Giant Pyogenic Liver Abscess Caused by Enterobacter cloacae complex

We present the clinical case of a 75-year-old woman with no significant past medical history who presented to the emergency department with a 3-month history of abdominal distension, early satiety, and unexplained weight loss. The patient denied having fever or recent travel to endemic regions. Owing to hemodynamic instability at admission, the patient was promptly evaluated in the emergency room. Physical examination revealed a markedly distended abdomen. Point-of-care abdominal ultrasound identified a suspicious cystic mass. Following stabilization, an abdominal computed tomography (CT) scan was performed, revealing a large cystic lesion in the left hepatic lobe measuring 21.6x24.7x15.2cm, causing a mass effect on the pancreas and stomach, with associated peritoneal effusion shown in Figure 1. Paracentesis revealed a high polymorphonuclear cell count (95%), suggestive of secondary peritonitis. Laboratory tests showed elevated inflammatory markers (CRP 400 mg/L) and acute kidney injury. A diagnosis of sepsis secondary to a pyogenic liver abscess with secondary peritonitis and multiorgan dysfunction was made, prompting initiation of empiric antibiotic therapy with piperacillin-tazobactam. Percutaneous drainage of the liver abscess was performed, yielding 3800cc of brown purulent fluid, and an abdominal drain was placed. Due to multiorgan failure, the patient was transferred to the intensive care unit (ICU). During hospitalization, microbiological analysis of the pus isolated Enterobacter cloacae complex, with the adjustment in antibiotic therapy to meropenem, targeted the identified pathogen. The patient showed favorable clinical and laboratory improvement under the instituted antibiotic regimen. ICU stay was prolonged due to respiratory insufficiency associated with pulmonary atelectasis, resulting from the abdominal cyst compressive effect. A follow-up CT scan two weeks after drainage demonstrated a reduction in the hepatic cyst to 14.2x5.5x2cm, with residual content drained via the abdominal catheter. A magnetic resonance cholangiopancreatography (MRCP) performed during hospitalization showed no evidence of underlying hepatobiliary pathology. The patient was discharged after a one-month hospital stay with targeted antibiotic coverage. At a 6-month outpatient follow-up, imaging demonstrated a marked reduction in the size of the lesion shown in Figure 2. Hepatic abscesses are relatively rare but potentially life-threatening. They typically present with a triad of fever, right upper quadrant pain or masses, and jaundice. Infection may result from hematogenous spread, contiguous extension, biliary tract disease, or trauma. [1] The most common causative organisms include Streptococcus species and Escherichia coli, followed by Staphylococcus and Klebsiella species. [2] Enterobacter cloacae complex is a facultative anaerobic bacterium and an uncommon pathogen in pyogenic liver abscesses without predisposing factors such as hepatobiliary-pancreatic disease or malignancy. [3] In this case, etiological investigation with CT and MRCP revealed no evidence of malignancy or underlying hepatobiliary disease, supporting the diagnosis of a spontaneous liver abscess. To our knowledge, only one previous case of spontaneous pyogenic liver abscess caused by Enterobacter cloacae complex has been reported, involving lesions of significantly smaller dimensions. [3] Thus, this clinical case is notable for the striking size of the liver abscess and the identification of an unusual etiological agent in the absence of known risk factors such as diabetes or chronic kidney disease.