Ocean may hold clues to antibiotic resistance
■ People may spread resistant bacteria when swimming, but the sea may offer potential solutions to defeat these toughened bugs.
By Victoria Stagg Elliott — Posted March 2, 2009
By looking to the ocean and other natural bodies of water, scientists are discovering novel ways drug-resistant bacteria are spreading as well as new compounds that may make old antibiotics more useful again, according to findings presented Feb. 13 at the American Assn. for the Advancement of Science annual meeting in Chicago.
"Without a doubt, this research will develop new understandings of ocean health risks and perhaps, more importantly, crucial discoveries that will lead to new solutions to looming public health problems," said Carolyn Sotka, the event's moderator and a senior science-policy analyst with the National Oceanic and Atmospheric Administration's Oceans and Human Health Initiative.
For example, one study indicated that when someone with methicillin-resistant Staphylococcus aureus goes to the beach, the bacteria will be spread in the water and on the sand.
"MRSA is not just found in the locker rooms and our hospitals, but also on the beaches," said Lisa Plano, MD, PhD, lead author and associate professor of clinical pediatrics and microbiology and immunology at the University of Miami. "We have to conclude that the beach may be a source for community-acquired staph infections."
Dr. Plano reiterated calls for renewed efforts to prescribe antibiotics appropriately to prevent resistance from developing and urged physicians to wash their hands more frequently to prevent spread.
But, she added, it is still safe to go to the beach. "We should not fear the beach. We can shower before we go into the water, and we can shower when we come out of the water. That way we can protect ourselves."
But another study suggested that resistance is not entirely from too many antibiotic prescriptions. Sometimes it develops because of interactions with other organisms before bacteria come into contact with a human.
Scientists with the Bigelow Laboratory for Ocean Sciences in West Boothbay Harbor, Maine, analyzed Vibrio bacteria collected from water and sediment along the East Coast. Many samples showed at least some resistance to the most common antibiotics used to treat infections that can have a high fatality rate. The authors say clinical studies are now needed to determine if treatment recommendations need to be changed.
"The Vibrio appears to be much more resistant than we expected, but this is an ecological study. It's not enough to change what physicians should use to treat patients," said Ramunas Stepanauskas, PhD, a senior research scientist at Bigelow.
A source for solutions?
But while antibiotic resistance can develop and spread in natural bodies of water, the creatures that make their homes there may be a source of compounds that may help solve this problem. Researchers with NOAA's Hollings Marine Laboratory and the Medical University of South Carolina, both in Charleston, in collaboration with those at North Carolina State University, analyzed compounds derived from a sea sponge thriving on a diminishing coral reef.
"We wanted to know how it survives in a world where everything is dying," said Peter Moeller, PhD, who presented these data and is a research scientist at Hollings.
They identified a part of the chemical structure of ageliferin, which disrupts and prevents additional production of bacterial biofilms. Test-tube experiments have suggested that this substance resensitizes resistant bacteria and is not toxic to humans. It also does not prompt bacteria to develop defenses against its effect. Researchers plan to test whether ageliferin can reduce the number of infections associated with medical devices such as stents and intravenous lines.
"This could lead to a new class of helper drugs and result in a rebirth for antibiotics no longer thought effective," Moeller said.
Public health agencies and medical societies have long hunted for strategies to combat antibiotic resistance. The American Medical Association has programs to educate physicians on appropriate prescribing practices, encourages continued research on the subject and has supported legislation that would preserve the effectiveness of antibiotics for treating human illnesses. The AMA also is working with others to develop Food and Drug Administration guidance on the prudent use of antibiotics in livestock.