Comparative analysis of <i>Klebsiella pneumoniae</i> strains isolated in 2012–2016 that differ by antibiotic resistance genes and virulence genes profiles

The antibacterial resistance and virulence genotypes and phenotypes of 148 non-duplicate Klebsiella pneumoniae strains collected from 112 patients in Moscow hospitals in 2012-2016 including isolates from the respiratory system (57%), urine (30%), wounds (5%), cerebrospinal fluid (4%), blood (3%), and rectal swab (1%) were determined. The majority (98%) were multidrug resistant (MDR) strains carrying bla_SHV (91%), bla_CTX-M (74%), bla_TEM (51%), bla_OXA (38%), and bla_NDM (1%) beta-lactamase genes, class 1 integrons (38%), and the porin protein gene ompK36 (96%). The beta-lactamase genes bla_TEM-1, bla_SHV-1, bla_SHV-11, bla_SHV-110, bla_SHV-190, bla_CTX-M-15, bla_CTX-M-3, bla_CTX-M-55, bla_OXA-48, bla_OXA-244, and bla_NDM-1 were detected; class 1 integron gene cassette arrays (aadA1), (dfrA7), (dfrA1-orfC), (aadB-aadA1), (dfrA17-aadA5), and (dfrA12-orfF-aadA2) were identified. Twenty-two (15%) of clinical K. pneumoniae strains had hypermucoviscous (HV) phenotype defined as string test positive. The rmpA gene associated with HV phenotype was detected in 24% of strains. The intrapersonal mutation of rmpA gene (deletion of one nucleotide at the polyG tract) was a reason for negative hypermucoviscosity phenotype and low virulence of rmpA-positive K. pneumoniae strain KPB584. Eighteen virulent for mice strains with LD₅₀ ≤ 10⁴ CFU were attributed to sequence types ST23, ST86, ST218, ST65, ST2174, and ST2280 and to capsular types K1, K2, and K57. This study is the first report about hypervirulent K. pneumoniae strain KPB2580-14 of ST23^K1 harboring extended-spectrum beta-lactamase CTX-M-15 and carbapenemase OXA-48 genes located on pCTX-M-15-like and pOXA-48-like plasmids correspondingly.