Determination of the prevalence of hypervirulent Klebsiella pneumoniae strains in Northeast Iran, Mashhad.

Hypervirulent Klebsiella pneumoniae (hvKp) has emerged as a clinically significant pathogen that can cause severe infections, even in immunocompetent hosts. Unlike classical K. pneumoniae (cKp), hvKp exhibits enhanced virulence characterized by hypermucoviscosity and the presence of key genetic determinants. Its increasing detection in hospital settings, particularly in intensive care units (ICUs), raises concerns regarding nosocomial transmission and antibiotic resistance. A total of 187 K. pneumoniae isolates from patients at the Imam Reza Hospital, Mashhad, Iran, were screened phenotypically and genotypically. The hypermucoviscous phenotype was assessed using the string test and PCR was used to detect virulence genes (rmpA, rmpA2, and iucA). Antimicrobial susceptibility testing and extended-spectrum β-lactamase (ESBL) detection were conducted, and statistical analyses were performed to compare the hvKp and cKp isolates. hvKp accounted for 9.63% of all isolates. These strains were significantly associated with the presence of rmpA, rmpA2, and iucA genes. Although no statistically significant differences in antimicrobial resistance were observed between hvKp and cKp, the hvKp strains exhibited relatively lower resistance rates. A slightly higher but non-significant ESBL production rate was noted among the hvKp isolates. Diabetes and renal failure emerged as significant risk factors for hvKp infection, whereas age showed no such association. The detection of hvKp in ICU settings, coupled with its virulence potential and relative antibiotic susceptibility, underscores the urgent need for enhanced surveillance, infection control, and targeted antimicrobial stewardship. Future research should focus on the genomic evolution of hvKp and its interplay with host factors to develop effective prevention and treatment strategies.