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The presence and dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) often cause life-threatening infections worldwide, but the therapeutic option is limited. In this study, whole-genome sequencing (WGS) was applied to assess the epidemiological characteristics and transmission dynamics of CRKP isolates recovered from two fetal outbreaks of nosocomial infections. Between April 2016 and March 2018, a total of 70 isolates of K. pneumoniae were collected from sterile samples in a tertiary hospital in Hangzhou, China. The minimal inhibitory concentrations (MICs) of 21 antimicrobial agents were determined using the broth microdilution methods. Pulsed-field gel electrophoresis (PFGE) was performed on 47 CRKP isolates, and 16 clonally related isolates were further characterized by Illumina sequencing. In addition, the complete genome sequences of three representative isolates (KP12, KP36, and KP37) were determined by Oxford Nanopore sequencing. The K. pneumoniae isolates were recovered from patients diagnosed with pulmonary infection, cancer, or encephalopathy. For all CRKP isolates, PFGE separated three clusters among all strains. The most predominant PFGE cluster contained 16 isolates collected from patients who shared close hospital units and represented a potential outbreak. All 16 isolates showed an extremely high resistance level (≥87.5%) to 18 antimicrobials tested but remain susceptible to colistin (CST). Multiple antimicrobial resistance and virulence determinants, such as the carbapenem resistance gene bla KPC-2, and genes encoding the virulence factor aerobactin and the regulator of the mucoid phenotype (rmpA and rmpA2), were observed in the 16 CRKP isolates. These isolates belonged to sequence type 11 (ST11) and capsular serotype KL64. A core genome single nucleotide polymorphism (cgSNP)-based phylogenetic analysis indicated that the 16 CRKP isolates could be partitioned into two separate clades (≤15 SNPs), suggesting the two independent transmission scenarios co-occurred. Moreover, a high prevalence of IncFIB/IncHI1B type virulence plasmid with the iroBCDN locus deleted, and an IncFII/IncR type bla KPC-2-bearing plasmid was co-harbored in ST11-KL64 CRKP isolates. In conclusion, our data indicated that the nosocomial dissemination of ST11-KL64 CRKP clone is a potential threat to anti-infective therapy. The development of novel strategies for surveillance, diagnosis, and treatment of this high-risk CRKP clone is urgently needed. [ABSTRACT FROM AUTHOR]

Background: The prevalence of multidrug-resistant Klebsiella pneumoniae is increasingly being implicated worldwide in a variety of infections with high mortalities. Here, we report the complete genome sequence of K. pneumoniae strain KP58, a pandrug-resistant K. pneumoniae strain that exhibits high levels of resistance to colistin and tigecycline in China. Methods: The K. pneumoniae strain KP58 was recovered from a urine sample of a female patient hospitalized in a tertiary hospital in Hangzhou, China. Antimicrobial susceptibility testing was performed and the minimum inhibitory concentrations (MICs) were determined. Whole-genome sequencing was performed using Illumina and Oxford nanopore sequencing technologies. Genomic features, antimicrobial resistance genes and virulence genes were comprehensively analysed by various bioinformatics approaches. In addition, genomic epidemiological and phylogenetic analyses of K. pneumoniae KP58 and closely related isolates were performed using the core genome multilocus sequence typing (cgMLST) analysis in BacWGSTdb, an online bacterial whole-genome sequence typing and source tracking database. Results: K. pneumoniae KP58 was resistant to all antimicrobial agents tested, including tigecycline and colistin. Combining the two sequencing technologies allowed a high-quality complete genome sequence of K. pneumoniae KP58 comprising one circular chromosome and five circular plasmids to be obtained. This strain harbours a variety of acquired antimicrobial resistance and virulence determinants. It also carried an ISKpn26-like insertion in the disrupted mgrB gene, which confers colistin resistance. The tigecycline resistance was associated with overexpression of the AcrAB efflux system. The closest relative of K. pneumoniae KP58 was another clinical isolate recovered from Hangzhou that differed by only 10 cgMLST loci. Conclusion: The dataset presented in this study provides essential insights into the evolution of antimicrobial-resistant K. pneumoniae in hospital settings and assists in the development of effective control strategies. Appropriate surveillance and control measures are essential to prevent its further dissemination. [ABSTRACT FROM AUTHOR]