Characteristics of ST11-K64 carbapenem-resistant hypervirulent Klebsiella pneumoniae in Central-South China

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-HvKP) poses an increasing global threat. However, studies on virulence characteristics of CR-HvKP are limited. In this study, we investigated the virulence characteristics of 49 CRKP and 50 strains of carbapenem-sensitive Klebsiella pneumoniae (CSKP) from a Chinese tertiary hospital. In the Galleria mellonella infection model, 10 CRKP and nine CSKP strains were hypervirulent (mortality > 50%). Biofilm assays showed that six CR-HvKP and six hypervirulent CSKP (CS-HvKP) exhibited moderate-to-strong biofilm formation. By PCR testing, 22 CRKP and 28 CSKP carried at least two hypervirulence genes ( rmpA, rmpA2, iucA, iroB, peg344 ) and eight CRKP had truncated rmpA2. Whole-genome sequencing identified bla KPC−2 as the dominant carbapenemase (85.7%) and sporadic bla NDM variants (two bla NDM−1 and one bla NDM−4 ). The 49 CRKP and nine CS-HvKP were divided into 17 sequence types (STs). Notably, all nine CR-HvKP belonged to the ST11-K64 clone, whereas three CS-HvKP were ST60-K5. Complete genome analysis of a representative CR-HvKP (A40) revealed a rare plasmid, pKpA40plas3 (194,337 bp), harboring iucABCD, iutA, rmpA, rmpA2 and peg344 . This study reveals CR-HvKP virulence characteristics in Central-South China, highlighting the predominant ST11-K64 clone and a rare virulence plasmid, and emphasizes the need for enhanced surveillance.