Myopericarditis associated with Fusobacterium nucleatum-caused liver abscess

Fusobacterium nucleatum Pyogenic Liver Abscess and the Role of Bacterial Virulence and Gut Microbiota Dysbiosis

In the United States, pyogenic liver abscesses are often due to monomicrobial infection and are rarely documented to be a consequence of Fusobacterium infection, a common cause of Lemierre's syndrome. Recent advances in gut microbial studies have identified Fusobacterium as a commensal gut flora that becomes pathogenic in the setting of dysbiosis resulting from colorectal diseases, such as diverticulitis. While the bacteria's tropism for the liver remains to be elucidated, the virulence pattern of Fusobacterium and the portal venous drainage system have allowed us to understand the bacterium's propensity for causing right hepatic abscesses. In this case report, we detail an immunocompetent man with a history of sigmoid diverticulitis who developed a right hepatic abscess due to Fusobacterium nucleatum, while delineating a review of the literature on the virulent properties of the bacterium and the impact of gut microbiota dysbiosis in its pathogenicity. A descriptive analysis was also performed to identify the characteristics of patients who are at risk in hopes of further improving the clinical diagnostic schema for this condition.

Enhanced Fusobacterium nucleatum Genetics Using Host DNA Methyltransferases To Bypass Restriction-Modification Systems

Bacterial restriction-modification (R-M) systems are a first-line immune defense against foreign DNA from viruses and other bacteria. While R-M systems are critical in maintaining genome integrity, R-M nucleases unfortunately present significant barriers to targeted genetic modification. Bacteria of the genus Fusobacterium are oral, Gram-negative, anaerobic, opportunistic pathogens that are implicated in the progression and severity of multiple cancers and tissue infections, yet our understanding of their direct roles in disease have been severely hindered by their genetic recalcitrance. Here, we demonstrate a path to overcome these barriers in Fusobacterium by using native DNA methylation as a host mimicry strategy to bypass R-M system cleavage of transformed plasmid DNA. We report the identification, characterization, and successful use of Fusobacterium nucleatum type II and III DNA methyltransferase (MTase) enzymes to produce a multifold increase in gene knockout efficiency in the strain Fusobacterium nucleatum subsp. nucleatum 23726, as well as the first system for efficient gene knockouts and complementations in F. nucleatum subsp. nucleatum 25586. We show plasmid protection can be accomplished in vitro with purified enzymes, as well as in vivo in an Escherichia coli host that constitutively expresses F. nucleatum subsp. nucleatum MTase enzymes. In summary, this proof-of-concept study characterizes specific MTases that are critical for bypassing R-M systems and has enhanced our understanding of enzyme combinations that could be used to genetically modify clinical isolates of Fusobacterium that have thus far been inaccessible to molecular characterization. IMPORTANCE Fusobacterium nucleatum is an oral opportunistic pathogen associated with diseases that include cancer and preterm birth. Our understanding of how this bacterium modulates human disease has been hindered by a lack of genetic systems. Here, we show that F. nucleatum DNA methyltransferase-modified plasmid DNA overcomes the transformation barrier and has allowed the development of a genetic system in a previously inaccessible strain. We present a strategy that could potentially be expanded to enable the genetic modification of highly recalcitrant strains, thereby fostering investigational studies to uncover novel host-pathogen interactions in Fusobacterium.

Fusobacterium nucleatum causing a pyogenic liver abscess: a rare complication of periodontal disease that occurred during the COVID-19 pandemic

Fusobacterium nucleatum is a periodontal commensal and pathogen. In rare cases, these anaerobic gram-negative bacilli have been reported to cause pyogenic liver abscesses (PLAs). We describe a patient who developed a periodontal abscess during the COVID-19 pandemic and was unable to access the restricted General Dental Services at this time. She subsequently developed a F. nucleatum bacteraemia and liver abscess. The non-specific signs and symptoms experienced meant the patient self-isolated due to suspected COVID-19 infection and presentation to hospital was delayed. We also include the results of a literature search of other cases of PLAs attributed to F. nucleatum PLAs often develop insidiously. They require percutaneous drainage and prolonged antimicrobial therapy. Clinicians should be aware of this rare complication of a dentoalveolar infection in a patient who is systemically unwell.

Concurrent fusobacterial pyogenic liver abscess and empyema

We present a very rare case of concurrent empyema and liver abscess caused by Fusobacterium. Our patient presented with 3-month history of subtle abdominal discomfort and cough leading to eventually presenting with marked chest pain, dyspnoea and septic shock. CT revealed a liver abscess and large right-sided pleural effusion. Drainage of the pleural effusion yielded gross pus with the growth of Fusobacterium varium, while drainage of the liver abscess yielded Fusobacterium nucleatum The patient responded to drainage and antibiotic therapy with resolution of symptoms and decrease in the size of empyema and abscess on follow-up imaging. We also include a review if literature of related fusobacterial infections.

Fusobacterium nucleatum: A cause of subacute liver abscesses with extensive fibrosis crossing the diaphragm, mimicking actinomycosis

Introduction

Fusobacterium nucleatum is a Gram-negative, obligate anaerobic bacterium which predominantly resides within the oral cavity and causes acute abscesses and venous thrombosis, primarily in the head and neck region, but could have unique clinical presentations in different anatomical regions of the body.

Case report

We present a case of subacute liver abscesses extending to the lung. The histopathological examination showed extensive necrosis and fibrosis. The chronic course, extensive fibrosis and extension across the anatomic barriers were suggestive of actinomycosis. two sets of blood cultures grew Fusobacterium nucleatum, only 16s rRNA analysis of the liver tissue and pleural fluid revealed F. nucleatum DNA without other organisms. The clinical and pathological features of our case illustrate that F. nucleatum may mimic actinomycosis.

Conclusions

This case illustrates that F. nucleatum should be considered in patients with subacute infections with extensive fibrosis that crosses anatomic barriers, mimicking actinomycosis.

A rare case of pericarditis and pleural empyema secondary to transdiaphragmatic extension of pyogenic liver abscess

BACKGROUND

Transdiaphragmatic extension of pyogenic liver abscess is the rarest cause of pericarditis and pleural empyema. It is a rapidly progressive and highly lethal infection with mortality rates reaching 100% if left untreated. However, the transmission route, treatment methods and prognosis have not been well studied.

CASE PRESENTATION

A 65-year-old male patient presented with a fever, dyspnea, and right upper quadrant abdominal pain. Computed tomography of the chest and abdomen showed huge liver abscess without full liquefaction in the left lobe, large amount of left pleural effusion, and mild pericardial effusion, and the patient was treated with parenteral antibiotics and pigtail insertion at the left pleura. However, four days later, cardiac tamponade was developed and surgical drainage of the abscess and pericardium was performed. Klebsiella pneumonia was isolated from pleural empyema. Twenty-five days after surgery, the patient was discharged without any complications.

CONCLUSIONS

Herein, we report a rare case of pleural empyema and pericarditis in that resulted from the extension of huge pyogenic liver abscess. Early surgical treatment may have prevented progression of the pericarditis to the more dismal purulent pericarditis. We also review pertinent English literature on pericarditis as a complication of PLA.

Fusobacterial liver abscess: a case report and review of the literature

Background

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.

Case presentation

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.

Conclusion

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