Friday, September 07, 2007

Some dolphins fight "tough" bacterias

"Super bugs" resistant to penicillin and several other common antibiotics grow in the guts of one in every five bottlenose dolphins in the Indian River Lagoon, researchers found.

The bacteria appear harmless to dolphins so far, but could trigger disease in those dolphins with compromised immune systems.

There's no evidence to date that antibiotic-resistant bacteria are causing human illness in the lagoon region.

But researchers say people exposed to higher concentrations of the "super" E. coli bacteria by eating the same lagoon seafood that dolphins eat or swimming in the same water may face an increased risk of potentially deadly digestive and skin infections, the researchers say.

And dolphins could become "reservoirs" for stronger bacteria more likely to make people sick.
"What I think we're seeing right now is sort of the tip of the iceberg," said Greg Bossart, a marine mammal pathologist at Harbor Branch Oceanographic Institution in Fort Pierce and one of the study's authors.

The researchers published their findings last month in the journal Aquatic Mammals.

Bossart and colleagues from The National Oceanic and Atmospheric Administration in Charleston, S.C. examined fecal samples from 38 bottlenose dolphins from the lagoon and Charleston Harbor area, S.C.

Their findings included:

E. coli from dolphins showed resistance to 19 of 25 antibiotics tested.

Of the 38 dolphins successfully screened, 18, or 47 percent, had bacteria in their feces resistant to one or more antibiotics.

The problem was worse in Charleston, where 15 of 23 bottlenose dolphins, or 65 percent, tested positive for bacteria resistant to one or more antibiotics.

Of the 15 lagoon bottlenose successfully screened, three dolphins had resistant E. coli bacteria.
Lagoon dolphins had bacteria resistant to penicillin, amoxicillin, cephalothin and nitrofurantoin.
Amoxicillin is used to treat pneumonia, bronchitis, gonorrhea and ear, nose and throat infections.
Nitrofurantoin kills bacteria that cause urinary tract infections.

"Those are drugs that are really quite often used for human and veterinary medicine," Bossart said.
While a recent environmental group's report touted Brevard's clean surf, less is known about bacteria levels in the lagoon.

The "super" bacteria could be seeping into the lagoon from septic tanks, sewage treatment plants and farm runoff, the researchers said. Farmers use antibiotics to promote growth in their cattle.
"Many cows and farm animals, they have this in their system," said Heidar Heshmati, director of Brevard County Health Department.

Doctors who over prescribe antibiotics also contribute to the problem, he said.

People who fail to take their full course of prescribed antibiotics also can breed a stronger next generation of bacteria. They flush unused medicines down the drain, where they enter wastewater and ultimately the lagoon.

The researchers found higher bacteria resistance near urbanized areas of the lagoon.
There are 19 wastewater treatment plants along Brevard's barrier island. One dolphin that harbored antibiotic resistant bacteria was captured in the Banana River near Cocoa Beach's sewer and reclaimed water treatment plant at 1600 Minutemen Causeway. Two others were found close to the St. Lucie River, which has had ongoing sewage problems. None of the eight dolphins tested near Merritt Island National Wildlife Refuge -- which lacks any large-scale sewer plants -- had resistant bacteria.

Antibiotic resistant bacteria were significantly higher overall in South Carolina dolphins than in lagoon dolphins. The Charleston area is far more urbanized than the lagoon region.

The research was part of an estimated $1.2 million dolphin health study, funded mostly through the "Protect Wild Dolphin" license plates and state grants.

The 40 scientists have generally found lagoon bottlenose the less healthy of the two dolphin populations, and they seem to be getting sicker. Bottlenose here suffer from a mix of emerging ailments, including genital tumors, stomach ulcers, fungal growths and viral infections that can lead to cancer.

The researchers also have discovered flame retardants called polybrominated diphenyl ethers or PBDEs in dolphin tissue from both populations. The chemicals are widely used in plastics and foams for computer casings, carpet pads and cushions on chairs and couches.

Quick "Facts about Dolphins"