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Objectives This study aims to assess the effects of rinsing with zinc- and chlorhexidine-containing mouth rinse with or without adjunct tongue scraping on volatile sulfur compounds (VSCs) in breath air, and the microbiota at the dorsum of the tongue. Material and methods A randomized single-masked controlled clinical trial with a cross-over study design over 14 days including 21 subjects was performed. Bacterial samples from the dorsum of the tongue were assayed by checkerboard DNA–DNA hybridization. Results No halitosis (identified by VSC assessments) at day 14 was identified in 12/21 subjects with active rinse alone, in 10/21with adjunct use of tongue scraper, in 1/21 for negative control rinse alone, and in 3/21 in the control and tongue scraping sequence. At day 14, significantly lower counts were identified only in the active rinse sequence ( p  < 0.001) for 15/78 species including , Fusobacterium sp., Porphyromonas gingivalis , Pseudomonas aeruginosa , Staphylococcus aureus , and Tannerella forsythia . A decrease in bacteria from baseline to day 14 was found in successfully treated subjects for 9/74 species including: P. gingivalis , Prevotella melaninogenica , S. aureus , and Treponema denticola . Baseline VSC scores were correlated with several bacterial species. The use of a tongue scraper combined with active rinse did not change the levels of VSC compared to rinsing alone. Conclusions VSC scores were not associated with bacterial counts in samples taken from the dorsum of the tongue. The active rinse alone containing zinc and chlorhexidine had effects on intra-oral halitosis and reduced bacterial counts of species associated with malodor. Tongue scraping provided no beneficial effects on the microbiota studied. Clinical relevance Periodontally healthy subjects with intra-oral halitosis benefit from daily rinsing with zinc- and chlorhexidine-containing mouth rinse.

Bovine postpartum diseases remain one of the most significant and highly prevalent illnesses with negative effects on the productivity, survival, and welfare of dairy cows. Antibiotics are generally considered beneficial in the treatment of endometritis; however, frequent usage of each antibiotic drug is reason for the emergence of multidrug resistance (MDR) of the pathogenic microorganisms, representing a major impediment for the successful diagnosis and management of infectious diseases in both humans and animals. We synthesized silver nanoparticles (AgNPs) with an average size of 10 nm using the novel biomolecule apigenin as a reducing and stabilizing agent, and evaluated the efficacy of the AgNPs on the MDR pathogenic bacteria Prevotella melaninogenica and Arcanobacterium pyogenes isolated from uterine secretion samples. AgNPs inhibited cell viability and biofilm formation in a dose- and time-dependent manner. Moreover, the metabolic toxicity of the AgNPs was assessed through various cellular assays. The major toxic effect of cell death was caused by an increase in oxidative stress, as evidenced by the increased generation of reactive oxygen species (ROS), malondialdehyde, protein carbonyl content, and nitric oxide. The formation of ROS is considered to be the primary mechanism of bacterial death. Therefore, the biomolecule-mediated synthesis of AgNPs shows potential as an alternative antimicrobial therapy for bovine metritis and endometritis.

Abstract We investigated the mechanism of the oxidative DNA damage induction by exposure to O2 in Prevotella melaninogenica, a strict anaerobe. Flow cytometry with hydroethidine and dichlorofluorescein diacetate showed that O2 exposure generated O2●− and H2O2. Results of electron spin resonance with α-(4-pyridyl-1-oxide)-N-tert-butylnitrone and ethanol showed that O2 exposure also induced ●OH radical generation in P. melaninogenica loaded with FeCl2 but not in samples without FeCl2 loading. In P. melaninogenica, O2 exposure increased 8-hydroxydeoxyguanosine (8OHdG), typical of oxidative DNA damage. Catalase inhibited the increase, but the ●OH radical scavengers did not. Phenanthroline, a membrane-permeable Fe and Cu chelator, increased the 8OHdG induction. In FeCl2-loaded samples, induction of 8OHdG decreased. Addition of H2O2 markedly increased 8OHdG levels. These results indicate that in P. melaninogenica, exposure to O2 generated and accumulated O2●− and H2O2, and that a crypto-OH radical generated through H2O2 was the active species in the 8OHdG induction.

Some oral gram-negative anaerobic species have been intensively examined in connection with periodontal diseases during the last decade. However, less attention has been paid to the normal oral flora in persons without periodontitis. In our recent studies, Prevotella melaninogenica has seemed to be the most frequent gram-negative anaerobic species in the oral cavity in both young children and their mothers. Moreover, in studies by our group and by other investigators, a high frequency of beta -lactamase-positive strains has been observed among several anaerobic bacterial species, especially pigmented Prevotella (previously Bacteroides) species. By means of a molecular typing method (e.g., ribotyping), bacterial isolates can be distinguished to the strain level. We have previously ribotyped oral isolates of P. melaninogenica and have found this species to be genotypically heterogeneous, with several ribotypes simultaneously recovered from the same mouth. The aim of the present study was to determine the rate of beta -lactamase production and the penicillin susceptibility status of these previously ribotyped oral isolates of P. melaninogenica from young children and their mothers.

Smoldering multiple myeloma (SMM), which is in principle curable, may develop into life-threatening MM. Intestinal microbiota and gut-born T helper-17 (Th17) lymphocytes may contribute to this development, but the mechanisms are unclear. Here we demonstrate that administering the human commensal Prevotella melaninogenica to transgenic Vk*MYC mice that exhibit SMM-like phenotypes delays the evolution to full-blown MM. Mechanistically, P. melaninogenica increases the production of short-chain fatty acids (SCFA), thereby preventing the skewing of dendritic cells towards a pro-Th17 phenotype and subsequently accumulation of Th17 cells in the bone marrow of treated mice. P. melaninogenica or butyrate synergizes with anti-PD-L1 or anti-TIGIT to suppress myeloma progression by restraining Th17 cell expansion while inducing effector CD8 + T cells. P. melaninogenica also attenuates IL-17-mediated skin lesions that mimic anti-PD-L1-induced adverse events. Our results thus suggest that gut microbiota modulation or SCFAs administration may represent treatment options for patients affected by plasma cell dyscrasias. Smoldering multiple myeloma (SMM) may develop into life- threatening MM, with gut microbiota and Th17 possibly contributing to this progression via unknown mechanisms. Here the authors use a mouse SMM model, VkMYC mice, to show that treatments with butyrate or the commensal, Prevotella melaninogenica , suppress Th17 and cancer progression.

Checkpoint inhibitor pneumonitis (CIP) and radiation pneumonitis (RP) lead to anti-cancer therapy discontinuation and poor diagnosis. The human microbiome is related to various respiratory diseases. However, the role of the lung microbiome in CIP and RP remains unknown. Our study aimed to explore the lower respiratory tract (LRT) microbiome in CIP/RP patients. The study enrolled 61 patients with pneumonitis or pneumonia, including 23 with CIP/RP, and 38 with lung cancer with pneumonia (LC-P). Metagenomic next-generation sequencing (mNGS) was performed to identify the microbiota in bronchoalveolar lavage fluid (BALF), and bioinformatics methods were used to compare the microbial differences between CIP/RP and LC-P groups. Correlation analysis was conducted to explore the relationship between LRT microbiota and clinical features. The was the dominant genus in both groups. The , which belongs to the genus, was the dominant species in the CIP/RP group and the second most abundant species in the LC-P group. Compared to the LC-P group, the CIP/RP group had significantly high levels of species and lymphocyte percentage in BALF but significantly low levels of lymphocytes, eosinophils and albumin in peripheral blood. In addition, the species had a negative correlation with peripheral blood lymphocytes. The enrichment of species in LRT and a decreased level of peripheral blood lymphocytes are associated with CIP/RP.

Atopic dermatitis (AD), a chronic relapsing inflammatory pruritic skin disorder with a unique pathophysiology, has a high incidence in the perioral zone among infants. This study aimed to analyze the association of skin microfloral dynamics with disease severity and treatment of AD in 0–1-year-old infants. Based on the eczema area and severity index, subjects were divided into five groups, i.e., mild, moderate, severe, and severe post-treatment, with a healthy control group, and bacterial density at the perioral lesion, disease severity, and treatment were assessed in 0–1-year-old infants with AD. The perioral lesions were colonized predominantly by Firmicutes, followed in abundance by Proteobacteria, Actinobacteria, and Bacteroidetes. In the phylum Firmicutes, Streptococcus was the most predominant genus. In AD infants, the abundance of Bacteroidetes and Fusobacterium decreased significantly with an increase in disease severity (p < 0.01). The abundance of 6 genera, including Prevotella, decreased significantly with an increase in disease severity (p < 0.05). The abundance of Prevotella melaninogenica decreased gradually with an increase in disease severity and increased after treatment; this trend was reversed for Corynebacterium simulans. A reduction in the abundance of Staphylococcus and an increase in that of skin microflora including Prevotella spp., Staphylococcus epidermidis, and Erwinia dispersa were associated with treatment and clinical improvement. Skin bacterial composition varies with AD severity, and Corynebacterium simulans and Prevotella melaninogenica are positively and negatively correlated with AD severity, respectively. This study provides a theoretical basis to identify potential biomarkers AD occurrence and pathogenesis.

The legalization of marijuana (MJ) for medicinal and recreational use has raised concerns about its potential impact on health, including oral health. While MJ use has been linked to poor oral health, its effects on the composition of the oral microbiome remain unclear. This cross-sectional study analyzed saliva samples from chronic MJ users (n = 18) and nonusers (n = 20) to investigate MJ-related changes in salivary microbiome composition. We identified significant differences in the relative abundance of 16 taxa, including seven species, such as Megasphaera micronucliformis, Prevotella melaninogenica, and Streptococcus anginosus. Additionally, five species showed positive correlations with cumulative lifetime MJ use, including Streptococcus vestibularis and Streptococcus parasanguinis. By grouping salivary microbial communities into clusters based on their association with periodontal health, we found that the cluster with species associated with poor periodontal health had the highest percentage of MJ users. Moreover, MJ use significantly contributed to variance in microbial communities in individuals with relatively good periodontal health. These findings suggest that chronic MJ use is associated with alterations in the salivary microbiome, highlighting its potential broader impact on oral and systemic health.

Background: This study determined the β-lactamase production and the antimicrobial resistance of 72 Prevotella species and 48 Porphyromonas species isolated from different clinical specimens. Methods: All strains were identified using API 32 ID. The β-lactamase production was determined by nitrocefin disks. E test strips of benzylpenicillin, ampicillin + sulbactam, cefoxitin, clindamycin, metronidazole and imipenem were tested for each strain. Results: Nineteen Prevotella melaninogenica, 18 Prevotella intermedia, 16 Prevotella denticola, 11 Prevotella loescheii and 8 Prevotella bivia strains were identified. Four wereclindamycin resistant. The highest β-lactamase production was found at a rate of 68.4% in P. melaninogenica species. Additionally, 33 Porphyromonas asaccharolytica and 15 Porphyromonas gingivalis strains were identified. None of them produced β-lactamase. Conclusion: In view of the emerging antibiotic resistance among anaerobes, the current local susceptibility profile of our Prevotella and Porphyromonas species will establish the basis for additional surveys tracing significant changes in the antimicrobial resistance of our clinical isolates.

Disk diffusion is an economical and convenient method for routine tests of antimicrobial susceptibility in clinical laboratories. The antimicrobial agent, which is impregnated into a paper disk, diffuses through an inoculated agar medium in a continuous concentration gradient, creating a zone of inhibition that can be measured. The disk diffusion method is not used for clinical anaerobic bacteria because results are not reproducible presumably as a result of the varied or insufficient growth rates of anaerobes. Early studies were abandoned because clinical isolates grew inconsistently on the test media, and the intermediate range was too broad to be useful for determining susceptibility or resistance. In addition, the results were not reproducible from one laboratory to another, and they did not correlate with those of the reference agar dilution method. The results of susceptibility tests are influenced by many factors, which must be standardized for reproducibility. They include the growth phase of the inoculum; the incubation time and temperature; the age, composition, cation content, and depth of the test medium; and the manner in which the results are interpreted. In addition, the number of viable organisms in the inoculum must be standardized. A suspension of large organisms (Clostridia species) or small organisms (Peptostreptococcus species) equivalent to a 0.5 McFarland standard will differ from the target inoculum size of 1.5 x 10 super(8) cfu/mL by less than or greater than a log factor, respectively. The purpose of this study was to determine whether exposing the inoculum to oxygen during performance of the disk diffusion method influences the size of the zone of inhibition for various antimicrobial agents tested against selected anaerobic bacteria.