Study: Seafood Safety at Risk Due to Antibiotic-Resistant Bacterial Strains

Antibiotic resistance tests: Bacteria are streaked on dishes with white disks, each impregnated with a different antibiotic. Clear rings, such as those on the left, show that bacteria have not grown—indicating that these bacteria are not resistant. The bacteria on the right are fully susceptible to only three of the seven antibiotics tested. (Photo by Dr. Graham Beards via Wikipedia Commons)

(CN) – New bacterial strains that have developed resistance to antibiotics used to treat humans are increasingly showing up in dolphins and fish, posing a health risk that threatens the safety of global seafood supply according to a new study released Sunday.

The study, published in the journal Aquatic Mammals, looked for the presence of antibiotic-resistant pathogens among bottlenose dolphins in Florida’s Indian River Lagoon over a period of 12 years. The lagoon features a large coastal human population, which scientists said carries with it “significant environmental impacts.”

“In 2009, we reported a high prevalence of antibiotic resistance in wild dolphins, which was unexpected,” said Adam Schaefer, lead author and an epidemiologist at Florida Atlantic University. “Since then, we have been tracking changes over time and have found a significant increase in antibiotic resistance in isolates from these animals. This trend mirrors reports from human health care settings. Based on our findings, it is likely that these isolates from dolphins originated from a source where antibiotics are regularly used, potentially entering the marine environment through human activities or discharges from terrestrial sources.”

The research team gathered 733 pathogen samples from 171 individual dolphins over the course of the study. The scientists discovered 88.2% of the pathogen isolates were resistant to at least one antibiotic. The highest prevalence of resistance was found to erythromycin, an antibiotic used to treat a wide range of bacterial infections. Although the study focused on dolphins, researchers also noted an increase of resistant bacteria in fish as well, threatening global fish farming.

“The Health and Environmental Risk Assessment or HERA Project has helped discover that the emerging bacterial resistance to antibiotics in bottlenose dolphins is prevalent. Bottlenose dolphins are a valuable sentinel species in helping us understand how this affects human and environmental health. Through HERA we’ve been able to provide a large database of information in order to continue learning from these impressive animals,” said Gregory Bossart, co-author and senior vice president at the Georgia Aquarium. “Antibiotic resistance is one of the most significant risks to public health. As resistance increases, the probability of successfully treating infections caused by common pathogens decreases.”

The researchers said the new strains are a risk to human health as “new antibiotics aren’t being developed fast enough to combat the problem.”

In the U.S. alone, 2 million people are infected by antibiotic-resistant bacteria each year, with at least 23,000 fatalities.

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