A groundbreaking study from a University of Georgia research team has identified imported shrimp and scallops as a vector spreading bacteria resistant to the potent antibiotic colistin. Resistant bacteria pose a threat to our medical community’s ability to treat life-threatening infections. Notably, the research team found no similar threat posed by locally produced seafood. The study highlights the need to address the use of banned antibiotics in foreign shrimp supply chains.
The researchers’ findings build upon a rapidly growing body of academic literature ringing alarm bells regarding the spread of colistin resistance. Recent studies have confirmed high levels of antimicrobial resistance in bacteria found in Chinese shrimp farms where colistin resistance may be transferable and have described how foreign aquaculture constitutes a potential reservoir of colistin and carbapenem resistance.
While academics have continued to identify the health risks posed by the U.S. market’s over-reliance on imported seafood, the Department of Health of the state of Louisiana recently posted a warning encouraging the consumption of local seafood:
“The Louisiana Department of Health encourages residents of and visitors to the state to eat Louisiana seafood whenever it is available; imported seafood carries the risk of possible contamination by physical, chemical, and/or microbiological hazards.”
Critical Facts
- Colistin is a “last-resort” antibiotic used only for dangerous, life-threatening bacterial infections resistant to other drugs.
- The World Health Organization (WHO) categorizes colistin as a “high priority critically important antibiotic”
- Imported seafood is not normally screened for bacteria carrying colistin resistance genes
- The tested seafood was purchased from eight Atlanta-area food markets
- Importantly, no colistin resistance was found in locally produced seafood
Resistance Effects All Americans
This study again confirms that imported seafood—primarily foreign, farm-raised shrimp—is a potential extrinsic source for transmissible colistin resistance in humans. Shrimp is the most consumed seafood in America. More than 90% of shrimp consumed in the U.S. comes from foreign countries, with the majority coming from countries known to abuse antibiotics in shrimp aquaculture. American families are unknowingly exposed to antimicrobial resistance genes that can transfer between bacteria through contaminated imported shrimp.
Antimicrobial-resistant infections already kill hundreds of thousands of people globally each year. The spread of colistin resistance through foreign aquaculture creates additional pathways for these dangerous genes to enter U.S. communities, potentially rendering our last-line antibiotics ineffective against serious Gram-negative bacterial infections.
The U.S. Food and Drug Administration (FDA) has not approved the use of any antibiotics in shrimp aquaculture, meaning that no shrimp containing antibiotics may be sold in the U.S. market. However, the FDA tests 0.1% of all imported seafood for the presence of banned antibiotics, making detection of even the most frequently abused antibiotics unlikely.
Countries that test 100% of shrimp imports from problem countries, such as India, have documented the use of a broad range of antibiotics in shrimp supply chains. These different classes of critical antibiotics, such as colistin, avoid detection by importing countries.
Urgent Need for Standards Equivalency and Expanded Testing
The study’s lead researcher, Dr. Issmat Kassem, noted that the results emphasize the importance of investing in monitoring systems, expanding them, and collaborating on the global level to address antimicrobial resistance. The Southern Shrimp Alliance’s ongoing advocacy supports this goal:
1. Standards Equivalency: Require equivalent food safety standards for all shrimp entering the U.S. market (see the Safer Shrimp Imports Act of 2025)
2. Enhanced Import Inspection Provisions: Expand FDA authority to permit the destruction of foreign seafood that poses health risks and increase resources for testing (see the Destruction of Hazardous Imports Act of 2025 and LESS Act of 2024)
3. Enhanced Transparency: Increase publicly available reporting of findings of antimicrobial resistance genes on seafood.
About the Study
The research was conducted by microbiologist Issmat Kassem, Ph.D., and his team at the University of Georgia, with findings presented at the American Society of Microbiology’s (ASM) annual meeting, Microbe 2025. The paper will be published in the peer-reviewed journal mSphere. The study represents the first documented isolation of colistin-resistance genes in imported shrimp and scallops sold in the U.S. markets.
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About the Louisiana Department of Health Warning
In January 2025, Louisiana state law (RS 40:5.5.2) was revised to require that “[t]he state health officer [] produce a statement that may be included on labels, placards, menu boards, or other promotional signage that encourages consumers to consume Louisiana seafood and warns of the risks that may be associated with the consumption of imported seafood.”
In April, the Department of Health updated its website to include the following statement: “The Louisiana Department of Health encourages residents of and visitors to the state to eat Louisiana seafood whenever it is available; imported seafood carries the risk of possible contamination by physical, chemical, and/or microbiological hazards.”