculated with F. nucleatum DSM15643 alone (mean ± SD: 9243.3 ± 3408.4 vs 29688.9 ± 4993.9 copies/µl). Furthermore, 16S rRNA amplicon analysis revealed a significant difference in the mean relative abundances of Fusobacterium between samples inoculated with both S. salivarius DPC6993 and F. nucleatum DSM15643 (0.05%) and F. nucleatum DSM15643 only (0.32%). Diversity analysis indicated minimal impact exerted by S. salivarius DPC6993 on the surrounding microbiota. Overall, this study highlights the ability of a natural gut bacterium to target a bacterial pathogen associated with CRC. The specific targeting of CRC-associated pathogens by biotherapeutics may ultimately reduce the risk of CRC development and positively impact CRC outcomes.

Improvement of Psoriasis Using Oral Probiotic Streptococcus salivarius K-12: a Case-Control 24-Month Longitudinal Study.

Psoriasis is a common chronic skin disease, associated with an important physical and physiological involvement for any age. There is a strong link between psoriasis and streptococcal infection, particularly that of the tonsils. There are many therapies to treat psoriasis including topical, systemic, and biologic agents but these treatments are not free from side effects. Streptococcus salivarius K-12 is an oral probiotic product useful for the prophylaxis and treatment of tonsillar infections in children and adults, now tested here for the first time for control of psoriasis. Our retrospective analysis was conducted on 198 patients affected by mild to moderate psoriasis: 100 patients were first treated for 90 days with Streptococcus salivarius K-12, while 98 did not receive any probiotics and were the control group. The patients treated with S. salivarius K-12 exhibited a significant improvement of their psoriasis from the baseline condition: 83.7% patients treated achieved a 100% improvement of the PASI score at 24 weeks and efficacy continued to improve with longer treatment, maintaining same result also during follow-up observation. In all patients, the treatment was well tolerated, and no adverse events have been observed. Our data show that oral preparations containing Streptococcus salivarius may provide a beneficial option for the prevention and cure of pediatric and adult psoriasis.