Clinical Microbiology and Antimicrobial Chemotherapy. 2025; 27(3):342-358
To study genetic determinants of resistance and virulence of K. pneumoniae strains received by the reference center for the prevention of the spread of biological threats of the National Medical Research Center for Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of Ministry of Healthcare of Russian Federation.
The study included 153 strains of Klebsiella pneumoniae isolated from the biological material of pregnant women and newborns in Perinatal centers in various regions of the Russian Federation with infectious and inflammatory diseases and included in the collection of opportunistic microorganisms of the reference center in 2023. For all strains, minimum inhibitory concentrations (MIC) to the main antimicrobials were determined by broth microdilution tests and whole-genome data were obtained using high-throughput sequencing technology. Bioinformatic analysis of whole-genome data, including genome assembly, multilocus sequence typing (MLST), strain typing by capsule and lipopolysaccharide loci, detection of the resistance and virulence genes, was performed. Strains with five (iucA, rmpA2, rmpA, peg344, terB) and more virulence genes combined in their genome were conditionally classified as hypervirulent. The hypermucoid phenotype in hypervirulent strains was detected using a string test.
All 153 strains of K. pneumoniae were searched for virulence genes. Virulence genes associated with the hypervirulent phenotype were not detected in 30 strains (19.6%) of K. pneumoniae. In 18 strains (11.8%), five or more virulence genes were combined in the genome, they were classified as hypervirulent. The remaining strains had a number of virulence genes ranging from 1 to 4. Sequence types of strains with different combinations of virulence genes were determined. For hypervirulent strains of K. pneumoniae capsule typing was performed, the spectrum of resistance to the main antimicrobials was determined, resistance genes of ten different groups were identified, and hypermucoid phenotype was detected in five strains.
The detection of multidrug-resistant hypervirulent K. pneumoniae strains in patients of Perinatal Centers, most of which belong to clones of high epidemic risk, indicates an increasing biological threat associated primarily with the horizontal transfer of plasmids with determinants of resistance and virulence, which makes it difficult to treat diseases caused by such bacteria.