Bacteriocin-producing oral streptococci and inhibition of respiratory pathogens

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.

Upper respiratory microbial communities of healthy populations are shaped by niche and age

Background

Alterations in upper respiratory microbiomes have been implicated in shaping host health trajectories, including by limiting mucosal pathogen colonization. However, limited comparative studies of respiratory microbiome development and functioning across age groups have been performed. Herein, we perform shotgun metagenomic sequencing paired with pathogen inhibition assays to elucidate differences in nasal and oral microbiome composition and functioning across healthy 24-month-old infant (n=229) and adult (n=100) populations.

Results

We find that beta diversity of nasal and oral microbiomes varies with age, with nasal microbiomes showing greater population-level variation compared to oral microbiomes. Infant microbiome alpha diversity was significantly lower across nasal samples and higher in oral samples, relative to adults. Accordingly, we demonstrate significant differences in genus- and species-level composition of microbiomes between sites and age groups. Antimicrobial resistome patterns likewise varied across body sites, with oral microbiomes showing higher resistance gene abundance compared to nasal microbiomes. Biosynthetic gene clusters encoding specialized metabolite production were found in higher abundance across infant oral microbiomes, relative to adults. Investigation of pathogen inhibition revealed greater inhibition of gram-negative and gram-positive bacteria by oral commensals, while nasal isolates had higher antifungal activity.

Conclusions

In summary, we identify significant differences in the microbial communities inhabiting nasal and oral cavities of healthy infants relative to adults. These findings inform our understanding of the interactions impacting respiratory microbiome composition and functioning, with important implications for host health across the lifespan.

Klebsiella pneumoniae peptide hijacks a Streptococcus pneumoniae permease to subvert pneumococcal growth and colonization

Treatment of pneumococcal infections is limited by antibiotic resistance and exacerbation of disease by bacterial lysis releasing pneumolysin toxin and other inflammatory factors. We identified a previously uncharacterized peptide in the Klebsiella pneumoniae secretome, which enters Streptococcus pneumoniae via its AmiA-AliA/AliB permease. Subsequent downregulation of genes for amino acid biosynthesis and peptide uptake was associated with reduction of pneumococcal growth in defined medium and human cerebrospinal fluid, irregular cell shape, decreased chain length and decreased genetic transformation. The bacteriostatic effect was specific to S. pneumoniae and Streptococcus pseudopneumoniae with no effect on Streptococcus mitis, Haemophilus influenzae, Staphylococcus aureus or K. pneumoniae. Peptide sequence and length were crucial to growth suppression. The peptide reduced pneumococcal adherence to primary human airway epithelial cell cultures and colonization of rat nasopharynx, without toxicity. We identified a peptide with potential as a therapeutic for pneumococcal diseases suppressing growth of multiple clinical isolates, including antibiotic resistant strains, while avoiding bacterial lysis and dysbiosis.

Detailed Characterization of the Lung-Gut Microbiome Axis Reveals the Link between PD-L1 and the Microbiome in Non-Small-Cell Lung Cancer Patients

Next-generation sequencing technologies have started a new era of respiratory tract research in recent years. Alterations in the respiratory microbiome between healthy and malignant conditions have been revealed. However, the composition of the microbiome varies among studies, even in similar medical conditions. Also, there is a lack of complete knowledge about lung-gut microbiome interactions in lung cancer patients. The aim of this study was to explore the lung-gut axis in non-small-cell lung cancer (NSCLC) patients and the associations between lung-gut axis microbiota and clinical parameters (CRP, NLR, LPS, CD8, and PD-L1). Lung tissue and fecal samples were used for bacterial 16S rRNA sequencing. The results revealed, for the first time, that the bacterial richness in lung tumor tissue gradually decreased with an increase in the level of PD-L1 expression (p < 0.05). An analysis of β-diversity indicated a significant positive correlation between the genera Romboutsia and Alistipes in both the lung tumor biopsies and stool samples from NSCLC patients (p < 0.05). Survival analysis showed that NSCLC patients with higher bacterial richness in their stool samples had prolonged overall survival (HR: 2.06, 95% CI: 1.025-4.17, p = 0.0426).

Insights into the role of the respiratory tract microbiome in defense against bacterial pneumonia

The respiratory tract microbiome (RTM) is a microbial ecosystem inhabiting different niches throughout the airway. A critical role for the RTM in dictating lung infection outcomes is underlined by recent efforts to identify community members benefiting respiratory tract health. Obligate anaerobes common in the oropharynx and lung such as Prevotella and Veillonella are associated with improved pneumonia outcomes and activate several immune defense pathways in the lower airway. Colonizers of the nasal cavity, including Corynebacterium and Dolosigranulum, directly impact the growth and virulence of lung pathogens, aligning with robust clinical correlations between their upper airway abundance and reduced respiratory tract infection risk. Here, we highlight recent work identifying respiratory tract bacteria that promote airway health and resilience against disease, with a focus on lung infections and the underlying mechanisms driving RTM-protective benefits.

Role of probiotics in managing various human diseases, from oral pathology to cancer and gastrointestinal diseases

The imbalance of microbial composition and diversity in favor of pathogenic microorganisms combined with a loss of beneficial gut microbiota taxa results from factors such as age, diet, antimicrobial administration for different infections, other underlying medical conditions, etc. Probiotics are known for their capacity to improve health by stimulating the indigenous gut microbiota, enhancing host immunity resistance to infection, helping digestion, and carrying out various other functions. Concurrently, the metabolites produced by these microorganisms, termed postbiotics, which include compounds like bacteriocins, lactic acid, and hydrogen peroxide, contribute to inhibiting a wide range of pathogenic bacteria. This review presents an update on using probiotics in managing and treating various human diseases, including complications that may emerge during or after a COVID-19 infection.

Animal Microbiomes as a Source of Novel Antibiotic-Producing Strains

Natural compounds continue to serve as the most fruitful source of new antimicrobials. Analysis of bacterial genomes have revealed that the biosynthetic potential of antibiotic producers by far exceeds the number of already discovered structures. However, due to the repeated discovery of known substances, it has become necessary to change both approaches to the search for antibiotics and the sources of producer strains. The pressure of natural selection and the diversity of interactions in symbiotic communities make animal microbiomes promising sources of novel substances. Here, microorganisms associated with various animals were examined in terms of their antimicrobial agents. The application of alternative cultivation techniques, ultrahigh-throughput screening, and genomic analysis facilitated the investigation of compounds produced by unique representatives of the animal microbiota. We believe that new strategies of antipathogen defense will be discovered by precisely studying cell-cell and host-microbe interactions in microbiomes in the wild.

The Microbiome and Infectious Diseases

Our perception of microbes has considerably changed since the recognition of their pathogenic potential in the 19th century. The discovery of antibiotics and their subsequent widespread adoption have substantially altered the landscape of medicine, providing us with treatment options for many infectious diseases and enabling the deployment of previously risky interventions (eg, surgical procedures and chemotherapy), while also leading to the rise of AMR. The latter is commonly viewed as the predominant downside of antibiotic use. However, with the increasing recognition that all metazoan organisms rely on a community of microbes (the microbiota) for normal development and for most physiologic processes, the negative impacts of antibiotic use now extend well beyond AMR. Using the iceberg as a metaphor, we argue that the effects of antibiotics on AMR represent the tip of the iceberg, with much greater repercussions stemming from their role in the rise of so-called noncommunicable diseases (including obesity, diabetes, allergic and autoimmune diseases, neurodevelopmental disorders, and certain cancers). We highlight some of the emerging science around the intersection of the microbiome, antibiotic use, and health (including biological costs and future therapeutic avenues), and we advocate a more nuanced approach in evaluating the impacts of proposed antibiotic use, especially in the setting of preexposure and postexposure prophylaxis.

Antibiotic-induced collateral damage to the microbiota and associated infections

Antibiotics have transformed medicine, saving millions of lives since they were first used to treat a bacterial infection. However, antibiotics administered to target a specific pathogen can also cause collateral damage to the patient's resident microbial population. These drugs can suppress the growth of commensal species which provide protection against colonization by foreign pathogens, leading to an increased risk of subsequent infection. At the same time, a patient's microbiota can harbour potential pathogens and, hence, be a source of infection. Antibiotic-induced selection pressure can cause overgrowth of resistant pathogens pre-existing in the patient's microbiota, leading to hard-to-treat superinfections. In this Review, we explore our current understanding of how antibiotic therapy can facilitate subsequent infections due to both loss of colonization resistance and overgrowth of resistant microorganisms, and how these processes are often interlinked. We discuss both well-known and currently overlooked examples of antibiotic-associated infections at various body sites from various pathogens. Finally, we describe ongoing and new strategies to overcome the collateral damage caused by antibiotics and to limit the risk of antibiotic-associated infections.

Bacterial quorum sensing orchestrates longitudinal interactions to shape microbiota assembly

BACKGROUND

The mechanism of microbiota assembly is one of the main problems in microbiome research, which is also the primary theoretical basis for precise manipulation of microbial communities. Bacterial quorum sensing (QS), as the most common means for bacteria to exchange information and interactions, is characterized by universality, specificity, and regulatory power, which therefore may influence the assembly processes of human microbiota. However, the regulating role of QS in microbiota assembly is rarely reported. In this study, we developed an optimized in vitro oral biofilm microbiota assembling (OBMA) model to simulate the time-series assembly of oral biofilm microbiota (OBM), by which to excavate the QS network and its regulating power in the process.

RESULTS

By using the optimized OBMA model, we were able to restore the assembly process of OBM and generate time-series OBM metagenomes of each day. We discovered a total of 2291 QS protein homologues related to 21 QS pathways. Most of these pathways were newly reported and sequentially enriched during OBM assembling. These QS pathways formed a comprehensive longitudinal QS network that included successively enriched QS hubs, such as Streptococcus, Veillonella-Megasphaera group, and Prevotella-Fusobacteria group, for information delivery. Bidirectional cross-talk among the QS hubs was found to play critical role in the directional turnover of microbiota structure, which in turn, influenced the assembly process. Subsequent QS-interfering experiments accurately predicted and experimentally verified the directional shaping power of the longitudinal QS network in the assembly process. As a result, the QS-interfered OBM exhibited delayed and fragile maturity with prolonged membership of Streptococcus and impeded membership of Prevotella and Fusobacterium.

CONCLUSION

Our results revealed an unprecedented longitudinal QS network during OBM assembly and experimentally verified its power in predicting and manipulating the assembling process. Our work provides a new perspective to uncover underlying mechanism in natural complex microbiota assembling and a theoretical basis for ultimately precisely manipulating human microbiota through intervention in the QS network. Video Abstract.

Association between oral microbial dysbiosis and poor functional outcomes in stroke-associated pneumonia patients

BACKGROUND

Despite advances in our understanding of the critical role of the microbiota in stroke patients, the oral microbiome has rarely been reported to be associated with stroke-associated pneumonia (SAP). We sought to profile the oral microbial composition of SAP patients and to determine whether microbiome temporal instability and special taxa are associated with pneumonia progression and functional outcomes.

METHODS

This is a prospective, observational, single-center cohort study that examined patients with acute ischemic stroke (AIS) who were admitted within 24 h of experiencing a stroke event. The patients were divided into three groups based on the occurrence of pneumonia and the use of mechanical ventilation: nonpneumonia group, SAP group, and ventilator-associated pneumonia (VAP) group. We collected oral swabs at different time points post-admission and analyzed the microbiota using 16 S rRNA high-throughput sequencing. The microbiota was then compared among the three groups.

RESULTS

In total, 104 nonpneumonia, 50 SAP and 10 VAP patients were included in the analysis. We found that SAP and VAP patients exhibited significant dynamic differences in the diversity and composition of the oral microbiota and that the magnitude of this dysbiosis and instability increased during hospitalization. Then, by controlling the potential effect of all latent confounding variables, we assessed the changes associated with pneumonia after stroke and explored patients with a lower abundance of Streptococcus were more likely to suffer from SAP. The logistic regression analysis revealed that an increase in specific taxa in the phylum Actinobacteriota was linked to a higher risk of poor outcomes. A model for SAP patients based on oral microbiota could accurately predict 30-day clinical outcomes after stroke onset.

CONCLUSIONS

We concluded that specific oral microbiota signatures could be used to predict illness development and clinical outcomes in SAP patients. We proposed the potential of the oral microbiota as a non-invasive diagnostic biomarker in the clinical management of SAP patients.

CLINICAL TRIAL REGISTRATION

NCT04688138. Registered 29/12/2020, https://clinicaltrials.gov/ct2/show/NCT04688138 .

Diversity of the bacteriocins, their classification and potential applications in combat of antibiotic resistant and clinically relevant pathogens

There is almost a century since discovery of penicillin by Alexander Fleming, a century of enthusiasm, abuse, facing development of antibiotic-resistance and clear conclusion that the modern medicine needs a new type of antimicrobials. Bacteriocins produced by Gram-positive and Gram-negative bacteria, Archaea and Eukaryotes were widely explored as potential antimicrobials with several applications in food industry. In last two decades bacteriocins showed their potential as promising alternative therapeutic for the treatment of antibiotic-resistant pathogens. Bacteriocins can be characterised as highly selective antimicrobials and therapeutics with low cytotoxicity. Most probably in order to solve the problems associated with the increasing number of antibiotic-resistant bacteria, the application of natural or bioengineered bacteriocins in addition to synergistically acting preparations of bacteriocins and conventional antibiotics, can be the next step in combat versus drug-resistant pathogens. In this overview we focussed on diversity of specific lactic acid bacteria and their bacteriocins. Moreover, some additional examples of bacteriocins from non-lactic acid, Gram-positive and Gram-negative bacteria, Archaea and eukaryotic organisms are presented and discussed. Therapeutic properties of bacteriocins, their bioengineering and combined applications, together with conventional antibiotics, were evaluated with the scope of application in human and veterinary medicine for combating (multi-)drug-resistant pathogens.

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.

Staphylococcus aureus in Polymicrobial Skinand Soft Tissue Infections: Impact of Inter-Species Interactionsin Disease Outcome

Polymicrobial biofilms provide a complex environment where co-infecting microorganisms can behave antagonistically, additively, or synergistically to alter the disease outcome compared to monomicrobial infections. Staphylococcus aureus skin and soft tissue infections (Sa-SSTIs) are frequently reported in healthcare and community settings, and they can also involve other bacterial and fungal microorganisms. This polymicrobial aetiology is usually found in chronic wounds, such as diabetic foot ulcers, pressure ulcers, and burn wounds, where the establishment of multi-species biofilms in chronic wounds has been extensively described. This review article explores the recent updates on the microorganisms commonly found together with S. aureus in SSTIs, such as Pseudomonas aeruginosa, Escherichia coli, Enterococcus spp., Acinetobacter baumannii, and Candida albicans, among others. The molecular mechanisms behind these polymicrobial interactions in the context of infected wounds and their impact on pathogenesis and antimicrobial susceptibility are also revised.

Bridging biotechnology and nanomedicine to produce biogreen whey-nanovesicles for intestinal health promotion

New intestinal health-promoting biotechnological nanovesicles were manufactured by combining the main environmental pollutant generated from the cheese-making process, whey, with phospholipid, sodium hyaluronate and dextrin, thus overcoming environmental and medical challenges. An efficient, consolidated and eco-friendly preparation method was employed to manufacture the vesicles and the bioactive whey was obtained by mesophilic dark fermentation without external inoculum through a homolactic pathway, which was operated in such a way as to maximize the production of lactic acid. The biotechnological nutriosomes and hyalonutriosomes were relatively small (∼100 nm) and characterized by the net negative surface charge (>-30 mV). The addition of maltodextrin to the liposomes and especially to the hyalurosomes significantly stabilized the vesicles under acidic conditions, simulating the gastric environment, as their size and polydispersity index were significantly lower (p < 0.05) than those of the other formulations. The vesicles were effectively internalized by Caco-2 cells and protected them against oxidative stress. Nutriosomes promoted the proliferation of Streptococcus salivarius, a human commensal bacterium, to a better extent (p < 0.05) than liposomes and hyalurosomes, as a function of the concentration tested. These findings could open a new horizon in intestinal protection and health promotion by integrating biotechnology, nanomedicine, sustainability principles and bio-circular economy.

An Isolate of Streptococcus mitis Displayed In Vitro Antimicrobial Activity and Deleterious Effect in a Preclinical Model of Lung Infection

Microbiota studies have dramatically increased over these last two decades, and the repertoire of microorganisms with potential health benefits has been considerably enlarged. The development of next generation probiotics from new bacterial candidates is a long-term strategy that may be more efficient and rapid with discriminative in vitro tests. Streptococcus strains have received attention regarding their antimicrobial potential against pathogens of the upper and, more recently, the lower respiratory tracts. Pathogenic bacterial strains, such as non-typable Haemophilus influenzae (NTHi), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), are commonly associated with acute and chronic respiratory diseases, and it could be interesting to fight against pathogens with probiotics. In this study, we show that a Streptococcus mitis (S. mitis) EM-371 strain, isolated from the buccal cavity of a human newborn and previously selected for promising anti-inflammatory effects, displayed in vitro antimicrobial activity against NTHi, P. aeruginosa or S. aureus. However, the anti-pathogenic in vitro activity was not sufficient to predict an efficient protective effect in a preclinical model. Two weeks of treatment with S. mitis EM-371 did not protect against, and even exacerbated, NTHi lung infection.

The Discovery of Oropharyngeal Microbiota with Inhibitory Activity against Pathogenic Neisseria gonorrhoeae and Neisseria meningitidis: An In Vitro Study of Clinical Isolates

With increasing incidence of pathogenic Neisseria infections coupled with emerging resistance to antimicrobials, alternative approaches to limit the spread are sought. We investigated the inhibitory effect of oropharyngeal microbiota on the growth of N. gonorrhoeae and N. meningitidis and the impact of the essential oil-based mouthwash Listerine Cool Mint^® (Listerine). Oropharyngeal swabs from 64 men who have sex with men (n = 118) from a previous study (PReGo study) were analysed (ClinicalTrials.gov, NCT03881007). These included 64 baseline and 54 samples following three months of daily use of Listerine. Inhibition was confirmed by agar overlay assay, and inhibitory bacteria isolated using replica plating and identified using MALDI-TOF. The number of inhibitory isolates were compared before and after Listerine use. Thirty-one pharyngeal samples (26%) showed inhibitory activity against N. gonorrhoeae and/or N. meningitidis, and 62 inhibitory isolates were characterised. Fourteen species belonging to the genera Streptococci and Rothia were identified. More inhibitory isolates were observed following Listerine use compared to baseline, although this effect was not statistically significant (p = 0.073). This study isolated and identified inhibitory bacteria against pathogenic Neisseria spp. and established that daily Listerine use did not decrease their prevalence. These findings could provide a new approach for the prevention and treatment of pharyngeal Neisseria infections.

A Brief Review of Local Bacteriotherapy for Preventing Respiratory Infections

Recurrent respiratory infections (RRIs) account for relevant economic and social implications and significantly affect family life. Local Bacteriotherapy (LB) represents an innovative option in preventing RRIs. Local bacteriotherapy consists of administering “good” and safe bacteria (probiotics) by nasal or oral route. In particular, two strains (Streptococcus salivarius 24SMB and Streptococcus oralis 89a) are commonly used. The present article presents and discusses the literature concerning LB. Infections of airways include the upper and lower respiratory tract. A series of clinical trials investigated the preventive role of LB in preventing upper and lower RIs. These studies demonstrated that LB safely reduced the prevalence and severity of RIs, the use of antibiotics, and absences from school. Therefore, Local Bacteriotherapy may be considered an interesting therapeutic option in RRI prevention.

Streptococcus salivarius 24SMBc Genome Analysis Reveals New Biosynthetic Gene Clusters Involved in Antimicrobial Effects on Streptococcus pneumoniae and Streptococcus pyogenes

Streptococcus salivarius 24SMBc is an oral probiotic with antimicrobial activity against the otopathogens Streptococcus pyogenes and Streptococcus pneumoniae. Clinical studies have reinforced its role in reducing the recurrence of upper respiratory tract infections (URTIs) and rebalancing the nasal microbiota. In this study, for the first time, we characterized 24SMBc by whole genome sequencing and annotation; likewise, its antagonistic activity vs. Streptococcus pneumoniae and Streptococcus pyogenes was evaluated by in vitro co-aggregation and competitive adherence tests. The genome of 24SMBc comprises 2,131,204 bps with 1933 coding sequences (CDS), 44 tRNA, and six rRNA genes and it is categorized in 319 metabolic subsystems. Genome mining by BAGEL and antiSMASH tools predicted three novel biosynthetic gene clusters (BGCs): (i) a Blp class-IIc bacteriocin biosynthetic cluster, identifying two bacteriocins blpU and blpK; (ii) an ABC-type bacteriocin transporter; and (iii) a Type 3PKS (Polyketide synthase) involved in the mevalonate pathway for the isoprenoid biosynthetic process. Further analyses detected two additional genes for class-IIb bacteriocins and 24 putative adhesins and aggregation factors. Finally, in vitro assays of 24SMBc showed significant anti-adhesion and co-aggregation effects against Streptococcus pneumoniae strains, whereas it did not act as strongly against Streptococcus pyogenes. In conclusion, we identified a novel blpU-K bacteriocin-encoding BGC and two class-IIb bacteriocins involved in the activity against Streptococcus pneumoniae and Streptococcus pyogenes; likewise the type 3PKS pathway could have beneficial effects for the host including antimicrobial activity. Furthermore, the presence of adhesins and aggregation factors might be involved in the marked in vitro activity of co-aggregation with pathogens and competitive adherence, showing an additional antibacterial activity not solely related to metabolite production. These findings corroborate the antimicrobial activity of 24SMBc, especially against Streptococcus pneumoniae belonging to different serotypes, and further consolidate the use of this strain in URTIs in clinical settings.

Oralbiotica/Oralbiotics: The Impact of Oral Microbiota on Dental Health and Demineralization: A Systematic Review of the Literature

The oral microbiota plays a vital role in the human microbiome and oral health. Imbalances between microbes and their hosts can lead to oral and systemic disorders such as diabetes or cardiovascular disease. The purpose of this review is to investigate the literature evidence of oral microbiota dysbiosis on oral health and discuss current knowledge and emerging mechanisms governing oral polymicrobial synergy and dysbiosis; both have enhanced our understanding of pathogenic mechanisms and aided the design of innovative therapeutic approaches as ORALBIOTICA for oral diseases such as demineralization. PubMed, Web of Science, Google Scholar, Scopus, Cochrane Library, EMBEDDED, Dentistry & Oral Sciences Source via EBSCO, APA PsycINFO, APA PsyArticles, and DRUGS@FDA were searched for publications that matched our topic from January 2017 to 22 April 2022, with an English language constraint using the following Boolean keywords: ("microbio*" and "demineralization*") AND ("oral microbiota" and "demineralization"). Twenty-two studies were included for qualitative analysis. As seen by the studies included in this review, the balance of the microbiota is unstable and influenced by oral hygiene, the presence of orthodontic devices in the oral cavity and poor eating habits that can modify its composition and behavior in both positive and negative ways, increasing the development of demineralization, caries processes, and periodontal disease. Under conditions of dysbiosis, favored by an acidic environment, the reproduction of specific bacterial strains increases, favoring cariogenic ones such as Bifidobacterium dentium, Bifidobacterium longum, and S. mutans, than S. salivarius and A. viscosus, and increasing of Firmicutes strains to the disadvantage of Bacteroidetes. Microbial balance can be restored by using probiotics and prebiotics to manage and treat oral diseases, as evidenced by mouthwashes or dietary modifications that can influence microbiota balance and prevent or slow disease progression.

Airway Prevotella promote TLR2-dependent neutrophil activation and rapid clearance of Streptococcus pneumoniae from the lung

This study investigates how specific members of the lung microbiome influence the early immune response to infection. Prevotella species are a major component of the endogenous airway microbiota. Increased abundance of Prevotella melaninogenica correlates with reduced infection with the bacterial pathogen Streptococcus pneumoniae, indicating a potentially beneficial role. Here, we show that P. melaninogenica enhances protection against S. pneumoniae, resulting in rapid pathogen clearance from the lung and improved survival in a mouse lung co-infection model. This response requires recognition of P. melaninogenica lipoproteins by toll-like receptor (TLR)2, the induction of TNFα, and neutrophils, as the loss of any of these factors abrogates Prevotella-induced protection. Improved clearance of S. pneumoniae is associated with increased serine protease-mediated killing by lung neutrophils and restraint of P. melaninogenica-induced inflammation by IL-10 in co-infected mice. Together, these findings highlight innate immune priming by airway Prevotella as an important protective feature in the respiratory tract.

How the airway microbiome protects against bacterial pneumonia remains unclear. Here, the authors identify airway bacterial species that activate the immune system to facilitate rapid clearance of the pathogen Streptococcus pneumoniae from the lung.

Identification of a two-component regulatory system involved in antimicrobial peptide resistance in Streptococcus pneumoniae

Two-component regulatory systems (TCS) are among the most widespread mechanisms that bacteria use to sense and respond to environmental changes. In the human pathogen Streptococcus pneumoniae, a total of 13 TCS have been identified and many of them have been linked to pathogenicity. Notably, TCS01 strongly contributes to pneumococcal virulence in several infection models. However, it remains one of the least studied TCS in pneumococci and its functional role is still unclear. In this study, we demonstrate that TCS01 cooperates with a BceAB-type ABC transporter to sense and induce resistance to structurally-unrelated antimicrobial peptides of bacterial origin that all target undecaprenyl-pyrophosphate or lipid II, which are essential precursors of cell wall biosynthesis. Even though tcs01 and bceAB genes do not locate in the same gene cluster, disruption of either of them equally sensitized the bacterium to the same set of antimicrobial peptides. We show that the key function of TCS01 is to upregulate the expression of the transporter, while the latter appears the main actor in resistance. Electrophoretic mobility shift assays further demonstrated that the response regulator of TCS01 binds to the promoter region of the bceAB genes, implying a direct control of these genes. The BceAB transporter was overexpressed and purified from E. coli. After reconstitution in liposomes, it displayed substantial ATPase and GTPase activities that were stimulated by antimicrobial peptides to which it confers resistance to, revealing new functional features of a BceAB-type transporter. Altogether, this inducible defense mechanism likely contributes to the survival of the opportunistic microorganism in the human host, in which competition among commensal microorganisms is a key determinant for effective host colonization and invasive path.

Streptococcus pneumoniae is a commensal bacterium of the human nasopharynx that can switch to an invasive pathogen causing a variety of diseases, leading to over one million deaths worldwide each year. The sophisticated strategies that allow S. pneumoniae to survive in various environments within the human body are still poorly understood. One of the most widespread tools that enable bacteria to sense environmental changes and to promote adaptative responses by modulating gene expression are two-component regulatory systems (TCS). TCS01 was identified as an important virulence factor, and understanding its biological function is key to comprehend bacterial pathogenesis. In this study, we demonstrated that this TCS upregulates the expression of an ABC transporter that mediates resistance to bacterial antimicrobial peptides targeting cell wall synthesis. Because competition among microorganisms is a key element for host colonization and persistence, our findings contribute to explain the potent role of TCS01 in bacterial survival within the human host.

Relationships Between Oral Microecosystem and Respiratory Diseases

Oral microecosystem is a very complicated ecosystem that is located in the mouth and comprises oral microbiome, diverse anatomic structures of oral cavity, saliva and interactions between oral microbiota and between oral microbiota and the host. More and more evidence from studies of epidemiology, microbiology and molecular biology is establishing a significant link between oral microecosystem and respiratory diseases. Microbiota settling down in oral microecosystem is known as the main source of lung microbiome and has been associated with the occurrence and development of respiratory diseases like pneumonia, chronic obstructive pulmonary disease, lung cancer, cystic fibrosis lung disease and asthma. In fact, it is not only indigenous oral microbes promote or directly cause respiratory infection and inflammation when inhaled into the lower respiratory tract, but also internal environment of oral microecosystem serves as a reservoir for opportunistic respiratory pathogens. Moreover, poor oral health and oral diseases caused by oral microecological dysbiosis (especially periodontal disease) are related with risk of multiple respiratory diseases. Here, we review the research status on the respiratory diseases related with oral microecosystem. Potential mechanisms on how respiratory pathogens colonize oral microecosystem and the role of indigenous oral microbes in pathogenesis of respiratory diseases are also summarized and analyzed. Given the importance of oral plaque control and oral health interventions in controlling or preventing respiratory infection and diseases, we also summarize the oral health management measures and attentions, not only for populations susceptible to respiratory infection like the elderly and hospitalized patients, but also for dentist or oral hygienists who undertake oral health care. In conclusion, the relationship between respiratory diseases and oral microecosystem has been established and supported by growing body of literature. However, etiological evidence on the role of oral microecosystem in the development of respiratory diseases is still insufficient. Further detailed studies focusing on specific mechanisms on how oral microecosystem participate in the pathogenesis of respiratory diseases could be helpful to prevent and treat respiratory diseases.

Formation, Development, and Cross-Species Interactions in Biofilms

Biofilms, which are essential vectors of bacterial survival, protect microbes from antibiotics and host immune attack and are one of the leading causes that maintain drug-resistant chronic infections. In nature, compared with monomicrobial biofilms, polymicrobial biofilms composed of multispecies bacteria predominate, which means that it is significant to explore the interactions between microorganisms from different kingdoms, species, and strains. Cross-microbial interactions exist during biofilm development, either synergistically or antagonistically. Although research into cross-species biofilms remains at an early stage, in this review, the important mechanisms that are involved in biofilm formation are delineated. Then, recent studies that investigated cross-species cooperation or synergy, competition or antagonism in biofilms, and various components that mediate those interactions will be elaborated. To determine approaches that minimize the harmful effects of biofilms, it is important to understand the interactions between microbial species. The knowledge gained from these investigations has the potential to guide studies into microbial sociality in natural settings and to help in the design of new medicines and therapies to treat bacterial infections.

In vitro Inhibition of respiratory pathogens by lactobacillus and alpha haemolytic streptococci from Aboriginal and Torres Strait Islander children

AIMS

To explore the in vitro ability of alpha haemolytic streptococcus (AHS) and lactobacilli (LBs), from Indigenous Australian children, to inhibit the growth of respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis), also from Indigenous Australian children.

METHODS AND RESULTS

The bacterial interference of 91 isolates, from Indigenous Australian children both with and without otitis media (OM) or rhinorrhoea, was investigated using agar overlay and cell-free supernatant. Promising isolates underwent whole genome sequencing to investigate upper respiratory tract tropism, antibiotic resistance and virulence. Antibiotic susceptibility was examined for ampicillin, amoxicillin +clavulanic acid and azithromycin. Differences in the strength of bacterial inferences in relation to OM was examined using a case series of three healthy and three children with OM. LBs readily inhibited the growth of pathogens. AHS were less effective, although several isolates inhibited S. pneumoniae. One L. rhamnosus had genes coding for pili to adhere to epithelial cells. We detected antibiotic resistance genes coding for antibiotic efflux pump and ribosomal protection protein. LBs were susceptible to antimicrobials in vitro. Screening for virulence detected genes encoding for two putative capsule proteins. Healthy children had AHS and LB that were more potent inhibitors of respiratory pathogens in vitro than children with OM.

CONCLUSIONS

L. rhamnosus from remote Indigenous Australian children are potent inhibitors of respiratory pathogens in vitro.

SIGNIFICANCE AND IMPACT OF STUDY

Respiratory/ear disease are endemic in Indigenous Australians. There is an urgent call for more effective treatment/prevention; beneficial microbes have not been explored. L. rhamnosus investigated in this study are potent inhibitors of respiratory pathogens in vitro and require further investigation.

Development of a new antimicrobial concept for boar semen preservation based on bacteriocins

The conventional storage temperature of 16-18 °C provides optimal conditions for the preservation of boar sperm quality, which are extremely cold sensitive cells. On the other hand, however, it requires the addition of antibiotics to inhibit bacterial growth. Rising numbers of antibiotic resistant bacteria call for alternatives to this conventional storing method. As potential alternative, three different bacteriocin candidates with known bacteriolytic activity against E. coli were examined on possible negative effects concerning the sperm quality and on their impact on bacterial growth of E. coli ILSH 02692 in BTS-extended semen w/o antibiotics. Although the lower concentrations (0.01 and 0.25%) of all bacteriocins did not show any impact on the quality of the semen, the higher concentrations (0.5 and 1.0%) of two bacteriocins led to a significant (P < 0.05) reduction in several sperm quality characteristics. The bacteriocin 860/1c after AMS/dialysis did not affect the sperm quality in any of the tested concentrations and in all tested extenders (BTS, MIII, Androstar Premium and Androhep all w/o antibiotics) at 16 °C as well as at 6 °C. This bacteriocin reduced growth of E. coli ILSH 02692 in BTS-extended semen by 50% compared to the control w/o bacteriocin. Furthermore, a preliminary insemination trial indicated no impact of the selected bacteriocin on fertility. These promising results show that the application of bacteriocins in liquid-preserved semen is a feasible possibility in the future.

Oral microbiome in Proliferative Verrucous Leukoplakia exhibits loss of diversity and enrichment of pathogens

OBJECTIVES

Oral microbiome plays an important role in oral diseases. Among them, proliferative verrucous leucoplakia (PVL) is an uncommon form of progressive multifocal leukoplakia with a worryingly rate of malignant transformation. Here, we aimed to characterize the oral microbiome of PVL patients and compare it with those of healthy controls.

MATERIAL AND METHODS

Oral biopsies from ten PVL patients and five healthy individuals were obtained and used to compare their microbial communities. The sequence of the V3-V4 region of 16S rRNA gene was used as the taxonomic basis to estimate and analyze the composition and diversity of bacterial populations present in the samples.

RESULTS

Our results show that the oral microbial composition and diversity are significantly different among PVL patients and healthy donors. The average number of observed operational taxonomic units (OTUs) was higher for healthy donors than for PVL, proving a loss of diversity in PVL. Several OTUs were found to be more abundant in either group. Among those that were significantly enriched in PVL patients, potential protumorigenic pathogens like Oribacterium sp. oral taxon 108, Campylobacter jejuni, uncultured Eubacterium sp., Tannerella, and Porphyromonas were identified.

CONCLUSION

Oral microbiome dysbiosis was found in patients suffering from PVL. To the best of our knowledge, this is the first study investigating the oral microbiome alterations in PVL and, due to the limited number of participants, additional studies are needed. Oral microbiota-based biomarkers may be helpful in predicting the risks for the development of PVL.

Characterization of Exopolysaccharides (EPSs) Obtained from Ligilactobacillus salivarius Strains and Investigation at the Prebiotic Potential as an Alternative to Plant Prebiotics at Poultry

In this study, it was aimed to reveal the potential of using exopolysaccharides (EPS) obtained from Ligilactobacillus salivarius as a prebiotic that regulates chicken intestinal microbiota. Characterization of EPS obtained from L. salivarius BIS312 (EPSBIS312) and BIS722 (EPSBIS722) strains was demonstrated by high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and size-exclusion chromatography (SEC) analyses. It was determined that the molecular weight of both EPS is in the range of 10⁴-10⁶ Daltons, and there are 4 types of monomers in their structure. Anti-biofilm and anti-quorum sensing effects of EPSBIS312 and EPSBIS722 were determined. EPSBIS312 and EPSBIS722 showed a strong anti-biofilm effect on Enterococcus faecalis ATCC 29212, Staphylococcus aureus EB-1, and Escherichia coli ATCC 11229. The anti-quorum sensing study revealed that the EPSBIS722 had a higher effect than the EPSBIS312. The effect of different concentrations of EPS (2.5%, 5%, 10%) on lactobacilli growth stimulator (LGS) was evaluated. The highest LGS was promoted at 10% concentration while the lowest LGS was promoted at 2.5% concentration by EPSBIS722. In addition, adhesion abilities of EPSBIS312 and EPSBIS722 in HT-29 colorectal adenocarcinoma cell line were tested. EPSs significantly increased the ability to adhere to HT-29 cells. The characterized EPSs may be an alternative to plant prebiotics such as inulin at poultry.

Antimicrobial properties of Lactobacillus cell-free supernatants against multidrug-resistant urogenital pathogens

The healthy vaginal microbiota is dominated by Lactobacillus spp., which provide an important critical line of defense against pathogens, as well as giving beneficial effects to the host. We characterized L. gasseri 1A‐TV, L. fermentum 18A‐TV, and L. crispatus 35A‐TV, from the vaginal microbiota of healthy premenopausal women, for their potential probiotic activities. The antimicrobial effects of the 3 strains and their combination against clinical urogenital bacteria were evaluated together with the activities of their metabolites produced by cell‐free supernatants (CFSs). Their beneficial properties in terms of ability to interfere with vaginal pathogens (co‐aggregation, adhesion to HeLa cells, biofilm formation) and antimicrobial activity mediated by CFSs were assessed against multidrug urogenital pathogens (S. agalactiae, E. coli, KPC‐producing K. pneumoniae, S. aureus, E. faecium VRE, E. faecalis, P. aeruginosa, P. mirabilis, P. vulgaris, C. albicans, C. glabrata). The Lactobacilli tested exhibited an extraordinary ability to interfere and co‐aggregate with urogenital pathogens, except for Candida spp., as well as to adhere to HeLa cells and to produce biofilm in the Lactobacillus combination. Lactobacillus CFSs and their combination revealed a strong bactericidal effect on the multidrug resistant indicator strains tested, except for E. faecium and E. faecalis. The antimicrobial activity was maintained after heat treatment but decreased after enzymatic treatment. All Lactobacilli showed lactic dehydrogenase activity and production of D‐ and L‐lactic acid isomers on Lactobacillus CFSs, while only 1A‐TV and 35A‐TV released hydrogen peroxide and carried helveticin J and acidocin A bacteriocins. These results suggest that they can be employed as a new vaginal probiotic formulation and bio‐therapeutic preparation against urogenital infections. Further, in vivo studies are needed to evaluate human health benefits in clinical situations.

The microbiota in pneumonia: From protection to predisposition

Mucosal surfaces of the upper respiratory tract and gut are physiologically colonized with their own collection of microbes, the microbiota. The normal upper respiratory tract and gut microbiota protects against pneumonia by impeding colonization by potentially pathogenic bacteria and by regulating immune responses. However, antimicrobial therapy and critical care procedures perturb the microbiota, thus compromising its function and predisposing to lung infections (pneumonia). Interindividual variations and age-related alterations in the microbiota also affect vulnerability to pneumonia. We discuss how the healthy microbiota protects against pneumonia and how host factors and medical interventions alter the microbiota, thus influencing susceptibility to pneumonia.

Oral probiotics in coronavirus disease 2019: connecting the gut-lung axis to viral pathogenesis, inflammation, secondary infection and clinical trials

Defined as helpful live bacteria that can provide medical advantages to the host when administered in tolerable amounts, oral probiotics might be worth considering as a possible preventive or therapeutic modality to mitigate coronavirus disease 2019 (COVID-19) symptom severity. This hypothesis stems from an emerging understanding of the gut-lung axis wherein probiotic microbial species in the digestive tract can influence systemic immunity, lung immunity, and possibly viral pathogenesis and secondary infection co-morbidities. We review the principles underlying the gut-lung axis, examples of probiotic-associated antiviral activities, and current clinical trials in COVID-19 based on oral probiotics.

Infections of the lung: a predictive, preventive and personalized perspective through the lens of evolution, the emergence of SARS-CoV-2 and its pathogenesis

The long evolutionary battle between humans and pathogens has played an important role in shaping the current network of host-pathogen interactions. Each organ brings new challenges from the perspective of a pathogen to establish a suitable niche for survival while subverting the protective mechanisms of the host. Lungs, the organ for oxygen exchange, have been an easy target for pathogens due to its accessibility. The organ has evolved diverse capabilities to provide the flexibility required for an organism's health and at the same time maintain protective functionality to prevent and resolve assault by pathogens. The pathogenic invasions are strongly challenged by healthy lung architecture which includes the presence and activity of the epithelium, mucous, antimicrobial proteins, surfactants, and immune cells. Competitively, the pathogens in the form of viruses, bacteria, and fungi have evolved an arsenal of strategies that can over-ride the host's protective mechanisms. While bacteria such as Mycobacterium tuberculosis (M. tuberculosis) can survive in dormant form for years before getting active in humans, novel pathogens can wreak havoc as they pose a high risk of morbidity and mortality in a very short duration of time. Recently, a coronavirus strain SARS-CoV-2 has caused a pandemic which provides us an opportunity to look at the host manipulative strategies used by respiratory pathogens. Their ability to hide, modify, evade, and exploit cell's processes are key to their survival. While pathogens like M. tuberculosis have been infecting humans for thousands of years, SARS-CoV-2 has been the cause of the recent pandemic. Molecular understanding of the strategies used by these pathogens could greatly serve in design of predictive, preventive, personalized medicine (PPPM). In this article, we have emphasized on the clinically relevant evasive strategies of the pathogens in the lungs with emphasis on M. tuberculosis and SARS-CoV-2. The molecular basis of these evasive strategies illuminated through advances in genomics, cell, and structural biology can assist in the mapping of vulnerable molecular networks which can be exploited translationally. These evolutionary approaches can further assist in generating screening and therapeutic options for susceptible populations and could be a promising approach for the prediction, prevention of disease, and the development of personalized medicines. Further, tailoring the clinical data of COVID-19 patients with their physiological responses in light of known host-respiratory pathogen interactions can provide opportunities to improve patient profiling and stratification according to identified therapeutic targets.

In vitro Inhibition of Clinical Isolates of Otitis Media Pathogens by the Probiotic Streptococcus salivarius BLIS K12

Otitis media is a common childhood infection, frequently requiring antibiotics. With high rates of antibiotic prescribing and increasing antibiotic resistance, new strategies in otitis media prevention and treatment are needed. The aim of this study was to assess the in vitro inhibitory activity Streptococcus salivarius BLIS K12 against otitis media pathogens. Efficacy of the bacteriocin activity of S. salivarius BLIS K12 against the otitis media isolates was assessed using the deferred antagonism test. Overall, 48% of pathogenic isolates exhibited some growth inhibition by S. salivarius BLIS K12. S. salivarius BLIS K12 can inhibit the in vitro growth of the most common pathogens.

Local Bacteriotherapy - a promising preventive tool in recurrent respiratory infections

INTRODUCTION

Children with recurrent respiratory infections (RRI) represent a social issue for the economic burden and the negative family impact. Local Bacteriotherapy is an attractive therapeutic strategy that could be potentially effective in preventing infections. The current article remarks on the existing evidence of preventing RRI by Local Bacteriotherapy.

AREAS COVERED

The literature search methodology was based on the articles cited by PubMed from 1980 to 2020. Respiratory infections include rhino-pharyngitis, otitis media, rhinosinusitis, pharyngo-tracheitis, bronchitis, and pneumonia. Several studies were performed to investigate the effects of Local Bacteriotherapy in children with RRI. Both intranasal and oral Local Bacteriotherapy were evaluated. The findings showed that Local Bacteriotherapy significantly reduced the number of RI episodes, their severity, the use of antibiotics, and school absences.

EXPERT OPINION

Local Bacteriotherapy is a promising approach to RRI prevention and could be a profitable strategy to contrast infections in the future.

Cell-free supernatant of Streptococcus salivarius M18 impairs the pathogenic properties of Pseudomonas aeruginosa and Klebsiella pneumonia

M18 strain of Streptococcus salivarius is a bacterial replacement probiotic that has been suggested for use in the oral cavity. Here, we have shown that S. salivarius M18 cell-free supernatant reduced the growth of the two most common human pathogens Pseudomonas aeruginosa and Klebsiella pneumonia and sensitized the pathogenic bacteria to antibiotic. Besides, the supernatant inhibited biofilm formation of P. aeruginosa drastically. For pinpointing the biomolecular changes that occurred in P. aeruginosa incubated with the probiotic supernatant, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used. Unsupervised learning algorithms, principal component analysis (PCA) and hierarchical cluster analysis (HCA), and intensity analyses of individual spectral bands exhibited comprehensive alterations in the polysaccharide and lipid contents and compositions of P. aeruginosa cultivated with S. salivarius M18 cell-free supernatant. These results indicate that S. salivarius M18 has the potential for the prevention or alleviation of different pathogen-induced infections along with the infections of oral pathogens.

Oral-lung microbiome interactions in lung diseases

The proximity and continuity of the oral cavity and the lower respiratory tract allows the oropharyngeal microbiome to be a major determinant of the lung microbiome. In addition, host-pathogen interactions related to the oropharyngeal microbiome or its metabolites could propagate systemic inflammation or modulate host defense mechanisms that could affect other organs, including the lung. There is increasing appreciation of the pathophysiologic significance of the lung microbiome, not only in the classical infection-related diseases, pneumonia, bronchiectasis, and cystic fibrosis, but also in chronic noninfectious lung diseases, such as chronic obstructive pulmonary disease, asthma, and pulmonary fibrosis. In this review, we will explore the relationship of the oral microbiome with lung diseases, such as pneumonia, chronic obstructive pulmonary disease, asthma, and cystic fibrosis.

Putative Microbial Population Shifts Attributable to Nasal Administration of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a

Changes in bacterial composition of nasal microbiota may alter the host's susceptibility to several infectious and allergic diseases such as chronic rhinosinusitis and allergic rhinitis. The aim of this study was to evaluate the effects of 1-week administration of a probiotic product, composed by a combination of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a, on the nostril microbiota. Differences in the nasal microbiota composition were investigated by using a next-generation sequencing approach. A strong and significant decrease in Staphylococcus aureus abundance was detected immediately after the bacterial administration. Moreover, comparing the microbial networks of nostril microbiota before and 1 month after the end of treatment, we detected an increase in the total number of both bacterial nodes and microbial correlations, with particular regard to the beneficial ones. Furthermore, a less abundance of microbial genera commonly associated to potential harmful bacteria has been observed. These results suggest a potential ability of S. salivarius 24SMBc and S. oralis 89a to regulate and reorganize the nasal microbiota composition, possibly favoring those microorganisms that may be able to limit the overgrowth of potential pathogens.

Commensal bacteria in the upper respiratory tract regulate susceptibility to infection

The human body is host to several distinct microbial communities. Disruption of these communities increases susceptibility to a wide range of diseases, including respiratory tract infections. While commensal bacteria in the gut contribute to this effect, recent studies point to a role for commensals occupying the upper respiratory tract through direct pathogen killing and by modifying nasal and lung immune homeostasis. Clinical trials exploring 'probiotic' respiratory tract commensals are an exciting development in this area. Upper respiratory tract microbiome sequencing has revealed that destabilization of this community precedes infection, indicating that microbiome profiling of individuals has predictive value. Further investigation of respiratory tract commensal-host interactions will be critical to translate bacterial-mediated protection toward new therapeutic approaches for respiratory tract disease.

Preventing recurrent acute otitis media with Streptococcus salivarius 24SMB and Streptococcus oralis 89a five months intermittent treatment: An observational prospective cohort study

INTRODUCTION

Acute otitis media (AOM) is the most common childhood disease leading to antibiotic use. More than 80% of children under three years of age experience at least one episode, and about one-third of these report significant recurrence of episodes. In recent years, several studies reported that normal nasopharyngeal flora inhibits growth of common otopathogens, suggesting that maintenance of an "adequate" nasopharyngeal flora might prevent occurrence of upper respiratory tract infections, including AOM. This study aims to determine whether five-month treatment with Streptococcus salivarius 24SMB and Streptococcus oralis 89a nasal spray prevents recurrence of AOM and prescription of antibiotics in children with diagnosis of recurrent AOM.

METHODS

Observational prospective cohort study including children aged 1-6 years with diagnosis of recurrent AOM registered with 31 Italian family pediatricians. 81 children were enrolled in the study from September 2016 to the end of the five therapeutic cycles of the Streptococcus salivarius 24SMB and Streptococcus oralis 89a supplied 7 days each month for 5 consecutive months. For each treated child, one untreated control was randomly selected, 1:1 matched for gender, age, and follow-up.

RESULTS

158 children (79 treated and 70 untreated) were included into the analysis (mean age, 3.9 years; 47% female). Univariate analysis showed a statistically significant 34% (95% CI 1%-56%) reduction in number of AOM episodes in treated children compared with those not treated. Significantly fewer antibiotics were dispensed among treated children (24%, 95% CI 1%-41%).

CONCLUSIONS

Our findings suggest that intermittent treatment of children with diagnosis of recurrent AOM with nasal spray containing Streptococcus salivarius 24SMB and Streptococcus oralis 89a for a period of five months might be effective in preventing antibiotic use associated with recurrent episodes of AOM. Additional larger studies to address this important clinical problem are recommended.

Bacteriotherapy with Streptococcus salivarius 24SMB and Streptococcus oralis 89a nasal spray for treatment of upper respiratory tract infections in children: a pilot study on short-term efficacy

Background

Recurrent respiratory infections (RRIs) are defined by the presence of at least one of the following criteria: (i) > 6 annual respiratory infections (RIs); (ii) > 1 monthly RIs involving the upper airways from September to April; (iii) > 3 annual RIs involving the lower airways represent a very common health problem in the first years of life. We conducted a multi-centre, prospective, single-open study to assess the efficacy and the safety of Streptococcus salivarius 24SMBc and Streptococcus oralis 89a in the prevention of upper respiratory tract infections (URTIs) in children.

Methods

Ninety-one children (M:F = 47:44, mean age 7.4 ± 2.3 years) with RRIs were enrolled in the study between September and November 2018. At baseline, children received Streptococcus salivarius 24SMBc and Streptococcus oralis 89a as 2 puffs for nostril twice/day for 7 days/months. The treatment lasted for 3 consecutive months. Efficacy was expressed in terms of absence or presence of fever, cough, bronchospasm, rhinorrhea and otalgia, at 1 month (T1), and 3 (T3) months. Safety and tolerability of the probiotic were evaluated on the basis of the number and type of adverse events (AEs) recorded during the treatment.

Results

Children treated with Streptococcus salivarius 24SMBc and Streptococcus oralis 89a showed a significant decrease of symptoms including episodes of fever, cough, bronchospasm, rhinorrhea, and otalgia (p < 0.001) compared to baseline. The treatment significantly reduced the number of episodes of fever, cough, bronchospasm, rhinorrhea, otalgia, and cough also in patients with positive familial history for atopy and in atopic children (p < 0.05). No significant differences in symptoms among children with negative familial history for atopy and children with positive familial history for atopy subgroups, not atopic and atopic children subgroups, and smoke-exposed and not smoke-exposed subgroups were observed (p > 0.05). Conducting a subgroup analysis according to the age, it has been reported that children aged 1–3 years old showed an improvement in all symptoms, however, they become statistically significant only at the end of the 3 months of treatment (p < 0.05). Conversely, in children aged 3–6 and 6–12 years old, the therapeutic efficacy was progressive and significant already from the first month of therapy (p < 0.05). None of the children were withdrawn from the study because of AEs, although 9 children experienced burning nose leading to interruption of therapy.

Conclusions

Our findings suggest that Streptococcus salivarius 24SMBc and Streptococcus oralis 89a treatment is safe and seems to be effective on short-term in the treatment of RRIs. Studies involving a longer observation period are necessary to establish the real efficacy of the product for the treatment of pediatric patients affected by RRIs.

Nasal Delivery of a Commensal Pasteurellaceae Species Inhibits Nontypeable Haemophilus influenzae Colonization and Delays Onset of Otitis Media in Mice

Nasopharyngeal colonization with nontypeable Haemophilus influenzae (NTHi) is a prerequisite for developing NTHi-associated infections, including otitis media. Therapies that block NTHi colonization may prevent disease development. We previously demonstrated that Haemophilus haemolyticus, a closely related human commensal, can inhibit NTHi colonization and infection of human respiratory epithelium in vitro. We have now assessed whether Muribacter muris (a rodent commensal from the same family) can prevent NTHi colonization and disease in vivo using a murine NTHi otitis media model.

Nasopharyngeal colonization with nontypeable Haemophilus influenzae (NTHi) is a prerequisite for developing NTHi-associated infections, including otitis media. Therapies that block NTHi colonization may prevent disease development. We previously demonstrated that Haemophilus haemolyticus, a closely related human commensal, can inhibit NTHi colonization and infection of human respiratory epithelium in vitro. We have now assessed whether Muribacter muris (a rodent commensal from the same family) can prevent NTHi colonization and disease in vivo using a murine NTHi otitis media model. Otitis media was modeled in BALB/c mice using coinfection with 1 × 10^4.5 PFU of influenza A virus MEM H3N2, followed by intranasal challenge with 5 × 10⁷ CFU of NTHi R2866 Spec^r. Mice were pretreated or not with an intranasal inoculation of 5 × 10⁷ CFU M. muris 24 h before coinfection. NTHi and M. muris viable counts and inflammatory mediators (gamma interferon [IFN-γ], interleukin-1β [IL-1β], IL-6, keratinocyte chemoattractant [KC], and IL-10) were measured in nasal washes and middle ear tissue homogenate. M. muris pretreatment decreased the median colonization density of NTHi from 6 × 10⁵ CFU/ml to 9 × 10³ CFU/ml (P = 0.0004). Only 1/12 M. muris-pretreated mice developed otitis media on day 5 compared to 8/15 mice with no pretreatment (8% versus 53%, P = 0.0192). Inflammation, clinical score, and weight loss were also lower in M. muris-pretreated mice. We have demonstrated that a single dose of a closely related commensal can delay onset of NTHi otitis media in vivo. Human challenge studies investigating prevention of NTHi colonization are warranted to reduce the global burden of otitis media and other NTHi diseases.

Updated Guidelines for the Management of Acute Otitis Media in Children by the Italian Society of Pediatrics: Prevention

BACKGROUND

In recent years, new information has been acquired regarding the diagnosis, treatment and prevention of acute otitis media (AOM). The Italian Pediatric Society, therefore, decided to issue an update to the Italian Pediatric Society guidelines published in 2010.

METHODS

The search was conducted on Pubmed, and only those studies regarding the pediatric age alone, in English or Italian, published between January 1, 2010 and December 31, 2018, were included. Each study included in the review was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methodology. The quality of the systematic reviews was evaluated using the A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 appraisal tool. The guidelines were formulated using the GRADE methodology by a multidisciplinary panel of experts.

RESULTS

The importance of eliminating risk factors (passive smoking, environmental pollution, use of pacifier, obesity, limitation of day-care center attendance) and the promotion of breastfeeding and hygiene practices (nasal lavages) was confirmed. The importance of pneumococcal vaccination in the prevention of AOM was reiterated with regard to the prevention of both the first episode of AOM and recurrences. Grommets can be inserted in selected cases of recurrent AOM that did not respond to all other prevention strategies. Antibiotic prophylaxis is not recommended for the prevention of recurrent AOM, except in certain carefully selected cases. The use of complementary therapies, probiotics, xylitol and vitamin D is not recommended.

CONCLUSIONS

The prevention of episodes of AOM requires the elimination of risk factors and pneumococcal and influenza vaccination. The use of other products such as probiotics and vitamin D is not supported by adequate evidence.

Commensal Bacteria: An Emerging Player in Defense Against Respiratory Pathogens

A diverse community of trillions of commensal bacteria inhabits mucosal and epidermal surfaces in humans and plays an important role in defense against pathogens, including respiratory pathogens. Commensal bacteria act on the host's immune system to induce protective responses that prevent colonization and invasion by pathogens. On the other hand, these bacteria can directly inhibit the growth of respiratory pathogens by producing antimicrobial products/signals and competing for nutrients and adhesion sites. Such mechanisms preserve the niche for commensal bacteria and support the host in containing respiratory infections. Herein, we discuss current evidence on the role of commensal bacteria in conferring protection against respiratory pathogens and the underlying mechanisms by which these bacteria do so. A deeper knowledge of how commensal bacteria interact with the host and pathogens might provide new insights that are poised to aid in the development of vaccines and therapeutics that target infectious diseases.

Resistance diagnostics as a public health tool to combat antibiotic resistance: A model-based evaluation

Rapid point-of-care resistance diagnostics (POC-RD) are a key tool in the fight against antibiotic resistance. By tailoring drug choice to infection genotype, doctors can improve treatment efficacy while limiting costs of inappropriate antibiotic prescription. Here, we combine epidemiological theory and data to assess the potential of resistance diagnostics (RD) innovations in a public health context, as a means to limit or even reverse selection for antibiotic resistance. POC-RD can be used to impose a nonbiological fitness cost on resistant strains by enabling diagnostic-informed treatment and targeted interventions that reduce resistant strains' opportunities for transmission. We assess this diagnostic-imposed fitness cost in the context of a spectrum of bacterial population biologies and find that POC-RD have a greater potential against obligate pathogens than opportunistic pathogens already subject to selection under "bystander" antibiotic exposure during asymptomatic carriage (e.g., the pneumococcus). We close by generalizing the notion of RD-informed strategies to incorporate carriage surveillance information and illustrate that coupling transmission-control interventions to the discovery of resistant strains in carriage can potentially select against resistance in a broad range of opportunistic pathogens.

Bacteriotherapy with Streptococcus salivarius 24SMB and Streptococcus oralis 89a oral spray for children with recurrent streptococcal pharyngotonsillitis: a randomized placebo-controlled clinical study

PURPOSE

Group A beta-hemolytic Streptococcus (GABHS) causes a recurrent acute pharyngotonsillitis (RAPT) in children. Moreover, the repeated use of antibiotics contributes to its resistance. However, S. Salivarius 24SMB and S. oralis 89a were effective probiotics in other infections. Thus, we decided to evaluate this combination efficacy compared to placebo in RAPT.

METHODS

Patients with microbiologically confirmed GABHS were enrolled in this randomized, placebo-controlled trial. They received the aforementioned combination or placebo as an oral spray. We investigated episodes of frequency and duration, need for antibiotics, school days lost, the treatment impact on life quality, treatment compliance and side effects during a 90-day treatment and a 6-month follow-up.

RESULTS

We included 41 patients in each group. The mean number of GABHS infection was significantly lower during both study periods for the two groups. However, our treatment group showed a lower rate. Moreover, the probiotic group had a lower mean number and a shorter median duration of GABHS episodes during both study periods than controls. Furthermore, the mean duration of antibiotic treatment was lower in the probiotic group during the 90-day and 6-month follow-up periods. Similarly, patients in the probiotic group showed a significantly lower mean number of absence days from school but higher EQ-VAS score. Indeed, all patients included were compliant to treatment.

CONCLUSIONS

We identified potential probiotics, possessing desirable features against GABHS pharyngotonsillitis. Our findings represent the first evidence which throws the light on using these probiotics that can reduce antibiotics use which did not have efficient results regarding recurrence.

Microbiological Aspects of Acute and Chronic Pediatric Rhinosinusitis

The microbiology of acute and chronic rhinosinusitis has been extensively studied, but there are still some differences of view concerning the etiology of the former, and many disagreements regarding the microbiology of the latter. Establishing the concomitant distribution of the causative micro-organisms in cases that involve multiple sinuses is scientifically and practically important. The main problems are the variety of aerobes and anaerobes that may be involved, and the fact that different tracts of the sinuses of the same patient may be simultaneously affected. Rhinosinusitis may also involve the formation of biofilm, which may play a significant role in its pathogenesis and persistence. Biofilms have a number of advantages in terms of bacterial survival, and their perpetuation can create a certain degree of instability in host-bacteria interactions. Sinonasal microflora may further complicate pathogenesis and the identification of the pathogen(s) involved. Furthermore, the concentration, uniformity, and type/number of strains of nasal microbiota may vary from one site to another. The relative and total micro-organism counts can also be affected by various factors, and microbiota can modulate the course of both acute and chronic rhinosinusitis.

Effectiveness of the probiotic Streptococcus salivarius K12 for the treatment and/or prevention of sore throat: a systematic review

BACKGROUND

Sore throat resulting from pharyngotonsillitis is one of the commonest reasons for primary care consultation and inappropriate antibiotic prescription and finding effective alternative treatments is important.

OBJECTIVES

To review the evidence for using the probiotic Streptococcus salivarius K12 (SsK12) for the prevention or treatment of pharyngotonsillitis.

DATA SOURCES

PubMed, Embase, CINAHL and Cochrane Library.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials (RCTs).

PARTICIPANTS

Adults or children.

INTERVENTIONS

SsK12 as active treatment or prophylaxis, against pharyngotonsillitis.

METHODS

Literature search.

RESULTS

Four articles were identified (1846 participants). All were deemed to be of poor quality using the Cochrane risk-of-bias assessment. Two trials studied SsK12 prophylaxis for streptococcal pharyngitis (children without history of recurrence). One compared daily administration of SsK12 to no treatment over 6 months (n = 222, age 33-45 months), reporting significantly lower incidence in the SsK12 group (16.2% vs. 48.6%, p < 0.01), whereas another placebo-controlled RCT over four school terms (n = 1314, 5-14 years) found no significant difference (7.8% vs. 8.8%, p 0.34) with SsK12 (administered on school days). Another trial found daily SsK12 to significantly protect children (n = 250, 6-7 years) against chronic adenoiditis exacerbation over 3 months compared to no treatment (71.7% vs. 100%, p < 0.0001). The one placebo-controlled RCT in adults that studied the use of SsK12 for acute pharyngotonsillitis (concurrently with penicillin) showed no significant benefit. In all trials, SsK12 was safe and well tolerated.

CONCLUSIONS

SsK12 appears safe and well tolerated. However, further RCTs are required to establish its role as a prophylactic therapy, particularly among patients experiencing frequent exacerbations of pharyngitis. In the acute setting, SsK12 is unlikely to be effective if given concurrently with antibiotics; however, further RCTs should establish its role as an alternative to antibiotics in nonsevere cases or when prescribed after antibiotic therapy for the prevention of disease recurrence and/or secondary infection.

Probiotics in the treatment of otitis media. The past, the present and the future

Otitis media (OM) is one of the most common infectious diseases in children and the leading cause for medical consultations and antibiotic prescription in this population. The burden of disease associated with OM is greater in developing nations and indigenous populations where the associated hearing loss contributes to poor education and employment outcomes. Current treatment and prevention is largely focused on vaccination and antibiotics. However, rates of OM, particularly in indigenous populations, remain high. With growing concerns regarding antibiotic resistance and antibiotic-associated complications, an alternative, more effective treatment is required. Administration of probiotics, both locally and systemically have been investigated for their ability to treat and prevent OM in children. This review explores the theoretical bases of probiotics, successful application of probiotics in medicine, and their use in the treatment and prevention of OM. We conclude that local administration of niche-specific probiotic bacteria that demonstrates the ability to inhibit the growth of otopathogens in vitro shows promise in the prevention and treatment of OM and warrants further investigation.

Probiotics Streptococcus salivarius 24SMB and Streptococcus oralis 89a interfere with biofilm formation of pathogens of the upper respiratory tract

Background

Infections of the ears, paranasal sinuses, nose and throat are very common and represent a serious issue for the healthcare system. Bacterial biofilms have been linked to upper respiratory tract infections and antibiotic resistance, raising serious concerns regarding the therapeutic management of such infections. In this context, novel strategies able to fight biofilms may be therapeutically beneficial and offer a valid alternative to conventional antimicrobials. Biofilms consist of mixed microbial communities, which interact with other species in the surroundings and communicate through signaling molecules. These interactions may result in antagonistic effects, which can be exploited in the fight against infections in a sort of “bacteria therapy”. Streptococcus salivarius and Streptococcus oralis are α-hemolytic streptococci isolated from the human pharynx of healthy individuals. Several studies on otitis-prone children demonstrated that their intranasal administration is safe and well tolerated and is able to reduce the risk of acute otitis media. The aim of this research is to assess S. salivarius 24SMB and S. oralis 89a for the ability to interfere with biofilm of typical upper respiratory tract pathogens.

Methods

To investigate if soluble substances secreted by the two streptococci could inhibit biofilm development of the selected pathogenic strains, co-cultures were performed with the use of transwell inserts. Mixed-species biofilms were also produced, in order to evaluate if the inhibition of biofilm formation might require direct contact. Biofilm production was investigated by means of a spectrophotometric assay and by confocal laser scanning microscopy.

Results

We observed that S. salivarius 24SMB and S. oralis 89a are able to inhibit the biofilm formation capacity of selected pathogens and even to disperse their pre-formed biofilms. Diffusible molecules secreted by the two streptococci and lowered pH of the medium revealed to be implied in the mechanisms of anti-biofilm activity.

Conclusions

S. salivarius 24SMB and S. oralis 89a possess desirable characteristics as probiotic for the treatment and prevention of infections of the upper airways. However, the nature of the inhibition appear to be multifactorial and additional studies are required to get further insights.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3576-9) contains supplementary material, which is available to authorized users.