Sharks Carrying Drug-Resistant "Bacterial Monsters"

Flushed medicines spawning antibiotic-resistant bacteria in oceans, study says.

Our leftover medicines are spawning drug-resistant "bacterial monsters" that thrive inside sharks, scientists say.

The finding suggests antibiotics such as penicillin may be leaching into the environment and spurring drug-resistant bacteria to evolve and multiply in the oceans.

(See: "Drug-Resistant Bacteria Found in Wild Arctic Birds.")

"Bacteria have sex, basically. They can transfer genetic material," said study leader Mark Mitchell, professor of veterinary clinical medicine at the University of Illinois at Urbana-Champaign.

Mitchell and colleagues found antibiotic-resistant bacteria in seven species of shark—such as bull sharks, lemon sharks, and nurse sharks—as well as the redfish Sciaenops ocellata. The fish live in coastal waters off Belize, Florida, Louisiana, and Massachusetts. (See shark pictures.)

Though random mutations can account for the drug-resistant bacteria, there's ample evidence for human origin, he noted.

"What do people do with antibiotics when they don't finish them? They flush them down the toilet [or] put them in the garbage," Mitchell said.

Trashed Medicines Making Monsters

Bacteria exposed to the drugs develop resistance, Mitchell said, so "we have the risk of creating these bacterial monsters."

These monsters may cause particularly virulent illnesses in sharks and fish. But the researchers are also concerned the resistant bacteria will find their way back into the human food chain.

(Related: "Cocaine, Spices, Hormones Found in Drinking Water.")

Though sharks aren't a staple in the human diet, we eat what they eat—crab, shrimp, and other fish. So people should be aware of these risks and handle food appropriately to avoid infection, Mitchell cautioned. (Check out Green Guide's tips for buying healthy fish.)

"I will eat things like sushi," he said. "But knowing there are those types of risks, I'm going to try and get it from healthy, wild-caught fish, where there might be more of a minimal exposure [to drugs]."

Findings appear this month in the Journal of Zoo and Wildlife Medicine.

Read This Next

Can science help personalize your diet?
Hogs are running wild in the U.S.—and spreading disease
Salman Rushdie on the timeless beauty of the Taj Mahal

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet