Case Presentation: An 18-year-old female with type 1 diabetes (HbA1c 8%) on omalizumab therapy for severe allergic asthma presented with five weeks of fluctuating fevers, malaise, myalgias, and five days of right shoulder and chest pain. CT imaging revealed a large right lobe hepatic lesion (11.3 × 7.8 × 11.4 cm) with central fluid and surrounding edema consistent with a hepatic abscess. Percutaneous drainage yielded Fusobacterium necrophorum (4+); blood cultures were negative. Despite drainage and intravenous ampicillin-sulbactam, alkaline phosphatase (ALP) rose from 187 to greater than 600 U/L over the next five days. Repeat imaging on hospital day 6 demonstrated only partial abscess involution with new perihepatic fluid. The drain was subsequently removed on day 8 of hospital admission, and she transitioned to oral amoxicillin-clavulanate, maintaining targeted anaerobic coverage. Outpatient follow-up demonstrated continued cavity involution (4.2 × 3.6 × 3.9 cm), declining ALP (384 U/L), and complete symptom resolution.
Discussion: Fusobacterium necrophorum is a rare cause of pyogenic liver abscesses (PLAs), particularly in young adults without biliary disease or an identifiable seeding event. The patient’s only identifiable risk factor was newly diagnosed type 1 diabetes mellitus—possibly contributing to subtle immune dysregulation and highlighting a potentially underrecognized susceptibility. Culture-directed therapy with intravenous ampicillin-sulbactam followed by oral amoxicillin-clavulanate provided prolonged and targeted anaerobic coverage. Thoughtful drain management and serial imaging were both pivotal in guiding therapy, preventing premature removal, and ensuring safe outpatient follow-up despite the severity of disease and presence of a residual cavity. This case is novel not only because of the rarity of a drainage-refractory Fusobacterium necrophorum hepatic abscess presentation in a young adult patient, but also because it demonstrates that even severe PLAs without an antecedent seeding event can resolve fully with appropriate oral antibiotics in the setting of incomplete evacuation due to drain complications. Hospitalists should maintain a high index of suspicion for unusual anaerobes in young adults presenting with a PLA, severe pain, and cholestatic enzyme patterns.
Conclusions: PLAs typically arise from biliary disease, intra-abdominal infection, or hematogenous spread, but they are rare and often cryptogenic in young adults. Fusobacterium necrophorum, an anaerobic gram-negative bacillus, is classically associated with Lemierre’s syndrome and an exceedingly uncommon hepatic pathogen. Recognition is critical, as idiopathic anaerobic PLAs may manifest with disproportionate pain, cholestatic enzyme elevations, and a suboptimal response to standard drainage. We describe a large F. necrophorum PLA, complicated by drain-related adverse effects, in an 18-year-old female with newly diagnosed type 1 diabetes mellitus to highlight the difficulties in identifying and treating a rare anaerobic pathogen.