Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1022867 | ENA |
REPOSITORIES: ENA
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Project description:Background: The rapid evolution and dissemination of mobilized colistin resistance gene (mcr) family has revealed as a severe threat to the global public health. Nevertheless, dramatic reduction in the prevalence of mcr-1, the major member of mcr family, was observed after the withdrawal of colistin in animal fodder in China since 2017, demonstrating that colistin acts as a selective stress to promote the dissemination of mcr-1. As the second largest lineage, mcr-3 was firstly discovered in 2017 and has been identified from numerous sources. However, whether the spreading of mcr-3 is driven by colistin remains unknown. Methods: To this end, we investigated the global prevalence of mcr-3 from 2005 to 2022 by an up-to-date systematic review, along with a nation-wide epidemiological study to establish the change of mcr-3 prevalence in China before and after 2017. To investigate the fitness cost imposed by MCR-3 upon bacterial host, in vitro and in vivo competitive assays were employed, along with morphological study and fluorescent observation. Moreover, by replacing non-optimal codons with optimal codons, synonymous mutations were introduced into the 5’-coding region of mcr-3 to study mechanisms accounting for the distinct fitness cost conferred by MCR-1 and MCR-3. Furthermore, by combining AlphaFold and molecular dynamics (MD) simulation, we provided a complete characterization on the putative lipid A binding pocket localized at the linker domain of MCR-3. Crucially, inhibitors targeting at the putative binding pocket of MCR-1 or MCR-3 were identified from small molecules library using the pipeline of virtual screening. Findings: The global prevalence of mcr-3 increased continuously from 2005 to 2022. The average prevalence was 0.18% during 2005-2014 and rapidly increased to 3.41% during 2020-2022. The prevalence of mcr-3 in China increased from 0.79% in 2016 to 5.87% in 2019. We found that the fitness of mcr-3-bearing E. coli and empty plasmid control was comparable but higher than that of mcr-1-positive strain. Although the putative lipid A binding pocket of MCR-3 was similar to that of in MCR-1, mcr-3 occupies remarkable codon bias at the 5’-end of coding region that disrupted the stability of mRNA, further reduced its protein expression in E. coli, resulting in the low fitness burden of bacterial host. Moreover, the 5’-end codon usage frequency appeared as a critical factor related with the evolution of mcr family. Furthermore, based on the similar lipid A binding pocket among MCR family protein, we identified three novel MCR inhibitors targeting at such pocket by screening from small-molecule library, which effectively restored the colistin susceptibility of mcr-bearing E. coli. Interpretation: For the first time, we found that the prevalence of mcr-3 increased continuously during 2016-2019 in China, demonstrating that the withdrawal of colistin in husbandry failed to prevent the dissemination of mcr-3. Our study evidenced that the 5’-end codon bias appeared as a crucial regulator upon the fitness cost conferred by horizontally transferred genes. Most importantly, the putative lipid A binding pocket verified from current study was a promising target site for designing inhibitors against mcr-positive strains.
2025-06-29 | GSE300593 | GEO
Project description:Conjugative plasmids, major vehicles for the spread of antibiotic resistance genes, often contain multiple toxin‒antitoxin (TA) systems. However, the physiological functions of TA systems remain obscure. By studying TA families commonly found on colistin-resistant IncI2 mcr-1-bearing plasmids, we discovered that the HicAB TA, acts as a crucial addiction module to increase horizontal plasmid‒plasmid competition.
2024-12-25 | GSE284789 | GEO
Project description:Acinetobacter baumannii is often highly resistant to multiple antimicrobials, posing a risk of treatment failure. Colistin is often chosen as a “last resort” for treatment of the bacterial infection, but resistance is easily developed when the bacteria is exposed to the drug. Thus a comprehensive analysis of colistin-mediated changes in colistin-susceptible and colistin-resistant A. baumannii is needed. In this study, we used a colistin-susceptible A. baumannii clinical isolate and a colistin-resistant isogenic mutant. Whole genome sequencing revealed that the resistant isolate harbored a PmrBL208F mutation conferring colistin resistance, and all other single nucleotide alterations were located in intergenic regions. Using scanning electron microscopy, we observed that the colistin-resistant mutant had a shorter cell length than the parental isolate, and filamented cells were observed when both isolates were exposed to inhibitory concentration of colistin. When the isolates were treated with inhibitory concentrations of colistin, more than 80% of the genes were upregulated, including genes associated with antioxidative stress response pathways. This results helped a better understanding for the morphological difference between the colistin-susceptible and –resistant isolates and differed colistin-mediated responses in A. baumannii isolates by their susceptibility to this drug.
2025-05-02 | GSE267612 | GEO
Project description:Zoonotic transmission of the mcr-1 colistin resistance gene from non-intensive poultry farms in Vietnam
| PRJEB14873 | ENA
Project description:Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multi-drug resistant strains of the Gram-negative bacteria, Acinetobacter baumannii. However, colistin resistant A. baumannii isolates can be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered an isogenic pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment that displayed low/intermediate and high levels of colistin resistance, respectively. To understand how increased colistin-resistance arose, we genome sequenced each isolate which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS-family transcriptional regulator. Consequently, transcriptomic analysis of the clinical isolates identified was performed and more than 150 genes as differentially expressed in the colistin-resistant, hns mutant, 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase, but not pmrC, was significantly increased in the hns mutant. This is the first time an H-NS-family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
2018-02-19 | GSE107964 | GEO
Project description:Mcr-1 mediated colistin resistant Escherichia coli ST95 from Qatar
| PRJNA421388 | ENA