S5580 Huge Liver Abscess Caused by Prevotella Species in an Immunocompetent Patient: A Rare Cause

Introduction: Liver abscess is a rare infectious disease that is caused by microbes invading the liver parenchyma, mainly from the biliary tree or the bloodstream. In developed countries, the most common causes are bacterial, with Klebsiella pneumoniae and Escherichia coli being the most common. Here we describe a case of a huge liver abscess measuring up to 30 cm in an immunocompetent young patient, that was caused by Prevotella species. Case Description/Methods: A 29-year-old man presented to our hospital complaining of vague abdominal pain. He reported an abdominal pain, mainly in the right upper quadrant and right lower quadrant that started 2 weeks before his presentation, he described the pain as dull and aching, and that is progressively getting worse, he denied systemic symptoms like fever, weight loss or loss of appetite. Due to the increasing severity, he decided to come to the hospital. In the emergency department, his vitals were within normal limits, and examination showed abdominal fullness with mild diffuse tenderness, his labs were all normal including a complete blood count and liver function. He underwent a Computed tomography scan of the abdomen and pelvis, which showed subcapsular liver abscess measuring 15.6 × 6 × 30 cm, with a second pelvic abscess measuring 16.8 × 13 × 10.8 cm in size. He was started on empiric antibiotics and admitted to the hospital. Interventional radiology (IR) was consulted and drained both abscesses, with 1600 ml of purulent discharge drained. Cultures from the abscesses grew Prevotella species. Blood cultures remained with no growth, and patient continued to improve. All other Infectious workup, including HIV, was negative. Repeat CT scan showed resolution of the abscess. He was discharged on oral augmentin. Discussion: This case describes a rare occurrence of large liver and pelvic abscesses caused by Prevotella species in an otherwise healthy 29-year-old man. Prevotella is an anaerobic bacterium typically found in the oral and gastrointestinal tracts, and is more commonly associated with dental or pelvic infections. Its role in deep-seated abscesses is uncommon, especially without an identifiable source or systemic symptoms. The patient responded well to abscess drainage and antibiotic therapy with Augmentin. This case highlights the need to consider anaerobic organisms like Prevotella in cryptogenic abscesses and supports the effectiveness of combined interventional and medical management.