Abstract
BackgroundThe molecular characterization of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) isolates is not well studied. Our goal was to investigate the molecular epidemiology of CR-hvKP strains that were isolated from a Chinese hospital.ResultsAll clinical carbapenem-resistant K. pneumoniae (CR-KP) isolates were collected and identified from patient samples between 2014 and 2017 from a Chinese hospital. The samples were subjected to screening for CR-hvKP by string test and the detection of the aerobactin gene. CR-hvKP isolates were further confirmed through neutrophil phagocytosis and a mice lethality assay. The CR-hvKP isolates were investigated for their capsular genotyping, virulence gene profiles, and the expression of carbapenemase genes by PCR and DNA sequencing. Multilocus sequence type (MLST) and pulsed-field gel electrophoresis (PFGE) were performed to exclude the homology of these isolates. Twenty strains were identified as CR-hvKP. These strains were resistant to imipenem and several other antibiotics, however, most were susceptible to amikacin. Notably, two isolates were not susceptible to tigecycline. Capsular polysaccharide synthesis genotyping revealed that 17 of the 20 CR-hvKP strains belonged to the K2 serotype, while the others belonged to serotypes other than K1, K2, K5, K20, and K57. The strains were found to be positive for 10 types of virulence genes and a variety of these genes coexisted in the same strain. Two carbapenemase genes were identified: blaKPC-2 (13/20) and blaNDM-1 (1/20). PFGE typing revealed eight clusters comprising isolates that belonged to MLST types ST25, ST11 and ST375, respectively. PFGE cluster A was identified as the main cluster, which included 11 isolates that belong to ST25 and mainly from ICU department.ConclusionsOur findings suggest that hospital-acquired infections may contribute in part to the CR-hvKP strains identified in this study. It also suggests that ST25 CR-hvKP strain has a clonal distribution in our hospital. Therefore, effective surveillance and strict infection control strategies should be implemented to prevent outbreak by CR-hvKP strains in hospitals setting.
Highlights
The molecular characterization of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-Hypervirulent Klebsiella pneumoniae (hvKP)) isolates is not well studied
Several studies have shown that Klebsiella pneumoniae carbapenemase (KPC)-like genes have the potential for dissemination among hvKP isolates [8, 9]
We found that 2 Modified carbapenem inactivation method (mCIM)-negative carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) strains were positive for the blaKPC-2 gene
Summary
The molecular characterization of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) isolates is not well studied. Hypervirulent Klebsiella pneumoniae (hvKP) is a variant of K. pneumoniae, and was first reported in Taiwan in 1986 [1]. The resistance of hvKP to commonly used antimicrobial agents has rarely been reported, except for an intrinsic resistance to ampicillin [3]. Carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) isolates have been described in some case reports [6,7,8,9]. Several studies have shown that Klebsiella pneumoniae carbapenemase (KPC)-like genes have the potential for dissemination among hvKP isolates [8, 9]. Carbapenem-resistant K. pneumoniae (CR-KP) isolates have the potential to be converted into CR-hvKP through the acquisition of virulence related plasmids, such as pLVPK [9, 10]. The confluence of multidrug resistance and enhanced virulence may cause serious outbreaks and public-health problems
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