Virulence and genomic features of hypervirulent Klebsiella pneumoniae species complex

Hypervirulent Klebsiella pneumoniae is a pathotype capable of causing invasive infections with high morbidity and mortality rates. In this study, we conducted a surveillance analysis of hypervirulent isolates circulating in Mexico to characterize their phenotypic and genomic features. Presumptive hypervirulent isolates were identified at a frequency of 6.48 % (19/293), comprising 17 K. pneumoniae sensu stricto and two K. quasipneumoniae subsp. similipneumoniae. Isolates were predominantly recovered from male patients (12/19, 63 %). Clinical samples were obtained from lower respiratory tract (15/19, 78.9 %), blood (3/19, 15.7 %), and pleural fluid (1/19, 5.2 %). Further genetic and phenotypic analyses revealed substantial heterogeneity among these strains, including significant phenotype-genotype discordance. Notably, this cohort includes the first identified convergent hypervirulent K. pneumoniae strain in Mexico, as well as two hypervirulent K. quasipneumoniae isolates, a phenomenon that is less frequent in K.quasipneumoniae than in K. pneumoniae. These discrepancies prompted us to propose a local classification scheme based on the presence of virulence-associated genes, lethality in mice and antimicrobial susceptibility. Phylogenetic and pangenome analysis revealed clustering patterns associated with sequence types and capsule serotypes. The data generated in this study contribute to a deeper understanding of Hypervirulent K. pneumoniae species complex biology and provide valuable insights into the diversity of strains currently circulating in Mexico.