Lozenges with probiotic strains enhance oral immune response and health

Advancements in Lactiplantibacillus plantarum: probiotic characteristics, gene editing technologies and applications

The exploration of microorganisms in fermented products has become a pivotal area of scientific research, primarily due to their widespread availability and profound potential to improve human health. Among these, Lactiplantibacillus plantarum (formerly known as Lactobacillus plantarum) stands out as a versatile lactic acid bacterium, prevalent across diverse ecological niches. Its appeal extends beyond its well-documented probiotic benefits to include the remarkable plasticity of its genome, which has captivated both scientific and industrial stakeholders. Despite this interest, substantial challenges persist in fully understanding and harnessing the potential of L. plantarum. This review aims to illuminate the probiotic attributes of L. plantarum, consolidate current advancements in gene editing technologies, and explore the multifaceted applications of both wild-type and genetically engineered strains.

The Impact of Lactobacillus reuteri on Oral and Systemic Health: A Comprehensive Review of Recent Research

Oral diseases, particularly dental caries and periodontal disease, pose significant global health challenges. The imbalance of the oral microbiota plays a key role in the occurrence of these diseases, prompting researchers to seek new strategies to restore oral ecological balance. Lactobacillus reuteri is a Gram-positive rod-shaped bacterium that exists in various body parts of humans, including the gastrointestinal tract, urinary tract, skin, and so on. This species has a potentially positive impact on oral health and plays an important role in maintaining systemic health. Recent studies have explored the application of Lactobacillus reuteri in the prevention and treatment of oral diseases, and its impact on systemic health has also been preliminarily revealed. The current review summarizes the role of Lactobacillus reuteri in oral health and systemic health and outlines its potential applications in the future. Lactobacillus reuteri has shown promising prospects in treating non-communicable biofilm-dependent oral diseases, but its mechanism of action and efficacy still need further research. In addition, Lactobacillus reuteri has also displayed some potential benefits in promoting overall health. Future research should focus on revealing the specific pathways of action of Lactobacillus reuteri, screening for the most beneficial strains, determining the most effective drug delivery strategies, developing oral and systemic health products based on Lactobacillus reuteri, and ensuring their safety in clinical applications.

The role of Lactobacillus plantarum in oral health: a review of current studies

Background

Oral non-communicable diseases, particularly dental caries and periodontal disease, impose a significant global health burden. The underlying microbial dysbiosis is a prominent factor, driving interest in strategies that promote a balanced oral microbiome. Lactobacillus plantarum, a gram-positive lactic acid bacterium known for its adaptability, has gained attention for its potential to enhance oral health. Recent studies have explored the use of probiotic L. plantarum in managing dental caries, periodontal disease, and apical periodontitis. However, a comprehensive review on its effects in this context is still lacking.

Aims

This narrative review evaluates current literature on L. plantarum's role in promoting oral health and highlights areas for future research.

Content

In general, the utilization of L. plantarum in managing non-communicable biofilm-dependent oral diseases is promising, but additional investigations are warranted. Key areas for future study include: exploring its mechanisms of action, identifying optimal strains or strain combinations of L. plantarum, determining effective delivery methods and dosages, developing commercial antibacterial agents from L. plantarum, and addressing safety considerations related to its use in oral care.

Balancing the Oral-Gut-Brain Axis with Diet

Background: The oral microbiota is the second largest microbial community in humans. It contributes considerably to microbial diversity and health effects, much like the gut microbiota. Despite physical and chemical barriers separating the oral cavity from the gastrointestinal tract, bidirectional microbial transmission occurs between the two regions, influencing overall host health. Method: This review explores the intricate interplay of the oral-gut-brain axis, highlighting the pivotal role of the oral microbiota in systemic health and ageing, and how it can be influenced by diet. Results: Recent research suggests a relationship between oral diseases, such as periodontitis, and gastrointestinal problems, highlighting the broader significance of the oral-gut axis in systemic diseases, as well as the oral-gut-brain axis in neurological disorders and mental health. Diet influences microbial diversity in the oral cavity and the gut. While certain diets/dietary components improve both gut and oral health, others, such as fermentable carbohydrates, can promote oral pathogens while boosting gut health. Conclusions: Understanding these dynamics is key for promoting a healthy oral-gut-brain axis through dietary interventions that support microbial diversity and mitigate age-related health risks.

Oral microbiome in human health and diseases

The oral cavity contains the second-largest microbiota in the human body. The cavity's anatomically and physiologically diverse niches facilitate a wide range of symbiotic bacteria living at distinct oral sites. Consequently, the oral microbiota exhibits site specificity, with diverse species, compositions, and structures influenced by specific aspects of their placement. Variations in oral microbiota structure caused by changes in these influencing factors can impact overall health and lead to the development of diseases-not only in the oral cavity but also in organs distal to the mouth-such as cancer, cardiovascular disease, and respiratory disease. Conversely, diseases can exacerbate the imbalance of the oral microbiota, creating a vicious cycle. Understanding the heterogeneity of both the oral microbiome and individual humans is important for investigating the causal links between the oral microbiome and diseases. Additionally, understanding the intricacies of the oral microbiome's composition and regulatory factors will help identify the potential causes of related diseases and develop interventions to prevent and treat illnesses in this domain. Therefore, turning to the extant research in this field, we systematically review the relationship between oral microbiome dynamics and human diseases.

Postbiotic mediators derived from Lactobacillus species enhance riboflavin-mediated antimicrobial photodynamic therapy for eradication of Streptococcus mutans planktonic and biofilm growth

BACKGROUND

Streptococcus mutans has been implicated as a primary causative agent of dental caries and one of its important virulence properties is an ability to form biofilm on tooth surfaces. Thus, strategies to prevent and control S. mutans biofilms are requested. The present study aimed to examine the eradication of S. mutans planktonic and biofilm cells using riboflavin (Rib)-mediated antimicrobial photodynamic therapy (aPDT) enhanced by postbiotic mediators derived from Lactobacillus species.

MATERIALS AND METHODS

Minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Rib and postbiotic mediators were determined. The antimicrobial and anti-biofilm effects of Rib-mediated aPDT (Rib plus blue light), Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus casei (LC) (aPDT+ LC), and Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus plantarum (LP) (aPDT+ LP) were evaluated. The anti-virulence potential of Rib-mediated aPDT, aPDT+ LC, and aPDT+ LP were assessed by measuring the expression of the gtfB gene using quantitative real-time polymerase chain reaction (qRT-PCR) at the highest concentrations of Rib, LC, and LP, at which the S. mutans had proliferation as the same as in the control (non-treated) group.

RESULTS

According to the results, the MIC doses of LC, LP, and Rib were 64 µg/mL, 128 µg/mL, and 128 µg/mL, respectively, while the MBC values of LC, LP, and Rib were 128 µg/mL, 256 µg/mL, and 256 µg/mL, respectively. Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC showed a significant reduction in Log10 CFU/mL of S. mutans compared to the control group (4.2, 4.9, and 5.2 Log10 CFU/mL, respectively; all P < 0.05). The most destruction of S. mutans biofilms was observed after treatment with aPDT+ LC followed by aPDT+ LP and Rib-mediated aPDT (77.5%, 73.3%, and 67.6%, respectively; all P < 0.05). The concentrations of 31.2 µg/mL, 62.5 µg/mL, and 62.5 µg/mL were considered as the highest concentrations of LC, LP, and Rib, respectively, at which S. mutans replicates as same as the control group and were used for gtfB gene expression assay using qRT-PCR during Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC treatments. Gene expression results revealed that aPDT+ LP and aPDT+ LC could decrease the gene expression level of gtfB by 6.3- and 5.7-fold, respectively (P < 0.05), while only 5.1-fold reduction was observed after Rib-mediated aPDT (P < 0.05).

CONCLUSION

Our findings indicate that aPDT+ LP and aPDT+ LC hold promise for use as a treatment to combat S. mutans planktonic and biofilms growth as well as anti-virulence as a preventive strategy to inhibit biofilms development via reduction of gtfB gene expression.

Development and Evaluation of Bioconverted Milk with Anti-Microbial Effect against Periodontal Pathogens and α-Glucosidase Inhibitory Activity

To decrease periodontal pathogens and increase the number of beneficial bacteria, probiotics and bioactive compounds made via microbial bioconversion are recently used. In addition, the interest regarding probiotics-mediated bioconversion with popular medicinal plants is increasing. Artemisia herba-alba, a type of wormwood, has recently been attention as a medicinal plant due to its various bioactive compounds. Therefore, we developed bioconverted milk containing A. herba-alba that effectively inhibited periodontal pathogens and α-glucosidase. To select the appropriate lactic acid bacteria for the probiotic candidate strain, 74 strains of lactic acid bacteria were screened. Among them, Lactiplantibacillus plantarum SMFM2016-RK was chosen as the probiotic due to its beneficial characteristics such as high acid and bile tolerance, antioxidant activity, and α-glucosidase inhibition. Based on the minimal bactericidal concentration against three periodontal pathogens, the following appropriate concentrations of Artemisia herba-alba extract were added to milk: 5 mg/mL of A. herba-alba ethanol extract and 25 mg/mL of A. herba-alba hot-water extract. Four bioconverted milks (BM), BM1, BM2, BM3, and BM4, were produced by combining L. plantarum SMFM2016-RK alone, L. plantarum SMFM2016-RK and ethanol extract, L. plantarum SMFM2016-RK and hot-water extract, and L. plantarum SMFM2016-RK with both extracts. As a result of antimicrobial activity, BM3 inhibited the growth of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis the most, and BM4 suppressed the growth of Fusobacterium nucleatum the most. In addition, bioconverted milk containing A. herba-alba (BM2, BM3, and BM4) inhibited α-glucosidase more effectively than BM1. The whole genome of L. plantarum SMFM2016-RK was obtained, and 3135 CDS, 67 tRNA, and 16 RNA were predicted. The genome annotation of L. plantarum SMFM2016-RK revealed 11 CDS related to proteolysis and amino acid metabolism and 2 CDS of phenolic acid-metabolizing enzymes. In conclusion, A. herba-alba-added milk bioconverted by L. plantarum SMFM2016-RK displayed both the growth inhibitory effect on periodontal pathogens and the α-glucosidase inhibitory activity; thus, it necessitates to evaluate the effects on the alleviation of periodontal diseases and glycemic control through future animal experiments.

The Health Benefits of Probiotic Lactiplantibacillus plantarum: A Systematic Review and Meta-Analysis

To ensure effective administration of probiotics in clinical practice, it is crucial to comprehend the specific strains and their association with human health. Therefore, we conducted a systematic review and meta-analysis to evaluate the scientific evidence on the impact of Lactiplantibacillus plantarum probiotic consumption on human health. Out of 11,831 records, 135 studies were assessed qualitatively, and 18 studies were included in the meta-analysis. This systematic review demonstrated that probiotic supplementation with L. plantarum, either alone or in combination, can significantly improve outcomes for patients with specific medical conditions. Meta-analysis revealed notable benefits in periodontal health, evidenced by reduced pocket depth and bleeding on probing (p < 0.001); in gastroenterological health, marked by significant reductions in abdominal pain (p < 0.001); and in infectious disease, through a reduction in C-reactive protein levels (p < 0.001). Cardiovascular benefits included lowered total cholesterol and low-density lipoprotein cholesterol in the L. plantarum intervention group (p < 0.05). Our study's clinical significance highlights the importance of considering probiotic strain and their application to specific diseases when planning future studies and clinical interventions, emphasizing the need for further research in this area.

Distribution and roles of Ligilactobacillus murinus in hosts

Ligilactobacillus murinus, a member of the Ligilactobacillus genus, holds significant potential as a probiotic. While research on Ligilactobacillus murinus has been relatively limited compared to well-studied probiotic lactic acid bacteria such as Limosilactobacillus reuteri and Lactobacillus gasseri, a mounting body of evidence highlights its extensive involvement in host intestinal metabolism and immune activities. Moreover, its abundance exhibits a close correlation with intestinal health. Notably, beyond the intestinal context, Ligilactobacillus murinus is gaining recognition for its contributions to metabolism and regulation in the oral cavity, lungs, and vagina. As such, Ligilactobacillus murinus emerges as a potential probiotic candidate with a pivotal role in supporting host well-being. This review delves into studies elucidating the multifaceted roles of Ligilactobacillus murinus. It also examines its medicinal potential and associated challenges, underscoring the imperative to delve deeper into unraveling the mechanisms of its actions and exploring its health applications.

Short-term use of Lacticaseibacillus rhamnosus SD11 and the oral microbiome: Low caries RCT study

OBJECTIVES

The objective of the study was to investigate the effect of short-term lozenges containing Lacticaseibacillus rhamnosus SD11 on cariogenic pathogens and on oral microbiota.

MATERIALS AND METHODS

This double-blind, randomized, controlled trial included 121 subjects and was randomly divided into the control and probiotic group. All subjects were blindly administered to receive the control- or probiotic L. rhamnosus SD11 lozenges every day for 4 weeks and then followed up for another 4 weeks.

RESULTS

After probiotic consumption, the probiotic group had significantly lower levels of Streptococcus mutans and significantly higher levels of total lactobacilli at 4 and 8 weeks compared with the baseline. The 16S rRNA sequencing revealed an increase in bacterial diversity and beneficial bacteria in the Firmicutes phylum, Bacilli class, and a reduction in the mutans streptococci group in the probiotic group. The opposite results were found in the control group. This study did not find any caries increment, nor did the subjects have any side effects after product consumption.

CONCLUSION

With the limitation of a short-time study in low caries children, it showed that L. rhamnosus SD11 could increase beneficial bacteria in the Firmicutes phylum and Bacilli class that might support good oral health in children.

Evaluating the Role of Postbiotics in the Modulation of Human Oral Microbiota: A Randomized Controlled Clinical Trial

There is a lack of clinical data to support the effectiveness and safety of postbiotics in the modulation of human oral microbiota and oral health care. Here, volunteers were recruited and randomly assigned to two cohorts: a placebo group (n = 15) and a postbiotic group (n = 16). The placebo group used toothpaste that did not contain postbiotics, while the postbiotic group used toothpaste with postbiotics (3 × 1010 CFU inactivated Lactobacillus salivarius LS97, L. paracasei LC86, and L. acidophilus LA85). Saliva samples were collected at different time points and the immunoglobulin A (IgA) and short-chain fatty acid (SCFA) levels were determined, while the salivary microbiota was analyzed by 16S rRNA amplicon sequencing. The results showed that salivary IgA levels and acetic and propionic acid levels were notably higher in the postbiotic group (P < 0.05), accompanied by an increase in the level of alpha diversity of the salivary microbiota, and these indexes remained high 1 month after discontinuing the use of toothpaste with or without postbiotics. A notable decrease in the relative abundance of the unclassified_Enterobacteriaceae, Klebsiella, Escherichia, etc. in the postbiotic group was accompanied by a notable increase in Ruminofilibacter and Lactobacillus. However, both groups did not cause significant changes in the overall structure of the host salivary microbiota. In conclusion, postbiotics dramatically and consistently improved oral immunity levels and SCFA content in the host. In addition, postbiotics were able to increase the level of microbial alpha diversity and down-regulate the abundance of some harmful microbes without significantly altering the structure of the host salivary microbiota. Chinese Clinical Trial Registry (ChiCTR) ( www.chictr.org.cn ) under the registration number ChiCTR2300074088.

Manipulating the diseased oral microbiome: the power of probiotics and prebiotics

Dental caries and periodontal disease are amongst the most prevalent global disorders. Their aetiology is rooted in microbial activity within the oral cavity, through the generation of detrimental metabolites and the instigation of potentially adverse host immune responses. Due to the increasing threat of antimicrobial resistance, alternative approaches to readdress the balance are necessary. Advances in sequencing technologies have established relationships between disease and oral dysbiosis, and commercial enterprises seek to identify probiotic and prebiotic formulations to tackle preventable oral disorders through colonisation with, or promotion of, beneficial microbes. It is the metabolic characteristics and immunomodulatory capabilities of resident species which underlie health status. Research emphasis on the metabolic environment of the oral cavity has elucidated relationships between commensal and pathogenic organisms, for example, the sequential metabolism of fermentable carbohydrates deemed central to acid production in cariogenicity. Therefore, a focus on the preservation of an ecological homeostasis in the oral environment may be the most appropriate approach to health conservation. In this review we discuss an ecological approach to the maintenance of a healthy oral environment and debate the potential use of probiotic and prebiotic supplementation, specifically targeted at sustaining oral niches to preserve the delicately balanced microbiome.

Safety Assessment and Probiotic Potential Comparison of Bifidobacterium longum subsp. infantis BLI-02, Lactobacillus plantarum LPL28, Lactobacillus acidophilus TYCA06, and Lactobacillus paracasei ET-66

Bifidobacterium longum subsp. infantis BLI-02, Lactobacillus paracasei ET-66, Lactobacillus plantarum LPL28, and Lactobacillus acidophilus TYCA06, isolated from healthy breast milk, miso, and the healthy human gut, were assessed for safety in this study. BLI-02, LPL28, TYCA06, and ET-66 exhibited no antibiotic resistance and mutagenic activity in the Ames test at the highest dosage (5000 μg/plate). No genotoxicity was observed in micronucleus and chromosomal aberration assays in rodent spermatogonia at the maximum dosage of 10 g/kg body weight (BW). No acute and sub-chronic toxicity occurred in mice and rats at the maximum tested dosage of 10 g/kg BW and 1.5 g/kg BW, respectively. The lyophilized powder of these strains survived a low pH and high bile salt environment, adhering strongly to Caco-2 cells. Unique antimicrobial activities were noted in these strains, with BLI-02 demonstrating the best growth inhibition against Vibrio parahaemolyticus, LPL28 exhibiting the best growth inhibition against Helicobacter pylori, and ET-66 showing the best growth inhibition against Aggregatibacter actinomycetemcomitans. Based on the present study, the lyophilized powder of these four strains appears to be a safe probiotic supplement at tested dosages. It should be applicable for clinical or healthcare applications.

Lactobacillus paracasei ET-22 and derived postbiotics reduce halitosis and modulate oral microbiome dysregulation - a randomized, double-blind placebo-controlled clinical trial

Oral microbial dysbiosis is the primary etiologic factor for halitosis and may be the critical preventive target for halitosis. This study included randomized controlled trials (RCTs) assessing the effects of Lactobacillus paracasei ET-22 live and heat-killed bacteria on halitosis and the related oral microbiome. 68 halitosis subjects were divided into placebo, ET-22 live (ET-22.L) and ET-22 heat-killed (ET-22.HK) groups. Subjects took different lozenges three times a day for 4 weeks and underwent saliva collection and assessment of breath volatile sulfur compound (VSC) levels at the beginning and end of the intervention. Salivary volatile organic compounds were measured using HS-SPME-GC/MS, and the microbiome profile was determined by 16S rRNA gene amplicon sequencing. A positive decrease in breath volatile sulfur compound (VSC) levels was observed in the means of both ET-22.L and ET-22.HK groups after 4 weeks of intervention, being more marked in the ET-22.L group (p = 0.0148). Moreover, ET-22.L and ET-22.HK intervention remarkably changed the composition of total salivary volatile organic compounds (VOCs) and aroma-active VOCs. Key undesirable VOCs, such as indole, pyridine, nonanoic acid, benzothiazole, and valeric acid, were significantly reduced. Meanwhile, ET-22.L or ET-22.HK also altered the taxonomic composition of the salivary microbiome. The halitosis pathogens Rothia and Streptococcus were significantly reduced in the ET-22.HK group and the pathogenic Solobacterium and Peptostreptococcus were significantly inhibited in the ET-22.L group. Collectively, our study suggests that both ET-22.L and ET-22.HK can significantly inhibit the production of undesirable odor compounds in subjects with halitosis, which may be related to the changes of the oral microbiome.

Altered oral microbiome in Sudanese Toombak smokeless tobacco users carries a newly emerging risk of squamous cell carcinoma development and progression

There are an estimated 6-10 million smokeless tobacco (Toombak) users in Sudan, the majority being males. Toombak is known to be a carcinogenic product that is likely to modify the oral microbiome spatiality into a high-risk potential for the development and progression of oral cancer, but previous studies are lacking in this field. Here, we endeavour for the first time the exploration of the oral microbiome in key mucosal areas of the oral cavity and assess the microbiome variations in premalignant and oral squamous cell carcinoma (OSCC) samples from both users and non-users of Toombak. 16S rRNA sequencing was performed on DNA obtained from pooled saliva, oral mucosa and supragingival plaque from 78 Sudanese users and non-users of Toombak, aged between 20 and 70 years. In 32 of the pooled saliva samples, the mycobiome (fungal) environment was analysed through ITS sequencing. Then, 46 formalin-fixed paraffin-embedded samples of premalignant and OSCC samples were collected, and their associated microbiomes sequenced. The oral Sudanese microbiome was found to be enriched in Streptococcaceae, but Staphylococcaceae were significantly more abundant amongst Toombak users. Genera enriched in the oral cavity of Toombak users included Corynebacterium_1 and Cardiobacterium while in non-users, Prevotella, Lactobacillus and Bifidobacterium were prominent. Aspergillus was the most abundant fungus in the mouths of Toombak users with a marked loss of Candida. The genus Corynebacterium_1 was abundant in the buccal, floor of the mouth and saliva microbiomes as well as in oral cancer samples from Toombak users indicating a possible role for this genus in the early stages of oral cancer development. An oral cancer microbiome that favours poor survival and metastasis in those who use Toombak also emerged that includes the genera Stenotrophomonas and Schlegelella. Those utilising Toombak carry an altered oral microbiome that may be an additional risk factor for this products carcinogenicity to the oral structures. These significant microbiome modulations are a newly emerging key driving factor in oral cancer development and progression in Toombak users while it is also shown that Toombak users carry an oral cancer microbiome that may increase the potential for a poorer prognosis.

Effectiveness of the Lorodent Probiotic Lozenge in Reducing Plaque and Streptococcus mutans Levels in Orthodontic Patients: A Double-Blind Randomized Control Trial

Orthodontic patients are at a significant risk for oral diseases due to increased plaque accumulation and oral bacterial dysbiosis. We aimed to determine the efficacy of the commercially available Lorodent Probiotic Complex at reducing plaque accumulation and Streptococcus mutans bacterial levels in adolescent orthodontic patients. Sixty adolescents undergoing fixed orthodontic treatment for a minimum of 6 months were recruited in a randomized, double-blind, parallel-group, placebo-controlled trial. They received either Lorodent probiotic lozenge (intervention, n = 30) or placebo lozenge (control, n = 30) orally every day for a 28-day administration period. Participants were assessed at four appointments (T1–T4) over a total of 56 days. Compliance and lozenge satisfaction were monitored. Saliva samples and supragingival plaques were collected for evaluation of S. mutans levels. Clinical assessment using a Plaque Index (PI) was used. Compliance with lozenge intake of all participants was over 90%. There was no significant change in the PI and composite PI scores in both placebo and probiotic groups at each time frame (all p &gt; 0.05) or the relative S. mutans DNA levels in the saliva and plaque between the probiotic and placebo groups. The findings of high compliance and satisfaction with the probiotic lozenges combined with the study's rigorous design offer a baseline for subsequent testing of further potential probiotics (of varying formulations, concentrations), especially in adolescents.

Impact of the food grade heat-killed probiotic and postbiotic oral lozenges in oral hygiene

The oral cavity plays a crucial role in food digestion and immune protection. Thus, maintaining oral health is necessary. Postbiotic and heat-killed probiotic cells have shown increased antibacterial potential with stable viability compared with live strains. However, clinical evidence regarding their effect on oral health is insufficient. Therefore, in this study, we tested postbiotic lozenges of Lactobacillus salivarius subsp. salicinius AP-32, L. paracasei ET-66, and L. plantarum LPL28 and heat-killed probiotic lozenges of L. salivarius subsp. salicinius AP-32 and L. paracasei ET-66 for their effect on oral health. In total, 75 healthy individuals were blindly and randomly divided into placebo, postbiotic lozenge, and heat-killed probiotic lozenge groups and were administered the respective lozenge type for 4 weeks. Postbiotic and heat-killed probiotic lozenge groups demonstrated antibacterial activities with a considerable increase in L. salivarius in their oral cavity. Furthermore, their salivary immunoglobulin A, Lactobacillus, and Bifidobacterium increased. Subjective questionnaires completed by the participants indicated that participants in both the experimental groups developed better oral health and intestinal conditions than those in the placebo group. Overall, our study revealed that a food additive in the form of an oral postbiotic or heat-killed probiotic lozenge may effectively enhance oral immunity, inhibit the growth of oral pathogens, and increase the numbers of beneficial oral microbiota.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically "trap" the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Assessing the drug resistance profiles of oral probiotic lozenges

Background

Probiotic lozenges have been developed to harvest the benefits of probiotics for oral health, but their long-term consumption may encourage the transfer of resistance genes from probiotics to commensals, and eventually to disease-causing bacteria.

Aim

To screen commercial probiotic lozenges for resistance to antibiotics, characterize the resistance determinants, and examine their transferability in vitro.

Results

Probiotics of all lozenges were resistant to glycopeptide, sulfonamide, and penicillin antibiotics, while some were resistant to aminoglycosides and cephalosporins. High minimum inhibitory concentrations (MICs) were detected for streptomycin (>128 µg/mL) and chloramphenicol (> 512 µg/mL) for all probiotics but only one was resistant to piperacillin (MIC = 32 µg/mL). PCR analysis detected erythromycin (erm(T), ermB or mefA) and fluoroquinolone (parC or gyr(A)) resistance genes in some lozenges although there were no resistant phenotypes. The dfrD, cat-TC, vatE, aadE, vanX, and aph(3")-III or ant(2")-I genes conferring resistance to trimethoprim, chloramphenicol, quinupristin/dalfopristin, vancomycin, and streptomycin, respectively, were detected in resistant probiotics. The rifampicin resistance gene rpoB was also present. We found no conjugal transfer of streptomycin resistance genes in our co-incubation experiments.

Conclusion

Our study represents the first antibiotic resistance profiling of probiotics from oral lozenges, thus highlighting the health risk especially in the prevailing threat of drug resistance globally.

OUP accepted manuscript

This proof-of-principle study aims to find commensal oral bacteria that can produce extracellular polymeric substances (EPS), which have similar lubrication properties to saliva and could serve as saliva substitutes. Saliva and plaque samples were collected from 21 generally healthy individuals. Primary screening was done by conventional culturing and Gram-staining; all species selected for further analysis were identified by MALDI-TOF and deposited in DSMZ. Lactobacillus gasseri (DSM32453 and DSM32455), Lactobacillus rhamnosus (DSM32452), Lactobacillus paracasei (DSM32454), and Streptococcus sanguinis (DSM32456) produced 413.6, 415.7, 431.1, 426.8, and 877.6 µg/ml of EPS, respectively. At the same time calcium dissolution could not be detected for both L. gasseri strains, minimal dissolution for the other three: S. sanguinis 0.3 mm, and 3.7 mm for L. rhamnosus and L. paracasei. There were no differences found between the EPS samples and the saliva for the effect of shear rate on the viscosity and for the effect of sliding speed on lubrication properties. In conclusion, five commensal bacterial strains have been isolated, all able to produce EPS and lead to no or to low calcium dissolution. EPS produced exhibits rheological and tribological properties comparable to human saliva. A total of four out of five selected strains are probiotic and, therefore, may exhibit additional beneficial influence within the oral cavity.

Ligilactobacillus salivarius functionalities, applications, and manufacturing challenges

Ligilactobacillus salivarius is a lactic acid bacteria that has been gaining attention as a promising probiotic. Numerous strains exhibit functional properties with health benefits such as antimicrobial activity, immunological effects, and the ability to modulate the intestinal microbiota. However, just a small number of them are manufactured at an industrial scale and included in commercial products. The under exploitation of L. salivarius strains that remain in the freezer of companies is due to their incapacity to overcome the environmental stresses induced by production and stabilization processes.The present study summarizes the functionalities and applications of L. salivarius reported to date. It aims also at providing a critical evaluation of the literature available on the manufacturing steps of L. salivarius concentrates, the bacterial quality after each step of the process, and the putative degradation and preservation mechanisms. Here, we highlight the principal issues and future research challenges for improving the production and long-term preservation at the industrial scale of this microorganism, and probably of other probiotics.Key points• L. salivarius beneficial properties and commercialized products.• Production conditions and viability of L. salivarius after stabilization processes.• Prospects for identifying preservation mechanisms to improve L. salivarius stability.

Viable and Heat-Killed Probiotic Strains Improve Oral Immunity by Elevating the IgA Concentration in the Oral Mucosa

Oral-nasal mucosal immunity plays a crucial role in protecting the body against bacterial and viral invasion. Safe probiotic products have been used to enhance human immunity and oral health. In this study, we verified the beneficial effects of mixed viable probiotic tablets, consisting of Lactobacillus salivarius subsp. salicinius AP-32, Bifidobacterium animalis subsp. lactis CP-9, and Lactobacillus paracasei ET-66, and heat-killed probiotic tablets, consisting of L. salivarius subsp. salicinius AP-32 and L. paracasei ET-66, on oral immunity among 45 healthy participants. Participants were randomly divided into viable probiotic, heat-killed probiotic, and placebo groups. The administration of treatment lasted for 4 weeks. Saliva samples were collected at Weeks 0, 2, 4, and 6, and Lactobacillus, Bifidobacterium and Streptococcus mutans populations and IgA concentration were measured. IgA concentrations, levels of TGF-beta and IL-10 in PBMCs cells were quantified by ELISA method. Results showed that salivary IgA levels were significantly increased on administration of both the viable (119.30 ± 12.63%, ***P < 0.001) and heat-killed (116.78 ± 12.28%, ***P < 0.001) probiotics for 4 weeks. Among three probiotic strains, AP-32 would effectively increase the levels of TGF-beta and IL-10 in PBMCs. The oral pathogen Streptococcus mutans was significantly reduced on viable probiotic tablet administration (49.60 ± 31.01%, ***P < 0.001). The in vitro antibacterial test confirmed that viable probiotics effectively limited the survival rate of oral pathogens. Thus, this clinical pilot study demonstrated that oral probiotic tablets both in viable form or heat-killed form could exert beneficial effects on oral immunity via IL-10, TGB-beta mediated IgA secretion. The effective dosage of viable probiotic content in the oral tablet was 10⁹ CFUs/g and the heat-killed oral tablet was 1 × 10¹⁰ cells/g.