Klebsiella pneumoniae liver abscesses: pathogenesis, treatment, and ongoing challenges

Over the past 30 years, a distinct pathotype of hypervirulent Klebsiella pneumoniae (hvKp) has emerged, characterized by its ability to cause severe tissue-invasive infections, including liver abscesses in otherwise healthy individuals. Klebsiella liver abscesses (KLA) are most prevalent in East and Southeast Asia; however, their global incidence is rising, with hvKp now recognized as an important pathogen in Europe and the United States. While K. pneumoniae often colonizes the gut asymptomatically, KLAs develop when hvKp disseminates from the gut to the liver via the portal vein. Strains expressing K1 and K2 capsule types demonstrate the highest resistance to clearance by Kupffer cells, the liver resident macrophages, and are responsible for most KLA cases. KLAs present as fibrously encapsulated lesions composed of bacteria, pus, and immune cells. Treatment typically involves a combination of abscess drainage and antibiotic therapy; however, clinical outcomes are often poor, even in the absence of antibiotic resistance. This is due, in part, to significant barriers to achieving effective antibiotic efficacy within abscesses that can result in devastating complications such as metastatic infection, liver resection, or death. The emergence of KLA caused by multidrug-resistant hvKp strains, although still rare, represents an additional and alarming therapeutic challenge. This review explores the pathogenesis of KLA and highlights critical obstacles to effective management and therapy.