• anaerobic bacterial
• immunocompetent adult infection
• liver abscess
• metagenomic next-generation sequencing (mNGS)
• sepsis

• Fusobacterium nucleatum
• empyema
• lung cancer
• next-generation sequencing
• squamous cell carcinoma

• bacterial virulence
• diverticulitis
• fusobacterium nucleatum
• gut microbiota dysbiosis
• pyogenic liver abscess

Parvimonas micra (P. micra) and Fusobacterium necrophorum (F. necrophorum) are two pathogens known to cause odontogenic and oropharyngeal infections. It is exceedingly rare for these bacteria to cause coinfection and even systemic infection. There is limited literature on liver abscesses and bacteremia involving P. micra. Most cases are found in elderly patients with associated gastrointestinal malignancy (24%) or laryngeal pharynx malignancy (28%). However, a substantial portion of described cases were unable to identify a source (36%). A 36-year-old, otherwise healthy male presented for fevers and chills for 2 weeks. After testing negative for initial infectious workup, including COVID-19 multiple times, he was found to have multiple liver abscesses which grew P. micra and F. necrophorum. This case highlights a rare coinfection of hepatic abscesses in an otherwise healthy young immunocompetent adult with a solitary dental caries, resulting in septic shock.

Fusobacterium nucleatum (F. nucleatum) is a resident anaerobic bacterium, which in rare cases may invade blood from the head and neck or the digestive tract to cause bacteremia and induce venous thrombosis. F. nucleatum is closely related to abdominal tumors, but it has not been reported in relation to renal tumors. We report herein a possible case.

This patient had kidney cancer with thrombosis in the right renal vein but had no sign of infection. After radical nephrectomy, thrombi formed in his left renal vein, and when removed, severe sepsis occurred. He did not respond to treatment with antibiotics and died, but the blood culture done confirmed that he had F. nucleatum bacteremia.

F. nucleatum may also be associated with kidney cancer, and could cause post-operative renal vein thrombosis, and sepsis or septic shock after thrombectomy.

• Fusobacterium nucleatum
• Kidney cancer
• Renal vein thrombosis
• Sepsis

Pyogenic liver abscesses (PLAs) are a rare condition in North America and Europe and, rarer still, the cause of septic shock. This case report will describe the rare occurrence of a PLA producing septic shock in a 36-year-old male residing in the United Kingdom following a case of complicated appendicitis.

The patient presented to the emergency department (ED) with a three-week history of intermittent loose stools, cramping abdominal pain, recurrent fevers, a heart rate of 111 beats per minute, a blood pressure of 94/58 mmHg, and a fever of 40.1 degrees Celsius. Despite prompt broad spectrum antibiotic administration and three liters of fluid resuscitation, the patient remained shocked which led to an ICU admission.

A CT scan prior to transfer found a 7 cm x 6 cm x 6 cm lesion representing a liver abscess (LA) as well as gross inflammatory change affecting the distal small bowel. The LA was managed through insertion of a percutaneous drain under ultrasound guidance performed by the interventional radiology team, as well as ongoing IV antibiotics. Following growth of the gut commensal Streptococcus constellatus from the abscess fluid culture, a colonoscopy was performed which found a severely distorted and inflamed terminal ileum with an impassable stricture, raising not only the suspicion of appendicitis but also Crohn’s disease.

Following the colonoscopy, after a total of 10 days admission, the patient was allowed to go home with a four-week course of oral co-amoxiclav. After discharge, the patient’s case was discussed in the gastroenterology inflammatory bowel disease (IBD) multi-disciplinary team meeting due to concerns raised about possible Crohn’s disease from the admission CT and following colonoscopy findings. Given the absence of relevant IBD symptoms, a reassuring outpatient MRI small bowel scan (found considerable resolution of the right iliac fossa inflammatory process) and a fecal calprotectin of 29 four months post discharge (normal=0-51 μg/g), it was concluded the terminal ileum changes were most likely accounted for by a complicated course of appendicitis. When reviewed in a telephone clinic 10 weeks post discharge, he was found to have no persistent gastrointestinal (GI) symptoms and was subsequently discharged.

This case highlights the importance of comprehensive imaging and colonoscopy in the work up of those patients with PLAs with no otherwise evident precipitating factor.

• : liver abscess
• abscess
• appendicitis
• pyogenic liver abscess
• sepsis
• septic shock

• AML acute myelogenous leukemia
• APCs antigen-presenting cells
• CAFs cancer-associated fibroblasts
• CRC colorectal cancer
• DC Dendritic Cells
• DFS disease-free survival
• EMT epithelial-mesenchymal transition
• ETBF Bacteroides fragilis
• F. nucleatum Fusobacterium nucleatum
• Fgl2 fibrinogen-like protein 2
• Grb2 growth factor receptor-bound protein 2
• IBD inflammatory bowel diseases
• ICIs Immune checkpoint inhibitors
• IHC immunohistochemistry
• List of Abbreviations and symbols:
• MAPK mitogen-activated protein kinase
• MDSCs myeloid-derived suppressor cells
• MSI Microsatellite instability
• MSS microsatellite-stable
• NFκB nuclear factor-kappa B
• NK Natural Killer cell
• NSCLC non-small cell lung cancer
• PI3K phosphoinositide 3-kinase
• PVR poliovirus receptor
• RR-MS relapsing-remitting multiple sclerosis
• SHIP1 SH2 domain-containing inositol-5-phosphatase 1
• TAMs tumor-associated macrophages
• TANs tumor-associated neutrophils
• TFH follicular helper T cells
• TFR follicular regulatory T cells
• TIGIT
• TIGIT T cell immunoglobulin and ITIM domain
• TILs tumor-infiltrating lymphocytes
• TME tumor microenvironment
• TNM staging spread of cancer to other parts of the body
• Tregs regulatory T cells
• cancer immunotherapy
• colorectal cancer
• dMMR defective DNA mismatch repair
• immune checkpoint
• mAb monoclonal antibody

• dentistry and oral medicine
• general surgery
• infections
• oral and maxillofacial surgery

• Anti-Bacterial Agents/therapeutic use
• Bacteremia/diagnosis
• COVID-19/epidemiology
• Drainage
• Female
• Fusobacterium Infections/diagnosis
• Fusobacterium Infections/diagnostic imaging
• Fusobacterium Infections/drug therapy
• Humans
• Liver Abscess, Pyogenic/diagnostic imaging
• Liver Abscess, Pyogenic/drug therapy
• Liver Abscess, Pyogenic/microbiology
• Middle Aged
• Pandemics
• Periodontal Abscess/microbiology
• Quarantine
• SARS-CoV-2
• Time-to-Treatment
• Tomography, X-Ray Computed

A 21-year-old previously healthy young man was admitted with five days of fever, persistent cough, worsening shortness of breath, and vomiting. On presentation, laboratory evaluation revealed extremely elevated procalcitonin and leukopenia followed by leukocytosis. The patient was started on empiric antibiotics. Further diagnostic evaluation after initiation of antibiotics included a computed tomography scan, which revealed a large hepatic abscess. Blood cultures obtained on admission grew Fusobacterium nucleatum; fluid obtained from the hepatic abscess also grew F. nucleatum. The patient’s antibiotic regimen was narrowed for specific coverage of F. nucleatum. The liver abscess was drained several times via image-guided percutaneous abscess drainage, with eventual resolution of the abscess. Patient received a prolonged course of intravenous antibiotics and, once stabilized, was discharged on two weeks of Augmentin. Here, we present a rare case of hepatic abscess and bacteremia due to F. nucleatum in a previously healthy young man with good oral hygiene. With this case, we aim to demonstrate the following: (1) the acute onset and rapid disease progression of F. nucleatum bacteremia and liver abscess; (2) how extreme procalcitonin elevation may serve to be a clinically useful early marker of F. nucleatum infection; and (3) the importance of early diagnosis, treatment, and definitive abscess drainage of F. nucleatum bacteremia and liver abscess.

• bacteremia
• fusobacterium
• liver abscess

• 16S deep sequencing
• 16S profiling
• 16S rRNA
• Abscess
• Kidney
• Liver
• Next generation sequencing
• Pancreas

• emerging pathogen
• fusobacterium nucleatum
• liver abscess
• septic shock

A 40-year-old man presented to the emergency room and was evaluated in the internal medicine department for unexplained weight loss, asthenia, anorexia and night sweats over the previous 2 months. After a loculated pleural effusion was identified on thoracic computed tomography, purulent fluid was drained from the lung and Fusobacterium nucleatum was isolated. The patient was successfully treated for 27 days with amoxicillin-clavulanic acid. This was an atypical presentation of a common micro-organism implicated in lung infections.

• Fusobacterium nucleatum
• empyema
• unexplained weight loss

• Fusobacterium
• Pyogenic liver abscess

• infectious diseases
• intensive care
• liver disease
• respiratory medicine

• Fusobacterium nucleatum
• Liver abscess
• actinomycosis
• fibrosis

• Anaerobe
• Denture
• Fusobacterium nucleatum
• Liver abscess
• Periodontitis
• Pyogenic

• Carcinoma
• Colon and rectal carcinoma
• Fusobacterium nucleatum
• Gut microbiome
• Host immunity

Although uncommon, Fusobacterium infections have a wide clinical spectrum, ranging from local pharyngeal infections to septic shock. Our aim was to characterize and analyze the clinical features and outcomes in patients with Fusobacterium infections, and determine which variables were able to predict a poor outcome.

We conducted a retrospective, hospital-based study using the computerized records of a second-level Spanish general hospital, serving a population of 155,000 inhabitants. The cohort was enrolled among patients cared for at the hospital between 2007 and 2016. Demographic, clinical data, microbiological characterization and outcomes at discharge, were analyzed.

We collected data for all 26 patients over a 10-year period (annual incidence of 1.78 per 100,000), with an incidence of bacteremia of 0.53 cases per 100,000 population per year. F. nucleatum and F. necrophorum were the most frequent isolations (53.8% and 38.5%, respectively). F. necrophorum was found to be associated with a younger population. Although we found no deaths attributable to Fusobacterium, 15 patients (57%) were found to have severe infections due to this pathogen, and 7 patients (26.9%) were admitted to the Intensive Care Unit (ICU). The only identifiable risk factor for a severe infection (sepsis, septic shock or ICU admission) was the presence of bacteremia.

Fusobacterium infections are uncommon. F. necrophorum tends to cause infection in younger individuals, while F. nucleatum has a preference for older patients. The clinical spectrum is wide, ranging from local, nonsevere infections, such as sinusitis or pharyngitis, to abscess formation and life-threatening infections.

• Fusobacterium
• bacteremia
• epidemiology
• incidence
• risk factors
• sepsis

Fusobacterium nucleatum is an oral pathogen that is linked to multiple human infections and colorectal cancer. Strikingly, F. nucleatum achieves virulence in the absence of large, multiprotein secretion systems (Types I, II, III, IV, and VI), which are widely used by Gram-negative bacteria for pathogenesis. By contrast, F. nucleatum strains contain genomic expansions of Type V secreted effectors (autotransporters) that are critical for host cell adherence, invasion, and biofilm formation. Here, we present the first characterization of an F. nucleatum Type Vd phospholipase class A1 autotransporter (strain ATCC 25586, gene FN1704) that we hereby rename Fusobacterium phospholipase autotransporter (FplA). Biochemical analysis of multiple Fusobacterium strains revealed that FplA is expressed as a full-length 85-kDa outer membrane–embedded protein or as a truncated phospholipase domain that remains associated with the outer membrane. Whereas the role of Type Vd secretion in bacteria remains unidentified, we show that FplA binds with high affinity to host phosphoinositide-signaling lipids, revealing a potential role for this enzyme in establishing an F. nucleatum intracellular niche. To further analyze the role of FplA, we developed an fplA gene knock-out strain, which will guide future in vivo studies to determine its potential role in F. nucleatum pathogenesis. In summary, using recombinant FplA constructs, we have identified a biochemical toolbox that includes lipid substrates for enzymatic assays, potent inhibitors, and chemical probes to detect, track, and characterize the role of Type Vd secreted phospholipases in Gram-negative bacteria.

• Fusobacterium
• autotransporter
• chemical biology
• colorectal cancer
• host-pathogen interaction
• phospholipase A
• protein secretion

• Hepatitis and other GI infections
• Infection (gastroenterology)
• Liver disease

Fusobacteriae are facultative anaerobic gram-negative bacilli which cause a range of invasive infections, amongst which pyogenic liver abscesses are rare. We describe a case of Fusobacterium nucleatum liver abscess and review the relevant literature.

A 51-year-old lady presented with a 4-day history of abdominal pain, diarrhoea, fever, rigors, and lethargy. Imaging revealed an abscess which was drained. Cultures of the blood and abscess aspirate grew Fusobacterium nucleatum and Prevotella pleuritidis respectively. She achieved full recovery following treatment.

A MEDLINE search was undertaken using free-text and Medical Subject Headings (MeSH), keywords “Fusobacterium” and “Liver abscess”. Non-English language reports and cases without confirmed growth of Fusobacterium species were excluded. Additional cases were identified by surveying the references of each report and by using the same keywords in a web-based search.

Forty-eight cases were identified, 41 in men. The median age was 42.5, with an interquartile range of 33. F. nucleatum and F. necrophorum were in involved in 22 cases each, and 4 cases were not further speciated. Among cases of F. nucleatum liver abscess, nine were attributed to periodontal disease, four to lower gastrointestinal tract disease, one to Lemierre’s Syndrome, and eight were considered cryptogenic. All patients treated made a full recovery. Antimicrobial treatment duration ranged from 2 weeks to 6 months with a median of 6 weeks.

Fusobacterium nucleatum is an uncommon cause of liver abscess generally associated with good clinical outcomes with contemporary medical and surgical care.

• Case reports
• Fusobacterium
• Lemierre’s syndrome
• Liver abscess
• Periodontal diseases
• Review

Pyogenic liver abscesses (PLAs) are the most common form of liver abscesses in the United States. Most cases are caused by enteric bacteria and anaerobes. We report a case of PLA caused by a rare pathogen, Fusobacterium nucleatum, from an unusual primary site of infection.

A 60-year-old male presented with subacute fever. Initial work-up revealed leukocytosis and elevated alkaline phosphatase (ALP). Dental examination and Panorex x-ray were normal. Imaging of the liver with abdominal computed tomography demonstrated a 5.5 cm abscess in the right lobe of the liver. Culture of the aspirate grew Fusobacterium nucleatum. He improved with abscess drainage and antibiotic therapy with moxifloxacin and metronidazole. Colonoscopy performed a few weeks later, demonstrated sigmoid ulceration most likely from the previous diverticulitis.

PLAs can be a complication of sigmoid diverticulitis and as a result of occult dental disease as well. The clinical presentation of Fusobacterium infection is diverse and can be fatal if diagnosis is delayed. Therefore, early diagnosis and treatment are the keys to preventing serious complications.

• Diverticulitis
• fusobacterium nucleatum
• oral infection
• pyogenic liver abscess

While pyogenic liver abscesses are uncommon, they are associated with significant mortality and morbidity. Most pyogenic liver abscesses are polymicrobial and are caused by enteric bacteria and anaerobes. Rarely, mono-microbial infections may occur, typically in immunocompromised individuals. We report the unusual case of a 69 year-old immunocompetent female who developed a pyogenic liver abscess due to Fusobacterium nucleatum infection, likely from a dental source. Poor oropharyngeal hygiene seems to have a major role in infection from this organism and therefore F. nucleatum should be considered as a differential for causes of pyogenic liver abscess in such patients. Drainage of the abscess and antibiotic therapy are the mainstays of therapy.

• Fusobacterium
• Immunocompromised state
• Poor dental hygiene
• Pyogenic liver abscess