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Investigation of Escherichia coli Harboring the mcr-1 Resistance Gene - Connecticut, 2016
Abstract:
The mcr-1 gene confers resistance to the polymyxins, including the antibiotic colistin, a medication of last resort for multidrug-resistant infections. The mcr-1 gene was first reported in 2015 in food, animal, and patient isolates from China (1) and is notable for being the first plasmid-mediated colistin resistance mechanism to be identified. Plasmids can be transferred between bacteria, potentially spreading the resistance gene to other bacterial species. Since its discovery, the mcr-1 gene has been reported from Africa, Asia, Europe, South America, and North America (2,3), including the United States, where it has been identified in Escherichia coli isolated from three patients and from two intestinal samples from pigs (2,4-6). In July 2016, the Pathogen Detection System at the National Center for Biotechnology Information (Bethesda, Maryland) identified mcr-1 in the whole genome sequence of an E. coli isolate from a Connecticut patient (7); this is the fourth isolate from a U.S. patient to contain the mcr-1 gene.
Insights
The mcr-1 gene, conferring resistance to colistin, has spread globally. This plasmid-mediated resistance mechanism has now been detected in E. coli from a U.S. patient, highlighting its increasing prevalence.
Area of Science:
- Microbiology
- Genetics
- Public Health
Background:
- Polymyxins, like colistin, are last-resort antibiotics for multidrug-resistant infections.
- The mcr-1 gene confers resistance to polymyxins, notably colistin.
- mcr-1 is the first identified plasmid-mediated colistin resistance mechanism.
Observation:
- First reported in 2015 in China from food, animal, and patient isolates.
- Since 2015, mcr-1 has been reported across all inhabited continents.
- Identified in Escherichia coli from patients and pigs in the United States.
Findings:
- The mcr-1 gene has been detected in an E. coli isolate from a U.S. patient in Connecticut.
- This represents the fourth U.S. patient isolate found to contain the mcr-1 gene.
- Plasmids carrying mcr-1 can transfer between bacteria, facilitating the spread of resistance.
Implications:
- The global dissemination of mcr-1 poses a significant threat to the efficacy of colistin.
- Widespread plasmid-mediated colistin resistance necessitates enhanced surveillance and control strategies.
- Understanding the transmission dynamics of mcr-1 is crucial for combating antimicrobial resistance.
