Hypervirulent Klebsiella pneumoniae: An update on epidemiology, detection and antibiotic resistance.

Klebsiella pneumoniae is a major human pathogen as it is responsible for various infections. In the past years hypervirulent K. pneumoniae (hvKP) emerged and disseminated worldwide. In this review a summary will be given about epidemiology, detection and antibiotic resistance of hypervirulent K. pneumoniae. A common feature of hypervirulent K. pneumoniae is a combined expression of several virulence factors. A mucoviscosus phenotype, certain capsulare serotypes (e.g.: K1, K2, K28, K47, K63) together with additional genetic markers namely, magA, rmpA or iucABCD, are needed in combinations to achieve the hypervirulent pathotype. Plasmid coded virulence determinants are also detected, that indicates horizontal gene transfer of hypervirulence factors in K. pneumoniae.Interestingly, infections caused by hypervirulent K. pneumoniae occur usually in the community in otherwise healthy people, and during these infections multiple infection sites are detected. Clinical pictures include both invasive infections and local abscess formation. Pyogenic liver abscess is the most frequently reported clinical manifestation and abscess formation in brain, spleen and lung are also diagnosed. Additionally, meningitis, endophthalmitis, trombophlebitis, pneumonia can also develop.In the early reports, hypervirulent K. pneumoniae strains exhibited enhanced virulence but these were susceptible to commonly used antibiotics. However, recently KPC, VIM, NDM and OXA-48 carbapenemase producing hypervirulent K. pneumoniae strains are increasingly reported, furthermore, well-known high-risk K. pneumoniae clones (e.g.: ST11, ST147, ST307) can develop hypervirulent pathotype, that poses an even more alarming challenge.