Comprehensive Genomic Investigation of Coevolution of genes in Strains via Nanopore Sequencing.

Horizontal gene transfer facilitates the spread of antibiotic resistance genes, which constitutes a global challenge. However, the evolutionary trajectory of the mobile colistin resistome in bacteria is largely unknown. To investigate the coevolution and fitness cost of the colistin resistance genes in wild strains, different assays to uncover the genomic dynamics of and in bacterial populations are utilized. strains harboring both and are isolated and genes are associated with diverse mobile elements. Under exposure to colistin, the -bearing resistome is stably inherited during bacterial replication, but is prone to be eliminated in populations of certain strains. In the absence of colistin, the persistence rates of the and -bearing subclones varies depending on the genomic background. The decay of the -bearing bacterial populations can be mediated by the elimination of -containing segments, large genomic deletions, and plasmid loss. Mobile elements, including plasmids and transposons, are double-edged swords in the evolution of the resistome. The findings support the idea that antibiotic overuse accounts for global spread of multidrug-resistant (MDR) bacteria. Therefore, stringent regulation of antibiotic prescription for humans and animals should be performed systematically to alleviate the threat of MDR bacteria.