Polymicrobial Pyogenic Liver Abscess Without Classical Risk Factors: A Case Report of Streptococcus constellatus and Fusobacterium nucleatum Infection

Pyogenic liver abscesses are uncommon, often polymicrobial, and can be fatal if left untreated, with a mortality rate of 5-15%. Established risk factors include diabetes mellitus, hepatobiliary disease, malignancy, recent abdominal surgery, and immunosuppression. This case report describes a 69-year-old female who developed a large hepatic abscess despite lacking traditional predisposing risk factors. The patient is a 69-year-old female, generally healthy with only a history of osteopenia and hyperlipidemia, who presented with progressive fevers, chills, fatigue, myalgias, nasal congestion, minimally productive cough, decreased appetite, and a single episode of non-bloody, non-bilious vomiting. She had no abdominal pain but endorsed nausea and significant anorexia. Her laboratory evaluation revealed leukocytosis and elevated transaminases, coupled with a persistent fever, nausea, and anorexia, prompting a contrast-enhanced computed tomography (CT) of the abdomen and pelvis. The scan identified a hepatic abscess in the right hepatic lobe measuring 6.1 x 8.1 x 8.9 cm (volume = 439.75 cm³). The abscess was drained by interventional radiology, and cultures from the aspirate ultimately grew Streptococcus constellatus and Fusobacterium nucleatum; a percutaneous drain was left in place. After confirming penicillin tolerance, the patient was transitioned to oral amoxicillin-clavulanate for outpatient management. Follow-up CT imaging at two weeks showed marked improvement, enabling drain removal. Complete resolution was confirmed on ultrasound at two months. This case highlights the importance of maintaining a broad differential diagnosis and utilizing early laboratory tests and CT imaging when systemic signs of infection are present, even in the absence of traditional risk factors for a hepatic abscess. The patient's vague gastrointestinal symptoms of anorexia and nausea, along with the absence of focal abdominal pain or jaundice, reinforce the subtle clinical manifestation in this case. A thorough approach to identifying the cause of fever in the setting of gastrointestinal symptoms is crucial for making the challenging diagnosis of hepatic abscesses. Early detection through timely laboratory studies and imaging, combined with appropriate antimicrobial and procedural interventions, was imperative for achieving a favorable outcome in this patient. As pyogenic liver abscesses continue to be reported in patients without classical risk profiles, clinicians must remain vigilant in pursuing definitive diagnosis and management strategies in similar atypical clinical scenarios.