Imported Shrimp with Scary Antibiotic-Resistant Bacteria

A while back I wrote two posts on imported farmed shrimp and I think readers got the gist of it: Farmed imported shrimp, especially from Asia, scares the hell out of me. Well, here is even more news about how some imported shrimp comes with as an added “bonus.” How about some E. coli or Staph to go with your shrimp cocktail?

According to this shocking video by CBC in Canada, many shrimp imports from Asia and sold in Canadian supermarkets, are testing positive for antibiotic-resistant “superbugs.” The video is a little long but I suggest watching it to check out the results toward the end.

Testing Shrimp for Antibiotic Resistant Bacteria: CBC News

Shrimp is the most popular seafood in the US, and the demand by and large outstrips the supply of our native shrimp. Thanks to warming temperatures in the Gulf of Maine, my hometown no longer has a winter shrimp fishery. Canada is one of the world’s greatest exporters of seafood, but they love their shrimp too, and import quite a bit from Asia, especially India.

Compared to wild-caught shrimp, the imported farm-raised shrimp harbored distinct gut microbiota communities and a higher prevalence of antibiotic-resistance genes in their gut. The presence of antibiotic-resistant strains in cooked shrimps calls for change in processing for their mitigation.

Sharma, L., Nagpal, R., Jackson, C.R. et al. Antibiotic-resistant bacteria and gut microbiome communities associated with wild-caught shrimp from the United States versus imported farm-raised retail shrimp. Sci Rep 11, 3356 (2021).

The Dangers of Antibiotic Resistant Bacteria

Antibiotic-resistant bacteria, including strains of E. coli, pose a formidable and evolving threat to public health. E. coli is a normally harmless bacterium inhabiting the human intestines, has become a focal point in discussions about antibiotic resistance due to its adaptability. The widespread use of antibiotics in medicine, agriculture and in this case, aquaculture has contributed to the growth of these strains.

The rise of antibiotic resistance occurs when bacteria undergo genetic mutations or acquire resistance genes through horizontal gene transfer. The bacterium can quickly evolve mechanisms to neutralize the effects of antibiotics, rendering these drugs ineffective. When these shrimp farms overuse antibiotics, it accelerates the evolution of resistant bacteria.

What Antibiotics are Used in Imported Shrimp

I am not pointing fingers at any particular shrimp farm, these are some of the antibiotics used to fight infections and for other purposes. Each operation is different, and local conditions would dictate what is being used.

  • Enrofloxacin: A fluoroquinolone antibiotic, enrofloxacin is used to treat bacterial infections in shrimp. It works by inhibiting bacterial DNA replication and is effective against a broad spectrum of bacteria.
  • Oxytetracycline: Oxytetracycline is a tetracycline-class antibiotic widely used in aquaculture, including shrimp farming. It is effective against various bacterial pathogens and is used for both treatment and prevention.
  • Florfenicol: This antibiotic belongs to the phenicol class and is used to treat bacterial infections in shrimp. Florfenicol inhibits protein synthesis in bacteria and is effective against certain strains that may be resistant to other antibiotics.
  • Sulfonamides (e.g., Sulfamethoxazole): Sulfonamides are a class of antibiotics used in aquaculture to treat bacterial infections. They interfere with the synthesis of folic acid, essential for bacterial growth.
  • Trimethoprim-Sulfamethoxazole (Co-trimoxazole): This combination of antibiotics is used in shrimp farming to target a broader range of bacterial pathogens. It works by inhibiting the synthesis of folic acid and disrupting bacterial DNA replication.

Why do They Need Antibiotics?

Antibiotics are not just to treat sick animals or to prevent infection. Aquaculture operations use antibiotics to reduce stress in overcrowded pens or poor water quality. However there is a more nefarious approach to antibiotics that encourages animal growth and better food conversion rates. This practice is known as sub-therapeutic antibiotic use and contributes to the development of antibiotic-resistant bacteria in imported shrimp.

Unfortunately it may not be just the imported shrimp. If you watched the video, some of the organic labeled farmed shrimp tested positive for superbugs. And even BAP (Best Aquaculture Practices) certification was no security as some of the samples carried this seal of “quality” and still tested positive.

Americans are Addicted to Imported Shrimp

Curry Shrimp Disney Animal Kingdom imported shrimp

An estimated 80% of the shrimp consumed in the US is farmed. On my trip to Seafood Expo North America 2019 in Boston, there were lots of shrimp farms represented, most of them from Asian countries and of course all of them tout how clean their shrimp farms are. So where is the antibiotic-resistant bacteria coming from?

While I doubt all of these farms are pumping antibiotics into their grow areas, I’m sure it is part of the problem. The video states that India uses more antibiotics than any other country. But the rest? That may be due to an even more difficult problem: cross-contamination, which can happen at any point in the supply chain. Stay vigilant, read labels, and buy domestic wild-caught over imported shrimp when available.