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Study: Farmed Fish Could Be Another Source of Antibiotic Resistance

The concern surrounding animal antibiotics focuses on meat and poultry production, but a new study suggests we should also be paying attention to fish.

Researchers at Arizona State University investigated 47 antibiotics in U.S.-purchased shrimp, salmon, catfish, trout, tilapia and swai originating from 11 different countries.

Their findings, published in the Journal of Hazardous Materials, identified five antibiotics detected in shrimp, salmon, tilapia and trout.

Oxytetracycline was the most commonly detected antibiotic compound, and it was found in farmed fish and wild shrimp. The researchers also found 4-epioxytetracycline, sulfadimethoxine, and ormetoprim in certain species and virginiamycin in farmed salmon marketed as antibiotic-free.

Lead author Hansa Done, a Ph.D. candidate at ASU’s Center for Environmental Security, told Time.com that antibiotics are added to the water in fish farms to treat and prevent disease or are directly injected into fish, but that they are not used for growth promotion.

The antibiotic levels detected in the study were within legal limits, and the researchers report low risk of drug exposure from seafood consumption, but even the low levels can promote antibiotic resistance.

The authors add that publications reporting antibiotic resistance in aquaculture have increased eight-fold over three decades.

© Food Safety News
  • Kristin Woods

    How do they explain oxytetracycline in wild caught shrimp?

  • bobmilne

    I have read the research paper. They explain it by stating:

    ” The unexpected detection of oxytetracycline at a concentrationof 7.7 ng/g fw in wild-caught shrimp imported from Mexico maybe due to several reasons. Unintentional or intentional mislabelingof the product and cross-contamination of seafood during hand-ling, processing and packaging are possible. Uptake of the drug from coastal waters and sediments impacted by inputs of raw andtreated wastewater [27] also could explain the observed detection but ultimately the origin of contamination remains unknown.”

    My question is. Why should we believe that all the other samples are any different? The above quote is an admission that these researchers have no clue what they are actually testing let alone where it specifically came from. Some studies really should not get their samples from supermarkets. This looks like one of them. No chain of custody and no idea if the samples come from treated animals.

    The wild shrimp tested highest of all samples.

    What is your guess?

  • Kristin Woods

    My guess would be mislabeling or co-mingling. Hard for me to believe that detectable levels would be found if the shrimp were fished from contaminated waters – the water would have to be highly contaminated.

  • Rob Bashar

    This research seems to be questionable about the reliability on it.

    As it seems, samples tested were not taken directly from the harvesting sites (farms or wild). It was really questionable when they found Oxytetracycline of 7.7 ng/g wild shrimp. Even the researchers were not quite sure of the origin/s of antibiotics (for shrimp, for example). Similarly, other samples are also doubtful about the source/s of antibiotics. When they mentioned potential sources of antibiotics such as processing, handling, packaging materials etc., but aquaculture necessarily, then their findings blaming on aquaculture became pointless. Plus, they admitted, in general, antibiotic levels in fish are in compliance with US FDA.

    According to the article, aquaculture yield tripled in last two decades and use of antibiotics increased eight times in about three decades. According to them, tracking on the use of antibiotics is still not 100% correct. However, it’s true that use of antibiotics is increasing with the increase of aquaculture production with time regardless of the accuracy of the information in this connection. In intensive and super intensive aquaculture, antibiotics may be required as the last weapon. Caution must be taken when antibiotics to apply as the means of treatment. Bottom line is “prevention is better than cure”. Rob Bashar

  • Guest

    I believe that all findings in the samples are very likely to be false positives due to lab contamination, carry-over, or mass spectral interferences. All results are very close to the detection limits and they only looked at 1 product ion in tandem mass spectrometry. Thus, they did not even meet standard mass spectral identification criteria by using multiple product ions, and no findings were confirmed by re-analysis as they should have done. Their allowable retention time difference for the drug analytes were as high as a 48 second window (+/- .4 min), which is quite wide. The analytical chemistry conducted in this work is poor.