Low usefulness of reporting tonsillar PCR Ct-values in pharyngeal infections with Fusobacterium necrophorum.

Tonsillar Fusobacterium necrophorum PCR Ct-values were higher in participants with asymptomatic tonsillar carriage than patients with pharyngeal infections. However, Ct-values were not associated with severity of disease or predictive of development of complications and hence lacked clinical usefulness. The reporting of F. necrophorum Ct-values in clinical samples is not recommended.

The first case report: diagnosis and management of necrotizing fusobacterium lung abscess via BALF next-generation sequencing.

BACKGROUND: Fusobacterium necrophorum (F. necrophorum)-induced necrotizing pneumonia is a rare but severe pulmonary infection. Insufficient microbiological detection methods can lead to diagnostic difficulties. METHODS: We report a case of F. necrophorum lung abscess diagnosed by next-generation sequencing (NGS) of bronchoalveolar lavage fluid (BALF). RESULTS: BALF-NGS detected F. necrophorum, guiding subsequent targeted antibiotic therapy. With active drainage and metronidazole treatment, the patient's condition was effectively treated. CONCLUSION: BALF-NGS is a valuable tool for the rapid diagnosis of infections caused by difficult-to-culture bacteria. It played a decisive role in the early identification of F. necrophorum, enabling timely and targeted antibiotic intervention. Early diagnosis and appropriate treatment are crucial for the management of F. necrophorum pneumonia.

The ways Fusobacterium nucleatum translocate to breast tissue and contribute to breast cancer development.

Breast cancer is among the most prevalent malignancies in women worldwide. Epidemiological findings suggested that periodontal diseases may be associated with breast cancer, among which Fusobacterium nucleatum is considered an important cross-participant. In this work, we comprehensively summarize the known mechanisms of how F. nucleatum translocates to, colonizes in mammary tumors, and promotes the carcinogenesis. Specifically, F. nucleatum translocates to mammary tissue through the mammary-intestinal axis, direct nipple contact, and hematogenous transmission. Subsequently, F. nucleatum takes advantage of fusobacterium autotransporter protein 2 to colonize breast cancer and uses virulence factors fusobacterium adhesin A and lipopolysaccharide to promote proliferation. Moreover, the upregulated matrix metalloproteinase-9 induced by F. nucleatum does not only trigger the inflammatory response but also facilitates the tumor-promoting microenvironment. Aside from the pro-inflammatory effect, F. nucleatum may also be engaged in tumor immune evasion, which is achieved through the action of virulence factors on immune checkpoint receptors highly expressed on T cells, natural killer cells, and tumor-infiltrating lymphocytes. Taking breast cancer as an example, more relevant research studies may expand our current knowledge of how oral microbes affect systemic health. Hopefully, exploring these mechanisms in depth could provide new strategies for safer and more effective biologic and targeted therapies targeted at breast cancer.

Fabrication of hyaluronic acid-inulin coated Enterococcus faecium for colon-targeted delivery to fight Fusobacterium nucleatum.

The abundance of Fusobacterium nucleatum (F. nucleatum) is highly associated with the development and poor prognosis of colorectal cancer (CRC), which is regarded as a promising target for CRC. However, until now, the novel strategy to clear F. nucleatum in the colon and CRC has not been well proposed. Herein, a probiotic strain Enterococcus faecium (E. faecium, EF47) is verified to secrete various organic acids and bacteriocins to exert superior antimicrobial activity towards F. nucleatum. However, the oral delivery of EF47 is affected by the complex digestive tract environment, so we design the hyaluronic acid-inulin (HA-IN) coated EF47 for colon-targeted delivery to fight F. nucleatum. IN can protect EF47 from the harsh gastrointestinal tract environment and is degraded specifically in the colon, acting as prebiotics to further promote the proliferation of EF47. The exposed HA can also enhance the targeting effect to the tumor area via the interaction with the CD44 receptor on the tumor cells, which is confirmed to increase the adhesive ability in tumor tissues and inhibit the growth of F. nucleatum. Therefore, this colon-targeted delivery system provides a novel platform to realize high-activity and adhesive delivery of probiotics to assist the therapeutic efficiency of CRC.

Clinical characteristics and antimicrobial susceptibility of Fusobacterium species isolated over 10 years at a Japanese university hospital.

PURPOSE: Anaerobic bacteria, existing on human skin and mucous membranes, can cause severe infections with complications or mortality. We examined the clinical characteristics of patients infected with Fusobacterium spp. and assessed their antibiotic susceptibility. METHODS: Clinical data were collated from patients diagnosed with Fusobacterium infections in a Japanese university hospital between 2014 and 2023. Antibiotic susceptibility tests were conducted following the Clinical and Laboratory Standards Institute guidelines. RESULTS: We identified 299 Fusobacterium isolates. The median age was 61 years (range, 14-95 years), with females constituting 43.1% of the patients. Most infections were community-acquired (84.6%, 253/299). Multiple bacterial strains were isolated simultaneously in 74.6% of cases. One-fourth of the patients had solid organ malignancies (25.4%, 76/299), and 14.5% (11/76) of those had colorectal cancer. The 30-day mortality rate was 1.3%. Fusobacterium species were isolated from blood cultures in 6% (18/299) of the patients. Patients, aged 75 years or older, with cerebrovascular disease or hematologic malignancy exhibited significantly higher prevalence of blood culture isolates in univariate analysis. Each Fusobacterium species had its characteristic infection site. Approximately 5% F. nucleatum and F. necrophorum isolates showed penicillin G resistance. Moxifloxacin resistance was observed in varying degrees across strains, ranging from 4.6 to 100% of isolates. All isolates were sensitive to ß-lactam/ß-lactamase inhibitors, carbapenems, and metronidazole. CONCLUSION: We show a link between Fusobacterium species and solid organ malignancies. We observed resistance to penicillin, cefmetazole, clindamycin, and moxifloxacin, warranting caution in their clinical use. This study offers valuable insights for managing Fusobacterium infections and guiding empirical treatments.

Cryptogenic pyogenic liver abscess caused by Fusobacterium necrophorum in an immunocompetent patient.

Pyogenic liver abscesses are potentially fatal conditions that require prompt treatment with drainage and appropriate antimicrobial therapy. Fusobacterium necrophorum is a gram-negative rod that is found in the oral cavity, gastrointestinal tract and female genital tract. It is an extremely rare cause of liver abscess, particularly in the absence of risk factors or exposures. We describe an unusual case of a cryptogenic F. necrophorum hepatic abscess without a clear source despite extensive investigation in a young, immunocompetent patient without known risk factors or exposures for such an infection.

Fusobacterium nucleatum upregulates MMP7 to promote metastasis-related characteristics of colorectal cancer cell via activating MAPK(JNK)-AP1 axis.

BACKGROUND: Colorectal cancer (CRC) is the third most common malignant tumor. Fusobacterium nucleatum (F. nucleatum) is overabundant in CRC and associated with metastasis, but the role of F. nucleatum in CRC cell migration and metastasis has not been fully elucidated. METHODS: Differential gene analysis, protein-protein interaction, robust rank aggregation analysis, functional enrichment analysis, and gene set variation analysis were used to figure out the potential vital genes and biological functions affected by F. nucleatum infection. The 16S rDNA sequencing and q-PCR were used to detect the abundance of F. nucleatum in tissues and stools. Then, we assessed the effect of F. nucleatum on CRC cell migration by wound healing and transwell assays, and confirmed the role of Matrix metalloproteinase 7 (MMP7) induced by F. nucleatum in cell migration. Furthermore, we dissected the mechanisms involved in F. nucleatum induced MMP7 expression. We also investigated the MMP7 expression in clinical samples and its correlation with prognosis in CRC patients. Finally, we screened out potential small molecular drugs that targeted MMP7 using the HERB database and molecular docking. RESULTS: F. nucleatum infection altered the gene expression profile and affected immune response, inflammation, biosynthesis, metabolism, adhesion and motility related biological functions in CRC. F. nucleatum was enriched in CRC and promoted the migration of CRC cell by upregulating MMP7 in vitro. MMP7 expression induced by F. nucleatum infection was mediated by the MAPK(JNK)-AP1 axis. MMP7 was highly expressed in CRC and correlated with CMS4 and poor clinical prognosis. Small molecular drugs such as δ-tocotrienol, 3,4-benzopyrene, tea polyphenols, and gallic catechin served as potential targeted therapeutic drugs for F. nucleatum induced MMP7 in CRC. CONCLUSIONS: Our study showed that F. nucleatum promoted metastasis-related characteristics of CRC cell by upregulating MMP7 via MAPK(JNK)-AP1 axis. F. nucleatum and MMP7 may serve as potential therapeutic targets for repressing CRC advance and metastasis.

Delivery of short chain fatty acid butyrate to overcome Fusobacterium nucleatum-induced chemoresistance.

The gut microbiota is closely associated with the progression of colorectal cancer (CRC) in which Fusobacterium nucleatum (F. nucleatum) was found to induce cancer resistance to chemotherapeutics. To relieve F. nucleatum-induced drug resistance, herein, we found that short-chain fatty acid butyrate can inhibit the growth, enrichment and adhesion of F. nucleatum in colorectal cancer tissues by downregulating the expression of adhesion-associated outer membrane proteins, including RadD, FomA, and FadA, to reduce the colonization and invasion of F. nucleatum and relieve the chemoresistance induced by F. nucleatum. Leveraging the killing effect of butyrate on F. nucleatum, sodium butyrate (NaBu) was encapsulated in liposomes or prepared as NaBu tablets with Eudragit S100 coating and administered by intravenous injection or oral administration, respectively. Interestingly, both intravenous administration of NaBu liposomes and oral delivery of NaBu tablets could effectively inhibit the proliferation of F. nucleatum and significantly improve the therapeutic efficacy of oxaliplatin in mice with subcutaneous colorectal tumors, orthotopic colorectal tumors and even spontaneously formed colorectal tumors. Thus, our work provides a simple but effective formulation of NaBu to relieve F. nucleatum-induced chemoresistance, exhibiting ideal clinical application prospects.

Strain specificity in fusobacterial co-aggregation with colorectal cancer-relevant species.

OBJECTIVES: The purpose of the present study was to characterize co-aggregation interactions between isolates of Fusobacterium nucleatum subsp. animalis and other colorectal cancer (CRC)-relevant species. METHODS: Co-aggregation interactions were assessed by comparing optical density values following 2-h stationary strain co-incubations to strain optical density values when incubated alone. Co-aggregation was characterized between strains from a previously isolated, CRC biopsy-derived community and F. nucleatum subsp. animalis, a species linked to CRC and known to be highly aggregative. Interactions were also investigated between the fusobacterial isolates and strains sourced from alternate human gastrointestinal samples whose closest species match aligned with species in the CRC biopsy-derived community. RESULTS: Co-aggregation interactions were observed to be strain-specific, varying between both F. nucleatum subsp. animalis strains and different strains of the same co-aggregation partner species. F. nucleatum subsp. animalis strains were observed to co-aggregate strongly with several taxa linked to CRC: Campylobacter concisus, Gemella spp., Hungatella hathewayi, and Parvimonas micra. CONCLUSIONS: Co-aggregation interactions suggest the ability to encourage the formation of biofilms, and colonic biofilms, in turn, have been linked to promotion and/or progression of CRC. Co-aggregation between F. nucleatum subsp. animalis and CRC-linked species such as C. concisus, Gemella spp., H. hathewayi, and P. micra may contribute to both biofilm formation along CRC lesions and to disease progression.

Type IV pili facilitated natural competence in Fusobacterium nucleatum.

OBJECTIVES: Many bacterial species naturally take up DNA from their surroundings and recombine it into their chromosome through homologous gene transfer (HGT) to aid in survival and gain advantageous functions. Herein we present the first characterization of Type IV pili facilitated natural competence in Fusobacterium nucleatum, which is a Gram-negative, anaerobic bacterium that participates in a range of infections and diseases including periodontitis, preterm birth, and cancer. METHODS: Here we used bioinformatics on multiple Fusobacterium species, as well as molecular genetics to characterize natural competence in strain F. nucleatum subsp. nucleatum ATCC 23726. RESULTS: We bioinformatically identified components of the Type IV conjugal pilus machinery and show this is a conserved system within the Fusobacterium genus. We next validate Type IV pili in natural competence in F. nucleatum ATCC 23726 and show that gene deletions in key components of pilus deployment (pilQ) and cytoplasmic DNA import (comEC) abolish DNA uptake and chromosomal incorporation. We next show that natural competence may require native F. nucleatum DNA methylation to bypass restriction modification systems and allow subsequent genomic homologous recombination. CONCLUSIONS: In summary, this proof of principle study provides the first characterization of natural competence in Fusobacterium nucleatum and highlights the potential to exploit this DNA import mechanism as a genetic tool to characterize virulence mechanisms of an opportunistic oral pathogen.

Fusobacterium nucleatum Promotes Megakaryocyte Maturation in Patients with Gastric Cancer via Inducing the Production of Extracellular Vesicles Containing 14-3-3ε.

Fusobacterium nucleatum colonization contributes to the occurrence of portal vein thrombosis in patients with gastric cancer (GC). However, the underlying mechanism by which F. nucleatum promotes thrombosis remains unclear. In this study, we recruited a total of 91 patients with GC and examined the presence of F. nucleatum in tumor and adjacent non-tumor tissues by fluorescence in situ hybridization and quantitative PCR. Neutrophil extracellular traps (NETs) were detected by immunohistochemistry. Extracellular vesicles (EVs) were extracted from the peripheral blood and proteins in the EVs were identified by mass spectrometry (MS). HL-60 cells differentiated into neutrophils were used to package engineered EVs to imitate the EVs released from NETs. Hematopoietic progenitor cells (HPCs) and K562 cells were used for megakaryocyte (MK) in vitro differentiation and maturation to examine the function of EVs. We observed that F. nucleatum-positive patients had increased NET and platelet counts. EVs from F. nucleatum-positive patients could promote the differentiation and maturation of MKs and had upregulated 14-3-3 proteins, especially 14-3-3ε. 14-3-3ε upregulation promoted MK differentiation and maturation in vitro. HPCs and K562 cells could receive 14-3-3ε from the EVs, which interacted with GP1BA and 14-3-3ζ to trigger PI3K-Akt signaling. In conclusion, we identified for the first time that F. nucleatum infection promotes NET formation, which releases EVs containing 14-3-3ε. These EVs could deliver 14-3-3ε to HPCs and promote their differentiation into MKs via activation of PI3K-Akt signaling.

A new member of the flavodoxin superfamily from Fusobacterium nucleatum that functions in heme trafficking and reduction of anaerobilin.

Fusobacterium nucleatum is an opportunistic oral pathogen that is associated with various cancers. To fulfill its essential need for iron, this anaerobe will express heme uptake machinery encoded at a single genetic locus. The heme uptake operon includes HmuW, a class C radical SAM-dependent methyltransferase that degrades heme anaerobically to release Fe2+ and a linear tetrapyrrole called anaerobilin. The last gene in the operon, hmuF encodes a member of the flavodoxin superfamily of proteins. We discovered that HmuF and a paralog, FldH, bind tightly to both FMN and heme. The structure of Fe3+-heme-bound FldH (1.6 Å resolution) reveals a helical cap domain appended to the ⍺/ß core of the flavodoxin fold. The cap creates a hydrophobic binding cleft that positions the heme planar to the si-face of the FMN isoalloxazine ring. The ferric heme iron is hexacoordinated to His134 and a solvent molecule. In contrast to flavodoxins, FldH and HmuF do not stabilize the FMN semiquinone but instead cycle between the FMN oxidized and hydroquinone states. We show that heme-loaded HmuF and heme-loaded FldH traffic heme to HmuW for degradation of the protoporphyrin ring. Both FldH and HmuF then catalyze multiple reductions of anaerobilin through hydride transfer from the FMN hydroquinone. The latter activity eliminates the aromaticity of anaerobilin and the electrophilic methylene group that was installed through HmuW turnover. Hence, HmuF provides a protected path for anaerobic heme catabolism, offering F. nucleatum a competitive advantage in the colonization of anoxic sites of the human body.

Fusobacterium nucleatum-derived succinic acid induces tumor resistance to immunotherapy in colorectal cancer.

Immune checkpoint blockade therapy with anti-PD-1 monoclonal antibody (mAb) is a treatment for colorectal cancer (CRC). However, some patients remain unresponsive to PD-1 blockade. The gut microbiota has been linked to immunotherapy resistance through unclear mechanisms. We found that patients with metastatic CRC who fail to respond to immunotherapy had a greater abundance of Fusobacterium nucleatum and increased succinic acid. Fecal microbiota transfer from responders with low F. nucleatum, but not F. nucleatum-high non-responders, conferred sensitivity to anti-PD-1 mAb in mice. Mechanistically, F. nucleatum-derived succinic acid suppressed the cGAS-interferon-ß pathway, consequently dampening the antitumor response by limiting CD8+ T cell trafficking to the tumor microenvironment (TME) in vivo. Treatment with the antibiotic metronidazole reduced intestinal F. nucleatum abundance, thereby decreasing serum succinic acid levels and resensitizing tumors to immunotherapy in vivo. These findings indicate that F. nucleatum and succinic acid induce tumor resistance to immunotherapy, offering insights into microbiota-metabolite-immune crosstalk in CRC.

Culture-Negative Fusobacterium nucleatum Brain Abscess and Pleural Empyema Cases Revealed by 16S rRNA Sequencing.

BACKGROUND: We reported two Fusobacterium nucleatum cases each of brain abscesses and pleural empyema, using 16S rRNA sequencing technology. METHODS: We reviewed clinical records and microbiological findings in four patients with F. nucleatum infection. RESULTS: All conventional culture results from peripheral blood, cerebrospinal fluid, and pleural fluid samples were found to be negative for this pathogen. Three patients were treated with antimicrobial agents for more than a week before specimen sampling. All patients recovered from their fusobacterial infections and were discharged. CONCLUSIONS: Molecular identification methods such as 16S rRNA sequencing should accompany conventional culture to detect obligate anaerobic bacteria in deep-seated sites and organs.

Study of the inflammatory activating process in the early stage of Fusobacterium nucleatum infected PDLSCs.

Fusobacterium nucleatum (F. nucleatum) is an early pathogenic colonizer in periodontitis, but the host response to infection with this pathogen remains unclear. In this study, we built an F. nucleatum infectious model with human periodontal ligament stem cells (PDLSCs) and showed that F. nucleatum could inhibit proliferation, and facilitate apoptosis, ferroptosis, and inflammatory cytokine production in a dose-dependent manner. The F. nucleatum adhesin FadA acted as a proinflammatory virulence factor and increased the expression of interleukin(IL)-1ß, IL-6 and IL-8. Further study showed that FadA could bind with PEBP1 to activate the Raf1-MAPK and IKK-NF-κB signaling pathways. Time-course RNA-sequencing analyses showed the cascade of gene activation process in PDLSCs with increasing durations of F. nucleatum infection. NFκB1 and NFκB2 upregulated after 3 h of F. nucleatum-infection, and the inflammatory-related genes in the NF-κB signaling pathway were serially elevated with time. Using computational drug repositioning analysis, we predicted and validated that two potential drugs (piperlongumine and fisetin) could attenuate the negative effects of F. nucleatum-infection. Collectively, this study unveils the potential pathogenic mechanisms of F. nucleatum and the host inflammatory response at the early stage of F. nucleatum infection.

Oncomicrobial vaccines: The potential for a Fusobacterium nucleatum vaccine to improve colorectal cancer outcomes.

There is increasing awareness of the many different ways host-microbe interactions relate to cancer initiation and progression. Vaccines designed to drive immune responses against key tumor-promoting mechanisms of oncomicrobes like F. nucleatum may provide novel and effective interventions against colorectal cancer and other diseases.

Associations Between Findings of Fusobacterium necrophorum or ß-Hemolytic Streptococci and Complications in Pharyngotonsillitis-A Registry-Based Study in Southern Sweden.

BACKGROUND: Most pharyngotonsillitis guidelines focus on the identification of group A streptococci (GAS), guided by clinical scores determining whom to test with a rapid antigen detection test. Nevertheless, many patients testing negative with this test are evaluated for group C/G streptococci (GCS/GGS) and Fusobacterium necrophorum, yet their importance remains debated. Our primary aim was to evaluate associations between complications and findings of F. necrophorum, GAS, or GCS/GGS in pharyngotonsillitis. METHODS: This was a retrospective, registry-based study of pharyngotonsillitis cases tested for F. necrophorum (polymerase chain reaction) and ß-hemolytic streptococci (culture) in the Skåne Region, Sweden, in 2013-2020. Patients with prior complications or antibiotics (within 30 days) were excluded. Data were retrieved from registries and electronic charts. Logistic regression analyses were performed with a dichotomous composite outcome of complications as primary outcome, based on International Classification of Diseases, Tenth Revision, codes. Cases with negative results (polymerase chain reaction and culture) were set as reference category. Complications within 30 days were defined as peritonsillar or pharyngeal abscess, otitis, sinusitis, sepsis or septic complications, recurrence of pharyngotonsillitis (after 15-30 days) or hospitalization. RESULTS: Of 3700 registered cases, 28% had F. necrophorum, 13% had GCS/GGS, 10% had GAS, and 54% had negative results. The 30-day complication rates were high (20%). F. necrophorum (odds ratio, 1.8; 95% confidence interval, 1.5-2.1) and GAS (1.9; 1.5-2.5) were positively associated with complications, whereas GCS/GGS were negatively associated (0.7; 0.4-0.98). CONCLUSIONS: Our results indicate that F. necrophorum is a relevant pathogen in pharyngotonsillitis, whereas the relevance of testing for GCS/GGS is questioned. However, which patient to test and treat for F. necrophorum remains to be defined.

Fusobacteria behaving badly: Masquerading strains of strictly anaerobic Escherichiacoli misidentified due to the deletion of the hemB gene.

Three strictly anaerobic strains of Escherichia coli were misidentified as Fusobacterium mortiferum, due to a deletion of the hemB gene which is involved in anaerobic respiration. An unusual antimicrobial susceptibility pattern sparked the further diagnostic strategies that eventually identified these strains as true anaerobic E. coli This phenomenon is more common than appreciated and can have an impact on clinical practice including persistent and relapsing infections.

Fusobacterium nucleatum stimulates cell proliferation and promotes PD-L1 expression via IFIT1-related signal in colorectal cancer.

Fusobacterium nucleatum (F. nucleatum) is enriched in colorectal cancer (CRC) tissues and a high amount of F. nucleatum was associated with an immunosuppressive tumor environment. PD-L1 is an important immune checkpoint expressed on tumor cells and promotes tumor immune escape. Whether PD-L1 is regulated by F. nucleatum is still unclear. We demonstrated that F. nucleatum promoted CRC progression and upregulated PD-L1 protein expression in CRC cell lines. Combined m6A-seq and RNA-seq identified m6A-modified IFIT1 mediating F. nucleatum induced PD-L1 upregulation. IFIT1 mRNA was modified with m6A modifications in 3'UTR and the m6A levels were altered by F. nucleatum treatment. Our results also indicated that IFIT1 served as a potential oncogene in CRC and regulated PD-L1 protein levels through altering PD-L1 ubiquitination. Clinical CRC data confirmed the correlation among F. nucleatum abundance, IFIT1 and PD-L1 expressions. Our work highlighted the function of F. nucleatum in stimulating PD-L1 expression through m6A-modified IFIT1 and provided new aspects for understanding F. nucleatum mediated immune escape.

Fusobacterium and Colorectal Cancer: Important Association or Random Coincidence?

The role of the microbiome in human cancer has become an area of intensive research and controversy. Many reports have highlighted the physical association of Fusobacterium with colorectal cancer. This association has provided diagnostic and therapeutic promise but has also given rise to several controversies regarding the influence of Fusobacterium species on human colorectal cancer. Here, we discuss two areas of controversy surrounding this emerging pathogen: the influence of Fusobacterium on colorectal cancer proliferation and the effect of Fusobacterium on the immune microenvironment of colorectal cancer.