Clinical and molecular characteristics of multi-clone carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae isolates in a tertiary hospital in Beijing, China

Summary Objectives To provide the clinical and molecular characteristics of carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae (cr-hvKP) in a tertiary hospital in Beijing, China. Methods The clinical characteristics of four patients with cr-hvKP isolates and 29 patients with carbapenem-resistant classic K. pneumoniae (cr-cKP) infections were analyzed retrospectively. The molecular characteristics of cr-hvKP and cr-cKP isolates were compared. Results The KPC-2 gene was detected in all cr-hvKPs except for cr-hvKP6. The cr-hvKPs belonged to three sequence types (STs; ST25, ST65, and ST11), with three pulsed-field gel electrophoresis patterns (I, II, and III) and two capsular serotypes (K2 and non-typeable). Although cr-hvKP1–7 did not cause invasive clinical syndromes such as community-acquired liver abscess with or without extrahepatic complications, they were all nosocomially acquired; cr-hvKP1–5 were clones disseminated between patients A and B. Compared with cr-cKPs, pLVPK-related loci, rep A, iro N, and K2 capsular serotype were more prevalent in cr-hvKPs, although no significant difference was found in clinical characteristics between patients with cr-hvKP and cr-cKP infection. Conclusions The hypervirulent ST65 and ST25 K. pneumoniae , along with carbapenem-resistant clonal populations ST11, appear to have evolved into cr-hvKP strains. The evidence of bi-directional evolution and emergence of hospital-acquired multi-clone cr-hvKP indicates a confluence of virulence and carbapenem resistance, which might pose major problems in the management of K. pneumoniae infection.