A Case Series of Hypermucoid Klebsiella pneumoniae Liver Abscess in Caucasian Americans Without Travel History: An Epidemiologic Shift?

Hypervirulent Klebsiella pneumoniae (hvKp) is an emerging cause of community-acquired pyogenic liver abscess (PLA), classically described in East and Southeast Asia. We report two cases of hvKp-associated PLA in Caucasian women of American origin with no history of international travel, animal exposure, or Asian food consumption. Both patients presented with fever and right upper quadrant abdominal pain and were found to have solitary hepatic abscesses on imaging. Blood and abscess cultures confirmed K. pneumoniae with a positive string test (> 5 mm), K2 capsular serotype, and rmpA gene, establishing the hypermucoid phenotype. While one patient had diabetes mellitus, the other had no major underlying health condition apart from the bacterial infection reported here. Both patients were successfully treated with intravenous antimicrobial therapy, initially broad-spectrum and subsequently de-escalated based on susceptibility results, in combination with image-guided percutaneous drainage. Neither patient developed metastatic complications. These cases suggest a broader geographic and demographic distribution of hvKp-associated PLA than previously recognized. The string test served as an early diagnostic clue, facilitating timely intervention. Given the potential for rapid clinical progression, early recognition and aggressive management, including antimicrobial therapy and source control, remain essential to reducing morbidity associated with hvKp PLA.