Pyogenic liver abscess is a serious and potentially life-threatening condition, with an incidence between 0.006%-2.2% of hospital admissions and mortality reported to range from 10-40%. [1]

The most commonly isolated organisms associated with pyogenic liver abscesses are Klebsiella pneumonia and Escherichia coli. [2] Rarely, Fusobacterium nucleatum has been implicated with hepatic abscess though never previously in association with sigmoid carcinoma. It has been reported once following a colonoscopic biopsy for ulcerative colitis. [3]

Fusobacteria nucleatum is an anaerobic gram-negative, non-spore forming bacilli found in normal flora of the oral cavity. It is one of the most common oral species isolated from extra-oral infections such as blood, brain, lung, liver, joints, abdominal, obstetrical and gynaecological infections and abscesses. It has recently been reported as a cause of liver abscess in a patient suffering from recurrent periodontal disease. [4]

We report the first case of F. nucleatum pyogenic liver abscess as the initial presentation of a recto-sigmoid carcinoma.

A 72-year-old gentleman presented with a three week history of fatigue, night sweats and rigors. He was initially assessed by his General Practitioner who started a course of penicillin but, unfortunately, on completion of the antibiotics the rigors recurred. There was no associated cough, diarrhoea, weight loss, abdominal pain, dysuria or contact with any tuberculosis patients. Past medical history was remarkable only for nasal polyps and hypertension, for which he was treated with ramipril and bendroflumethiazide. The patient reported alcoholic intake of 16 units per week, with no history of intravenous drug abuse or of receiving any blood or blood product transfusions. The patient was immunocompetent and not diabetic or on steroid treatment. Examination was unremarkable but initial blood tests revealed an elevated ALP 421 IU/L (normal range 20-130iu/L), CRP 180 mg/L (Normal range <5 mg/L) and white cell count 16.1x109/L (normal range 4.0-11.0x109/L) with a neutrophilia of 15.40 x109/L (normal range 1.70-7.50 x109/L). Ultrasound scanning of the abdomen revealed three echo poor areas in the liver, the largest of which was 3.8 cm x 4.2 cm. This was thought to represent either an abscess or a metastatic deposit. Blood culture did not yield any results, but the patient was given a stat dose of 320 mg of gentamicin and 1.2 gm intra-venous co-amoxiclav three times a day. A CT scan of the abdomen was performed which revealed a hepatic abscess of 3.8 x 4.2 cm (Figure 1), which was drained percutaneously under ultrasound guidance. This aspirate was cultured and grew F. nucleatum noted to be sensitive to penicillin and metronidazole. Follow-up CT scan was performed, which showed marked resolution of the hepatic abscess.

Colorectal cancer is often associated with abscessformation in the ischio-rectum, abdominal wall, psoas and paravertebral areas. It may through direct extension of the tumor or as a result of bacteraemia from colonic pathogens. There is an increasing association between colonic cancer and liver abscess over the last few years. It has been reported that a pyogenic liver abscess may be associated with, or be the initial presentation of an underlying recto-sigmoid or colonic neoplasm. [5] [6] [7] The most common organism found in such liver abscess is Streptococcus bovis and also that this bacteraemia may precede the diagnosis of the cancer by several years. [8] It is now well established that S. bovis bacteraemia is associated with gastrointestinal disease, particularly colonic neoplasia. It has also been suggested that extracolonic malignancy is a common feature of a large proportion of patients with S bovis Bacteremia. [9]

Liver abscesses caused by periodontal bacterial infection are rare, however, the incidence is expected to increase in the future as periodontitis is extremely common and is on the rise as one of the most common chronic infections in the world. [10] Clinically significant infections caused by members of the genus Fusobacterium are rare, affect distinct patient groups and are associated with good clinical outcomes in the majority of cases. [11]

Fusobacterium bacteraemia is uncommon, accounting for approximately 0.9% of patients with bacteraemia and is associated with a high mortality rate for patients with renal insufficiency, heart failure or malignancy. [12] The proposed mechanism for bacteraemia is following mucosal disruption by the neoplasm resulting in the underlying blood vessels becoming exposed to the faecal flora. [13]

F. nucleatum has previously been implicated in pyogenic liver abscess formation,14 and in one study Fusobacterium species were implicated in 4.3% of microbiological isolates. [15]

F. nucleatum is a non-sporulating, immotile, Gram-negative bacterium which has pathogenic potential due to its frequency and numbers found in periodontal lesions. Interestingly, of all the bacteria linked with periodontal disease, F nucleatum has coaggregration properties which allow it to transport periodonto pathogenic bacteria. [16] This is imperative in supporting our hypothesis that F. nucleatum may have breached the mucosa of the colon due to the carcinoma, leading to a bacteraemia resulting in a hepatic abscess.

There was no sign of periodontal disease in our patient, the bacteria may have originated from colon, which makes this report a unique case presentation of Fusobacterium nucleatum presenting as a liver abscess in association with colorectal cancer.

We are reporting the first incidence in literature of colonic cancer in association with Fusobacterium nucleatum. Also, there is also no evidence to suggest F. nucleatum has been associated with colonic cancer in isolation. It is our aim to reinforce the suggestion that on exclusion of the predominant liver abscess etiologies, a diagnosis of colonic carcinoma is considered. It is also our view that unusual bacteraemia and microbiological isolates should be thoroughly investigated despite possible occurrence at sites distal to their usual colonization.

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