Diversity of hypervirulent Klebsiella pneumoniae clones causing cryptogenic liver abscesses and metastatic complications in Argentina

Abstract

Cryptogenic liver abscesses (CLA) caused by hypervirulent Klebsiella pneumoniae (hvKP) strains are emerging in Western countries. The aim of the study was to describe the clinical characteristics of patients from Argentina with hvKP-related CLA as well as the molecular analysis of isolated strains. A retrospective chart review of 15 patients hospitalized in 8 hospitals of Argentina between October 2015 and November 2018 was performed. PCR assays for genes associated with capsular and multilocus sequence typing (MLST) determination and virulence factors were conducted in 8 hvKP isolates from these patients. We found that the mean age of patients was 60 years, 73% of them were men and 40% suffered from diabetes. Bacteremia was detected in 60% of them and 73% had ≥1 metastatic foci of infection. There were no in-hospital deaths, but two patients with endophthalmitis required eye enucleation. Of the 8 studied isolates, 4 belonged to K1 and 4 to K2 serotypes, with the rpmA and iroB genes being present in all of them, and isolates 7 and 5 also harboring the iucA and the rmpA2 genes, respectively. MSLT analysis showed that most of the K1 serotypes belonged to ST23 while a diverse MLST pattern was observed among the K2 strains. In addition, the four hvKP strains associated with metastatic complications and belonging to three distinct sequence types, exhibited the rpmA, iroB and iuc virulence genes. We were able to demonstrate important morbidity associated with this syndrome, a significant diversity in the hvKP clones causing CLA in Argentina, and the potential utility of the rpmA and iroB genes as predictors of virulence.

Keywords: Absceso hepático criptogénico; Cryptogenic liver abscess; Hipermucoviscosidad; Hipervirulencia; Hypermucoviscous; Hypervirulence; Klebsiella pneumoniae.