14 February 2009

Antibiotic Resistance and Marine Ecosystems

New awareness is needed of the potential for antibiotic-resistant illnesses from the marine environment. At the same time, the ocean is a source for possible cures of those threats.

The American Association for the Advancement of Science stated that newly completed studies of ocean beach users point to an increasing risk of staph infections, and that current treatments for seafood poisoning may be less effective due to higher than expected antibiotic resistance. The group also asserts that new research has identified sponge and coral-derived chemicals with the potential for breaking down antibiotic resistant compounds and that could lead to new personalized medical treatments.

And a piece of advice: there is no reason to shun the beach, but people should shower before and after going in the water. And, it is wise to avoid the beach if you have an open wound.

Antibiotic Resistance: Rising Concern In Marine Ecosystems
ScienceDaily 13 Feb 09;
A team of scientists, speaking February 13 at the annual meeting of the American Association for the Advancement of Science, called for new awareness of the potential for antibiotic-resistant illnesses from the marine environment, and pointed to the marine realm as a source for possible cures of those threat.

The group stated that newly completed studies of ocean beach users point to an increasing risk of staph infections, and that current treatments for seafood poisoning may be less effective due to higher than expected antibiotic resistance. The group also asserts that new research has identified sponge and coral-derived chemicals with the potential for breaking down antibiotic resistant compounds and that could lead to new personalized medical treatments.

"While the marine environment can indeed be hostile to humans, it may also provide new resources to help reduce our risks from illnesses such as those caused by water borne staph or seafood poisoning," stated Paul Sandifer, Ph.D., former member of the U.S. Commission on Ocean Policy, chief scientist of NOAA's Oceans and Human Health Initiative, and co-organizer of the symposium.

Carolyn Sotka, also with the NOAA Oceans and Human Health Initiative and lead organizer of the session, stated "It is critically important that we continue research on the complex interactions between the condition of our oceans and human health. Without 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."

Coral, Sponges Point To Personalized Medicine Potential

"We've found significant new tools to fight the antibiotic resistance war," says NOAA research scientist Peter Moeller, Ph.D., in describing the identification of new compounds derived from a sea sponge and corals.

"The first hit originates with new compounds that remove the shield bacteria utilize to protect themselves from antibiotics. The second hit is the discovery of novel antibiotics derived from marine organisms such as corals, sponges and marine microbes that fight even some of the worst infectious bacterial strains. With the variety of chemicals we find in the sea and their highly specific activities, medicines in the near future can be customized to individuals' needs, rather than relying on broad spectrum antibiotics."

The research team, a collaboration between scientists at NOAA's Hollings Marine Laboratory in Charleston, S.C., the Medical University of South Carolina and researchers at North Carolina State University in Raleigh, N.C., noticed a sponge that seemed to thrive despite being located in the midst of a dying coral reef. After extraction, testing showed that one of the isolated chemicals, algeliferin, breaks down a biofilm barrier that bacteria use to protect themselves from threats including antibiotics. The same chemical can also disrupt or inhibit formation of biofilm on a variety of bacteria previously resistant to antibiotics which could lead to both palliative and curative response treatment depending on the problem being addressed.

"This could lead to a new class of helper drugs and result in a rebirth for antibiotics no longer thought effective," notes Moeller. "Its potential application to prevent biofilm build-up in stents, intravenous lines and other medical uses is incredible."

The compound is currently being tested for a variety of medical uses and has gone through a second round of sophisticated toxicity screening and thus far shows no toxic effects.

Staph: A Beach Going Concern

Research, funded by multiple agencies and conducted by the University of Miami's Rosenstiel School of Marine and Atmospheric Sciences and the Leonard M. Miller School of Medicine, found that swimmers using public ocean beaches increase their risk for exposure to staph organisms, and they may increase their risk for potential staph infections once they enter the water.

"Our study found that if you swim in subtropical marine waters, you have a significant chance , approximately 37 percent, of being exposed to staph — either yours or possibly that from someone else in the water with you," said Dr. Lisa Plano, a pediatrician and microbiologist with the Miller School of Medicine. Plano collaborated in the first large epidemiologic survey of beach users in recreational marine waters without a sewage source of pollution. "This exposure might lead to colonization or infection by water-borne bacteria which are shed from every person who enters the water. People who have open wounds or are immune-compromised are at greatest risk of infection."

The Miami research team does not advise avoiding beaches, but recommends that beach-goers take precautions to reduce risk by showering thoroughly before entering the water and after getting out. They also point out that while antibiotic resistant staph, commonly known as MRSA, has been increasingly found in diverse environments, including the marine environment, less than three percent of staph isolated from beach waters in their study was of the potentially virulent MRSA variety. More research is needed to understand how long staph (including MRSA) can live in coastal waters, and human uptake and infection rates associated with beach exposures.

Antibiotic Resistance in Seafood-borne Pathogens Increasing

Researchers at the Bigelow Laboratory for Ocean Science in West Boothbay Harbor, Maine, report that the frequency of antibiotic resistance in vibrio bacteria was significantly higher than expected. These findings suggest that the current treatment of vibirio infections should be re-examined, since these microbes are the leading cause of seafood-borne illness and death in the United States. The severity of these infections makes antibiotic resistance in vibrios a critical public health concern.

Naturally-occurring resistance to antibiotics among Vibrios may undermine the effectiveness of antibiotic treatment, but as yet this has not been extensively studied. Furthermore, antibiotics and other toxicants discharged into the waste stream by humans may increase the frequency of antibiotic-resistant Vibrio strains in contaminated coastal environments.

"We found resistance to all major classes of antibiotics routinely used to treat Vibrio infections, including aminoglycosides, tetracyclines, and cephalosporins," stated Bigelow's Ramunas Stepanauskas, Ph.D. "In contrast, we found that Vibrios were highly susceptible to carbapenems and new-generation fluoroquinolones, such as Imipenem and Ciprofloxacin. This information may be used to design better strategies to treat Vibrio infections."

Adapted from materials provided by National Oceanic And Atmospheric Administration, via EurekAlert!, a service of AAAS.

Infectious Superbug Invades Beaches
Robin Lloyd, livescience.com Yahoo News 14 Feb 09;
CHICAGO - Add the MRSA "superbug" to the list of concerns you bring to the beach nowadays, a research doctor said today.

It's still safe to go in the water, especially if you shower thoroughly before and after swimming, but antibiotic-resistant Staphylococcus aureus, a strain of bacteria that can cause staph infections that are difficult to treat with traditional anti-infection drugs such as methicillin, can be caught when you take a dip in ocean water, said Dr. Lisa Plano of the University of Miami's Miller School of Medicine.

MRSA stands for methicillin-resistant Staphylococcus aureus, or multiple-resistant Staphylococcus aureus. It has become a deadly and growing problem in hospitals in recent years.

"MRSA is in the water and potentially in the sand," Plano told a group of reporters today at the annual meeting of the American Association for the Advancement of Science. "This constitutes a risk to anyone who goes to the beach and uses the water ... Most of us won't get infected but it only takes one infected person to spread [MRSA to others]."

So-called staph or Staphylococcus aureus, the kind that responds to antibiotics, is not a big deal typically out in the general public. About a third of us has it living in the nose or on the skin all the time, and we don't get sick from the bug. But for babies, the elderly and other people with compromised immune systems, staph can lead to an infection that can be deadly.

And in any population, when people catch the antibiotic-resistant strain (MRSA), doctors struggle to find a way to kill the infection.

Both the staph that responds to antibiotics and MRSA (which does not) have long been problems in hospitals, but the bugs have cropped up in locker rooms full of healthy people more recently, including some rumored infections among NFL and NBA players. Staph and MRSA can also occur in daycare settings.

A 'complicated bug'

Scientists already knew staph could spread in water. Now the research led by Plano shows that MRSA is also found at the beach - in the sea water and potentially in the sand.

To pin this down, Plano and her colleagues recently studied 1,300 adult bathers at a South Florida beach, half of whom took a dip in the water and brought back a sample of water for later lab analysis, and the other half of whom sat on the beach for 15 minutes.

Some 37 percent of the ocean water samples had Staphylococcus aureus in them, and 3 percent of those were the antibiotic-resistant strain of the bug, Plano said, even though the beach is located nowhere near a sewage source.

In other words, the "call was coming from inside the house" - probably, the bathers.

The staph was relatively mild strain, Plano said, but the strain of MRSA was particularly virulent, she said.

One weird thing she found was that a later genetic analysis of the bugs in the water samples indicated a very low presence of markers for genes that cause the skin infections associated with staph.

"Staph is a really complicated bug," Plano told LiveScience in a phone interview earlier in the day. "S. aureus has an excess of 40 different virulence factors that it could potentially have and use to establish different types of infections, and not all staph will have all of them. Basically, most staph will have some of them, and what I looked at and what I compared these to are ones we knew to be associated with skin-infecting bugs."

In the sand too

Municipal pools and most private pools are safe from S. aureus if chlorine levels are appropriate, Plano said.

But there is some evidence that staph is spread in beach sand, she said. In one study, several quarts of staph-free sea water was poured over 14 previously staph-free toddlers in diapers who had played for 10 minutes in beach sand. The water that flowed off the kids was collected and analyzed - some of it was found to have S. aureus in it.

"If they had MRSA on their skin, they would've had MRSA in the sand," Plano said.
It's unclear if staph and MRSA incubate in ocean water, she said. "We know that MRSA can be isolated from marine mammals such as dolphins and seals, which suggests MRSA is still in the water," she said, but more research needs to be done to find out how long organisms can survive in the water.

Recommendations: shower

Still, there is no reason to shun the beach, Plano said, but people should shower before and after going in the water. And, it is wise to avoid the beach if you have an open wound.

Plano just wants people to be aware of the potential risks of S. aureus and MRSA at the beach.

"This is a very complicated issue," she said. "There is a tremendous amount of work that still needs to be done for us to understand the risk of person at beach being exposed to Staph aureus. You shouldn't fear the beach. You go to the beach. You should have fun. You should embrace it."

The research was funded by the National Science Foundation, the Florida Department of Health and Environmental Protection, the Centers for Disease Control and Prevention, and the Environmental Protection Agency.

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