Serratia Causing Liver Abscess in a Young Immunocompetent Female: A Rare Case With Literature Review

Pyogenic liver abscess (PLA) is a life-threatening condition predominantly caused by enteric Gram-negative bacilli in patients with diabetes, hepatobiliary disease, or immunosuppression. Serratia marcescens is a well-known opportunistic pathogen, typically causing nosocomial infections in compromised hosts. Community-acquired PLA due to S. marcescens in healthy individuals is exceedingly rare.

A 28-year-old immunocompetent postpartum female presented with a 40-day history of low-grade fever following a cesarean section, accompanied by fatigue, lower abdominal discomfort, and recent right upper quadrant pain. Initial laboratory investigations revealed marked leukocytosis, microcytic anemia, thrombocytosis, and elevated C-reactive protein (318.76 mg/L). Abdominal computed tomography (CT) demonstrated an 8.5 × 5.8 cm multiloculated hypodense hepatic abscess in segment IV. CT-guided needle aspiration yielded purulent material; pus cultures selectively grew S. marcescens. Concurrently, extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Enterococcus faecalis were isolated from urine, while Staphylococcus haemolyticus grew in a single blood culture bottle. Target antimicrobial therapy was adjusted to intravenous meropenem, leading to rapid clinical and inflammatory marker improvement. Because the patient demonstrated prompt clinical stabilization following diagnostic aspiration, percutaneous catheter placement was deferred by a multidisciplinary team. She completed a course of IV meropenem followed by 4 weeks of oral trimethoprim-sulfamethoxazole. Follow-up ultrasound at 1 month confirmed clinical resolution and regression of the abscess cavity to 1.0 cm.

S. marcescens should be considered in the differential diagnosis of PLA, even in immunocompetent individuals presenting with prolonged fever of unknown origin. Early cross-sectional imaging, microbiological aspiration, and multidisciplinary care are essential for prompt resolution without invasive surgical drainage.