Epidemiology, genetic dynamics, and transmission of the mcr-1 gene in China

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Colistin is a critical antibiotic for treating bacterial infections by disrupting cell membranes.
• The emergence of mobile colistin resistance (mcr-1) globally, first reported in China in 2015, poses a significant public health threat.
• Understanding the historical prevalence and transmission dynamics of mcr-1 is crucial for effective control strategies.

Purpose of the Study:

• To analyze the epidemiological and genetic characteristics of mcr-1 positive strains in China.
• To elucidate the evolutionary migration and transmission pathways of the mcr-1 gene.
• To investigate the emergence of co-harbored resistance genes and super-plasmids.

Main Methods:

• Analysis of 70 mcr-1 positive strains from Chinese surveillance hospitals.
• Screening of 671 strains from the NCBI database containing the mcr-1 gene.
• Epidemiological analysis and genetic dynamics investigation.

Main Results:

• The mcr-1 gene circulated undetected in China for over 30 years before its 2015 report.
• Extensive agricultural polymyxin use likely drove the emergence of mcr-1 and blaNDM co-harboring strains in livestock.
• Fecal-environmental transmission led to human infections, with evidence of adaptive evolution and dissemination across diverse hosts.

Conclusions:

• The study provides the first detailed elucidation of mcr-1's adaptive evolutionary migration and dissemination.
• The findings highlight the role of agricultural practices in the rise of antibiotic resistance.
• Emergence of super-resistant Enterobacterales and IncHI2(A) super-plasmids co-harboring mcr-1 and blaNDM is a significant concern.