The rapid spread of carbapenemase-producing Klebsiella pneumoniae(cpKP)poses seri-ous threats to public health;however,the underlying genetic basis for its dissemination is still unknown.We conducted a comprehensive genomic epidemiology analysis on 420 cpKP isolates col-lected from 70 hospitals in 24 provinces/autonomous regions/municipalities of China during 2009-2017 by short-/long-read sequencing.The results showed that most cpKP isolates were categorized into clonal group 258(CG258),in which ST11 was the dominant clone.Phylogenetic analysis revealed three major clades including the top one of Clade 3 for CG258 cpKP isolates.Additionally,carbapenemase gene analysis indicated that blaKPC was dominant in the cpKP isolates,and most blaKPC genes were located in five major incompatibility(Inc)groups of blaKPC-harboring plasmids.Importantly,three advantageous combinations of host-blaKPC-carrying plasmid(Clade 3.1+3.2-IncFⅡpHN7A8,Clade 3.1+3.2-IncFⅡpHN7A8:IncR,and Clade 3.3-IncFⅡpHN7A8:InCpA1763-KPC)were identified to confer cpKP isolates the advantages in both genotypes(strong correlation/coevolution)and phenotypes(resistance/growth/competition)to facilitate the nationwide spread of ST11/CG258 cpKP.Intriguingly,Bayesian skyline analysis illustrated that the three advanta-geous combinations might be directly associated with the strong population expansion during 2007-2008 and subsequent maintenance of the population of ST11/CG258 cpKP after 2008.We then examined drug resistance profiles of these cpKP isolates and proposed combination treatment regimens for CG258/non-CG258 cpKP infections.Thus,the findings of our systematical analysis shed light on the molecular epidemiology and genetic basis for the dissemination of ST11/CG258 cpKP in China,and much emphasis should be given to the close monitoring of advantageous cpKP-plasmid combinations.

Klebsiella pneumoniae(K.pneumoniae)is an important pathogen that can cause severe hospital-and community-acquired infections.To systematically investigate its methylation features,we determined the whole-genome sequences of 14 K.pneumoniae strains covering varying serotypes,multilocus sequence types,clonal groups,viscosity/virulence,and drug resistance.Their methy-lomes were further characterized using Pacific Biosciences single-molecule real-time and bisulfite technologies.We identified 15 methylation motifs[13 N6-methyladenine(6mA)and two 5-methylcytosine(5mC)motifs],among which eight were novel.Their corresponding DNA methyl-transferases were also validated.Additionally,we analyzed the genomic distribution of GATC and CCWGG methylation motifs shared by all strains,and identified differential distribution pat-terns of some hemi-/un-methylated GATC motifs,which tend to be located within intergenic regions(IGRs).Specifically,we characterized the in vivo methylation kinetics at single-base resolu-tion on a genome-wide scale by simulating the dynamic processes of replication-mediated passive demethylation and MTase-catalyzed re-methylation.The slow methylation of the GATC motifs in the replication origin(oriC)regions and IGRs implicates the epigenetic regulation of replication initiation and transcription.Our findings illustrate the first comprehensive dynamic methylome map of K.pneumoniae at single-base resolution,and provide a useful reference to better understand epigenetic regulation in this and other bacterial species.

Fecal microbiota transplantation (FMT) refers to using the intestinal microorganisms present in the feces or processed feces from healthy people for treating various types of diseases, such as digestive and metabolic diseases. The rapid development of metagenomic and culturomic technologies in gut microbiome analysis provides powerful tools for the FMT research and its clinical applications. Metagenomics technologies comprehensively revealed the diversity and functions of gut microbiota under health and disease conditions, while culturomics technologies helped isolation and identification of "unculturable" bacteria in the human gut under conventional culture conditions. The combination of these two technologies not only enabled us better understand the FMT regularities of cause and effect in clinical practices, but also effectively promoted its applications. Considering the above advantages, this article summarized the applications of metagenomics and culturomics technologies in FMT and prospected its future development trend.
Humans ; Fecal Microbiota Transplantation ; Metagenomics ; Feces/microbiology* ; Gastrointestinal Microbiome ; Bacteria