Laboratory Diagnostics of Hypervirulent Klebsiella pneumoniae: From Virulence Biomarkers to Integrated Clinical Workflows

Hypervirulent Klebsiella pneumoniae (hvKP) causes invasive and metastatic infections and is increasingly acquiring carbapenem resistance. However, its laboratory identification remains challenging because hypermucoviscosity is an imperfect surrogate for hypervirulence, and no universally accepted diagnostic definition exists. This narrative review critically examines the diagnostic relevance of major virulence determinants, including iucA, iroB, peg-344, rmpA, and rmpA2, in relation to the epidemiologically active lineages that carry them, and compares phenotypic assays, targeted molecular detection, whole-genome sequencing, and emerging analytical technologies, reporting performance estimates together with their evidence base. Particular attention is given to the convergence of hypervirulence and antimicrobial resistance, the frequent discordance between genotype, phenotype and clinical outcome, and the host-dependent variability of clinical expression. We propose a tiered laboratory framework that begins with isolation and identification of K. pneumoniae and that integrates a dedicated antimicrobial-resistance tier with targeted virulence-marker detection and genome-based characterization according to clinical need and laboratory capacity; isolates positive for both resistance and hypervirulence determinants are prioritized for confirmatory genomic characterization. Requirements for analytical validation, quality control, cost and feasibility across laboratory tiers, and the infection prevention and control response triggered by a positive result are also addressed. Standardized diagnostic criteria, externally validated assays, integrated reporting that incorporates host factors, and coordinated genomic surveillance are essential to improving the recognition and management of hvKP and its carbapenem-resistant variants.