Sharks Carry Drug-Resistant Bacteria That Could Infect Humans

two sharks tank photo

Photo via Serge Melki via Flickr CC

Scientists have found that sharks swimming off the Florida Keys and Belize carry a significant amount of drug-resistant bacteria strains that they worry could one day impact humans. In all, bacteria resistant to 13 types of anti-bodies -- including penicillin -- were found among the sharks sampled, and because the sample populations were somewhat small, the researchers think this could be an underestimate for the number of resistant strains. But it might be humans' fault the sharks are carrying the strains in the first place. According to MSNBC, "The bacteria don't harm the toothy fish, but scientists worry that the sharks and redfish may become incubators for nasty multidrug-resistant strains, which could possibly infect humans someday."

"It's not unexpected to find some drug resistance, but we were surprised to find the amount of resistance to that large suite of drugs," said Jason Blackburn, a spatial ecologist at the University of Florida in Gainesville.

Exactly how the sharks began carrying the drug-resistant strains isn't known. However, several possible causes researchers want to look into include exposure to sewage, exposure to humans who use antibiotics (interaction between human tourists and docile sharks is common in Belize where some of the sharks were tested), ingestion of other fish that are carrying the strains, or possibly even age.

Researchers are concerned that if it turns out it's what the sharks are eating, then humans could also be ingesting fish carrying the drug-resistant bacteria. They want to expand the study, looking at a greater variety of populations and species of shark.

"These species that we've targeted, these are apex or top-end predators in a similar position in the marine food web as we are," Blackburn told LiveScience. "Either their food source had directly ingested drug-resistant bacteria, or bacteria in the [shark] gut were exposed to antibiotic components...Knowing that this pool of drug resistance is out there, certainly we've presented enough evidence to argue for more routine sampling. The survey showed resistance everywhere we looked, even in remote areas."

If you're worried that sharks will spread superbugs to humans, don't. We have far more to worry about with antibiotic resistance in soils than we do among sharks. And at the rate sharks are being wiped out, we may lose them before they even have a chance to spread the bacteria to us, let alone find out how they're obtaining the strains in the first place.

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