Case report: Invasive Klebsiella pneumoniae liver abscess syndrome.

Invasive Klebsiella pneumoniae liver abscess syndrome (IKLAS) is a severe condition characterized by liver abscesses with systemic complications, often caused by hypervirulent strains. We present a 65-year-old woman with no predisposing factors who developed IKLAS complicated by septic pulmonary embolism and polymicrobial co-infections. The patient presented with a one-month history of right upper abdominal pain, fever (39.5°C), and respiratory distress. Initial laboratory findings revealed leukocytosis (WBC 15.97 G/L), elevated inflammatory markers (CRP 83.04 mg/dL, PCT 96.9 ng/mL), and hepatic dysfunction (ALT 361.7 U/L, AST 573.9 U/L). Imaging identified a massive liver abscess (153.7 × 112.6 mm) and septic pulmonary emboli. Blood and pus cultures confirmed Klebsiella pneumoniae (susceptible to imipenem/cefoperazone-sulbactam), prompting targeted therapy. Despite initial drainage and antibiotics, her condition deteriorated due to secondary hospital-acquired infections with Acinetobacter baumannii-calcoaceticus complex and Pichia ommerica, necessitating escalation to meropenem and voriconazole. This adjustment led to clinical resolution, with abscess reduction to 74.0 × 46.0 mm on follow-up imaging and normalization of laboratory parameters. The patient was discharged after completing antimicrobial therapy. This case underscores three critical lessons: IKLAS requires high suspicion in atypical presentations (e.g., isolated abdominal pain), as delays risk metastatic complications; polymicrobial infections may emerge secondary to invasive procedures, necessitating repeated microbiological evaluation; and large abscesses (>100 mm) often demand prolonged, tailored therapy and multidisciplinary management. Our findings highlight the importance of early imaging, comprehensive pathogen identification, and adaptive treatment strategies to improve outcomes in this complex syndrome.