Bacteroides fragilis Empyema Secondary to Ruptured Pyogenic Liver Abscess: A Rare Cause of Septic Shock

Abstract

Pyogenic liver abscess is an uncommon but potentially life-threatening intra-abdominal infection associated with significant morbidity and mortality. Although hepatic abscesses most commonly present with systemic infection or intra-abdominal complications, transdiaphragmatic spread into the pleural cavity resulting in empyema is rare. Bacteroides fragilis, an anaerobic gram-negative bacillus that forms part of the normal gastrointestinal flora, is a well-recognized pathogen in polymicrobial intra-abdominal infections but is infrequently reported as a primary pathogen in empyema originating from hepatic sources. We present the case of a 59-year-old man with uncontrolled hypertension, type 2 diabetes mellitus, and alcohol use disorder who presented with acute right-sided chest pain radiating to the back accompanied by dyspnea, fever, nausea, and malaise. On presentation, he was febrile, hypotensive, and tachypneic. Computed tomography (CT) imaging obtained to evaluate possible aortic pathology revealed a mild ascending thoracic aortic aneurysm measuring 4.1 cm without evidence of dissection, as well as a large fluid collection measuring 9.05 × 4.37 cm posterior to the right hepatic lobe concerning for a ruptured hepatic abscess and a moderate right-sided pleural effusion. Abdominal ultrasound confirmed a 9.6 cm hepatic abscess. The patient underwent interventional radiology-guided percutaneous drainage of the hepatic abscess and thoracentesis. Pleural fluid cultures grew Bacteroides fragilis and Staphylococcus warneri, while culture of the hepatic abscess also yielded Bacteroides fragilis, supporting transdiaphragmatic spread of infection from the ruptured hepatic abscess. Despite initial management with broad-spectrum intravenous antibiotics, persistent loculated pleural infection required video-assisted thoracoscopic surgery (VATS) with decortication. The patient subsequently improved clinically and was discharged on oral antibiotics to complete therapy. This case highlights the importance of early recognition of intra-abdominal sources in patients presenting with empyema and underscores the critical role of prompt diagnostic imaging, targeted antimicrobial therapy, and multidisciplinary source control, including percutaneous drainage and surgical intervention, in achieving favorable clinical outcomes and preventing disease progression.