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cWe report the emergence of five carbapenem-resistant K1 hypervirulent Klebsiella pneumoniae (hvKP) strains which caused fatal infections in hospital patients in Zhejiang Province, China, upon entry through surgical wounds. Genotyping results revealed the existence of three genetically related strains which exhibited a new sequence type, ST1797, and revealed that all strains harbored the magA and wcaG virulence genes and a plasmid-borne bla KPC-2 gene. These findings indicate that K1 hvKP is simultaneously hypervirulent, multidrug resistant, and transmissible.

A collection of 1159 enterococcal isolates from five Chinese hospitals were screened for the presence of the novel oxazolidinone resistance gene optrA, which was found in 34 (2.9%) isolates. Pulsed-field gel electrophoresis (PFGE) typing of 29 optrA-carrying Enterococcus faecalis isolates revealed 25 PFGE patterns, and multilocus sequence typing yielded 20 sequence types. Routine surveillance of optrA-positive enterococci in hospitals should be conducted to monitor and counteract their further dissemination. The data of this study may be used as a baseline from which to judge future decreases or increases in optrA-positive enterococci.

The rapid dissemination of non‐conjugative virulence plasmids among non‐K1/K2 types of Klebsiella pneumoniae poses an unprecedented threat to human health, yet the underlying mechanisms governing dissemination of such plasmids is unclear. In this study, a novel 68 581 bp IncFIA plasmid is discovered that can be fused to a hypervirulence‐encoding plasmid to form a hybrid conjugative virulence plasmid in conjugation experiments; such fusion events involve homologous recombination between a 241 bp homologous region located in each of the two plasmids. The fusion hypervirulence‐encoding plasmid can be conjugated to both classic and blaKPC‐2‐bearing carbapenem‐resistant K. pneumoniae strains through conjugation, enabling such strains to acquire the ability to express the hypervirulence phenotype. Dissemination of this fusion virulence plasmid will impose an enormous burden on current efforts to control and treat infections caused by multidrug resistant and hypervirulent K. pneumoniae.

Carbapenem-resistant and hypervirulent K. pneumoniae (CR-HvKP) strains that have emerged recently have caused infections of extremely high mortality in various countries. In this study, we discovered a conjugative plasmid that encodes carbapenem resistance and hypervirulence in a clinical ST86 K2 CR-HvKP, namely 17ZR-91. The conjugative plasmid (p17ZR-91-Vir-KPC) was formed by fusion of a non-conjugative pLVPK-like plasmid and a conjugative blaKPC-2-bearing plasmid and is present dynamically with two other non-fusion plasmids. Conjugation of p17ZR-91-Vir-KPC to other K. pneumoniae enabled them to rapidly express the carbapenem resistance and hypervirulence phenotypes. More importantly, genome analysis provided direct evidence that p17ZR-91-Vir-KPC could be directly transmitted from K2 CR-HvKP strain, 17ZR-91, to ST11 clinical K. pneumoniae strains to convert them into ST11 CR-HvKP strains, which explains the evolutionary mechanisms of recently emerged ST11 CR-HvKP strains.

One hundred and thirty-six bla OXA-51-negative strains were identified from 1,067 Acinetobacter calcoaceticus-A. baumannii complex (ACB complex) isolates, which were collected during October 2010 to March 2013 from 15 general hospitals in 10 cities throughout Zhejiang Province, China. Seven of the 136 bla OXA-51-negative ACB complex isolates were New Delhi metallo-β-lactamase-1 (NDM-1)-positive, among which three were identified as A. nosocomialis and four were identified as A. pittii strains using 16S-23S rRNA gene intergenic spacer (ITS) sequencing and partial RNA polymerase β-subunit (rpoB) sequencing. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) analysis showed that the seven NDM-positive isolates belonged to three clonal strains with three novel sequence types (STs). Polymerase chain reaction (PCR) assays and DNA sequence analysis of the carbapenemase and other β-lactamase genes indicated that all the isolates harbored the bla NDM-1 gene, and that only one strain of A. nosocomialis isolates harbored both bla NDM-1 and bla OXA-23. All of them were positive for bla ADC, from which three novel bla ADC genes (designated as bla ADC-69, bla ADC-70, and bla ADC-71) were detected for the first time. The presence of ISAba125 upstream of bla NDM-1 was identified through genetic environment analysis. Carbapenem resistance can be transferred from A. nosocomialis and A. pittii to Escherichia coli EC600 by the conjugation experiment. Plasmid analysis, DNA hybridization, and extraction experiments indicated that bla NDM-1 was located on a plasmid of approximately 50 kb. In conclusion, we characterized the dissemination of NDM-1-positive A. pittii strains in Zhejiang Province, China, and reported the NDM-producing A. nosocomialis for the first time.

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