Sammendrag
Community-acquired Klebsiella pneumoniae primary liver abscess (KLA) has been emerging worldwide over the past 2 decades and with high incidence in Asia. A specific syndrome with septicemia and metastatic spread to eyes, meninges or brain may occur and is associated with highly virulent strains of K. pneumoniae. In recent years, cases from Argentina, South Africa, Belgium, Spain, France, Ireland and Sweden have been reported, indicating a global dissemination of these strains causing invasive liver abscess in both Asian and non-Asian patients. We report the first 3 cases of KLA in Norway, all of whom were presented to a single institution during the period 2008-2011. Two of the patients were of West African descent from where KLA has not yet been reported, and 1 was diabetic. Virulence characterization revealed that all 3 isolates were of capsular serotype K1 and expressed the hypermucoviscous phenotype as shown by the formation of mucoviscous strings when a loop was passed through a colony. Furthermore, all isolates were positive for the virulence genes rmpA, aerobactin, kfu and allS as revealed by polymerase chain reaction using specific primers. Multilocus sequence typing (MLST) revealed that all strains belonged to sequence type (ST) 23. Our results conclude that the isolates exhibited similar characteristics as the highly virulent K. pneumoniae isolates associated with invasive infections in Asia, supporting the assumption that this is a globally emerging infectious disease.