Imported seafood carries lethal colistin‑resistance genes
Imported Seafood May Be Fueling Dangerous Antibiotic Resistance
Microbiologists are alarmed that the last‑line drug colistin loses potency as bacteria evolve R genes. A University of Georgia team traced these genes to shrimp and scallops imported into Atlanta.
How the Resistance Spreads
- Plasmids transfer R genes between bacteria.
- Imported seafood promotes transmissible colistin resistance.
- Over 90% of U.S. shrimp is imported.
Key Findings
In 2016 researchers isolated genes conferring colistin resistance from seafood purchased in Atlanta markets. This discovery links imported shrimp and scallops to the spread of a drug‑sparing weapons system, turning once‑curable infections into deadly threats.
Why It Matters
Colistin is reserved for the most severe, resistant infections. If bacteria outgrow it, clinical options narrow sharply, raising global health risks and market instability amid the U.S.–China trade tensions.
What’s Next?
Molecular surveillance must intensify, and import regulations may need tightening to curb the worldwide spread of this antibiotic threat.
Colistin Resistance Entering the United States via Imported Seafood
Severe cases of colistin exposure are not limited to human clinical settings. In many nations, the antibiotic is administered both to treat infections and to promote animal growth, especially in agricultural operations.
Microbiological Background
Imported shrimp are frequently contaminated with Gram‑negative bacteria, primarily members of the genera Serratia and Aeromonas. Recent studies have isolated the mobile colistin resistance gene, mcr, from these seafood samples.
Gene Mobility and Allelic Variants
The mcr gene is considered mobile because it can jump between bacterial species via plasmids. Since its first discovery, ten distinct mcr genes have been identified, along with several allelic variants—each representing a single base or a segment of bases at a given genomic location.
Global Implications
- Travel and food distribution create a “connected world” that facilitates the rapid spread of antimicrobial resistance.
- Monitoring systems must be expanded globally to detect and contain emerging resistance mechanisms.
Publication Details
The findings appear in the journal mSphere under the title “Introduction of the transmissible mobile colistin resistance genes mcr-3 and mcr-9 to the USA via imported seafood.”
Related Advances in Antimicrobial Resistance
In a separate line of research, scientists have identified a novel class of antibiotics that selectively induces a self‑destruct program in Neisseria gonorrhoeae, the bacterium responsible for gonorrhoea. This strategy is effective even against multi‑resistant strains.
