Fish tale: new study evaluates antibiotic content in farm-raised fish

Antibiotics - one of modernity’s great success stories - are charms that come with a curse. Their overuse in human and animal populations can lead to the development of resistant microbial strains, posing a dire threat to global health.

In a new study, Hansa Done, PhD candidate, and Rolf Halden, PhD, researchers at Arizona State University’s Biodesign Institute, examine antibiotic use in the rapidly expanding world of global aquaculture.

Done and Halden measured the presence of antibiotics in shrimp, salmon, catfish, trout, tilapia and swai, originating from 11 countries. Data showed traces of 5 of the 47 antibiotics evaluated.

The research findings and a discussion of their implications appear in the current issue of the Journal of Hazardous Materials.

Charting resistance

The menace of germs bearing resistance to our best medical defenses is reaching crisis proportions. Each year, resistant microbes sicken some 2 million people in the U.S. alone and kill about 23, 000, according to the Infectious Diseases Society of America.

On September 18, President Obama proposed the first governmental steps to address the problem, establishing a task force to be co-chaired by the secretaries of Health and Human Services, the Department of Defense, and the Department of Agriculture.

The new initiative to reign in antibiotic overuse has been welcomed in the medical community, though many believe that much more needs to be done to safeguard society. The chief complaint is that the proposed measures largely ignore the largest consumers of antibiotics - animals farmed for human consumption, including fish.

"The threat of living in a post-antibiotic era cannot be avoided without revising current practices in the use of antibiotics in animal husbandry, including in aquaculture," says Halden.

Halden, who directs the Biodesign Institute’s Center for Environmental Security, is a leading authority on the human and environmental impact of chemicals, (particularly their fate once their useful life has ended). In previous research, he has explored the intricate pathways from production to postconsumption fate of antimicrobials and the risks posed.

The new study examines the persistence of antibiotics in seafood raised by modern aquaculture. The research area is largely unexplored, as the primary focus of studies of antibiotics has been on drugs used in human medicine. The current research is the first to evaluate previously unmonitored antibiotics; it represents the largest reconnaissance conducted to date on antibiotics present in seafood.

Farming lifestyle

Aquaculture has undergone rapid growth to meet the burgeoning global demand, nearly tripling over the past 20 years to an estimated 83 million metric tons in 2013. The large increase has led to widespread antibiotic use, applied both to prevent and treat pathogens known to infect fish. The broad effects on health and the environment associated with these practices remain speculative.