Antibiotics-in-fish study found FDA-approved levels

While a new U.S. study found traces of antibiotics in farmed fish and wild shrimp samples, the amounts were below levels deemed acceptable by the U.S. Food and Drug Administration (FDA).

In the first-of-its-kind study, Arizona State University (ASU) researchers examined 27 seafood samples representing five of the most consumed seafood species in the U.S.: shrimp, tilapia, catfish, swai, and Atlantic salmon. The National Oceanic and Atmospheric Administration (NOAA) acquired the samples from stores in Arizona and California.

The researchers found five antibiotics in detectable amounts, including oxytetracycline in wild shrimp, farmed tilapia, farmed salmon and farmed trout; 4-epioxytetracycline in farmed salmon; sulfademiethoxine in farmed shrimp; ormetoprim in farmed salmon; and virginiamycin in farmed salmon that was marketed as “antibiotic free.”

“This is very different. No one has ever screened for so many antibiotics in seafood in the U.S.,” Hansa Done, lead author of the study and Ph.D. candidate with ASU’s Biodesign Institute, told SeafoodSource. While the issue of antibiotics in swine and poultry has been around for a while, there is more focus on aquaculture now because it “has only recently become a major player globally,” Done said.

The wild shrimp samples from Mexico, purchased unpackaged from the seafood counter, could have contained antibiotics because of mislabeling, contamination at the store, or contamination from water runoff, the researchers speculated.

While all 27 samples were in compliance with FDA regulations, even antibiotic levels below the FDA threshold can promote the development of antibiotic resistance, according to the researchers.

Antiobitic resistance and aquaculture is an important area of study, the researchers said, because many antibiotics used in aquaculture, such as amoxicillin, are used in human medicine. In addition, “with water there are so many issues with how antibiotic residues, bacteria and genetic material can spread,” Done said.

Even though ASU researchers discovered the presence of antibiotics in farmed fish and wild shrimp samples, they do not oppose the responsible use of antibiotics in aquaculture.

“I am not against using antibiotics and antimicrobials in farmed fish. However, it needs to be monitored better and only used in certain circumstances, under the presence of a veterinarian,” Done said.

In fact, she said, aquaculture is a “wonderful, sustainable way to feed a population that will be eight billion in a couple of years,” adding that she hoped the news of the study didn’t scare consumers away from farmed fish. “I am pretty optimistic that aquaculture [can be conducted] in a way that human health isn’t compromised.”

Next, ASU researchers are developing a method to detect all types of antibiotics in aquaculture.


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