Staphylococcus Hemolyticus Liver Abscess as an Uncommon Presentation of Silent Colonic Cancer: A Case Report

To the Editor: Although liver abscess is a common intra-abdominal infection, accounting for about one of every 4,500 to 7,000 hospital admissions,1 the clinical manifestation of colonic cancer as a liver abscess, in the absence of liver metastases, is not frequent. A 73-year-old man was admitted to the hospital complaining of fever resistant to antibiotic therapy (ciprofloxacin 500 mg two times a day) for 10 days with no presence of urinary, thoracic, or abdominal symptoms. His medical history indicated tubercular pleuritis 40 years before and mild hypertension, the latter being treated with thiazides. Physical examination revealed axillary temperature of 38.5°C (101.1°F), regular heart beat (94 beats/min) with no heart murmur, and absence of pulmonary noise. Examination of the abdomen revealed tenderness in the right upper quadrant, corresponding with a palpable swelling, with mild positive Murphy's sign. Chest radiography was negative. Abdominal ultrasonography revealed a hypoechogenic mass in the right hepatic lobe (V-VIII segment, maximum diameter 8 cm) with lobular margins and mainly liquid content. Laboratory data were as follows: white blood count, 21,600/mm3 with 90% neutrophils; hematocrit, 39.6%; hemoglobin, 12.9 g/dL; platelets, 506,000/mm3; sodium, 135 mEq/L; potassium 4.5 mEq/L; chloride, 105 mEq/L; creatinine, 0.7 mg/dL; glucose 104 mg/dL; alanine-aminotransferase, 82 U/L; alkaline phosphatase, 153 U/L; lactate dehydrogenase, 200 U/L; total bilirubin, 1.14 mg/dL; γ-glutamyltranspeptidase, 104 U/L; prothrombin time international normalized ratio, 1.0; fibrinogen, 750 mg/dL; erythrocyte sedimentation rate, 93 mm/h; and C-reactive protein, 24.5 mg/dL. Urinalysis was normal. Computed tomography confirmed the presence of a concamerated formation (Figure 1, upper half), suggestive of liver abscess. The patient underwent surgical drainage, with extraction of 250 mL of purulent material; cultural examination isolated Staphylococcus hemolyticus resistant to ciprofloxacin and sensitive to teicoplanin. After a few days of antibiotic therapy, his clinical condition and laboratory examination drastically improved. Given the peculiarity of microbial isolation and searching for a possible entrance gate, a colonoscopy was then performed. It revealed a colorectal mass, less than 3 cm from the anal orifice; histology indicated infiltrating adenocarcinoma (computerized tomography in Figure 1, lower half). Surgical intervention was successful, postoperative course was uneventful, and the patient was discharged in general good health a few days later. Computed tomography. Concamerated formation, mainly fluid density, with hypodense irregular circin (upper half). Colorectal mass, less than 3 cm from anal orifice (lower half). Bacterial, fungal, or parasitic organisms may cause liver abscesses. As for bacterial abscesses, one of the following mechanisms is typically present:2 portal vein bacteremia arising from an intra-abdominal infection; systemic bacteremia originating from a distant site; ascending cholangitis secondary to biliary tract obstruction; direct extension from a continuous focus of infection; or trauma, either penetrating or blunt, with secondary infection. However, many abscesses are still deemed cryptogenic.1 In the industrialized countries, pyogenic (bacterial and fungal) abscesses account for three-quarters of all liver abscesses.3 In two-thirds of cases of liver abscess, a bacterial pathogen is identified.4 Although, until a couple of decades ago, Escherichia coli was the most commonly isolated organism from patients with liver abscess, more recently Klebsiella pneumoniae isolations are growing fast.5 Colorectal neoplasms may represent a risk factor for liver abscess. The most likely mechanism may be bacteremia, secondary to mucosal disruption by colonic cancer and consequent exposition of the underlying blood vessels to the fecal flora.6 Recent literature include association between liver abscesses and colonic cancer with isolation of Streptococcus intermedius7 and Streptococcus milleri,8 but isolation of a Staphylococcus hemolyticus is infrequent. When gram-positive organisms such as staphylococci or streptococci are isolated from a pyogenic liver abscess, it is likely that the primary source is from outside the abdomen.5 Thus, in the presence of a liver abscess, and after the exclusion of prevailing etiologies, an aggressive search should be addressed to search for silent colonic cancer.9 Increased awareness of colonic cancer as one of the underlying causes of pyogenic liver abscesses, especially in patients aged 50 and older, is needed.10 Financial Disclosure: None. Author Contributions: Susanna Gamberini: original idea, clinical handling, acquisition of subject's data, literature search, preparation of manuscript. Gabriele Anania: surgical operation, literature search, check of the manuscript. Elena Incasa, Arnaldo Zangirolami, Marilena Tampieri, and Benedetta Boari: clinical handling, acquisition and interpretation of data, literature search, preparation of the manuscript. Giorgio Benea: acquisition and interpretation of imaging, literature search, preparation of the manuscript. Roberto Manfredini: original idea, acquisition of subject's data, literature search and elaboration, and preparation of manuscript. Sponsor's Role: None.