Journal of Oral Microbiology最新文献

Background: Patients hospitalized with severe odontogenic infections (SOI) receive empiric intravenous antibiotics. Microbiological cultivation and antibiotic susceptibility testing are commonly performed, although the clinical value is debated.

Objective: To assess the value of routine microbiological cultivation and susceptibility testing in patients hospitalized with SOI.

Design: This retrospective cohort study included patients hospitalized with SOI, at the University Hospital of Copenhagen, Denmark, from November 2012 to 2019. Data on microbiological cultivation, bacterial identification and antibiotic susceptibility testing were obtained from hospital records. Statistical analysis included χ² test, Fisher's exact test, analysis of variance and logistic regression.

Results: A total of 384 patients were included, with microbiological data available for 243 patients. Antibiotic treatment was modified in 47 patients and in seven cases, the modification was based on cultivation and antibiotic susceptibility testing. Higher age was associated with the need for cultivation and susceptibility testing (p = 0.006). The infections were polymicrobial, predominantly involving resident oral microbiota. Streptococcus was the most frequent genus (34% of isolates). Penicillin resistance was observed in 30% of all isolates.

Conclusion: Testing rarely influences antibiotic management in SOI. Higher age showed limited predictive value. The high prevalence of penicillin resistance among patients with SOI warrants further investigation.

Background: Fat taste impairment has been implicated in visceral lipid accumulation and insulin resistance, with emerging evidence linking it to the oral microbiota. However, the role and mechanisms of the oral microbiota in this process remain unclear.

Objective: We aimed to explore the manifestations of Prevotella in fat taste, visceral lipid accumulation and insulin sensitivity, as well as to elucidate the mechanism involved.

Design: We characterized the oral microbiota in humans with fat taste impairment, visceral lipid accumulation and insulin resistance, as well as in catch-up fat rats. Fat taste sensitivity, serum biochemistry and tissue morphology were assessed in rats colonized orally with Prevotella to explore potential mechanisms.

Results: Reduced fat taste sensitivity correlated with visceral lipid accumulation and insulin resistance in both individuals and rats. Prevotella was enriched in individuals and rats with low fat taste sensitivity. Additionally, rats with visceral lipid accumulation and insulin resistance were associated with lower proliferation in taste buds and inhibition in Hedgehog (Hh) signaling. Prevotella colonization downregulated the Hh signaling, fat taste impairment, visceral lipid accumulation and insulin resistance, whereas Hh pathway agonist supplementation mitigated these effects.

Conclusions: Oral microbiota and fat taste impairment are associated with visceral lipid accumulation and insulin resistance, and Prevotella may play a vital role in fat taste impairment, visceral lipid accumulation and insulin resistance by downregulating the Hh signaling in taste buds.

Background: Periodontal pathogens disrupt the gingival epithelial barrier, but the molecular links among junctional damage, ferroptosis, and inflammation remain unclear.

Objective: To investigate whether Bifidobacterium longum (BL) counteracts Aggregatibacter actinomycetemcomitans (Aa)-induced junctional injury via regulation of ferroptosis in human gingival epithelial cells (HGECs).

Design: Oral microbiota differences between periodontitis patients and healthy controls were analyzed using 16S rRNA sequencing, combined with GSE16134 bioinformatics analysis. HGECs were exposed to Aa (1 × 10⁴ CFU/ml) and treated with BL (1 × 10⁸ CFU/ml) or ferrostatin-1 (Fer-1, 2 μM). Cell viability, mitochondrial morphology, ROS, junction proteins (CDH1, CLDN1), ferroptosis markers (SLC7A11, GPX4, NFE2L2), and inflammatory cytokines (IL-6, IL-10, TNF) were assessed.

Results: Bioinformatics revealed enrichment of junction-related pathways associated with ferroptosis. Aa induced mitochondrial damage, ROS accumulation, suppression of ferroptosis-protective signaling and junction proteins, and pro-inflammatory cytokine imbalance. BL significantly restored mitochondrial integrity, ferroptosis-related signaling, epithelial junctions, and inflammatory homeostasis, with effects comparable to or exceeding Fer-1.

Conclusion: Aa disrupts gingival epithelial integrity through ferroptosis-mediated oxidative and inflammatory damage. BL effectively suppresses this cascade and protects epithelial junctions, highlighting its therapeutic potential for periodontitis.

Background: Candida albicans has been implicated in oral carcinogenesis, but its role in the progression of oral potentially malignant disorders (OPMDs) remains unclear. We investigated whether high Candida burden in OPMD lesions predicts malignant transformation (MT) and whether this association varied by OPMD subtype.

Patients and methods: In a multicenter prospective cohort study across seven hospitals in Taiwan, 734 OPMD patients were followed for a mean of 2.4 years. Oral lesion swabs were cultured on chromogenic agar to quantify Candida albicans level. Cox models were used to estimate hazard ratios (HRs) for MT to oral cancer.

Results: MT occurred in 6.8% of patients. High Candida burden was independently associated with increased MT risk (aHR = 2.84; 95% CI: 1.40-5.75). Patients with oral submucous fibrosis (OSF) or verrucous hyperplasia (VH) also had elevated risk (aHR = 4.99; 95% CI: 1.54-10.38). Interaction analysis revealed strong individual risks for high Candida burden (aHR = 13.83) and OSF/VH (aHR = 13.67), with an attenuating interaction term (aHR = 0.11), yielding a substantial combined risk (HR ≈ 20.8). Stratified analysis showed the strongest effect in leukoplakia (HR = 12.19).

Conclusions: High Candida albicans burden is a significant, subtype-dependent risk factor for malignant progression in OPMDs. These findings underline the role of fungal-host interactions in oral carcinogenesis and support the integration of fungal profiling into routine surveillance of OPMDs.

Aim: This study aimed to explore the composition of the tooth-surface plaque (subgingival with marginal supragingival) microbiome in dentate older adults residing in long-term care (LTC) facilities, stratified by clinically assessed oral disease burden (ODB). A total of 196 LTC residents aged ≥62 years underwent oral examinations and microbial sampling from each dentate quadrant. Microbial profiling was performed using 16S rRNA gene sequencing.

Results: Participants were more frequently categorized into Moderate (n = 95, 48%) than Low (n = 32, 16%) or High (n = 69, 35%) ODB groups. Those with High ODB were oldest and had lowest number of remaining teeth. Alpha diversity did not differ between the ODB groups, whereas beta diversity analysis revealed significant differences between groups (Bray-Curtis: P = 0.005; weighted Unifrac: P = 0.025). The Low and Moderate ODB groups were enriched with both commensals and disease-associated genera, such as Ottowia, Lactococcus, Pseudoramibacter, and Anaeroglobus. High ODB group exhibited an increased abundance of genera linked to both oral and systemic diseases, including Cardiobacterium, Leptotrichia, Stomatobaculum, and Pseudopropionibacterium. Among ODB groups, periodontitis was a stronger determinant of oral microbiome composition than caries, whereas caries had a stronger effect on bacterial diversity.

Conclusion: These findings indicate a progressive shift toward a dysbiotic oral microbiome with increasing ODB.

Background: Porphyromonas gingivalis is a Gram-negative bacterium that plays a central role in the development of periodontal disease. It uses a type IX secretion system (T9SS) to export virulence factors to the bacterial surface where they are attached to A-LPS, one of the two forms of lipopolysaccharide (LPS) produced in P. gingivalis, and then packaged into outer membrane vesicles (OMVs). We previously showed that 1-P dephosphorylation of the lipid A component of LPS is regulated by the T9SS outer membrane protein PorV, and this is linked to membrane destabilisation and OMV blebbing/formation. Objective: This study aimed to investigate whether other T9SS outer membrane proteins are required for correct OMV biogenesis. Design: We examined gingipain activity, gingipain secretion, A-LPS production, OMV morphology, and lipid A structure in P. gingivalis W50, T9SS mutant strains, and a lipid A 1-phosphatase (ΔlpxE) mutant strain. Results: A functional T9SS is required for LpxE activity and correct vesicle formation, and this is likely through the function of an exported type IX-cargo protein. Conclusion: This study provides insight into a new mechanism that links type IX cargo sorting with OMV blebbing, which may also be present in other Bacteroidota that colonise the gut and oral cavity.

Background: Streptococcus suis is a zoonotic pathogen, and its colonization of the host tonsil is believed to be a vital source causing infection, while its mechanism competing for a stable tonsil niche is unknown. Rearrangement hotspot (Rhs) proteins are characterized to facilitate interbacterial competition by their polymorphic C-terminal toxins (CTs) in diverse bacteria, while their distant homologues emerged in S. suis, referred to as wall-associated protein A (WapA), has not been identified.

Methods: Bioinformatics, western blot and interbacterial competition analyses were performed to identify Rhs/WapA toxins and their roles during S. suis infection.

Results: The 350 kDa WapA-CT1, linked with a SecF-like protein and a SrtB sortase, was verified to manipulate the tonsil microbiota for S. suis optimal colonization. The unfolded WapA-CT1 was translocated across the cell membrane via the canonical Sec pathway. Afterward, autocleavage generated four fragments: the N-terminal NCWB fragment, two middle Rhs domains (Rhs1&2) that may fold as a β-barrel structure, and a C-terminal PreT-CT toxin domain. SrtB interacts with the NCWB region, and plays vital roles for the interbacterial antagonism mediated by the toxic CT1.

Conclusion: This discovery underscores the diversity of mechanisms by which pathogens delivering Rhs/WapA polymorphic toxins, and their roles in competing with the host microbiota.

Background: Chlorhexidine (CHX) is widely used in oral care for its broad-spectrum antimicrobial activity but can cause significant side effects. Sodium DNA has emerged as a potential adjunct capable of modulating cellular responses.

Aim: This study assessed whether sodium DNA enhances the antibacterial and antibiofilm activity of 0.20% and 0.12% CHX mouthwashes against Streptococcus mutans and Escherichia coli, and evaluated their effects on the viability and phagocytic activity of Dictyostelium discoideum, a model for mammalian phagocytes.

Results: All CHX-containing mouthwashes were bactericidal against S.mutans, regardless of sodium DNA, whereas CHX-only formulations were more effective against E.coli in time-kill assays. All formulations inhibited biofilm formation at 50-0.01%. In S. mutans, early biofilms were strongly inhibited (50-0.39%), whereas mature biofilms were less affected. In E. coli, sodium DNA enhanced inhibition of both biofilm formation (50-1.56%) and mature biofilms (50-3.12%). The 0.12% CHX-sodium DNA formulation most effectively modulated D.discoideum viability and phagocytic activity, and metabolomics showed that sodium DNA reduced CHX-induced metabolic stress.

Conclusions: This study integrates antimicrobial, antibiofilm, cellular, and metabolomic analyses to assess CHX with sodium DNA. Sodium DNA reduces CHX-induced cytotoxicity and metabolic stress while maintaining antimicrobial activity, offering insights for optimizing oral hygiene formulations through combined microbial and host-cell evaluation.

Background: The oral cavity is an important yet understudied reservoir of antimicrobial resistance genes (ARGs), potentially shaped by geographic variation in antibiotic usage.

Objective: To compare the oral resistomes of healthy adults from Thailand and Norway, two countries with contrasting antimicrobial use practices, using shotgun metagenomic sequencing.

Design: Stimulated saliva samples were collected from healthy adults in Thailand (n = 43) and Norway (n = 50). ARGs were identified with AMRPlusPlus against the MEGARes database, and microbial taxonomy was profiled with KrakenUniq. Diversity metrics, ordination, and clustering analyses assessed resistome and microbiome structures.

Results: Thai samples exhibited significantly greater ARG richness, evenness, and diversity (p < 0.001), driven by higher abundances of multi-biocide, nucleoside, and copper resistance genes. Norwegian samples were enriched in aminoglycoside, sulfonamide, and quaternary ammonium compound resistance genes. Both cohorts shared core oral genera, but Thai samples showed greater taxonomic richness without differences in overall microbiome diversity. Non-metric multidimensional scaling and PERMANOVA revealed stronger geographic separation for resistomes (R² = 0.639) than microbiomes (R² = 0.382). Co-occurrence networks highlighted structured associations between ARG groups and bacterial genera, suggesting ecological influences beyond taxonomic composition.

Conclusions: These results reveal distinct geographic signatures in the oral resistome that are not fully explained by microbiome structure, reflecting the influence of local ecological and societal factors, including antimicrobial exposure. The findings highlight the oral cavity as a dynamic ARG reservoir and support its inclusion in regional antimicrobial resistance surveillance to inform public health strategies.

Background: The pathogenesis of oral squamous cell carcinoma (OSCC) in never-smoking females remains poorly understood, as these patients lack traditional risk factors. This subgroup accounts for an increasing proportion of OSCC cases and may exhibit distinct tumor biology. Here, we investigated the association between the alterations in the salivary microbiome and OSCC in never-smoking female patients.

Materials and methods: Saliva samples from 72 never-smoking female patients with OSCC and 494 never-smoking healthy female controls were analyzed using 16S rRNA gene sequencing. Microbial community structure and function were compared using statistical analyses, machine learning algorithms, and pathway prediction with PICRUSt2.

Results: Patients with OSCC exhibited significantly different microbial diversity and composition compared to controls. The genera Rhodococcus, Slackia, Lactobacillus, and Enterobacterales_g were enriched in the OSCC group, whereas Corynebacterium was more abundant in the Control group. These taxa were associated with oncogenic pathways, including PI3K-Akt signaling and nicotinate/nicotinamide metabolism. Functional inference also indicated enrichment of cancer-related orthologs such as LKB1, NFKB1, ITGAV, and TRAF4.

Conclusions: Salivary microbiome alterations, both taxonomic and functional, are associated with OSCC in never-smoking females. These findings suggest a potential microbial contribution to carcinogenesis in this unique patient population and offer novel insights into disease mechanisms.