Evolution, dissemination, and genetic dynamics of the carbapenem resistance gene in China.

BACKGROUND

, which encodes a metallo-β-lactamase that can hydrolyze most β-lactam antibiotics, has become a serious public health concern in China. It is crucial to investigate the evolution, dissemination, and genetic dynamics of to develop potential strategies to control the proliferation of .

METHODS

In this study, we collected 1021 -positive isolates, which features 67 new genomes from our laboratory and 954 genomes from NCBI. Through epidemiological big data analysis, phylogenetic tree-based geographic transmission analysis, and upstream-downstream genetic clustering evolution analysis, we systematically analyzed the evolution, dissemination, and genetic dynamics of -positive bacteria.

RESULTS

Analysis results indicate that bla is gradually supplanting in China and Acinetobacter has been replaced as the primary -harboring genus by the Enterobacter, Escherichia, and Klebsiella, which are both within the Enterobacteriaceae family and more easily transmitted among humans. Furthermore, -positive bacteria exhibit a distinct livestock-environment-human transmission cycle, while the phylogenetic diversity of and -co-carrying genera is progressively expanding with concomitantly enhanced resistance phenotypes. Currently, the predominant -positive bacterial strains have likely disseminated from southwest China to coastal regions. We further identified multiple transposon structures beyond Tn125 that may facilitate transfer.

CONCLUSIONS

The diversity of the and its carrier bacterial strains is continuously increasing, and its transmission range is also expanding. Of greater concern, super-resistant strains co-harboring and genes exhibit high potential for imminent emergence in human populations. Considering that the -carrier bacteria are increasingly adapted to inter-human spread, the analysis results above can provide methodological and data support for epidemiological surveillance, tracing, and early warning alerts.