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Purpose: The primary cause of pulp and periapical diseases is the invasion of bacteria into the root canal, which results from the continuous destruction of dental hard tissues. Effective management of infections during root canal therapy necessitates effectively irrigation. This study aims to investigate the effects of two antimicrobial peptides (AMPs), buCaTHL4B and Im-4, on root canal biofilms in vitro. Methods: Two-species biofilms (Enterococcus faecalis and Fusobacterium nucleatum) were selected and anaerobically cultivated. The following treatments were applied: 10 µg/mL buCaTHL4B, 10 µg/mL Im-4, 5 µg/mL buCaTHL4B, 5 µg/mL Im-4, 1 µg/mL buCaTHL4B, 1 µg/mL Im-4, 1% NaOCl, and sterile water. Each group was treated for 3 min. Subsequently, the two strains were co-cultured with 10 µg/mL buCaTHL4B, 10 µg/mL Im-4, 1% NaOCl, and sterile water for 24, 48, and 72 h. The biofilms were examined using confocal laser scanning microscopy (CLSM) with fluorescent staining, and the percentages of dead bacteria were calculated. Quantitative real-time PCR (qRT-PCR) was employed to assess the variations in bacterial proportions during biofilm formation. Results: Compared to 1% NaOCl, 10 µg/mL buCaTHL4B or Im-4 exhibited significantly greater bactericidal effects on the two-species biofilms (p < 0.05), leading to their selection for subsequent experiments. Over a 48-hour period, 10 µg/mL Im-4 demonstrated a stronger antibiofilm effect than buCaTHL4B (p < 0.05). Following a 24-hour biofilm formation period, the proportion of F. nucleatum decreased while the proportion of E. faecalis increased in the sterile water group. In the buCaTHL4B and 1% NaOCl groups, the proportion of F. nucleatum was lower than that of E. faecalis (p < 0.05), whereas in the Im-4 group, the proportion of F. nucleatum was higher than that of E. faecalis (p < 0.05). The proportions of bacteria in the two AMPs groups gradually stabilized after 24 h of treatment. Conclusion: buCaTHL4B and Im-4 exhibited remarkable antibacterial and anti-biofilm capabilities against pathogenic root canal biofilms in vitro, indicating their potential as promising additives to optimize the effectiveness of root canal treatment as alternative irrigants.

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Fusobacterium nucleatum (F. nucleatum), an anaerobic resident of the oral cavity, is increasingly recognized as a contributing factor to ulcerative colitis (UC). The adhesive properties of F. nucleatum are mediated by its key virulence protein, FadA adhesin. However, further investigations are needed to understand the pathogenic mechanisms of this oral pathogen in UC. The present study aimed to explore the role of the FadA adhesin in the colonization and invasion of oral F. nucleatum in dextran sulphate sodium (DSS)-induced colitis mice via molecular techniques. In this study, we found that oral inoculation of F. nucleatum strain carrying the FadA adhesin further exacerbated DSS-induced colitis, leading to elevated alveolar bone loss, disease severity, and mortality. Additionally, CDH1 gene knockout mice treated with DSS presented increases in body weight and alveolar bone density, as well as a reduction in disease severity. Furthermore, FadA adhesin adhered to its mucosal receptor E-cadherin, leading to the phosphorylation of ß-catenin and the degradation of IκBα, the activation of the NF-κB signalling pathway and the upregulation of downstream cytokines. In conclusion, this research revealed that oral inoculation with F. nucleatum facilitates experimental colitis via the secretion of the virulence adhesin FadA. Targeting the oral pathogen F. nucleatum and its virulence factor FadA may represent a promising therapeutic approach for a portion of UC patients.

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Fusobacterium nucleatum is an anaerobic commensal of the oral cavity recently reported to be associated with cancers of the gastrointestinal tract and oral squamous cell carcinoma (OSCC). In this study, we investigate the impact on oral keratinocytes of infection with a genetically diverse set of strains of F. nucleatum subsp. polymorphum recovered from patients with oral dysplasia (n=6). We employed H357 oral keratinocytes derived from a stage 1 OSCC and H376 cells derived from a stage 3 OSCC. Adhesion phenotypes were strain specific, with 3/6 clinical isolates examined exhibiting higher adherence to the stage 3 H376 cell line. Conversely, intracellular invasion was greatest in the H357 cells and was associated with specific transcriptional responses including autophagy and keratinization. Infection of both H357 and H376 cell lines induced transcriptional and cytokine responses linked to cancer cell migration and angiogenesis. F. nucleatum infection induced greater levels of MMP9 secretion in the H376 cell line which was associated with enhanced motility and invasion phenotypes. Additionally, the degree of F. nucleatum induced invasive growth by H376 cells varied between different clinical isolates of F. nucleatum subsp. polymorphum. Blockage of CCL5 signalling using the inhibitor metCCL5 resulted in reduced keratinocyte invasion. F. nucleatum infection also induced expression of the pro-angiogenic chemokine MCP-1 and the angiogenic growth factor VEGF-A resulting in increased capillary-like tube formation in HUVEC cells, most significantly in H376 cells. Treatment of HUVEC cells with resveratrol, a VEGF-A signalling inhibitor, significantly attenuated F. nucleatum induced tube formation. Our data indicate that the outcomes of F. nucleatum-oral cell interactions can vary greatly depending on the bacterial genotype and the malignant phenotype of the host cell.

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Neoadjuvant immune checkpoint blockade (ICB) has achieved significant success in treating various cancers, leading to improved therapeutic responses and survival rates among patients. However, in colorectal cancer (CRC), ICB has yielded poor results in tumors that are mismatch repair proficient, microsatellite-stable, or have low levels of microsatellite instability (MSI-L), which account for up to 95% of CRC cases. The underlying mechanisms behind the lack of immune response in MSI-negative CRC to immune checkpoint inhibitors remain an open conundrum. Consequently, there is an urgent need to explore the intrinsic mechanisms and related biomarkers to enhance the intratumoral immune response and render the tumor "immune-reactive". Intestinal microbes, such as the oral microbiome member Fusobacterium nucleatum (F. nucleatum), have recently been thought to play a crucial role in regulating effective immunotherapeutic responses. Herein, we advocate the idea that a complex interplay involving F. nucleatum, the local immune system, and the tumor microenvironment (TME) significantly influences ICB responses. Several mechanisms have been proposed, including the regulation of immune cell proliferation, inhibition of T lymphocyte, natural killer (NK) cell function, and invariant natural killer T (iNKT) cell function, as well as modification of the TME. This review aims to summarize the latest potential roles and mechanisms of F. nucleatum in antitumor immunotherapies for CRC. Additionally, it discusses the clinical application value of F. nucleatum as a biomarker for CRC and explores novel strategies, such as nano-delivery systems, for modulating F. nucleatum to enhance the efficacy of ICB therapy.

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Background: Fusobacterium nucleatum, a pathobiont in periodontal disease, contributes to alveolar bone destruction. We assessed the efficacy of a new targeted antimicrobial, FP-100, in eradicating F. nucleatum from the oral microbial community in vitro and in vivo and evaluated its effectiveness in reducing bone loss in a mouse periodontitis model. Methods: A multispecies bacterial community was cultured and treated with two concentrations of FP-100 over two days. Microbial profiles were examined at 24-h intervals using 16S rRNA sequencing. A ligature-induced periodontitis mouse model was employed to test FP-100 in vivo. Results: FP-100 significantly reduced Fusobacterium spp. within the in vitro community (p < 0.05) without altering microbial diversity at a 2 µM concentration. In mice, cultivable F. nucleatum was undetectable in FP-100-treated ligatures but persistent in controls. Beta diversity plots showed distinct microbial structures between treated and control mice. Alveolar bone loss was significantly reduced in the FP-100 group (p = 0.018), with concurrent decreases in gingival IL-1ß and TNF-α expression (p = 0.052 and 0.018, respectively). Conclusion: FP-100 effectively eliminates F. nucleatum from oral microbiota and significantly reduces bone loss in a mouse periodontitis model, demonstrating its potential as a targeted therapeutic agent for periodontal disease.

FP-100 eliminates F. nucleatum from an in vitro multispecies microbial community at low doses without affecting bacterial diversity. FP-100 treatment leads to the in vivo elimination of F. nucleatum, reducing alveolar bone loss and levels of pro-inflammatory cytokines in the gingiva. FP-100 is a new antimicrobial to target F. nucleatum-mediated periodontal disease.

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F. nucleatum, involved in carcinogenesis of colon carcinomas, has been described as part of the commensal flora of the female upper reproductive tract. Although its contribution to destructive inflammatory processes is well described, its role as commensal uterine bacteria has not been thoroughly investigated. Since carcinogenesis shares similar mechanisms with early pregnancy development (including proliferation, invasion, blood supply and the induction of tolerance), these mechanisms induced by F. nucleatum could play a role in early pregnancy. Additionally, implantation and placentation require a well-balanced immune activation, which might be suitably managed by the presence of a limited amount of bacteria or bacterial residues. We assessed the effect of inactivated F. nucleatum on macrophage-trophoblast interactions. Monocytic cells (THP-1) were polarized into M1, M2a or M2c macrophages by IFN-γ, IL-4 or TGF-ß, respectively, and subsequently treated with inactivated fusobacteria (bacteria:macrophage ratio of 0.1 and 1). Direct effects on macrophages were assessed by viability assay, flow cytometry (antigen presentation molecules and cytokines), qPCR (cytokine expression), in-cell Western (HIF and P-NF-κB) and ELISA (VEGF secretion). The function of first trimester extravillous trophoblast cells (HTR-8/SVneo) in response to macrophage-conditioned medium was microscopically assessed by migration (scratch assay), invasion (sprouting assay) and tube formation. Underlying molecular changes were investigated by ELISA (VEGF secretion) and qPCR (matrix-degrading factors and regulators). Inflammation-primed macrophages (M1) as well as high bacterial amounts increased pro-inflammatory NF-κB expression and inflammatory responses. Subsequently, trophoblast functions were impaired. In contrast, low bacterial stimulation caused an increased HIF activation and subsequent VEGF-A secretion in M2c macrophages. Accordingly, there was an increase of trophoblast tube formation. Our results suggest that a low-mass endometrial/decidual microbiome can be tolerated and while it supports implantation and further pregnancy processes.

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The presence of Fusobacterium nucleatum is associated with an immunosuppressive tumor immune microenvironment (TIM) in primary colorectal cancer (CRC), contributing to tumor progression. Its persistence in CRC liver metastasis tissues raises questions about its role in modulating local and systemic immune responses and influencing recurrence patterns. This retrospective cohort study of 218 patients with CRC liver metastasis investigated the association of F. nucleatum in CRC liver metastasis tissues with systemic inflammation, TIM alterations, and the number of metastatic organs involved in recurrence. Two-step polymerase chain reaction (PCR), including digital PCR, detected F. nucleatum in 42% (92/218) of fresh-frozen specimens of CRC liver metastases. Compared with the F. nucleatum-none group, the F. nucleatum-high group showed higher C-reactive protein levels (0.82 vs. 0.22 mg/dL; Ptrend = 0.02), lower numbers of CD8+ cells (33.2 vs. 65.3 cells/mm2; Ptrend = 0.04) and FOXP3+ cells (11.3 vs. 21.7 cells/mm2; Ptrend = 0.01) in the TIM, and a greater number of metastatic organs involved in recurrence (1.6 vs. 1.1; p < 0.001). The presence of F. nucleatum in CRC liver metastasis tissues was associated with increased systemic inflammation, TIM alterations, and a greater number of metastatic organs involved in recurrence. These findings suggest a potential contribution of F. nucleatum to the metastatic propensity of CRC cells and could inform future research to enhance understanding of the interaction between tumor, host, and microbes in the metastatic process.

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Intestinal dysbiosis is a major contributor to colorectal cancer (CRC) development, leading to bacterial translocation into the bloodstream. This study aimed to evaluate the presence of circulated bacterial DNA (cbDNA) in CRC patients (n = 75) and healthy individuals (n = 25). DNA extracted from peripheral blood was analyzed using PCR, with specific primers targeting 16S rRNA, Escherichia coli (E. coli), and Fusobacterium nucleatum (F. nucleatum). High 16S rRNA and E. coli detections were observed in all patients and controls. Only the detection of F. nucleatum was significantly higher in metastatic non-excised CRC, compared to controls (p < 0.001), non-metastatic excised CRC (p = 0.023), and metastatic excised CRC (p = 0.023). This effect was mainly attributed to the presence of the primary tumor (p = 0.006) but not the presence of distant metastases (p = 0.217). The association of cbDNA with other clinical parameters or co-morbidities was also evaluated, revealing a higher detection of E. coli in CRC patients with diabetes (p = 0.004). These results highlighted the importance of bacterial translocation in CRC patients and the potential role of F. nucleatum as an intratumoral oncomicrobe in CRC.

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Previously, many studies have reported changes in the gut microbiota of patients with colorectal cancer (CRC). While CRC is a well-described disease, the relationship between its development and features of the intestinal microbiome is still being understood. Evidence linking Fusobacterium nucleatum enrichment in colorectal tumor tissue has prompted the elucidation of various molecular mechanisms and tumor-promoting attributes. In this review we highlight various aspects of our understanding of the relationship between the development of CRC and the alteration of intestinal microbiome, focusing specifically on the role of F. nucleatum. As the amount of F. nucleatum DNA in CRC tissue is associated with shorter survival, it may potentially serve as a prognostic biomarker, and most importantly may open the door for a role in CRC treatment.

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Fusobacterium nucleatum is a commensal pathogen typically found in the oral cavity, digestive tract, and urogenital system which has been associated with Lemierre's syndrome, periodontal diseases, sinusitis, endocarditis, and intra-abdominal and brain abscesses. Our case is of a 62-year-old male who presented with headaches, nausea, and vision loss. Brain imaging identified a right occipito-parietal brain abscess. Following surgery and abscess drainage, Fusobacterium nucleatum was isolated from intraoperative cultures, and the infectious disease service was consulted for antibiotic recommendations. Additional history uncovered that he had also been experiencing night sweats, generalized weakness and 40-pound weight loss for 2 months, and had a prior history of colon polyps and diverticulitis. Furthermore, the patient disclosed having substandard oral hygiene practices, particularly in relation to the care of his dental appliances. Despite negative blood cultures, suspicion for hematogenous seeding was high. Imaging ruled out periodontal disease, but identified a colovesical fistula and liver abscesses, indicating potential translocation of bacteria via portal circulation to his liver. Echocardiogram workup revealed a 1-cm mobile vegetation on the aortic valve. His course was complicated by breakthrough seizures, renal failure, and drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, and he ultimately completed 16 weeks of antibiotics. This case illustrates an uncommon presentation of brain abscess in an immunocompetent adult, with a prior episode of diverticulitis as the probable primary infection source, leading to development of a colovesical fistula and bacterial dissemination to the liver, heart, and brain. It highlights the importance of a comprehensive diagnostic approach, including consideration of atypical pathogens in immunocompetent adults.

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PURPOSE OF REVIEW: Fusobacterium nucleatum (F. nucleatum), an anaerobic, gram-negative microbe, commonly found in human dental biofilm and the gut flora. It has long been known to have a higher concentration in periodontal disease and has recently been implicated in both oral and distant cancers such as colorectal, gastrointestinal, esophageal, breast, pancreatic hepatocellular, and genitourinary cancers. However, the mechanism of its involvement in the development of cancer has not been fully discussed. This review aims to cover biological molecular and clinical aspects of F. nucleatum and cancers. RECENT FINDINGS: Studies indicate F. nucleatum promotes tumor development through chronic inflammation, immune evasion, cell proliferation activation, and direct cell interactions, as in oral squamous cell carcinoma (OSCC). In colorectal cancer (CRC), F. nucleatum contributes to tumorigenesis through ß-catenin signaling and NF-κB activation. It also induces autophagy, leading to chemoresistance in CRC and esophageal cancers, and enhances tumor growth and metastasis in breast cancer by reducing T-cell infiltration. F. nucleatum is linked to carcinogenesis and increased bacterial diversity in OSCC, with improved oral hygiene potentially preventing OSCC. F. nucleatum triggers cancer by causing mutations and epigenetic changes through cytokines and reactive oxygen species. It also promotes chemoresistance in CRC. F. nucleatum may potentially serve as a diagnostic tool in various cancers, with non-invasive detection methods available. Further investigation is needed to discover its potential in the diagnosis and treatment of OSCC and other cancers.

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BACKGROUND: Epidemiological studies have demonstrated that periodontitis is an independent risk factor for chronic obstructive pulmonary disease (COPD). However, the mechanism underlying the association between these two diseases remains unclear. The lung microbiota shares similarities with the oral microbiota, and there is growing evidence to suggest that the lung microbiome could play a role in the pathogenesis of COPD. This study aimed to investigate whether periodontal pathogens could contribute to the pathogenesis of COPD in a mouse model. METHODS: We established mouse models with oral infection by typical periodontal pathogens, porphyromonas gingivalis (Pg group) or fusobacterium nucleatum (Fn group), over a three-month period. Mice that did not receive oral infection were set as the control group (C group). We assessed the level of alveolar bone resorption, lung function, and histological changes in the lungs of the mice. Additionally, we measured the levels of inflammatory factors and tissue damage associated factors in the lung tissues. RESULTS: Lung function indices, including airway resistance, peak inspiratory/expiratory flow and expiratory flow-50%, were significantly reduced in the Fn group compared to the C group. Additionally, histological examination revealed an increased number of inflammatory cells and bullae formation in the lung tissue sections of the Fn group. Meanwhile, levels of inflammatory factors such as IL-1ß, IL-6, IFN-γ, and TNF-α, as well as tissue damage associated factors like matrix metalloproteinase-8 and neutrophil elastase, were significantly elevated in the lung tissue of the Fn group in comparison to the C group. The Pg group also showed similar but milder lung changes compared to the Fn group. Pg or Fn could be detected in the lungs of both oral infected groups. CONCLUSION: The results indicated that oral periodontal pathogens infection could induce COPD-like lung changes in mice, and they may play a biological role in the association between periodontitis and COPD.

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Fusobacterium nucleatum, (F. nucleatum) as a known factor in inducing oncogenic, invasive, and inflammatory responses, can lead to an increase in the incidence and progression of colorectal cancer (CRC). Cancer-associated fibroblasts (CAF) are also one of the key components of the tumor microenvironment (TME), which lead to resistance to treatment, metastasis, and disease recurrence with their markers, secretions, and functions. This study aimed to investigate the effect of F. nucleatum on the invasive phenotype and function of fibroblast cells isolated from normal and cancerous colorectal tissue. F. nucleatum bacteria were isolated from deep periodontal pockets and confirmed by various tests. CAF cells from tumor tissue and normal fibroblasts (NF) from a distance of 10 cm of tumor tissue were isolated from 5 patients by the explant method and were exposed to secretions and ghosts of F. nucleatum. The expression level of two markers, fibroblast activation protein (FAP), and α-smooth muscle actin (α-SMA), and the amount of production of two cytokines TGF-ß and IL-6 from fibroblast cells were measured by flow cytometry and ELISA test, respectively before and after exposure to different bacterial components. The expression of the FAP marker was significantly higher in CAF cells compared to NF cells (P < 0.05). Also, the expression of IL-6 in CAF cells was higher than that of NF cells. In investigating the effect of bacterial components on the function of fibroblastic cells, after comparing the amount of IL-6 produced between the normal tissue of each patient and his tumoral tissue under 4 treated conditions, it was found that the amount of IL-6 production from the CAF cells of patients in the control group, treated with heat-killed ghosts and treated with paraformaldehyde-fixed ghosts had a significant increase compared to NF cells (P < 0.05). Due to the significant increase in FAP marker expression in fibroblast cells of tumor tissue compared to normal tissue, it seems that FAP can be used as a very good therapeutic marker, especially in patients with high levels of CAF cells. Various components of F. nucleatum could affect fibroblast cells differentially and at least part of the effect of this bacterium in the TME is mediated by CAF cells.

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Intratumor microbes have attracted great attention in cancer research due to its influence on the tumorigenesis, progression and metastasis of cancer. However, the therapeutic strategies targeting intratumoral microbes are still in their infancy. Specific microorganisms, such as Fusobacterium nucleatum (F. nucleatum), are abundant in various cancer and always result in the CRC progression and chemotherapy resistance. Here, a combined anticancer and antibacterial therapeutic strategy is proposed to deliver antitumor drug to the tumors containing intratumor microbiota by the antibacerial polymeric drug carriers. We construct oral tellurium-containing drug carriers using a complex of tellurium-containing polycarbonate with cisplatin (PTE@CDDP). The results show that the particle size of the prepared nanoparticles could be maintained at about 105 nm in the digestive system environment, which is in line with the optimal particle size of oral nanomedicine. In vitro mechanism study indicates that the tellurium-containing polymers are highly effective in killing F.nucleatum through a membrane disruption mechanism. The pharmacokinetic experiments confirmed that PTE@CDDP has the potential function of enhancing the oral bioavailability of cisplatin. Both in vitro and in vivo studies show that PTE@CDDP could inhibit intratumor F.nucleatum and lead to a reduction in cell proliferation and inflammation in the tumor site. Together, the study identifies that the CDDP-loaded tellurium-containing nanoparticles have great potential for treating the F.nucleatum-promoted colorectal cancer (CRC) by combining intratumor microbiota modulation and chemotherapy. The synergistic therapeutic strategy provide new insight into treating various cancers combined with bacterial infection. STATEMENT OF SIGNIFICANCE: The synthesized antibacterial polymer was first employed to remodel the intratumor microbes in tumor microenvironment (TME). Moreover, it was the first report of tellurium-containing polymers against F.nucleatum and employed for treatment of the CRC. A convenient oral dosage form of cisplatin (CDDP)-loaded tellurium-containing nanoparticles (PTE@CDDP) was adopted here, and the synergistic antibacterial/chemotherapy effect occurred. The PTE@CDDP could quickly and completely eliminate F.nucleatum in a safe dose. In the CRC model, PTE@CDDP effectively reversed the inflammation level and even restored the intestinal barrier damaged by F.nucleatum. The ultrasensitive ROS-responsiveness of PTE@CDDP triggered the fast oxidation and efficient drug release of CDDP and thus a highly efficient apoptosis of the tumors. Therefore, the tellurium-containing polymers are expected to serve as novel antibacterial agents in vivo and have great potential in the F.nucleatum-associated cancers. The achievements provided new insight into treating CRC and other cancers combined with bacterial infection.

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The identification of biological fluids at crime scenes contributes to crime scene reconstruction and provides investigative leads. Traditional methods for body fluid identification are limited in terms of sensitivity and are mostly presumptive. Emerging methods based on mRNA and DNA methylation require high quality template source. An exploitable characteristic of body fluids is their distinct microbial profiles allowing for the discrimination of body fluids based on microbiome content. Microbial DNA is highly abundant within the body, robust and stable and can persist in the environment long after human DNA has degraded. 16S rRNA sequencing is the gold standard for microbial analysis; however, NGS is costly, and requires intricate workflows and interpretation. Also, species level resolution is not always achievable. Based on the current challenges, the first objective of this study was to develop a multiplex conventional PCR assay to identify vaginal fluid and saliva by targeting species-specific 16S rRNA microbial markers. The second objective was to employ droplet digital PCR (ddPCR) as a novel approach to quantify bacterial species alone and in a mixture of body fluids. Lactobacillus crispatus and Streptococcus salivarius were selected because of high abundance within vaginal fluid and saliva respectively. While Fusobacterium nucleatum and Gardnerella vaginalis, though present in healthy humans, are also frequently found in oral and vaginal infections, respectively. The multiplex PCR assay detected L. crispatus and G. vaginalis in vaginal fluid while F. nucleatum and S. salivarius was detected in saliva. Multiplex PCR detected F. nucleatum, S. salivarius and L. crispatus in mixed body fluid samples while, G. vaginalis was undetected in mixtures containing vaginal fluid. For samples exposed at room temperature for 65 days, L. crispatus and G. vaginalis were detected in vaginal swabs while only S. salivarius was detected in saliva swabs. The limit of detection was 0.06 copies/µl for F. nucleatum (2.5 ×10-9 ng/µl) and S. salivarius (2.5 ×10-6 ng/µl). L. crispatus and G. vaginalis had detection limits of 0.16 copies/µl (2.5 ×10-4 ng/µl) and 0.48 copies/µl (2.5 ×10-7 ng/µl). All 4 bacterial species were detected in mixtures and aged samples by ddPCR. No significant differences were observed in quantity of bacterial markers in saliva and vaginal fluid. The present research reports for the first time the combination of the above four bacterial markers for the detection of saliva and vaginal fluid and highlights the sensitivity of ddPCR for bacterial quantification in pure and mixed body fluids.

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Pleural empyema can lead to significant morbidity and mortality despite chest drainage and antibiotic treatment, necessitating novel and minimally invasive interventions. Fusobacterium nucleatum is an obligate anaerobe found in the human oral and gut microbiota. Advances in sequencing and puncture techniques have made it common to detect anaerobic bacteria in empyema cases. In this report, we describe the case of a 65-year-old man with hypertension who presented with a left-sided encapsulated pleural effusion. Initial fluid analysis using metagenomic next-generation sequencing (mNGS) revealed the presence of Fusobacterium nucleatum and Aspergillus chevalieri. Unfortunately, the patient experienced worsening pleural effusion despite drainage and antimicrobial therapy. Ultimately, successful treatment was achieved through intrapleural metronidazole therapy in conjunction with systemic antibiotics. The present case showed that intrapleural antibiotic therapy is a promising measure for pleural empyema.

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Fusobacterium nucleatum, a gram-negative anaerobic bacterium abundantly found in the human oral cavity, is widely recognized as a key pathobiont responsible for the initiation and progression of periodontal diseases due to its remarkable aggregative capabilities. Numerous clinical studies have linked F. nucleatum with unfavorable prognostic outcomes in various malignancies. In further research, scholars have partially elucidated the mechanisms underlying F. nucleatum's impact on various types of cancer, thus gaining a certain comprehension of the role played by F. nucleatum in cancer. In this comprehensive review, we present an in-depth synthesis of the interplay between F. nucleatum and different cancers, focusing on aspects such as tumor initiation, metastasis, chemoresistance, and modulation of the tumor immune microenvironment and immunotherapy. The implications for cancer diagnosis and treatment are also summarized. The objective of this review is to enhance our comprehension of the intricate relationship between F. nucleatum and oncogenic pathogenesis, while emphasizing potential therapeutic strategies.

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The morbidity and mortality of gastrointestinal (GI) malignancies are among the highest in the world, posing a serious threat to human health. Because of the insidious onset of the cancer, it is difficult for patients to be diagnosed at an early stage, and it rapidly progresses to an advanced stage, resulting in poor treatment and prognosis. Fusobacterium nucleatum (F. nucleatum) is a gram-negative, spore-free anaerobic bacterium that primarily colonizes the oral cavity and is implicated in the development of colorectal, esophageal, gastric, and pancreatic cancers via various intricate mechanisms. Recent development in novel research suggests that F. nucleatum may function as a biomarker in GI malignancies. Detecting the abundance of F. nucleatum in stool, saliva, and serum samples of patients may aid in the diagnosis, risk assessment, and prognosis monitoring of GI malignancies. This editorial systematically describes the biological roles and mechanisms of F. nucleatum in GI malignancies focusing on the application of F. nucleatum as a biomarker in the diagnosis and prognosis of GI malignancies to promote the clinical translation of F. nucleatum and GI tumors-related research.

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Oral malodor still constitutes a major challenge worldwide. A strong effort is invested in eliminating volatile sulfur compound-producing oral bacteria through organic natural products such as essential oils. Fusobacterium nucleatum is a known volatile sulfur compound-producing bacteria that inspires oral malodor. The aim of the present study was to test the effect of lavender essential oil on the bacterium's ability to produce volatile sulfide compounds, the principal components of oral malodor. Lavender (Lavandula angustifolia) essential oil was extracted by hydrodistillation and analyzed using GC-MS. The minimal inhibitory concentration (MIC) of lavender essential oil on Fusobacterium nucleatum was determined in a previous trial. Fusobacterium nucleatum was incubated anaerobically in the presence of sub-MIC, MIC, and above MIC concentrations of lavender essential oil, as well as saline and chlorhexidine as negative and positive controls, respectively. Following incubation, volatile sulfur compound levels were measured using GC (Oralchroma), and bacterial cell membrane damage was studied using fluorescence microscopy. Chemical analysis of lavender essential oil yielded five main components, with camphor being the most abundant, accounting for nearly one-third of the total lavender essential oil volume. The MIC (4 µL/mL) of lavender essential oil reduced volatile sulfur compound secretion at a statistically significant level compared to the control (saline). Furthermore, the level of volatile sulfur compound production attributed to 1 MIC of lavender essential oil was in the range of the positive control chlorhexidine with no significant difference. When examining bacterial membrane damage, 2 MIC of lavender essential oil (i.e., 8 µL/mL) demonstrated the same, showing antibacterial membrane damage values comparative to chlorhexidine. Since lavender essential oil was found to be highly effective in hindering volatile sulfur compound production by Fusobacterium nucleatum through the induction of bacterial cell membrane damage, the results suggest that lavender essential oil may be a suitable alternative to conventional chemical-based anti-malodor agents.

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AIM: Periodontitis is an inflammatory disease driven by opportunistic bacteria including Porphyromonas gingivalis and Fusobacterium nucleatum, where T-cell and NKT-cell responses to these bacteria in patients with periodontitis grade B or C are not fully elucidated. The objective is to determine if exaggerated proinflammatory Th-cell responses to periodontitis-associated bacteria, but not commensal bacteria, is a characteristic of increased periodontitis grade. METHODS: Mononuclear cells from patients with periodontitis grade C (n = 26) or grade B (n = 33) and healthy controls (HCs; n = 26) were stimulated with P. gingivalis, F. nucleatum or the commensal bacteria, Staphylococcus epidermidis and Cutibacterium acnes. Cytokine production by different T-cell populations and FOXP3-expression by regulatory T cells were assessed by flow cytometry. RESULTS: Compared to HCs, grade C patients had decreased frequencies of interleukin (IL)-10-producing CD4+ T cells before stimulation (p = .02) and increased frequencies of IFN-y-producing CD4+ T cells after stimulation with P. gingivalis (p = .0019). Grade B patients had decreased frequencies of FOXP3+ CD4+ T cells before (p = .030) before and after stimulation with anti-CD2/anti-CD3/anti-CD28-loaded beads (p = .047), P. gingivalis (p = .013) and S. epidermidis (p = .018). Clinical attachment loss correlated with the frequencies of IFN-y-producing Th1 cells in P. gingivalis- and F. nucleatum-stimulated cultures in grade B patients (p = .023 and p = .048, respectively) and with the frequencies of Th17 cells in P. gingivalis-stimulated cultures (p = .0062) in grade C patients. Patients with periodontitis grade C or grade B showed lower frequencies of IL-10-producing NKT cells than HCs in unstimulated cultures (p = .0043 and p = .027 respectively). CONCLUSIONS: Both periodontitis groups showed decreased frequencies of immunoregulatory T-cell and NKT cell subsets at baseline. Clinical attachment loss correlated with P. gingivalis-induced Th17-responses in grade C patients and with Th1-responses in grade B patients when cells were stimulated with P. gingivalis, supporting that dysregulated pro-inflammatory T-cell responses to periodontitis-associated bacteria contribute to the pathogenesis of periodontitis.