Klebsiella pneumoniae, a Gram-negative bacterium, comprises strains with diverse virulence potentials, ranging from classical to hypervirulent variants. Understanding the genetic basis underlying the virulence disparities between hypervirulent (hvKp) and classical K. pneumoniae (cKp) strains is crucial. hvKp strains are characterized by hypermucoviscosity, attributed to the presence of specific virulence genes and the production of molecules that aid in their ability to survive, evade host immune defenses, and cause infection. In contrast, classical strains exhibit a broader array of antimicrobial resistance determinants, conferring resistance to multiple antibiotics. Although current definitions of hvKp incorporate clinical features, phenotypes, and genotypes, identifying hvKp strains in clinical settings remains challenging. Genomic studies have been pivotal and have helped to identify distinct genetic profiles in hvKp strains, including unique virulence plasmids and chromosomal variations, underscoring the genetic diversity within K. pneumoniae populations. This review examines the virulence and genetic determinants associated with hvKp. The presence of genes defining hypervirulence, alongside considerations of their utility as biomarkers and targets for therapeutic strategies, is discussed, while also providing insight into biofilm formation by hvKp and key questions that need urgent responses in understanding hvKp.

Department of Agriculture Faculty of Agriculture University of Ilorin Ilorin Nigeria

Department of Microbiology College of Natural Sciences Federal University of Agriculture Abeokuta 111101 Nigeria

Department of Microbiology Faculty of Biological Sciences University of Nigeria Nsukka Enugu 410001 Nigeria

Department of Pharmaceutical Microbiology Faculty of Pharmacy University of Ibadan Ibadan 200005 Nigeria

Department of Physiology Faculty of Basic Medical Sciences Osun State University Osogbo Nigeria

Department of Public Health Faculty of Basic Medical and Health Sciences Lead City University Ibadan 200255 Nigeria

Medical Institute Sumy State University Sumy 40007 Ukraine

Western Kentucky University Bowling Green USA

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