Hypervirulent Klebsiella pneumoniae ST23 causing pyogenic liver abscess and metastatic endogenous endophthalmitis in Europe: a case report

Abstract

Introduction and importance: Pyogenic liver abscess (PLA) has traditionally been considered prevalent in Asia. However, its incidence is increasing in Europe. Klebsiella pneumoniae (Kp) has emerged as the leading causative pathogen, and hypervirulent strains pose a higher risk of invasive disease and metastatic complications, such as endogenous endophthalmitis (EE). Case presentation: The case describes a 77-year-old woman who presented with fever and right upper quadrant abdominal pain. She was diagnosed with a second episode of PLA within 3 months, caused by Kp. Despite prompt antimicrobial therapy and percutaneous transhepatic drainage, the patient developed acute vision loss in the left eye during hospitalization. Ophthalmologic assessment confirmed EE secondary to bacteremia. Whole-genome sequencing identified the isolate as hypervirulent Kp (hvKp) sequence type 23 (ST23). While the liver abscess resolved following treatment, the patient sustained permanent loss of vision in the affected eye despite aggressive medical and surgical management. Clinical discussion: This case illustrates the invasive nature of hvKp and its potential for recurrence and metastatic complications. Improved recognition through targeted virulence testing is essential to avoid underdiagnosis. Conclusion: This case highlights the aggressive nature of hvKp. Early recognition of systemic and ocular symptoms, prompt ophthalmologic evaluation, and timely source control are essential. Optimal management requires multidisciplinary collaboration and the use of molecular diagnostics, including whole-genome sequencing, to identify hypervirulent lineages and support surveillance.