Pyogenic liver abscess (PLA) is uncommon with an incidence of 0.5% to 0.8%, accounting for 15 per 100,000 hospital admissions, but it is an important entity due to the potential lethality . Currently, the most common cause of PLA is biliary tract disease, including cholelithiasis, benign and/or malignant biliary strictures, and congenital anomalies of the biliary tree, reported to account for 37% of cases [6, 7]. Appendicitis, diverticulitis, inflammatory bowel disease, and perforated hollow viscera are possible sources of septic emboli. Hematogenous dissemination of causative organisms in association with systemic bacteremia, for example from endocarditis or pyelonephritis, is a rare cause of PLA. The bacteriology of a PLA is polymicrobial, with Klebsiella, group D Streptococcus, E. coli, and Bacteroides. Although recovery of S. aureus from PLA with conservative therapy occurs in approximately 4% of cases, that of MRSA is rare .
Inflammatory bowel diseases, including Crohn’s disease, are associated with frequent portal venous bacteremia due to disruption of the bowel barrier, which easily results in bacterial translocation . In addition, the well-known complications of Crohn’s disease, such as fistulization, perforation, and intra-abdominal abscess formation could predispose patients to the development of microbial invasion of the portal venous system and seeding of the hepatic parenchyma . Thus, Crohn’s disease is associated with various hepatobiliary disorders, including pericholangitis, sclerosing cholangitis, granulomatous hepatitis, and cholelithiasis , but the development of PLA is rare, with only 47 reported cases in the English literature [8, 9, 11–13]. Many authors have pointed out that not only bowel inflammation itself but also treatment with steroids or infliximab, malnutrition, and the underlying immunologic impairment of patients with Crohn’s disease might have a role in developing PLA. To the best of our knowledge, this is the first report of a MRSA liver abscess developing in a patient with Crohn’s disease under infliximab treatment. In this particular case, the Crohn’s disease itself was well suppressed with successful remission induced after nine infusions of infliximab. In addition, a colon and intestinal examination before discharge revealed almost normal mucosa without any symptoms. It is also well-accepted that an immunocompromised condition plays a critical role in developing PLA [5, 14]. All these findings led us to speculate that the immunosuppressive state under infliximab treatment might have played a critical role in the development of the MRSA liver abscess in the present case, considering the documented association between cytokine inhibition by infliximab and infection [13, 15–17].
Systemic parenteral antimicrobial therapy with broad spectrum antibiotics remains the mainstay primary treatment of PLA. The regimen must be altered to target specific organisms isolated from the abscess aspirate . An abscess larger than three cm in diameter is generally required to be drained . The image-guided percutaneous technique is a standard treatment of drainage . Nevertheless, there remains a role for open or laparoscopic surgical intervention in the management of PLA with the documented indication as follows: no clinical response after four to seven days of percutaneous drainage; multiple, large, or loculated abscess; thick-walled abscess with viscous pus; and concomitant intra-abdominal surgical pathology [5, 16, 18, 19]. Some authors have reported the efficacy and safety of emergent surgical drainage or resection [9, 10, 14, 20, 21].
Because of its rarity, it is unclear whether PLA caused by S. aureus (or MRSA) follows a different or more severe clinical course than PLA caused by enteric flora. The aggressive nature of the present PLA might validate the decision to perform surgery. Considering that few cases of surgical resection of PLA  have been reported, the necessity of anatomic resection of PLA including the surrounding parenchyma might be a matter of debate, but the satisfactory course of the present case after resection justifies our decision.
However, there were some critical flaws in our management of this case. First, an expert panel has recently recommended the selection of daptomycin or linezolid as a second- or even first-line treatment for serious MRSA infection . Considering that the crucial points for the treatment of a patient with severe infection are prompt resuscitation management, adequate source control, and proper antibiotic therapy, the way we selected the antibiotic could be criticized as inappropriate in this case. Second, the operative procedure, anatomic segment 8 resection, took too long, which might have burdened some unnecessary stress on the patient. Yet, we would still like to emphasize that the conversion to surgical removal without delay seems crucial in a case with a complicated severe abscess as in the present patient.